WorldWideScience

Sample records for black light trap

  1. Wave optical simulation of the light trapping properties of black silicon surface textures.

    Science.gov (United States)

    Bett, Alexander Jürgen; Eisenlohr, Johannes; Höhn, Oliver; Repo, Päivikki; Savin, Hele; Bläsi, Benedikt; Goldschmidt, Jan Christoph

    2016-03-21

    Due to their low reflectivity and effective light trapping properties black silicon nanostructured surfaces are promising front side structures for thin crystalline silicon solar cells. For further optimization of the light trapping effect, particularly in combination with rear side structures, it is necessary to simulate the optical properties of black silicon. Especially, the angular distribution of light in the silicon bulk after passage through the front side structure is relevant. In this paper, a rigorous coupled wave analysis of black silicon is presented, where the black silicon needle shaped structure is approximated by a randomized cone structure. The simulated absorptance agrees well with measurement data. Furthermore, the simulated angular light distribution within the silicon bulk shows that about 70% of the light can be subjected to internal reflection, highlighting the good light trapping properties. PMID:27136865

  2. Wave optical simulation of the light trapping properties of black silicon surface textures.

    Science.gov (United States)

    Bett, Alexander Jürgen; Eisenlohr, Johannes; Höhn, Oliver; Repo, Päivikki; Savin, Hele; Bläsi, Benedikt; Goldschmidt, Jan Christoph

    2016-03-21

    Due to their low reflectivity and effective light trapping properties black silicon nanostructured surfaces are promising front side structures for thin crystalline silicon solar cells. For further optimization of the light trapping effect, particularly in combination with rear side structures, it is necessary to simulate the optical properties of black silicon. Especially, the angular distribution of light in the silicon bulk after passage through the front side structure is relevant. In this paper, a rigorous coupled wave analysis of black silicon is presented, where the black silicon needle shaped structure is approximated by a randomized cone structure. The simulated absorptance agrees well with measurement data. Furthermore, the simulated angular light distribution within the silicon bulk shows that about 70% of the light can be subjected to internal reflection, highlighting the good light trapping properties.

  3. The Technical and Performance Characteristics of a Low-Cost, Simply Constructed, Black Light Moth Trap.

    Science.gov (United States)

    White, Peter J T; Glover, Katharine; Stewart, Joel; Rice, Amanda

    2016-01-01

    The universal mercury vapor black light trap is an effective device used for collecting moth specimens in a wide variety of habitats; yet, they can present challenges for researchers. The mercury vapor trap is often powered by a heavy automotive battery making it difficult to conduct extensive surveys in remote regions. The mercury vapor trap also carries a considerable financial cost per trap unit, making trapping challenging with low research budgets. Here, we describe the development and trapping properties of a lighter, simply constructed, and less expensive trap. The LED funnel trap consists of a funnel, soda bottles with plastic vanes, and is powered by rechargeable 9-V batteries. Two strips of low-wavelength LEDs are used as attractants. We tested the trapping parameters of this trap design compared to a standard mercury vapor trap over 10 trap nights in a suburban woodlot in the summer of 2015. The mercury vapor trap caught significantly more moth individuals than the LED trap (average of 78 vs 40 moths per trap night; P < 0.05), and significantly more species than the LED trap (23 vs 15 per trap night; P < 0.05); the mercury vapor trap caught a total of 104 macromoth species over the duration of the study, compared to a total of 87 by the LED trap. Despite the lower yields, the low cost of the LED trap (<$30 ea.) makes it superior to the mercury vapor trap in cost-acquisition per moth species and per moth individual trapped. The LED trap may be a viable alternative to the standard mercury vapor trap, facilitating insect trapping in more diverse settings. PMID:26936923

  4. Seasonal Flight Activity of the Sugarcane Beetle (Coleoptera: Scarabaeidae) in North Carolina Using Black Light Traps.

    Science.gov (United States)

    Billeisen, T L; Brandenburg, R L

    2016-04-01

    Seasonal flight activity, adult beetle sex count, and egg production were examined in sugarcane beetles Euetheola rugiceps (LeConte) caught in light traps in North Carolina from the fall of 2009 through the summer of 2014. A regression model using variable environmental conditions as predictive parameters was developed to examine the impact of these conditions on flight activity. Depending on flight trap location and sampling years, beetles exhibited an inconsistent flight pattern, with the majority of adults flying in the spring (April-June) and intermittently in the fall (September-October). Our model indicated that larger numbers of adults collected from traps coincided with an increase in average soil temperature. Sugarcane beetles also exhibit a synchronous emergence during both periods of flight activity. Eggs were detected in females collected from light traps every week throughout the entire sampling period. The majority of females produced 7-12 eggs, with most egg production occurring between 15 May and 1 August. The findings of this research provide adult sugarcane beetle emergence and flight behavior information necessary to determine optimal pesticide application timing.

  5. Fabrication of broadband antireflective black metal surfaces with ultra-light-trapping structures by picosecond laser texturing and chemical fluorination

    Science.gov (United States)

    Zheng, Buxiang; Wang, Wenjun; Jiang, Gedong; Mei, Xuesong

    2016-06-01

    A hybrid method consisting of ultrafast laser-assisted texturing and chemical fluorination treatment was applied for efficiently enhancing the surface broadband antireflection to fabricate black titanium alloy surface with ultra-light-trapping micro-nanostructure. Based on the theoretical analysis of surface antireflective principle of micro-nanostructures and fluoride film, the ultra-light-trapping micro-nanostructures have been processed using a picosecond pulsed ultrafast laser on titanium alloy surfaces. Then fluorination treatment has been performed by using fluoroalkyl silane solution. According to X-ray diffraction phase analysis of the surface compositions and measurement of the surface reflectance using spectrophotometer, the broadband antireflective properties of titanium alloy surface with micro-nano structural characteristics were investigated before and after fluorination treatment. The results show that the surface morphology of micro-nanostructures processed by picosecond laser has significant effects on the antireflection of light waves to reduce the surface reflectance, which can be further reduced using chemical fluorination treatment. The high antireflection of over 98 % in a broad spectral range from ultraviolet to infrared on the surface of metal material has been achieved for the surface structures, and the broadband antireflective black metal surfaces with an extremely low reflectance of ultra-light-trapping structures have been obtained in the wavelength range from ultraviolet-visible to near-infrared, middle-wave infrared. The average reflectance of microgroove groups structured surface reaches as low as 2.43 % over a broad wavelength range from 200 to 2600 nm. It indicates that the hybrid method comprising of picosecond laser texturing and chemical fluorination can effectively induce the broadband antireflective black metal surface. This method has a potential application for fabricating antireflective surface used to improve the

  6. Limited attractant range of the black-light suction trap for the capture of Culicoides biting midges (Dipetera: Ceratopogonidae)

    NARCIS (Netherlands)

    Elbers, A.R.W.; Meiswinkel, R.

    2016-01-01

    The suction light trap (LT) is a standard tool used to capture Culicoides biting midges, when estimating abundances, and mapping species ranges. The exact range of attraction of the LT is in dispute, however, with several studies indicating the range to vary widely, between 4 and 50 m. In this study

  7. Black holes, marginally trapped surfaces and quasi-minimal surfaces

    Directory of Open Access Journals (Sweden)

    Bang-Yen Chen

    2009-12-01

    Full Text Available The concept of trapped surfaces introduced by Sir Roger Penrose in [Phys. Rev. Lett. 14 (1965, 57-59] plays an extremely important role in cosmology and general relativity. A black hole is a trapped region in a space-time enclosed by a marginally trapped surface. In term of mean curvature vector, a space-like surface in a space-time is marginally trapped if its mean curvature vector field is light-like at each point. In this article, we survey recent classification results on marginally trapped surfaces from differential geometric viewpoint. Also, we survey recent results on a closely related subject; namely, quasi-minimal surfaces in pseudo-Riemannian manifolds.

  8. Prisons of light : black holes

    Science.gov (United States)

    Ferguson, Kitty

    What is a black hole? Could we survive a visit to one -- perhaps even venture inside? Have we yet discovered any real black holes? And what do black holes teach us about the mysteries of our Universe? These are just a few of the tantalizing questions examined in this tour-de-force, jargon-free review of one of the most fascinating topics in modern science. In search of the answers, we trace a star from its birth to its death throes, take a hypothetical journey to the border of a black hole and beyond, spend time with some of the world's leading theoretical physicists and astronomers, and take a whimsical look at some of the wild ideas black holes have inspired. Prisons of Light - Black Holes is comprehensive and detailed. Yet Kitty Ferguson's lightness of touch and down-to-earth analogies set this book apart from all others on black holes and make it a wonderfully stimulating and entertaining read.

  9. Prisons of Light - Black Holes

    Science.gov (United States)

    Ferguson, Kitty

    1998-05-01

    In this jargon-free review of one of the most fascinating topics in modern science, acclaimed science writer Kitty Ferguson examines the discovery of black holes, their nature, and what they can teach us about the mysteries of the universe. In search of the answers, we trace a star from its birth to its death throes, take a hypothetical journey to the border of a black hole and beyond, spend time with some of the world's leading theoretical physicists and astronomers, and take a whimsical look at some of the wild ideas black holes have inspired. Prisons of Light--Black Holes is comprehensive and detailed. Yet Kitty Ferguson's lightness of touch and down-to-earth analogies set this book apart from all others on black holes and make it a wonderfully stimulating and entertaining read.

  10. Design of a mosquito trap support pole for use with CDC miniature light traps.

    Science.gov (United States)

    Evans, Christopher L; Wozniak, Arthur; McKenna, Bruce; Vaughan, David R; Dowda, Michael C

    2005-03-01

    A mosquito trap support pole constructed from polyvinyl chloride and aluminum pipes was designed to hang a Centers for Disease Control and Prevention miniature light trap and dry ice container. Miniature light traps normally hang from tree branches. The trap support pole is designed to hang traps and dry ice bait in areas where no suitable trees exist. PMID:15825774

  11. Laser trapping and spatial light modulators

    DEFF Research Database (Denmark)

    Glückstad, Jesper

    2012-01-01

    , even when using unshaped light, by using an appropriately shaped structure instead. Therefore, a generic approach for optimizing light-matter interaction would involve the combination of optimal light-shaping techniques with the use of optimized shapes in the micro-robotics structures. In this work, we......-dimensional microstructures. Furthermore, we exploit the light shaping capabilities available in the workstation to demonstrate a new strategy for controlling microstructures that goes beyond the typical refractive light deflections that are exploited in conventional optical trapping and manipulation e.g. of micro......INVITED: Robotics at the macro-scale typically uses light for carrying information in machine vision for monitoring and feedback in intelligent robotic guidance systems. With light’s miniscule momentum, shrinking robots down to the micro-scale regime creates opportunities for exploiting optical...

  12. Flexible, light trapping substrates for organic photovoltaics

    Science.gov (United States)

    Park, Yoonseok; Berger, Jana; Tang, Zheng; Müller-Meskamp, Lars; Lasagni, Andrés Fabián; Vandewal, Koen; Leo, Karl

    2016-08-01

    Micro-structured organic photovoltaic (OPV) devices on polyethylene terephthalate substrates are produced using direct laser interference patterning (DLIP). The performance of organic solar cells on these substrates is improved by a factor of 1.16, and a power conversion efficiency of 7.70% is achieved. We show that a shorter spatial period of the pattern allows for a stronger light trapping effect in solar cell, as it leads to a longer light path. Moreover, since the patterned structures are located on the outside of the fully encapsulated OPV devices, there are no problems with the roughness induced shunts.

  13. Trapping light by mimicking gravitational lensing

    CERN Document Server

    Sheng, C; Wang, Y; Zhu, S N; Genov, D A

    2013-01-01

    One of the most fascinating predictions of the theory of general relativity is the effect of gravitational lensing, the bending of light in close proximity to massive stellar objects. Recently, artificial optical materials have been proposed to study the various aspects of curved spacetimes, including light trapping and Hawking's radiation. However, the development of experimental toy models that simulate gravitational lensing in curved spacetimes remains a challenge, especially for visible light. Here, by utilizing a microstructured optical waveguide around a microsphere, we propose to mimic curved spacetimes caused by gravity, with high precision. We experimentally demonstrate both far-field gravitational lensing effects and the critical phenomenon in close proximity to the photon sphere of astrophysical objects under hydrostatic equilibrium. The proposed microstructured waveguide can be used as an omnidirectional absorber, with potential light harvesting and microcavity applications.

  14. Ellipsometrical detection of optical trapped nanoparticles by periodically localized light

    Science.gov (United States)

    Taki, Naoya; Mizutani, Yasuhiro; Iwata, Tetsuo; Kojima, Takao; Yamamoto, Hiroki; Kozawa, Takahiro

    2012-04-01

    The purpose of this study is development of a trapping system for nano-particles by periodically localized light and of a detecting system for the trapped state by an ellipsometoric method. Nano-particles are of interest for some different attractive properties with a bulk body in terms of their reactivity. Those attractive properties are applicable to production of an optical element and a device. For production of nano-particles, it is necessary to manipulate nano-particles and to measure the trapped state without contact in micro region. In this study, periodically localized light which is generated by the nano-periodic structure allows us to trap nano-particles. Evaluation of trapping can be accomplished by using a rotating-analyzer ellipsometer for comparing the ellipsometrical parameter before and after trapping. In confirmation of affectivity ellipsometrical method, we obtained that the trapped state associated with varying a shape of the nanoperiodic structure depends on polarization properties. The trapping light intensity also was found to depend on trapping volume of the nano-particles. From experimental results, the nano-particles can be trapped by the periodically localized light. And the trapping volume was found to increase with increasing in trapping light intensity. Hence, this system achieved trapping and deducing nano-particles.

  15. Light trapping effects in thin film silicon solar cells

    OpenAIRE

    Haug, FJ; Söderström, T; Dominé, D.; Ballif, C.

    2009-01-01

    We present advanced light trapping concepts for thin film silicon solar cells. When an amorphous and a microcrystalline absorber layers are combined into a micromorph tandem cell, light trapping becomes a challenge because it should combine the spectral region from 600 to 750 nm for the amorphous top cell and from 800 to 1100 for the microcrystalline bottom cell. Because light trapping is typically achieved by growing on textured substrates, the effect of interface textures on the material an...

  16. MIGRATION TRAPS IN DISKS AROUND SUPERMASSIVE BLACK HOLES

    Energy Technology Data Exchange (ETDEWEB)

    Bellovary, Jillian M.; Low, Mordecai-Mark Mac; McKernan, Barry; Ford, K. E. Saavik [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, NY 10024 (United States)

    2016-03-10

    Accretion disks around supermassive black holes (SMBHs) in active galactic nuclei (AGNs) contain stars, stellar mass black holes, and other stellar remnants, which perturb the disk gas gravitationally. The resulting density perturbations exert torques on the embedded masses causing them to migrate through the disk in a manner analogous to planets in protoplanetary disks. We determine the strength and direction of these torques using an empirical analytic description dependent on local disk gradients, applied to two different analytic, steady-state disk models of SMBH accretion disks. We find that there are radii in such disks where the gas torque changes sign, trapping migrating objects. Our analysis shows that major migration traps generally occur where the disk surface density gradient changes sign from positive to negative, around 20–300R{sub g}, where R{sub g} = 2GM/c{sup 2} is the Schwarzschild radius. At these traps, massive objects in the AGN disk can accumulate, collide, scatter, and accrete. Intermediate mass black hole formation is likely in these disk locations, which may lead to preferential gap and cavity creation at these radii. Our model thus has significant implications for SMBH growth as well as gravitational wave source populations.

  17. Charge trap memory based on few-layer black phosphorus

    Science.gov (United States)

    Feng, Qi; Yan, Faguang; Luo, Wengang; Wang, Kaiyou

    2016-01-01

    Atomically thin layered two-dimensional materials, including transition-metal dichalcogenide (TMDC) and black phosphorus (BP), have been receiving much attention, because of their promising physical properties and potential applications in flexible and transparent electronic devices. Here, for the first time we show nonvolatile charge-trap memory devices, based on field-effect transistors with large hysteresis, consisting of a few-layer black phosphorus channel and a three dimensional (3D) Al2O3/HfO2/Al2O3 charge-trap gate stack. An unprecedented memory window exceeding 12 V is observed, due to the extraordinary trapping ability of the high-k HfO2. The device shows a high endurance of over 120 cycles and a stable retention of ~30% charge loss after 10 years, even lower than the reported MoS2 flash memory. The high program/erase current ratio, large memory window, stable retention and high on/off current ratio, provide a promising route towards flexible and transparent memory devices utilising atomically thin two-dimensional materials. The combination of 2D materials with traditional high-k charge-trap gate stacks opens up an exciting field of nonvolatile memory devices.

  18. Charge trap memory based on few-layer black phosphorus.

    Science.gov (United States)

    Feng, Qi; Yan, Faguang; Luo, Wengang; Wang, Kaiyou

    2016-02-01

    Atomically thin layered two-dimensional materials, including transition-metal dichalcogenide (TMDC) and black phosphorus (BP), have been receiving much attention, because of their promising physical properties and potential applications in flexible and transparent electronic devices. Here, for the first time we show nonvolatile charge-trap memory devices, based on field-effect transistors with large hysteresis, consisting of a few-layer black phosphorus channel and a three dimensional (3D) Al2O3/HfO2/Al2O3 charge-trap gate stack. An unprecedented memory window exceeding 12 V is observed, due to the extraordinary trapping ability of the high-k HfO2. The device shows a high endurance of over 120 cycles and a stable retention of ∼30% charge loss after 10 years, even lower than the reported MoS2 flash memory. The high program/erase current ratio, large memory window, stable retention and high on/off current ratio, provide a promising route towards flexible and transparent memory devices utilising atomically thin two-dimensional materials. The combination of 2D materials with traditional high-k charge-trap gate stacks opens up an exciting field of nonvolatile memory devices. PMID:26758336

  19. Production of high stellar-mass primordial black holes in trapped inflation

    OpenAIRE

    Cheng, Shu-Lin; Lee, Wolung; Ng, Kin-Wang

    2016-01-01

    Trapped inflation has been proposed to provide a successful inflation with a steep potential. We discuss the formation of primordial black holes in the trapped inflationary scenario. We argue that primordial black holes are naturally produced in a trapped inflation. In particular, we have given an inflaton potenial with which particle production can induce large non-Gaussian curvature perturbation that leads to the formation of high stellar-mass primordial black holes. These primordial black ...

  20. Comparison of different light sources for trapping Culicoides biting midges, mosquitoes and other dipterans.

    Science.gov (United States)

    González, Mikel; Alarcón-Elbal, Pedro María; Valle-Mora, Javier; Goldarazena, Arturo

    2016-08-15

    The response of Culicoides biting midges, mosquitoes and other dipterans to different wavelengths was evaluated in a farm meadow in northern Spain. A total of 9449 specimens of 23 species of Culicoides, 5495 other ceratopogonids (non-biting midges), 602 culicids and 12428 other mixed dipterans were captured. Centers for Disease Control and Prevention (CDC) suction light traps fitted with five light emitting diodes (LEDs) (white, green, red, blue, ultraviolet) were run for 15 consecutive nights. Significantly more Culicoides were collected in those traps fitted with green, blue or ultraviolet (UV) lights than in red and white-baited LED traps for the most abundant species captured: C. punctatus (37.5%), C. cataneii (26.5%) and C. obsoletus/C. scoticus (20.4%). Similar results were obtained for non-Culicoides ceratopogonids, mosquitoes and other mixed dipterans. Wavelengths in green (570nm) resulted effective for targeting some Culicoides species, culicids and other midges. In a second trial, the effectiveness of 4-W white and UV tubes was compared to traps fitted with UV LED and a standard incandescent light bulb. More specimens of all taxa were collected with fluorescent black light (UV) traps than with the other light sources, except culicids, which were recovered in high numbers from fluorescent white light traps. PMID:27514882

  1. Light geodesics near an evaporating black hole

    Energy Technology Data Exchange (ETDEWEB)

    Guerreiro, Thiago, E-mail: thiago.barbosa@unige.ch; Monteiro, Fernando, E-mail: fernando.monteiro@unige.ch

    2015-10-16

    Quantum effects imply that an infalling observer cannot cross the event horizon of an evaporating black hole, even in her proper time. The Penrose diagram of an evaporating black hole is different from the one usually reported in the literature. We show that before the observer can cross the horizon the black hole disappears. Possible observational consequences are discussed. - Highlights: • We calculate the in-falling light geodesics in an evaporating black hole. • For our calculation we use a non-static metric called Vaydia metric. • We show that in-falling light cannot cross the event horizon. • In this case there is no information paradox.

  2. Light geodesics near an evaporating black hole

    International Nuclear Information System (INIS)

    Quantum effects imply that an infalling observer cannot cross the event horizon of an evaporating black hole, even in her proper time. The Penrose diagram of an evaporating black hole is different from the one usually reported in the literature. We show that before the observer can cross the horizon the black hole disappears. Possible observational consequences are discussed. - Highlights: • We calculate the in-falling light geodesics in an evaporating black hole. • For our calculation we use a non-static metric called Vaydia metric. • We show that in-falling light cannot cross the event horizon. • In this case there is no information paradox

  3. Nanoantennas for enhanced light trapping in transparent organic solar cells

    CERN Document Server

    Voroshilov, Pavel M; Belov, Pavel A

    2014-01-01

    We propose a light-trapping structure offering a significant enhancement of photovoltaic absorption in transparent organic solar cells operating at infrared while the visible light transmission keeps sufficiently high. The main mechanism of light trapping is related with the excitation of collective oscillations of the metal nanoantenna arrays, characterized by advantageous field distribution in the volume of the solar cell. It allows more than triple increase of infrared photovoltaic absorption.

  4. Twisting of light around rotating black holes

    CERN Document Server

    Tamburini, Fabrizio; Molina-Terriza, Gabriel; Anzolin, Gabriele; 10.1038/nphys1907

    2011-01-01

    Kerr black holes are among the most intriguing predictions of Einstein's general relativity theory. These rotating massive astrophysical objects drag and intermix their surrounding space and time, deflecting and phase-modifying light emitted nearby them. We have found that this leads to a new relativistic effect that imposes orbital angular momentum onto such light. Numerical experiments, based on the integration of the null geodesic equations of light from orbiting point-like sources in the Kerr black hole equatorial plane to an asymptotic observer, indeed identify the phase change and wavefront warping and predict the associated light-beam orbital angular momentum spectra. Setting up the best existing telescopes properly, it should be possible to detect and measure this twisted light, thus allowing a direct observational demonstration of the existence of rotating black holes. Since non-rotating objects are more an exception than a rule in the Universe, our findings are of fundamental importance.

  5. Twisting of light around rotating black holes

    Science.gov (United States)

    Tamburini, Fabrizio; Thidé, Bo; Molina-Terriza, Gabriel; Anzolin, Gabriele

    2011-03-01

    Kerr black holes are among the most intriguing predictions of Einstein's general relativity theory. These rotating massive astrophysical objects drag and intermix their surrounding space and time, deflecting and phase-modifying light emitted near them. We have found that this leads to a new relativistic effect that imprints orbital angular momentum on such light. Numerical experiments, based on the integration of the null geodesic equations of light from orbiting point-like sources in the Kerr black hole equatorial plane to an asymptotic observer, indeed identify the phase change and wavefront warping and predict the associated light-beam orbital angular momentum spectra. Setting up the best existing telescopes properly, it should be possible to detect and measure this twisted light, thus allowing a direct observational demonstration of the existence of rotating black holes. As non-rotating objects are more an exception than a rule in the Universe, our findings are of fundamental importance.

  6. Photonic crystals for light trapping in solar cells

    International Nuclear Information System (INIS)

    Solar energy is an abundant and non-polluting source of energy. Nevertheless, the installation of solar cells for energy production is still dependent on subsidies in most parts of the world. One way of reducing the costs of solar cells is to decrease their thickness. This will reduce material consumption and, at the same time, unlock the possibility of using cheaper lower quality solar cell material. However, a thinner solar cell will have a higher optical loss due to insufficient absorption of long wavelength light. Therefore, light-trapping must be improved in order to make thin solar cells economically viable. In this thesis I investigate the potential for light-trapping in thin silicon solar cells by the use of various photonic crystal back-side structures. The first structure I study consists of a periodic array of cylinders in a configuration with a layer of silicon oxide separating the periodic structure from the rear metal reflector. This configuration reduces unwanted parasitic absorption in the reflector and the thickness of the oxide layer provides a new degree of freedom for improving light trapping from the structure. I use a large-period and a small-period approximation to analyze the cylinder structure and to identify criteria that contributes to successful light-trapping. I explore the light-trapping potential of various periodic structures including dimples, inverted pyramids, and cones. The structures are compared in an optical model using a 20 m thick Si slab. I find that the light trapping potential differs between the structures, that the unit cell dimensions for the given structure is more important for light trapping than the type of structure, and that the optimum lattice period does not differ significantly between the different structures. The light-trapping effect of the structures is investigated as a function on incidence angle. The structures provide good light trapping also under angles of incidence up to 60 degrees. The behavior

  7. Photonic crystals for light trapping in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gjessing, Jo

    2012-07-25

    Solar energy is an abundant and non-polluting source of energy. Nevertheless, the installation of solar cells for energy production is still dependent on subsidies in most parts of the world. One way of reducing the costs of solar cells is to decrease their thickness. This will reduce material consumption and, at the same time, unlock the possibility of using cheaper lower quality solar cell material. However, a thinner solar cell will have a higher optical loss due to insufficient absorption of long wavelength light. Therefore, light-trapping must be improved in order to make thin solar cells economically viable. In this thesis I investigate the potential for light-trapping in thin silicon solar cells by the use of various photonic crystal back-side structures. The first structure I study consists of a periodic array of cylinders in a configuration with a layer of silicon oxide separating the periodic structure from the rear metal reflector. This configuration reduces unwanted parasitic absorption in the reflector and the thickness of the oxide layer provides a new degree of freedom for improving light trapping from the structure. I use a large-period and a small-period approximation to analyze the cylinder structure and to identify criteria that contributes to successful light-trapping. I explore the light-trapping potential of various periodic structures including dimples, inverted pyramids, and cones. The structures are compared in an optical model using a 20 m thick Si slab. I find that the light trapping potential differs between the structures, that the unit cell dimensions for the given structure is more important for light trapping than the type of structure, and that the optimum lattice period does not differ significantly between the different structures. The light-trapping effect of the structures is investigated as a function on incidence angle. The structures provide good light trapping also under angles of incidence up to 60 degrees. The behavior

  8. Photonic crystals for light trapping in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gjessing, Jo

    2012-07-25

    Solar energy is an abundant and non-polluting source of energy. Nevertheless, the installation of solar cells for energy production is still dependent on subsidies in most parts of the world. One way of reducing the costs of solar cells is to decrease their thickness. This will reduce material consumption and, at the same time, unlock the possibility of using cheaper lower quality solar cell material. However, a thinner solar cell will have a higher optical loss due to insufficient absorption of long wavelength light. Therefore, light-trapping must be improved in order to make thin solar cells economically viable. In this thesis I investigate the potential for light-trapping in thin silicon solar cells by the use of various photonic crystal back-side structures. The first structure I study consists of a periodic array of cylinders in a configuration with a layer of silicon oxide separating the periodic structure from the rear metal reflector. This configuration reduces unwanted parasitic absorption in the reflector and the thickness of the oxide layer provides a new degree of freedom for improving light trapping from the structure. I use a large-period and a small-period approximation to analyze the cylinder structure and to identify criteria that contributes to successful light-trapping. I explore the light-trapping potential of various periodic structures including dimples, inverted pyramids, and cones. The structures are compared in an optical model using a 20 m thick Si slab. I find that the light trapping potential differs between the structures, that the unit cell dimensions for the given structure is more important for light trapping than the type of structure, and that the optimum lattice period does not differ significantly between the different structures. The light-trapping effect of the structures is investigated as a function on incidence angle. The structures provide good light trapping also under angles of incidence up to 60 degrees. The behavior

  9. Production of high stellar-mass primordial black holes in trapped inflation

    CERN Document Server

    Cheng, Shu-Lin; Ng, Kin-Wang

    2016-01-01

    Trapped inflation has been proposed to provide a successful inflation with a steep potential. We discuss the formation of primordial black holes in the trapped inflationary scenario. We argue that primordial black holes are naturally produced in a trapped inflation. In particular, we have given an inflaton potenial with which particle production can induce large non-Gaussian curvature perturbation that leads to the formation of high stellar-mass primordial black holes. These primordial black holes could be the dark matter observed by the LIGO detectors through a binary black-hole merger.

  10. Light, Gravity and Black Holes

    Science.gov (United States)

    Falla, David

    2012-01-01

    The nature of light and how it is affected by gravity is discussed. Einstein's prediction of the deflection of light as it passes near the Sun was verified by observations made during the solar eclipse of 1919. Another prediction was that of gravitational redshift, which occurs when light emitted by a star loses energy in the gravitational field…

  11. Chernobyl radionuclides in a Black Sea sediment trap.

    Science.gov (United States)

    Buesseler, K O; Livingston, H D; Honjo, S; Hay, B J; Manganini, S J; Degens, E; Ittekkot, V; Izdar, E; Konuk, T

    The Chernobyl nuclear power station accident released large quantities of vaporized radionuclides, and, to a lesser extent, mechanically released small (less than 1-10 micron) aerosol particles. The total release of radioactivity is estimated to be out of the order of 1-2 x 10(18) Bq (3-5 x 10(7) Ci) not allowing for releases of the xenon and krypton gases. The 137Cs releases of 3.8 x 10(16) Bq from Chernobyl can be compared to 1.3 x 10(18) Bq 137Cs released due to atmospheric nuclear weapons testing. Chernobyl-derived radionuclides can be used as transient tracers to study physical and biogeochemical processes. Initial measurements of fallout Chernobyl radionuclides from a time-series sediment trap at 1,071 m during June-September 1986 in the southern Black Sea are presented. The specific activities of 137Cs, 144Ce and 106Ru in the trap samples (0.5-2, 4-12 and 6-13 Bq g-1) are independent of the particle flux while their relative activities reflect their rates of scavenging in the order Ce greater than Ru greater than Cs. PMID:3670387

  12. Geometric light trapping with a V-trap for efficient organic solar cells

    KAUST Repository

    Kim, Soo Jin

    2013-03-14

    The efficiency of today’s most efficient organic solar cells is primarily limited by the ability of the active layer to absorb all the sunlight. While internal quantum efficiencies exceeding 90% are common, the external quantum efficiency rarely exceeds 70%. Light trapping techniques that increase the ability of a given active layer to absorb light are common in inorganic solar cells but have only been applied to organic solar cells with limited success. Here, we analyze the light trapping mechanism for a cell with a V-shape substrate configuration and demonstrate significantly improved photon absorption in an 5.3%-efficient PCDTBT:PC70BM bulk heterojunction polymer solar cell. The measured short circuit current density improves by 29%, in agreement with model predictions, and the power conversion efficiency increases to 7.2%, a 35% improvement over the performance in the absence of a light trap.

  13. Exploration of external light trapping for photovoltaic modules.

    Science.gov (United States)

    van Dijk, Lourens; van de Groep, Jorik; Di Vece, Marcel; Schropp, Ruud E I

    2016-07-11

    The reflection of incident sunlight by photovoltaic modules prevents them from reaching their theoretical energy conversion limit. We explore the effectiveness of a universal external light trap that can tackle this reflection loss. A unique feature of external light traps is their capability to simultaneously recycle various broadband sources of reflection on the module level, such as the reflection from the metal front grid, the front interfaces, the reflective backside of the cell, and the white back sheet. The reflected light is recycled in the space between the solar cell and a mirror above the solar cell. A concentrator funnels the light into this cage through a small aperture in the mirror. As a proof-of-principle experiment, a significant reflectance reduction of a bare crystalline silicon (c-Si) photodiode is demonstrated. In contrast to conventional light trapping methods, external light trapping does not induce any damage to the active solar cell material. Moreover, this is a universally applicable technology that enables the use of thin and planar solar cells of superior electrical quality that were so far hindered by limited optical absorption. We considered several trap designs and identified fabrication issues. A series of prototype millimeter-scale external metal light traps were milled and applied on an untextured c-Si photodiode, which is used as a model for future thin solar cells. We determined the concentrator transmittance and analyzed the effect of both the concentration factor and cage height on the absorptance and spatial intensity distribution on the surface of the solar cell. This relatively simple and comprehensive light management solution can be a promising candidate for highly efficient solar modules using thin c-Si solar cells. PMID:27410902

  14. Fundamental limit of light trapping in grating structures

    KAUST Repository

    Yu, Zongfu

    2010-08-11

    We use a rigorous electromagnetic approach to analyze the fundamental limit of light-trapping enhancement in grating structures. This limit can exceed the bulk limit of 4n 2, but has significant angular dependency. We explicitly show that 2D gratings provide more enhancement than 1D gratings. We also show the effects of the grating profile’s symmetry on the absorption enhancement limit. Numerical simulations are applied to support the theory. Our findings provide general guidance for the design of grating structures for light-trapping solar cells.

  15. Modeling light trapping in nanostructured solar cells.

    Science.gov (United States)

    Ferry, Vivian E; Polman, Albert; Atwater, Harry A

    2011-12-27

    The integration of nanophotonic and plasmonic structures with solar cells offers the ability to control and confine light in nanoscale dimensions. These nanostructures can be used to couple incident sunlight into both localized and guided modes, enhancing absorption while reducing the quantity of material. Here we use electromagnetic modeling to study the resonances in a solar cell containing both plasmonic metal back contacts and nanostructured semiconductor top contacts, identify the local and guided modes contributing to enhanced absorption, and optimize the design. We then study the role of the different interfaces and show that Al is a viable plasmonic back contact material.

  16. Eliminating light shifts in single-atom optical traps

    CERN Document Server

    Hutzler, Nicholas R; Yu, Yichao; Ni, Kang-Kuen

    2016-01-01

    Microscopically controlled neutral atoms in optical tweezers and lattices have led to exciting advances in the study of quantum information and quantum many-body systems. The light shifts of atomic levels from the trapping potential in these systems can result in detrimental effects such as fluctuating dipole force heating, inhomogeneous detunings, and inhibition of laser cooling, which limits the atomic species that can be manipulated. In particular, these light shifts can be large enough to prevent loading into optical tweezers directly from a magneto-optical trap. We present a general solution to these limitations by loading, cooling, and imaging single atoms with temporally alternating beams. Because this technique does not depend on any specific spectral properties, we expect it to enable the optical tweezer method to control nearly any atomic or molecular species that can be laser cooled and optically trapped. Furthermore, we present an analysis of the role of heating and required cooling for single ato...

  17. Modeling nanostructure-enhanced light trapping in organic solar cells

    DEFF Research Database (Denmark)

    Adam, Jost

    A promising approach for improving the power conversion efficiencies of organic solar cells (OSCs) is by incorporating nanostructures in their thin film architecture to improve the light absorption in the device’s active polymer layers. Here, we present a modelling framework for the prediction....... Diffraction by fractal metallic supergratings. Optics Express, 15(24), 15628–15636 (2007) [3] Goszczak, A. J. et al. Nanoscale Aluminum dimples for light trapping in organic thin films (submitted)...

  18. Introduction to light forces, atom cooling, and atom trapping

    OpenAIRE

    Savage, Craig,

    1995-01-01

    This paper introduces and reviews light forces, atom cooling and atom trapping. The emphasis is on the physics of the basic processes. In discussing conservative forces the semi-classical dressed states are used rather than the usual quantized field dressed states.

  19. Light-trapping in perovskite solar cells

    Directory of Open Access Journals (Sweden)

    Qing Guo Du

    2016-06-01

    Full Text Available We numerically demonstrate enhanced light harvesting efficiency in both CH3NH3PbI3 and CH(NH22PbI3-based perovskite solar cells using inverted vertical-cone photonic-crystal nanostructures. For CH3NH3PbI3 perovskite solar cells, the maximum achievable photocurrent density (MAPD reaches 25.1 mA/cm2, corresponding to 92% of the total available photocurrent in the absorption range of 300 nm to 800 nm. Our cell shows 6% absorption enhancement compared to the Lambertian limit (23.7 mA/cm2 and has a projected power conversion efficiency of 12.9%. Excellent solar absorption is numerically demonstrated over a broad angular range from 0 to 60 degree for both S- and P- polarizations. For the corresponding CH(NH22PbI3 based perovskite solar cell, with absorption range of 300 nm to 850 nm, we find a MAPD of 29.1 mA/cm2, corresponding to 95.4% of the total available photocurrent. The projected power conversion efficiency of the CH(NH22PbI3 based photonic crystal solar cell is 23.4%, well above the current world record efficiency of 20.1%.

  20. Light-trapping in perovskite solar cells

    Science.gov (United States)

    Du, Qing Guo; Shen, Guansheng; John, Sajeev

    2016-06-01

    We numerically demonstrate enhanced light harvesting efficiency in both CH3NH3PbI3 and CH(NH2)2PbI3-based perovskite solar cells using inverted vertical-cone photonic-crystal nanostructures. For CH3NH3PbI3 perovskite solar cells, the maximum achievable photocurrent density (MAPD) reaches 25.1 mA/cm2, corresponding to 92% of the total available photocurrent in the absorption range of 300 nm to 800 nm. Our cell shows 6% absorption enhancement compared to the Lambertian limit (23.7 mA/cm2) and has a projected power conversion efficiency of 12.9%. Excellent solar absorption is numerically demonstrated over a broad angular range from 0 to 60 degree for both S- and P- polarizations. For the corresponding CH(NH2)2PbI3 based perovskite solar cell, with absorption range of 300 nm to 850 nm, we find a MAPD of 29.1 mA/cm2, corresponding to 95.4% of the total available photocurrent. The projected power conversion efficiency of the CH(NH2)2PbI3 based photonic crystal solar cell is 23.4%, well above the current world record efficiency of 20.1%.

  1. Effect of light trapping in an amorphous silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Iftiquar, S.M., E-mail: iftiquar@skku.edu [College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jung, Juyeon; Park, Hyeongsik [College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Cho, Jaehyun; Shin, Chonghoon [Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Park, Jinjoo [College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jung, Junhee [Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Bong, Sungjae [College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Sunbo [Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Yi, Junsin, E-mail: yi@yurim.skku.ac.kr [College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-07-31

    Light trapping in amorphous silicon based solar cell has been investigated theoretically. The substrate for these cells can be textured, including pyramidally textured c-Si wafer, to improve capture of incident light. A thin silver layer, deposited on the substrate of an n–i–p cell, ultimately goes at the back of the cell structure and can act a back reflector to improve light trapping. The two physical solar cells we investigated had open circuit voltages (V{sub oc}) of 0.87, 0.90 V, short circuit current densities (J{sub sc}) of 14.2, 15.36 mA/cm{sup 2} respectively. The first cell was investigated for the effect on its performance while having and not having light trapping scheme (LT), when thickness of the active layer (d{sub i}) was changed in the range of 100 nm to 800 nm. In both the approaches, for having or not having LT, the short circuit current density increases with d{sub i} while the V{sub oc} and fill factor, decreases steadily. However, maximum cell efficiency can be obtained when d{sub i} = 400 nm, and hence it was considered optimized thickness of the active layer, that was used for further investigation. With the introduction of light trapping to the second cell, it shows a further enhancement in J{sub sc} and red response of the external quantum efficiency to 16.6 mA/cm{sup 2} and by 11.1% respectively. Considering multiple passages of light inside the cell, we obtained an improvement in cell efficiency from 9.7% to 10.6%. - Highlights: • A theoretical analysis of light trapping in p–i–n and n–i–p type solar cells • J{sub sc} increases and V{sub oc} decreases with the increase in i-layer thickness. • Observed optimized thickness of i-layer as 400 nm • J{sub sc} improved from 15.4 mA/cm{sup 2} to 16.6 mA/cm{sup 2} due to the light trapping. • Efficiency (η) improved from 9.7% to 10.6% due to better red response of the EQE.

  2. Effect of light trapping in an amorphous silicon solar cell

    International Nuclear Information System (INIS)

    Light trapping in amorphous silicon based solar cell has been investigated theoretically. The substrate for these cells can be textured, including pyramidally textured c-Si wafer, to improve capture of incident light. A thin silver layer, deposited on the substrate of an n–i–p cell, ultimately goes at the back of the cell structure and can act a back reflector to improve light trapping. The two physical solar cells we investigated had open circuit voltages (Voc) of 0.87, 0.90 V, short circuit current densities (Jsc) of 14.2, 15.36 mA/cm2 respectively. The first cell was investigated for the effect on its performance while having and not having light trapping scheme (LT), when thickness of the active layer (di) was changed in the range of 100 nm to 800 nm. In both the approaches, for having or not having LT, the short circuit current density increases with di while the Voc and fill factor, decreases steadily. However, maximum cell efficiency can be obtained when di = 400 nm, and hence it was considered optimized thickness of the active layer, that was used for further investigation. With the introduction of light trapping to the second cell, it shows a further enhancement in Jsc and red response of the external quantum efficiency to 16.6 mA/cm2 and by 11.1% respectively. Considering multiple passages of light inside the cell, we obtained an improvement in cell efficiency from 9.7% to 10.6%. - Highlights: • A theoretical analysis of light trapping in p–i–n and n–i–p type solar cells • Jsc increases and Voc decreases with the increase in i-layer thickness. • Observed optimized thickness of i-layer as 400 nm • Jsc improved from 15.4 mA/cm2 to 16.6 mA/cm2 due to the light trapping. • Efficiency (η) improved from 9.7% to 10.6% due to better red response of the EQE

  3. Quantum interference and the formation of trapping regions around a Schwarzschild black hole

    International Nuclear Information System (INIS)

    Astrophysical processes in vicinity of black holes involve a coupling of spacetime geometry and the quantum effects. Using the quantum potential approach we investigate the quantum dynamics of a massive particle around a Schwarzschild black hole. The analysis shows the existence of typical quantum effects near the black hole region. In particular the R-amplitude variation leads to the formation of fringe-like trapping regions around the black hole where the particle is more likely to be located. However due to the energy loss, which gains a local maxima in the trapping regions, the particle in-fall eventually occurs. The energy loss during such a process will show up in frequency and amplitude modulation in X-ray signals from accreting black holes and may confirm the existence of such trapping regions.

  4. Photovoltaic cell with light trapping for enhanced efficiency

    Science.gov (United States)

    Brener, Igal; Fofang, Nche Tumasang; Luk, Ting S.

    2015-11-19

    The efficiency of a photovoltaic cell is enhanced by light trapping using Mie-scattering nanostructures. In one embodiment, an array of nanocylinders is formed on the front surface of a silicon film to enhance forward scattering into the film, and an array of nanocylinders is formed on the back surface to enhance backscattering so that more light is absorbed within the silicon film. In an alternate embodiment, a mirror layer is formed on the back surface of the silicon film to reflect light within the film back toward the front-surface nanocylinder array.

  5. The repellent effect of organic fatty acids on Culicoides midges as determined with suction light traps in South Africa.

    Science.gov (United States)

    Venter, G J; Labuschagne, K; Boikanyo, S N B; Morey, L; Snyman, M G

    2011-09-27

    The efficacy of a 15% (w/w) mixture of octanoic, nonanoic and decanoic acids in light mineral oil to repel Culicoides biting midges (Diptera; Ceratopogonidae) was determined in three replicates of a 4 × 4 Latin square design under South African field conditions. The fatty acids were applied to ± 0.07 m(2) polyester meshes with a mesh size 2-3mm fitted to 220 V 8 W Onderstepoort downdraught light traps. To reduce the relatively strong attraction of the light trap, the black light tubes in the Onderstepoort trap were replaced with 8 W 23 cm white light tubes. The traps were operating overnight next to cattle. Two traps treated with the mixture of fatty acids collected 1.7 times fewer midges than two untreated traps. Although this mixture of fatty acids had shown a repellent effect against a number of blood-feeding insects this is the first indication that it also has a significant repellent effect against Culicoides species and especially Culicoides (Avaritia) imicola Kieffer when applied to polyester mesh. PMID:21592665

  6. Study on the Species Diversity and Assessment of Black-light Trapped Insect Community in Yuanyang Terrace%元阳梯田黑光灯诱集昆虫群落多样性及其评价方法研究

    Institute of Scientific and Technical Information of China (English)

    张立敏; 张玉虎; 陈斌; 李正跃

    2012-01-01

    In order to make clear the species diversity of insect community in Yuanyang terrace and compare different diversity indexes, including Simpson index, Shannon index, Fisher' s α and biodiversity parameter 0 from community neutral theory, a case on the composition and diversity of insects trapped by black-light was studied in Yunnan Yuanyang terrace from 2007 to 2008. Firstly, the recognizable taxonomic unit ( RTUs) approach was applied to identify the trapped samples in lab. Secondly, the traditional diversity indexes, Simpson index, Shannon index and Fisher' s α were compared with neutral theory diversity parameter 9 based on the black-light trapped insect community of Lepidoptera, Coleoptera and Hymenoptera in 2007 and 2008 in Yuanyang terrace. The results showed; ( 1) Black-light trapped insect species are rich in Yuanyang terrace. There are totally 12 460 insects from 14 orders 539 species and 20 920 insects froml2 orders 576 species trapped by black light in Yuanyang terrace in 2007 and 2008 , respectively. (2) The diversity assessment result of Fisher' s α diversity index and neutral theory diversity index 9 on three main insect communities, Lepidoptera, Coleoptera and Hymenoptera was similar, while the diversity assessment result of traditional Simpson index and Shannon index was conflicted. The diversity index values of Fisher' s α and neutral theory diversity index θ were easier to be districted among different communities and different years than the values of traditional Simpson index and Shannon index. Conclusively, Fisher's α diversity index and neutral theory diθversity index 9 were better to describe the diversity features for the black-light trapped insect communities in Yuanyang terrace landscape.%为了探明云南元阳梯田昆虫群落物种多样性,进一步明确不同生物多样性指数在较大空间尺度多样性评价中的应用,于2007-2008年,采用黑光灯诱集法对元阳梯田昆虫群落进行调查,运用可识别分

  7. Optical particle trapping and dynamic manipulation using spatial light modulation

    DEFF Research Database (Denmark)

    Eriksen, René Lynge

    spots acting as tweezers beams are generated using phase-only spatial light modulation of an incident laser beam together with a generalized phase contrast (GPC) filter. The GPC method acts as a common-path interferometer, which converts encoded phase information into an appropriate intensity pattern...... proven capable of generating a phase pattern from an input amplitude distribution. The birefringent nature of liquid crystals in the SLM is utilized for the generation of an arbitrary two-dimensional state of polarization using two-cascaded SLMs. By means of elliptically polarized light, generated by one...... SLM and a lens-array, angular momentum transfer to multiple birefringent particles is achieved in an optical tweezers system. The rotation direction and angular orientation of the trapped particles are controlled from the SLM device that directly affects the state of polarization. In addition, a novel...

  8. Spherically symmetric trapping horizons, the Misner-Sharp mass and black hole evaporation

    OpenAIRE

    Nielsen, Alex B; Yeom, Dong-han

    2008-01-01

    Understood in terms of pure states evolving into mixed states, the possibility of information loss in black holes is closely related to the global causal structure of spacetime, as is the existence of event horizons. However, black holes need not be defined by event horizons, and in fact we argue that in order to have a fully unitary evolution for black holes, they should be defined in terms of something else, such as a trapping horizon. The Misner-Sharp mass in spherical symmetry shows very ...

  9. Light coupling and light trapping in alkaline etched multicrystalline silicon wafers for solar cells

    NARCIS (Netherlands)

    Hylton, J.D.

    2006-01-01

    The reflection reducing and light trapping properties of alkaline etched multicrystalline silicon wafers are investigated experimentally. Following an overview of various chemical texturisation methods and their effect upon the surface morphology, a high concentration saw-damage etch and a low conc

  10. Enhancement of light trapping in thin-film solar cells through Ag

    Institute of Scientific and Technical Information of China (English)

    Yiming Bai; Han Zhang; Jun Wang; Nuofu Chen; Jianxi Yao; Tianmao Huang; Xingwang Zhang; Zhigang Yin; Zhen Fu

    2011-01-01

    Forward-scattering efficiency (FSE) is first proposed when an Ag nanoparticle serves as the light-trapping structure for thin-film (TF) solar cells because the Ag nanoparticle's light-trapping efficiency lies on the light-scattering direction of metal nanoparticles. Based on FSE analysis of Ag nanoparticles with radii of 53 and 88 nm, the forward-scattering spectra and light-trapping efficiencies are calculated. The contributions of dipole and quadrupole modes to light-trapping effect are also analyzed quantitatively. When the surface coverage of Ag nanoparticles is 5%, light-trapping efficiencies are 15.5% and 32.3%, respectively, for 53- and 88-nm Ag nanoparticles. Results indicate that the plasmon quadrupole mode resonance of Ag nanoparticles could further enhance the light-trapping effect for TF solar cells.%@@ Forward-scattering efficiency (FSE) is first proposed when an Ag nanoparticle serves as the light-trapping structure for thin-film (TF) solar cells because the Ag nanoparticle's light-trapping efficiency lies on the light-scattering direction of metal nanoparticles.Based on FSE analysis of Ag nanoparticles with radii of 53 and 88 nm, the forward-scattering spectra and light-trapping efficiencies are calculated.The contributions of dipole and quadrupole modes to light-trapping effect are also analyzed quantitatively.When the surface coverage of Ag nanoparticles is 5%, light-trapping efficiencies are 15.5% and 32.3%, respectively, for 53- and 88-nm Ag nanoparticles.Results indicate that the plasmon quadrupole mode resonance of Ag nanoparticles could further enhance the light-trapping effect for TF solar cells.

  11. Black Holes Shed Light on Galaxy Formation

    Science.gov (United States)

    2000-01-01

    This videotape is comprised of several segments of animations on black holes and galaxy formation, and several segments of an interview with Dr. John Kormendy. The animation segments are: (1) a super massive black hole, (2) Centarus A active black hole found in a collision, (3) galaxy NGC-4261 (active black hole and jet model), (4) galaxy M-32 (orbits of stars are effected by the gravity of the black hole), (5) galaxy M-37 (motion of stars increases as mass of black hole increases), (6) Birth of active galactic nuclei, (7) the collision of two galaxy leads to merger of the black holes, (8) Centarus A and simulation of the collision of 2 galaxies. There are also several segments of an interview with John Kormendy. In these segments he discusses the two most important aspects of his recent black hole work: (1) the correlations between galaxies speed and the mass of the black holes, and (2) the existence of black holes and galactic formation. He also discusses the importance of the Hubble Space Telescope and the Space Telescope Imaging Spectrograph to the study of black holes. He also shows the methodology of processing images from the spectrograph in his office.

  12. A comparison of commercial light-emitting diode baited suction traps for surveillance of Culicoides in northern Europe

    OpenAIRE

    Hope, Andrew; Gubbins, Simon; Sanders, Christopher; Denison, Eric; Barber, James; Stubbins, Francesca; Baylis, Matthew; Carpenter, Simon

    2015-01-01

    Background The response of Culicoides biting midges (Diptera: Ceratopogonidae) to artificial light sources has led to the use of light-suction traps in surveillance programmes. Recent integration of light emitting diodes (LED) in traps improves flexibility in trapping through reduced power requirements and also allows the wavelength of light used for trapping to be customized. This study investigates the responses of Culicoides to LED light-suction traps emitting different wavelengths of ligh...

  13. Three-dimensional grating nanowires for enhanced light trapping.

    Science.gov (United States)

    Lee, Hoo-Cheol; Na, Jin-Young; Moon, Yoon-Jong; Park, Jin-Sung; Ee, Ho-Seok; Park, Hong-Gyu; Kim, Sun-Kyung

    2016-04-01

    We propose rationally designed 3D grating nanowires for boosting light-matter interactions. Full-vectorial simulations show that grating nanowires sustain high-amplitude waveguide modes and induce a strong optical antenna effect, which leads to an enhancement in nanowire absorption at specific or broadband wavelengths. Analyses of mode profiles and scattering spectra verify that periodic shells convert a normal plane wave into trapped waveguide modes, thus giving rise to scattering dips. A 200 nm diameter crystalline Si nanowire with designed periodic shells yields an enormously large current density of ∼28  mA/cm2 together with an absorption efficiency exceeding unity at infrared wavelengths. The grating nanowires studied herein will provide an extremely efficient absorption platform for photovoltaic devices and color-sensitive photodetectors.

  14. Graphene plasmonics for light trapping and absorption engineering

    CERN Document Server

    Zhang, Jianfa; Liu, Wei; Yuan, Xiaodong; Qin, Shiqiao

    2015-01-01

    Plasmonics can be used to improve absorption in optoelectronic devices and has been intensively studied for solar cells and photodetectors. Graphene has recently emerged as a powerful plasmonic material. It shows significantly less losses compared to traditional plasmonic materials such as gold and silver and its plasmons can be tuned by changing the Fermi energy with chemical or electrical doping. Here we propose the usage of graphene plasmonics for light trapping in optoelectronic devices and show that the excitation of localized plasmons in doped, nanostructured graphene can enhance optical absorption in its surrounding media including both bulky and two-dimensional materials by tens of times, which may lead to a new generation of highly efficient, spectrally selective photodetectors in mid-infrared and THz ranges. The proposed concept could even revolutionize the field of plasmonic solar cells if graphene plasmons in the visible and near-infrared are realized.

  15. Light trapping architecture for photovoltaic and photodector applications

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, Stephen R.; Lunt, Richard R.; Slootsky, Michael

    2016-08-09

    There is disclosed photovoltaic device structures which trap admitted light and recycle it through the contained photosensitive materials to maximize photoabsorption. For example, there is disclosed a photosensitive optoelectronic device comprising: a first reflective layer comprising a thermoplastic resin; a second reflective layer substantially parallel to the first reflective layer; a first transparent electrode layer on at least one of the first and second reflective layer; and a photosensitive region adjacent to the first electrode, wherein the first transparent electrode layer is substantially parallel to the first reflective layer and adjacent to the photosensitive region, and wherein the device has an exterior face transverse to the planes of the reflective layers where the exterior face has an aperture for admission of incident radiation to the interior of the device.

  16. Three-dimensional grating nanowires for enhanced light trapping.

    Science.gov (United States)

    Lee, Hoo-Cheol; Na, Jin-Young; Moon, Yoon-Jong; Park, Jin-Sung; Ee, Ho-Seok; Park, Hong-Gyu; Kim, Sun-Kyung

    2016-04-01

    We propose rationally designed 3D grating nanowires for boosting light-matter interactions. Full-vectorial simulations show that grating nanowires sustain high-amplitude waveguide modes and induce a strong optical antenna effect, which leads to an enhancement in nanowire absorption at specific or broadband wavelengths. Analyses of mode profiles and scattering spectra verify that periodic shells convert a normal plane wave into trapped waveguide modes, thus giving rise to scattering dips. A 200 nm diameter crystalline Si nanowire with designed periodic shells yields an enormously large current density of ∼28  mA/cm2 together with an absorption efficiency exceeding unity at infrared wavelengths. The grating nanowires studied herein will provide an extremely efficient absorption platform for photovoltaic devices and color-sensitive photodetectors. PMID:27192291

  17. How can horseflies be captured by solar panels? A new concept of tabanid traps using light polarization and electricity produced by photovoltaics.

    Science.gov (United States)

    Blahó, Miklós; Egri, Ádám; Barta, András; Antoni, Györgyi; Kriska, György; Horváth, Gábor

    2012-10-26

    Horseflies (Diptera: Tabanidae) can cause severe problems for humans and livestock because of the continuous annoyance performed and the diseases vectored by the haematophagous females. Therefore, effective horsefly traps are in large demand, especially for stock-breeders. To catch horseflies, several kinds of traps have been developed, many of them attracting these insects visually with the aid of a black ball. The recently discovered positive polarotaxis (attraction to horizontally polarized light) in several horsefly species can be used to design traps that capture female and male horseflies. The aim of this work is to present the concept of such a trap based on two novel principles: (1) the visual target of the trap is a horizontal solar panel (photovoltaics) attracting polarotactic horseflies by means of the highly and horizontally polarized light reflected from the photovoltaic surface. (2) The horseflies trying to touch or land on the photovoltaic trap surface are perished by the mechanical hit of a wire rotated quickly with an electromotor supplied by the photovoltaics-produced electricity. Thus, the photovoltaics is bifunctional: its horizontally polarized reflected light signal attracts water-seeking, polarotactic horseflies, and it produces the electricity necessary to rotate the wire. We describe here the concept and design of this new horsefly trap, the effectiveness of which was demonstrated in field experiments. The advantages and disadvantages of the trap are discussed. Using imaging polarimetry, we measured the reflection-polarization characteristics of the photovoltaic trap surface demonstrating the optical reason for the polarotactic attractiveness to horseflies.

  18. How can horseflies be captured by solar panels? A new concept of tabanid traps using light polarization and electricity produced by photovoltaics.

    Science.gov (United States)

    Blahó, Miklós; Egri, Ádám; Barta, András; Antoni, Györgyi; Kriska, György; Horváth, Gábor

    2012-10-26

    Horseflies (Diptera: Tabanidae) can cause severe problems for humans and livestock because of the continuous annoyance performed and the diseases vectored by the haematophagous females. Therefore, effective horsefly traps are in large demand, especially for stock-breeders. To catch horseflies, several kinds of traps have been developed, many of them attracting these insects visually with the aid of a black ball. The recently discovered positive polarotaxis (attraction to horizontally polarized light) in several horsefly species can be used to design traps that capture female and male horseflies. The aim of this work is to present the concept of such a trap based on two novel principles: (1) the visual target of the trap is a horizontal solar panel (photovoltaics) attracting polarotactic horseflies by means of the highly and horizontally polarized light reflected from the photovoltaic surface. (2) The horseflies trying to touch or land on the photovoltaic trap surface are perished by the mechanical hit of a wire rotated quickly with an electromotor supplied by the photovoltaics-produced electricity. Thus, the photovoltaics is bifunctional: its horizontally polarized reflected light signal attracts water-seeking, polarotactic horseflies, and it produces the electricity necessary to rotate the wire. We describe here the concept and design of this new horsefly trap, the effectiveness of which was demonstrated in field experiments. The advantages and disadvantages of the trap are discussed. Using imaging polarimetry, we measured the reflection-polarization characteristics of the photovoltaic trap surface demonstrating the optical reason for the polarotactic attractiveness to horseflies. PMID:22564663

  19. The dying of the light: crepuscular activity in Culicoides and impact on light trap efficacy at temperate latitudes

    NARCIS (Netherlands)

    Meiswinkel, R.; Elbers, A.R.W.

    2016-01-01

    The light trap is the tool of choice for conducting large-scale Culicoides (Diptera: Ceratopogonidae) vector surveillance programmes. Its efficacy is in doubt, however. To assess this, hourly changes in Culicoides activity over the 24-h diel were determined comparatively by way of light trapping and

  20. Visible, invisible and trapped ghosts as sources of wormholes and black universes

    CERN Document Server

    Bolokhov, S V; Korolyov, P A; Skvortsova, M V

    2015-01-01

    We construct explicit examples of globally regular static, spherically symmetric solutions in general relativity with scalar and electromagnetic fields, describing traversable wormholes with flat and AdS asymptotics and regular black holes, in particular, black universes. (A black universe is a regular black hole with an expanding, asymptotically isotropic space-time beyond the horizon.) Such objects exist in the presence of scalar fields with negative kinetic energy ("phantoms'', or "ghosts''), which are not observed under usual physical conditions. To account for that, we consider what we call "trapped ghosts'' (scalars whose kinetic energy is only negative in a strong-field region of space-time) and "invisible ghosts'', i.e., phantom scalar fields sufficiently rapidly decaying in the weak-field region. The resulting configurations contain different numbers of Killing horizons, from zero to four.

  1. Visible, invisible and trapped ghosts as sources of wormholes and black universes

    Science.gov (United States)

    Bolokhov, S. V.; Bronnikov, K. A.; Korolyov, P. A.; Skvortsova, M. V.

    2016-02-01

    We construct explicit examples of globally regular static, spherically symmetric solutions in general relativity with scalar and electromagnetic fields, describing traversable wormholes with flat and AdS asymptotics and regular black holes, in particular, black universes. (A black universe is a regular black hole with an expanding, asymptotically isotropic space-time beyond the horizon.) Such objects exist in the presence of scalar fields with negative kinetic energy (“phantoms”, or “ghosts”), which are not observed under usual physical conditions. To account for that, we consider what we call “trapped ghosts” (scalars whose kinetic energy is only negative in a strong-field region of space-time) and “invisible ghosts”, i.e., phantom scalar fields sufficiently rapidly decaying in the weak-field region. The resulting configurations contain different numbers of Killing horizons, from zero to four.

  2. Plastic cup traps equipped with light-emitting diodes for monitoring adult Bemisia tabaci (Homoptera: Aleyrodidae).

    Science.gov (United States)

    Chu, Chang-Chi; Jackson, Charles G; Alexander, Patrick J; Karut, Kamil; Henneberry, Thomas J

    2003-06-01

    Equipping the standard plastic cup trap, also known as the CC trap, with lime-green light-emitting diodes (LED-plastic cup trap) increased its efficacy for catching Bemisia tabaci by 100%. Few Eretmocerus eremicus Rose and Zolnerowich and Encarsia formosa Gahan were caught in LED-plastic cup traps. The LED-plastic cup traps are less expensive than yellow sticky card traps for monitoring adult whiteflies in greenhouse crop production systems and are more compatible with whitefly parasitoids releases for Bemisia nymph control.

  3. Black Hole Ringing, Quasinormal Modes, and Light Rings

    CERN Document Server

    Khanna, Gaurav

    2016-01-01

    Modelling of gravitational waves from binary black hole inspiral has played an important role in the recent observations of such signals. The late-stage ringdown phase of the gravitational waveform is often associated with the null particle orbit (\\light ring") of the black hole spacetime. With simple models we show that this link between the light ring and spacetime ringing is based more on the history of applications than on an actual constraining relationship. We also show, in particular, that a better understanding of the disassociation between the two, may be relevant to the astrophysically interesting case of rotating (Kerr) black holes.

  4. Light trapping in thin film solar cells using textured photonic crystal

    Science.gov (United States)

    Yi, Yasha; Kimerling, Lionel C.; Duan, Xiaoman; Zeng, Lirong

    2009-01-27

    A solar cell includes a photoactive region that receives light. A photonic crystal is coupled to the photoactive region, wherein the photonic crystal comprises a distributed Bragg reflector (DBR) for trapping the light.

  5. 3D-printed concentrator arrays for external light trapping on thin film solar cells

    NARCIS (Netherlands)

    van Dijk, Lourens; Marcus, E. A. Pepijn; Oostra, A. Jolt; Schropp, Ruud E. I.; Di Vece, Marcel

    2015-01-01

    After our recent demonstration of a 3D-printed external light trap on a small solar cell, we now consider its potential for large solar panels. An external light trap consists of a parabolic concentrator and a spacer that redirects the photons that are reflected by the solar cell back towards the so

  6. Self-induced light trapping in nonlinear Fabry-Perot resonators

    Science.gov (United States)

    Pichugin, K. N.; Sadreev, A. F.

    2016-10-01

    In the framework of the coupled mode theory we consider light trapping between two off-channel resonators which serve as self-adjusted Fano mirrors due to the Kerr effect. By inserting an auxiliary nonlinear resonator between the mirrors we achieve self-tuning of phase shift between the mirrors. That allows for the light trapping for arbitrary distance between the mirrors.

  7. The range of attraction for light traps catching Culicoides biting midges (Diptera: Ceratopogonidae)

    DEFF Research Database (Denmark)

    Kirkeby, Carsten; Græsbøll, Kaare; Stockmarr, Anders;

    2013-01-01

    Background Culicoides are vectors of e.g. bluetongue virus and Schmallenberg virus in northern Europe. Light trapping is an important tool for detecting the presence and quantifying the abundance of vectors in the field. Until now, few studies have investigated the range of attraction of light tr...... light trap was estimated to be approximately 15.25 meters. The attraction towards light traps is different from the attraction to host animals and thus light trap catches may not represent the vector species and numbers attracted to hosts.......Background Culicoides are vectors of e.g. bluetongue virus and Schmallenberg virus in northern Europe. Light trapping is an important tool for detecting the presence and quantifying the abundance of vectors in the field. Until now, few studies have investigated the range of attraction of light...... traps. Methods Here we test a previously described mathematical model (Model I) and two novel models for the attraction of vectors to light traps (Model II and III). In Model I, Culicoides fly to the nearest trap from within a fixed range of attraction. In Model II Culicoides fly towards areas...

  8. Dielectric nanostructures for broadband light trapping in organic solar cells

    KAUST Repository

    Raman, Aaswath

    2011-09-15

    Organic bulk heterojunction solar cells are a promising candidate for low-cost next-generation photovoltaic systems. However, carrier extraction limitations necessitate thin active layers that sacrifice absorption for internal quantum efficiency or vice versa. Motivated by recent theoretical developments, we show that dielectric wavelength-scale grating structures can produce significant absorption resonances in a realistic organic cell architecture. We numerically demonstrate that 1D, 2D and multi-level ITO-air gratings lying on top of the organic solar cell stack produce a 8-15% increase in photocurrent for a model organic solar cell where PCDTBT:PC71BM is the organic semiconductor. Specific to this approach, the active layer itself remains untouched yet receives the benefit of light trapping by nanostructuring the top surface below which it lies. The techniques developed here are broadly applicable to organic semiconductors in general, and enable partial decoupling between active layer thickness and photocurrent generation. © 2011 Optical Society of America.

  9. Glass buildings on river banks as ``polarized light traps'' for mass-swarming polarotactic caddis flies

    Science.gov (United States)

    Kriska, György; Malik, Péter; Szivák, Ildikó; Horváth, Gábor

    2008-05-01

    The caddis flies Hydropsyche pellucidula emerge at dusk from the river Danube and swarm around trees and bushes on the river bank. We document here that these aquatic insects can also be attracted en masse to the vertical glass surfaces of buildings on the river bank. The individuals lured to dark, vertical glass panes land, copulate, and remain on the glass for hours. Many of them are trapped by the partly open, tiltable windows. In laboratory choice experiments, we showed that ovipositing H. pellucidula are attracted to highly and horizontally polarized light stimulating their ventral eye region and, thus, have positive polarotaxis. In the field, we documented that highly polarizing vertical black glass surfaces are significantly more attractive to both female and male H. pellucidula than weakly polarizing white ones. Using video polarimetry, we measured the reflection-polarization characteristics of vertical glass surfaces of buildings where caddis flies swarmed. We propose that after its emergence from the river, H. pellucidula is attracted to buildings by their dark silhouettes and the glass-reflected, horizontally polarized light. After sunset, this attraction may be strengthened by positive phototaxis elicited by the buildings’ lights. The novelty of this visual ecological phenomenon is that the attraction of caddis flies to vertical glass surfaces has not been expected because vertical glass panes do not resemble the horizontal surface of waters from which these insects emerge and to which they must return to oviposit.

  10. Systematic Analysis of Diffuse Rear Reflectors for Enhanced Light Trapping in Silicon Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Pfeffer, Florian; Eisenlohr, Johannes; Basch, Angelika; Hermle, Martin; Lee, Benjamin G.; Goldschmidt, Jan Christoph

    2016-08-01

    Simple diffuse rear reflectors can enhance the light path length of weakly absorbed near infrared light in silicon solar cells and set a benchmark for more complex and expensive light trapping structures like dielectric gratings or plasmonic particles. We analyzed such simple diffuse rear reflectors systematically by optical and electrical measurements. We applied white paint, TiO2 nanoparticles, white backsheets and a silver mirror to bifacial silicon solar cells and measured the enhancement of the external quantum efficiency for three different solar cell geometries: planar front and rear side, textured front and planar rear side, and textured front and rear side. We showed that an air-gap between the solar cell and the reflector decreases the absorption enhancement significantly, thus white paint and TiO2 nanoparticles directly applied to the rear cell surface lead to the highest short circuit current density enhancements. The short circuit current density gains for a 200 um thick planar solar cell reached up to 1.8 mA/cm2, compared to a non-reflecting black rear side and up to 0.8 mA/cm2 compared to a high-quality silver mirror rear side. For solar cells with textured front side the short circuit current density gains are in the range between 0.5 and 1.0 mA/cm2 compared to a non-reflecting black rear side and do not significantly depend on the angular characteristic of the rear side reflector but mainly on its absolute reflectance.

  11. Light-trap design using multiple reflections and solid-angle attenuation - Application to a spaceborne electron spectrometer

    Science.gov (United States)

    Herrero, Federico A.

    1992-01-01

    The design and performance of a new light trap for a spaceborne electron spectrometer are described. The light trap has a measured photon-rejection ratio of 2 x 10 exp -11, allowing only one in 5 x 10 exp 10 incident photons to reach the sensitive area of the instrument. This rejection is more than sufficient because the ambient UV in earth orbit requires a rejection no better than 10 exp -8 to maintain the photon interference to less than 10 count/s. The light trap uses triple reflections to keep most of the light passing through the entrance slit away from the sensitive area of the spectrometer. It is shown that the average reflectance of all the internal surfaces must be less than 0.006, which is consistent with the data on the black coating applied to all surfaces. The analysis makes it possible to compare the photon contributions of each of the internal reflecting areas and to estimate the effective scattering width of the metallic electrode edge.

  12. Dynamic photophoresis-based optical trapping using a spatial light modulator

    Science.gov (United States)

    Porfirev, Aleksey P.; Skidanov, Roman V.

    2016-04-01

    We investigate optical trapping light-absorbing particles in the air employing photophoretic forces with optical tweezers generated by a spatial light modulator (SLM). SLM gives us the opportunity to form optical tweezers for multiple trapping in several planes. We investigate the possibility of using lenses with various focal lengths for trapping light-absorbing microparticles with the SLM. We used lenses with a large focal length and a large depth of focus. The results shown in this paper could be useful in various applications of optics and biology.

  13. Disorder improves nanophotonic light trapping in thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Paetzold, U. W., E-mail: u.paetzold@fz-juelich.de; Smeets, M.; Meier, M.; Bittkau, K.; Merdzhanova, T.; Smirnov, V.; Carius, R.; Rau, U. [IEK5—Photovoltaik, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Michaelis, D.; Waechter, C. [Fraunhofer Institut für Angewandte Optik und Feinmechanik, Albert Einstein Str. 7, D-07745 Jena (Germany)

    2014-03-31

    We present a systematic experimental study on the impact of disorder in advanced nanophotonic light-trapping concepts of thin-film solar cells. Thin-film solar cells made of hydrogenated amorphous silicon were prepared on imprint-textured glass superstrates. For periodically textured superstrates of periods below 500 nm, the nanophotonic light-trapping effect is already superior to state-of-the-art randomly textured front contacts. The nanophotonic light-trapping effect can be associated to light coupling to leaky waveguide modes causing resonances in the external quantum efficiency of only a few nanometer widths for wavelengths longer than 500 nm. With increasing disorder of the nanotextured front contact, these resonances broaden and their relative altitude decreases. Moreover, overall the external quantum efficiency, i.e., the light-trapping effect, increases incrementally with increasing disorder. Thereby, our study is a systematic experimental proof that disorder is conceptually an advantage for nanophotonic light-trapping concepts employing grating couplers in thin-film solar cells. The result is relevant for the large field of research on nanophotonic light trapping in thin-film solar cells which currently investigates and prototypes a number of new concepts including disordered periodic and quasi periodic textures.

  14. Natural evolution inspired design of light trapping structure in thin film organic solar cells

    Science.gov (United States)

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-09-01

    Light trapping has been developed to effectively enhance the efficiency of the thin film solar cell by extending the pathlength for light interacting with the active materials. Searching for optimal light trapping design requires a delicate balance among all the competing physical processes, including light refraction, reflection, and absorption. The existing design methods mainly depend on engineers' intuition to predefine the topology of the light-trapping structure. However, these methods are not capable of handling the topological variation in reaching the optimal design. In this work, a systematic approach based on Genetic Algorithm is introduced to design the scattering pattern for effective light trapping. Inspired by natural evolution, this method can gradually improve the performance of light trapping structure through iterative procedures, producing the most favorable structure with minimized reflection and substantial enhancement in light absorption. Both slot waveguide based solar cell and a more realistic organic solar with a scattering layer consisting of nano-scale patterned front layer is optimized to maximize absorption by strongly coupling incident sun light into the localized photonic modes supported by the multilayer system. Rigorous coupled wave analysis (RCWA) is implemented to evaluate the absorbance. The optimized slot waveguide cell achieves a broadband absorption efficiency of 48.1% and more than 3-fold increase over the Yablonovitch limit and the optimized realistic organic cell exhibits nearly 50% average absorbance over the solar spectrum with short circuit current density five times larger than the control case using planar ITO layer.

  15. Trapping of light in solitonic cavities and its role in the supercontinuum generation

    CERN Document Server

    Driben, R; Efimov, A; Malomed, B A

    2013-01-01

    We demonstrate that the fission of higher-order N-solitons with a subsequent ejection of fundamental quasi-solitons creates solitonic cavities, formed by a pair of solitons with dispersive light trapped between them. As a result of multiple reflections of the trapped light from the bounding solitons which act as mirrors, they bend their trajectories and collide. In the spectral-domain, the two solitons receive blue and red wavelength shifts, respectively. The spectrum of the bouncing trapped light alters as well. This phenomenon strongly affect spectral characteristics of the generated supercontinuum. Studies of the system's parameters, which are responsible for the creation of the cavities, reveal possibilities of predicting and controlling soliton-soliton collisions induced by multiple reflections of the trapped light.

  16. Highly efficient light-trapping structure design inspired by natural evolution.

    Science.gov (United States)

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-01-01

    Recent advances in nanophotonic light trapping open up the new gateway to enhance the absorption of solar energy beyond the so called Yablonovitch Limit. It addresses the urgent needs in developing low cost thin-film solar photovoltaic technologies. However, current design strategy mainly relies on the parametric approach that is subject to the predefined topological design concepts based on physical intuition. Incapable of dealing with the topological variation severely constrains the design of optimal light trapping structure. Inspired by natural evolution process, here we report a design framework driven by topology optimization based on genetic algorithms to achieve a highly efficient light trapping structure. It has been demonstrated that the optimal light trapping structures obtained in this study exhibit more than 3-fold increase over the Yablonovitch Limit with the broadband absorption efficiency of 48.1%, beyond the reach of intuitive designs.

  17. The dying of the light: crepuscular activity in Culicoides and impact on light trap efficacy at temperate latitudes.

    Science.gov (United States)

    Meiswinkel, R; Elbers, A R W

    2016-03-01

    The light trap is the tool of choice for conducting large-scale Culicoides (Diptera: Ceratopogonidae) vector surveillance programmes. Its efficacy is in doubt, however. To assess this, hourly changes in Culicoides activity over the 24-h diel were determined comparatively by way of light trapping and aerial sweeping, and correlated against light intensity. In the Netherlands, sweeping around cattle at pasture revealed that, in early summer, Culicoides are active throughout the diel, and that their abundance peaks during the crepuscular period and falls to a low during the brightest hours of the day. By contrast, the light trap was able to accumulate Culicoides only at night (i.e. after illuminance levels had dropped to 0 lux and midge activity had begun to decline). Although Culicoides chiopterus and species of the Culicoides obsoletus complex were similarly abundant around livestock, they differed critically in their hours of peak activity, being largely diurnal and nocturnal, respectively. This polarity helps to explain why, routinely, the C. obsoletus complex dominates light trap collections and C. chiopterus does not. Inability to accumulate Culicoides at light intensity levels above 0 lux means that, at ever-higher latitudes, particularly beyond 45° N, the progressive northward lengthening of the twilight period will have an increasingly adverse impact upon the efficacy of the light trap as a vector surveillance tool. PMID:26555116

  18. Ultraviolet Photodissociation Induced by Light-Emitting Diodes in a Planar Ion Trap.

    Science.gov (United States)

    Holden, Dustin D; Makarov, Alexander; Schwartz, Jae C; Sanders, James D; Zhuk, Eugene; Brodbelt, Jennifer S

    2016-09-26

    The first application of light-emitting diodes (LEDs) for ultraviolet photodissociation (UVPD) mass spectrometry is reported. LEDs provide a compact, low cost light source and have been incorporated directly into the trapping cell of an Orbitrap mass spectrometer. MS/MS efficiencies of over 50 % were obtained using an extended irradiation period, and UVPD was optimized by modulating the ion trapping parameters to maximize the overlap between the ion cloud and the irradiation volume.

  19. Self-organization effects and light amplification of collective atomic recoil motion in a harmonic trap

    OpenAIRE

    Zhang, L.; Yang, G. J.; Xia, L. X.

    2005-01-01

    Self-organization effects related to light amplification in the collective atomic recoil laser system with the driven atoms confined in a harmonic trap are investigated further. In the dispersive parametric region, our study reveals that the spontaneously formed structures in the phase space contributes an important role to the light amplification of the probe field under the atomic motion being modified by the trap.

  20. Spin squeezing and light entanglement in Coherent Population Trapping

    DEFF Research Database (Denmark)

    Dantan, Aurelien Romain; Cviklinski, Jean; Giacobino, Elisabeth;

    2006-01-01

    We show that strong squeezing and entanglement can be generated at the output of a cavity containing atoms interacting with two fields in a coherent population trapping situation, on account of a nonlinear Faraday effect experienced by the fields close to a dark-state resonance in a cavity...

  1. Three-dimensional simulations of supercritical black hole accretion discs - luminosities, photon trapping and variability

    Science.gov (United States)

    Sądowski, Aleksander; Narayan, Ramesh

    2016-03-01

    We present a set of four three-dimensional, general relativistic, radiation magnetohydrodynamical simulations of black hole accretion at supercritical mass accretion rates, dot{M} > dot{M}_Edd. We use these simulations to study how disc properties are modified when we vary the black hole mass, the black hole spin, or the mass accretion rate. In the case of a non-rotating black hole, we find that the total efficiency is of the order of 3 per cent dot{M} c^2, approximately a factor of 2 less than the efficiency of a standard thin accretion disc. The radiation flux in the funnel along the axis is highly super-Eddington, but only a small fraction of the energy released by accretion escapes in this region. The bulk of the 3 per cent dot{M} c^2 of energy emerges farther out in the disc, either in the form of photospheric emission or as a wind. In the case of a black hole with a spin parameter of 0.7, we find a larger efficiency of about 8 per cent dot{M} c^2. By comparing the relative importance of advective and diffusive radiation transport, we show that photon trapping is effective near the equatorial plane. However, near the disc surface, vertical transport of radiation by diffusion dominates. We compare the properties of our fiducial three-dimensional run with those of an equivalent two-dimensional axisymmetric model with a mean-field dynamo. The latter simulation runs nearly 100 times faster than the three-dimensional simulation, and gives very similar results for time-averaged properties of the accretion flow, but does not reproduce the time-variability.

  2. Quantifying the effectiveness of SiO2/Au light trapping nanoshells for thin film poly-Si solar cells

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In order to enhance light absorption of thin film poly-crystalline silicon(TF poly-Si)solar cells over a broad spectral range, and quantify the effectiveness of nanoshell light trapping structure over the full solar spectrum in theory,the effective photon trapping flux(EPTF)and effective photon trapping efficiency(EPTE)were firstly proposed by considering both the external quantum efficiency of TF poly-Si solar cell and scattering properties of light trapping structures.The EPTF,EPTE and scattering spectrum exhibit different behaviors depending on the geometric size and density of nanoshells that form the light trapping layer.With an optimum size and density of SiO2/Au nanoshell light trapping layer,the EPTE could reach up to 40%due to the enhancement of light trapping over a broad spectral range,especially from 500 to 800 nm.

  3. Advanced methods for light trapping in optically thin silicon solar cells

    Science.gov (United States)

    Nagel, James Richard

    2011-12-01

    The field of light trapping is the study of how best to absorb light in a thin film of material when most light either reflects away at the surface or transmits straight through to the other side. This has tremendous application to the field of photovoltaics where thin silicon films can be manufactured cheaply, but also fail to capture all of the available photons in the solar spectrum. Advancements in light trapping therefore bring us closer to the day when photovoltaic devices may reach grid parity with traditional fossil fuels on the electrical energy market. This dissertation advances our understanding of light trapping by first modeling the effects of loss in planar dielectric waveguides. The mathematical framework developed here can be used to model any arbitrary three-layer structure with mixed gain or loss and then extract the total field solution for the guided modes. It is found that lossy waveguides possess a greater number of eigenmodes than their lossless counterparts, and that these "loss guided" modes attenuate much more rapidly than conventional modes. Another contribution from this dissertation is the exploration of light trapping through the use of dielectric nanospheres embedded directly within the active layer of a thin silicon film. The primary benefit to this approach is that the device can utilize a surface nitride layer serving as an antireflective coating while still retaining the benefits of light trapping within the film. The end result is that light trapping and light injection are effectively decoupled from each other and may be independently optimized within a single photovoltaic device. The final contribution from this work is a direct numerical comparison between multiple light trapping schemes. This allows us to quantify the relative performances of various design techniques against one another and objectively determine which ideas tend to capture the most light. Using numerical simulation, this work directly compares the absorption

  4. Collisional cooling of light ions by co-trapped heavy atoms

    CERN Document Server

    Dutta, Sourav; Rangwala, S A

    2015-01-01

    The most generic cooling and thermalization pathway at the lowest temperatures is via elastic collisions. In hybrid ion-atom traps, ion cooling to temperatures where low partial wave collisions dominate require the collisional cooling mechanism to be well understood and controlled. There exists great uncertainty on whether cooling of light ions by heavier neutral atoms is possible. Here we experimentally demonstrate the cooling of light ions by co-trapped heavy atoms for the first time. We show that trapped 39K+ ions are cooled by localized ultracold neutral 85Rb atoms for an ion-atom mass ratio where most theoretical models predict ion heating. We demonstrate, based on detailed numerical simulation of our ion-cooling model, which is in excellent agreement with experiments, that cooling of ions by localized cold atoms is possible for any mass ratio. Our result opens up the possibility of studying quantum collisions and chemistry in trapped atom-ion systems.

  5. Light Trapping Effect in Wing Scales of Butterfly Papilio peranthus and Its Simulations

    Institute of Scientific and Technical Information of China (English)

    Zhiwu Han; Shichao Niu; Lufeng Zhang; Zhenning Liu; Luquan Ren

    2013-01-01

    Broadband light trapping ettect and arrays of sub-wavelength textured sructures based on the butterfly wing scales are applicable to solar cells and stealth technologies.In this paper,the fine optical structures in wing scales of butterfly Papilio peranthus,exhibiting efficient light trapping effect,were carefully examined.First,the reflectivity was measured by reflectance spectrum.Field Emission Scanning Electronic Microscope (FESEM) and Transmission Electron Microscope (TEM) were used to observe the coupling morphologies and structures of the scales.Then,the optimized 3D model of the coupling structure was created combining Scanning Electron Microscope (SEM) and TEM data.Afterwards,the mechanism of the light trapping effect of these structures was analyzed by simulation and theoretical calculations.A multilayer nano-structure of chitin and air was found.These structures are effective in increasing optical path,resulting in that most of the incident light can be trapped and adsorbed within the structure at last.Furthermore,the simulated optical results are consistent with the experimental and calculated ones.This result reliably confirms that these structures induce an efficient light trapping effect.This work can be used as a reference for in-depth study on the fabrication of highly efficient bionic optical devices,such as solar cells,photo detectors,high-contrast,antiglare,and so forth.

  6. Broadband perfect light trapping in the thinnest monolayer graphene-MoS$_{2}$ photovoltaic cell

    CERN Document Server

    Wu, Yun-Beng; Wang, Tong-Biao; Deng, Xin-Hua; Liu, Jiang-Tao

    2015-01-01

    The light absorption of a monolayer graphene-molybdenum disulfide photovoltaic (GM-PV) cell in a wedge-shaped microcavity with a spectrum-splitting structure is investigated theoretically. The GM-PV cell, which is three times thinner than the traditional photovoltaic cell, exhibits up to 98\\% light absorptivity in a wide wavelength range. This rate exceeds the fundamental limit of nanophotonic light trapping in solar cells. The effects of defect layer thickness, GM-PV cell position in the microcavity, incident angle, and lens aberration on the light absorption rate of the GM-PV cell is explored. Regardless of errors, the GM-PV cell can still achieve at least 90\\% light absorptivity with the current technology. Our proposal provides different methods to design light-trapping structures and apply spectrum-splitting systems.

  7. Trapping light into high orbital momentum modes of fiber tapers.

    Science.gov (United States)

    Strekalov, Dmitry V; Savchenkov, Anatoliy A; Savchenkova, Ekaterina A; Matsko, Andrey B

    2015-08-15

    A tapered cylindrical dielectric optical waveguide acts as a high quality factor white-light cavity providing high field concentration as well as long optical group delay. It is possible to optimize shape of a lossless taper to suppress reflection of the input light and to achieve infinitely high field concentration. These tapers can be used in sensing and optoelectronics applications instead of conventional microcavities. PMID:26274659

  8. An Ingenious Super Light Trapping Surface Templated from Butterfly Wing Scales.

    Science.gov (United States)

    Han, Zhiwu; Li, Bo; Mu, Zhengzhi; Yang, Meng; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

    2015-12-01

    Based on the super light trapping property of butterfly Trogonoptera brookiana wings, the SiO2 replica of this bionic functional surface was successfully synthesized using a simple and highly effective synthesis method combining a sol-gel process and subsequent selective etching. Firstly, the reflectivity of butterfly wing scales was carefully examined. It was found that the whole reflectance spectroscopy of the butterfly wings showed a lower level (less than 10 %) in the visible spectrum. Thus, it was confirmed that the butterfly wings possessed a super light trapping effect. Afterwards, the morphologies and detailed architectures of the butterfly wing scales were carefully investigated using the ultra-depth three-dimensional (3D) microscope and field emission scanning electronic microscopy (FESEM). It was composed by the parallel ridges and quasi-honeycomb-like structure between them. Based on the biological properties and function above, an exact SiO2 negative replica was fabricated through a synthesis method combining a sol-gel process and subsequent selective etching. At last, the comparative analysis of morphology feature size and the reflectance spectroscopy between the SiO2 negative replica and the flat plate was conducted. It could be concluded that the SiO2 negative replica inherited not only the original super light trapping architectures, but also the super light trapping characteristics of bio-template. This work may open up an avenue for the design and fabrication of super light trapping materials and encourage people to look for more super light trapping architectures in nature. PMID:26306539

  9. An Ingenious Super Light Trapping Surface Templated from Butterfly Wing Scales

    Science.gov (United States)

    Han, Zhiwu; Li, Bo; Mu, Zhengzhi; Yang, Meng; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

    2015-08-01

    Based on the super light trapping property of butterfly Trogonoptera brookiana wings, the SiO2 replica of this bionic functional surface was successfully synthesized using a simple and highly effective synthesis method combining a sol-gel process and subsequent selective etching. Firstly, the reflectivity of butterfly wing scales was carefully examined. It was found that the whole reflectance spectroscopy of the butterfly wings showed a lower level (less than 10 %) in the visible spectrum. Thus, it was confirmed that the butterfly wings possessed a super light trapping effect. Afterwards, the morphologies and detailed architectures of the butterfly wing scales were carefully investigated using the ultra-depth three-dimensional (3D) microscope and field emission scanning electronic microscopy (FESEM). It was composed by the parallel ridges and quasi-honeycomb-like structure between them. Based on the biological properties and function above, an exact SiO2 negative replica was fabricated through a synthesis method combining a sol-gel process and subsequent selective etching. At last, the comparative analysis of morphology feature size and the reflectance spectroscopy between the SiO2 negative replica and the flat plate was conducted. It could be concluded that the SiO2 negative replica inherited not only the original super light trapping architectures, but also the super light trapping characteristics of bio-template. This work may open up an avenue for the design and fabrication of super light trapping materials and encourage people to look for more super light trapping architectures in nature.

  10. Photonic antenna system for light harvesting, transport and trapping

    NARCIS (Netherlands)

    Calzaferri, G.; Pauchard, M.; Maas, H.; Huber, S.; Khatyr, A.; Schaafsma, T.J.

    2002-01-01

    Host¿guest composites with photonic antenna properties are described. The material consists of cylindrical zeolite L crystals the channels of which are filled with chains of joined but electronically non-interacting dye molecules. Light shining on a crystal is first absorbed and the energy is then t

  11. Trapping of Rift Valley Fever (RVF vectors using Light Emitting Diode (LED CDC traps in two arboviral disease hot spots in Kenya

    Directory of Open Access Journals (Sweden)

    Tchouassi David P

    2012-05-01

    Full Text Available Abstract Background Mosquitoes’ response to artificial lights including color has been exploited in trap designs for improved sampling of mosquito vectors. Earlier studies suggest that mosquitoes are attracted to specific wavelengths of light and thus the need to refine techniques to increase mosquito captures following the development of super-bright light-emitting diodes (LEDs which emit narrow wavelengths of light or very specific colors. Therefore, we investigated if LEDs can be effective substitutes for incandescent lamps used in CDC light traps for mosquito surveillance, and if so, determine the best color for attraction of important Rift Valley Fever (RFV vectors. Methods The efficiency of selected colored LED CDC light traps (red, green, blue, violet, combination of blue-green-red (BGR to sample RVF vectors was evaluated relative to incandescent light (as control in a CDC light trap in two RVF hotspots (Marigat and Ijara districts in Kenya. In field experiments, traps were baited with dry ice and captures evaluated for Aedes tricholabis, Ae. mcintoshi, Ae. ochraceus, Mansonia uniformis, Mn. africana and Culex pipiens, following Latin square design with days as replicates. Daily mosquito counts per treatment were analyzed using a generalized linear model with Negative Binomial error structure and log link using R. The incidence rate ratios (IRR that mosquito species chose other treatments instead of the control, were estimated. Results Seasonal preference of Ae.mcintoshi and Ae. ochraceus at Ijara was evident with a bias towards BGR and blue traps respectively in one trapping period but this pattern waned during another period at same site with significantly low numbers recorded in all colored traps except blue relative to the control. Overall results showed that higher captures of all species were recorded in control traps compared to the other LED traps (IRR  Conclusion Based on our trapping design and color, none of the LEDs

  12. Assessment of vector/host contact: comparison of animal-baited traps and UV-light/suction trap for collecting Culicoides biting midges (Diptera: Ceratopogonidae, vectors of Orbiviruses

    Directory of Open Access Journals (Sweden)

    Delécolle Jean-Claude

    2011-06-01

    Full Text Available Abstract Background The emergence and massive spread of bluetongue in Western Europe during 2006-2008 had disastrous consequences for sheep and cattle production and confirmed the ability of Palaearctic Culicoides (Diptera: Ceratopogonidae to transmit the virus. Some aspects of Culicoides ecology, especially host-seeking and feeding behaviors, remain insufficiently described due to the difficulty of collecting them directly on a bait animal, the most reliable method to evaluate biting rates. Our aim was to compare typical animal-baited traps (drop trap and direct aspiration to both a new sticky cover trap and a UV-light/suction trap (the most commonly used method to collect Culicoides. Methods/results Collections were made from 1.45 hours before sunset to 1.45 hours after sunset in June/July 2009 at an experimental sheep farm (INRA, Nouzilly, Western France, with 3 replicates of a 4 sites × 4 traps randomized Latin square using one sheep per site. Collected Culicoides individuals were sorted morphologically to species, sex and physiological stages for females. Sibling species were identified using a molecular assay. A total of 534 Culicoides belonging to 17 species was collected. Abundance was maximal in the drop trap (232 females and 4 males from 10 species whereas the diversity was the highest in the UV-light/suction trap (136 females and 5 males from 15 species. Significant between-trap differences abundance and parity rates were observed. Conclusions Only the direct aspiration collected exclusively host-seeking females, despite a concern that human manipulation may influence estimation of the biting rate. The sticky cover trap assessed accurately the biting rate of abundant species even if it might act as an interception trap. The drop trap collected the highest abundance of Culicoides and may have caught individuals not attracted by sheep but by its structure. Finally, abundances obtained using the UV-light/suction trap did not estimate

  13. The relative effectiveness of yellow sticky traps, yellow pan traps and different light sources in capturing Sitobion avenae and Rhopalosiphum padi%黄板、黄盆及灯光对麦长管蚜和禾谷缢管蚜的诱捕效果

    Institute of Scientific and Technical Information of China (English)

    巩中军; 武予清; 都振宝; 苗进; 段云; 蒋月丽

    2011-01-01

    The relative effectiveness of yellow sticky traps, yellow pan traps and light traps in capturing Sitobion avenae ( Fabricius) and Rhopalosiphum padi ( L. ) was investigated. These two aphid species both significantly preferred yellow pan traps with 7. 94 times the number of S. Avenae and 2. 13 times the number of R. Padi being caught in these traps than in yellow sticky traps. An experiment to determine the relative effectiveness of black light and fluorescent lamps in luring the two aphid species to traps showed that black lights were most effective. A combination of yellow pan traps and black light lamps should therefore be the most effective way of obtaining accurate, reliable and timely data on the abundance of these two aphid species.%通过黄板、黄盆及灯光的监测,研究了其对麦长管蚜Sitobion avenae( Fabricius)和禾谷缢管蚜Rhopalosiphum padi (L.)诱捕作用,结果表明2种麦蚜对黄盆的趋性最好,黄盆诱捕量分别为黄板诱捕量的7.94、2.13倍.黑光灯和荧光灯对2种麦蚜的诱捕作用比较试验表明,黑光灯对2种麦蚜的诱捕效果较好.黄盆和黑光灯2种监测手段的结合能够为预测预报提供准确可靠、适时的测报结果.

  14. Light-induced evaporative cooling in a magneto-optical trap

    Institute of Scientific and Technical Information of China (English)

    Ma Hong-Yu; Cheng Hua-Dong; Wang Yu-Zhu; Liu Liang

    2008-01-01

    This paper presents an experimental demonstration of light-induced evaporative cooling in a magneto-optical trap.An additional laser is used to interact with atoms at the edge of the atomic cloud in the trap.These atoms get an additional force and evaporated away from the trap by both the magnetic field and laser fields.The remaining atoms have lower kinetic energy and thus are cooled.It reports the measurements on the temperature and atomic number after the evaporative cooling with different parameters including the distance between the laser and the centre of the atomic cloud,the detuning,the intensity.The results show that the light-induced evaporative cooling is a way to generate an ultra-cold atom source.

  15. Tunable dual-band light trapping and absorption enhancement with graphene concentric ring arrays

    CERN Document Server

    Xiao, Shuyuan; Liu, Yuebo; Han, Xu; Yan, Xicheng

    2016-01-01

    Surface plasmon resonance (SPR) has been intensively studied and widely employed for light trapping and absorption enhancement. In the mid-infrared and terahertz (THz) regime, graphene supports the tunable SPR via manipulating its Fermi energy and enhances light-matter interaction at the selective wavelength. In this paper, a pair of graphene concentric rings has been proposed to introduce tunable dual-band light trapping with good angle polarization tolerance and enhance the absorption in the low light-absorbing efficiency materials nearby to more than one order. Moreover, the design principle here could be set as a template to achieve multi-band plasmonic absorption enhancement by introducing more graphene concentric rings into each unit cell. This work not only opens up new ways of employing graphene SPR, but also leads to practical applications in high-performance simultaneous multi-color photodetection with high efficiency and tunable spectral selectivity.

  16. Temporal tweezing of light: trapping and manipulation of temporal cavity solitons

    CERN Document Server

    Jang, Jae K; Coen, Stephane; Murdoch, Stuart G

    2014-01-01

    Optical tweezers use laser light to trap and move microscopic particles in space. Here we demonstrate a similar control over ultrashort light pulses, but in time. Our experiment involves temporal cavity solitons that are stored in a passive loop of optical fiber pumped by a continuous-wave "holding" laser beam. The cavity solitons are trapped into specific time slots through a phase-modulation of the holding beam, and moved around in time by manipulating the phase profile. We report both continuous and discrete manipulations of the temporal positions of picosecond light pulses, with the ability to simultaneously and independently control several pulses within a train. We also study the transient drifting dynamics and show complete agreement with theoretical predictions. Our study demonstrates how the unique particle-like characteristics of cavity solitons can be leveraged to achieve unprecedented control over light. These results could have significant ramifications for optical information processing.

  17. Unified Electromagnetic-Electronic Design of Light Trapping Silicon Solar Cells

    Science.gov (United States)

    Boroumand, Javaneh; Das, Sonali; Vázquez-Guardado, Abraham; Franklin, Daniel; Chanda, Debashis

    2016-08-01

    A three-dimensional unified electromagnetic-electronic model is developed in conjunction with a light trapping scheme in order to predict and maximize combined electron-photon harvesting in ultrathin crystalline silicon solar cells. The comparison between a bare and light trapping cell shows significant enhancement in photon absorption and electron collection. The model further demonstrates that in order to achieve high energy conversion efficiency, charge separation must be optimized through control of the doping profile and surface passivation. Despite having a larger number of surface defect states caused by the surface patterning in light trapping cells, we show that the higher charge carrier generation and collection in this design compensates the absorption and recombination losses and ultimately results in an increase in energy conversion efficiency. The fundamental physics behind this specific design approach is validated through its application to a 3 μm thick functional light trapping solar cell which shows 192% efficiency enhancement with respect to the bare cell of same thickness. Such a unified design approach will pave the path towards achieving the well-known Shockley-Queisser (SQ) limit for c-Si in thin-film (<30 μm) geometries.

  18. Determination of the trap-assisted recombination strength in polymer light emitting diodes

    NARCIS (Netherlands)

    Kuik, M.; Nicolai, H.T.; Lenes, M.; Wetzelaer, G.-J.A.H.; Lu, M.; Blom, P.W.M.

    2011-01-01

    The recombination processes in poly(p -phenylene vinylene) based polymer light-emitting diodes (PLEDs) are investigated. Photogenerated current measurements on PLED device structures reveal that next to the known Langevin recombination also trap-assisted recombination is an important recombination c

  19. Three-dimensional photonic crystal intermediate reflectors for enhanced light-trapping in tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Uepping, Johannes; Bielawny, Andreas; Wehrspohn, Ralf B. [Institute of Physics, Martin-Luther-Universitaet Halle-Wittenberg, Halle (Germany); Fraunhofer-Institute for Mechanics of Materials, Halle (Germany); Beckers, Thomas; Carius, Reinhard; Rau, Uwe [Institute of Energy and Climate Research 5 - Photovoltaics, Forschungszentrum Juelich GmbH, Juelich (Germany); Fahr, Stefan; Rockstuhl, Carsten; Lederer, Falk [Institute of Condensed Matter Theory and Solid State Optics and Abbe Center of Photonics, Friedrich-Schiller-Universitaet Jena (Germany); Kroll, Matthias; Pertsch, Thomas [Institute of Applied Physics, Friedrich-Schiller-Universitaet Jena (Germany); Steidl, Lorenz; Zentel, Rudolf [Institute of Organic Chemistry, Johannes Gutenberg-Universitaet Mainz (Germany)

    2011-09-08

    A three-dimensional photonic crystal intermediate reflector for enhanced light trapping in tandem solar cells is presented. The intermediate reflector consists of a transparent and conductive ZnO:Al inverted opal sandwiched in between the top amorphous silicon and bottom microcrystalline silicon cell. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Unified Electromagnetic-Electronic Design of Light Trapping Silicon Solar Cells

    Science.gov (United States)

    Boroumand, Javaneh; Das, Sonali; Vázquez-Guardado, Abraham; Franklin, Daniel; Chanda, Debashis

    2016-01-01

    A three-dimensional unified electromagnetic-electronic model is developed in conjunction with a light trapping scheme in order to predict and maximize combined electron-photon harvesting in ultrathin crystalline silicon solar cells. The comparison between a bare and light trapping cell shows significant enhancement in photon absorption and electron collection. The model further demonstrates that in order to achieve high energy conversion efficiency, charge separation must be optimized through control of the doping profile and surface passivation. Despite having a larger number of surface defect states caused by the surface patterning in light trapping cells, we show that the higher charge carrier generation and collection in this design compensates the absorption and recombination losses and ultimately results in an increase in energy conversion efficiency. The fundamental physics behind this specific design approach is validated through its application to a 3 μm thick functional light trapping solar cell which shows 192% efficiency enhancement with respect to the bare cell of same thickness. Such a unified design approach will pave the path towards achieving the well-known Shockley-Queisser (SQ) limit for c-Si in thin-film (<30 μm) geometries. PMID:27499446

  1. The Chaotic Light Curves of Accreting Black Holes

    Science.gov (United States)

    Kazanas, Demosthenes

    2007-01-01

    We present model light curves for accreting Black Hole Candidates (BHC) based on a recently developed model of these sources. According to this model, the observed light curves and aperiodic variability of BHC are due to a series of soft photon injections at random (Poisson) intervals and the stochastic nature of the Comptonization process in converting these soft photons to the observed high energy radiation. The additional assumption of our model is that the Comptonization process takes place in an extended but non-uniform hot plasma corona surrounding the compact object. We compute the corresponding Power Spectral Densities (PSD), autocorrelation functions, time skewness of the light curves and time lags between the light curves of the sources at different photon energies and compare our results to observation. Our model reproduces the observed light curves well, in that it provides good fits to their overall morphology (as manifest by the autocorrelation and time skewness) and also to their PSDs and time lags, by producing most of the variability power at time scales 2 a few seconds, while at the same time allowing for shots of a few msec in duration, in accordance with observation. We suggest that refinement of this type of model along with spectral and phase lag information can be used to probe the structure of this class of high energy sources.

  2. Stars and black holes in varying speed of light theories

    CERN Document Server

    Magueijo, J

    2001-01-01

    We investigate spherically symmetric solutions to a recently proposed covariant and locally Lorentz-invariant varying speed of light theory. We find the metrics and variations in $c$ associated with the counterpart of black holes, the outside of a star, and stellar collapse. The remarkable novelty is that $c$ goes to zero or infinity (depending on parameter signs) at the horizon. We show how this implies that, with appropriate parameters, observers are prevented from entering the horizon. Concomitantly stellar collapse must end in a ``Schwarzchild radius'' remnant. We then find formulae for gravitational light deflection, gravitational redshift, radar echo delay, and the precession of the perihelion of Mercury, highlighting how these may differ distinctly from their Einstein counterparts but still evade experimental constraints. The main tell-tale signature of this theory is the prediction of the observation of a different value for the fine structure constant, $\\alpha$, in spectral lines formed in the surfac...

  3. Trapping of quantum particles and light beams by switchable potential wells

    CERN Document Server

    Sonkin, Eduard; Granot, Er'el; Marchewka, Avi

    2010-01-01

    We consider basic dynamical effects in settings based on a pair of local potential traps that may be effectively switched on and off, or suddenly displaced, by means of appropriate control mechanisms, such as the scanning tunneling microscopy (STM) or photo-switchable quantum dots. The same models, based on the linear Schrodinger equation with time-dependent trapping potentials, apply to the description of optical planar systems designed for the switching of trapped light beams. The analysis is carried out in the analytical form, using exact solutions of the Schrodinger equation. The first dynamical problem considered in this work is the retention of a particle released from a trap which was suddenly turned off, while another local trap was switched on at a distance - immediately or with a delay. In this case, we demonstrate that the maximum of the retention rate is achieved at a specific finite value of the strength of the new trap, and at a finite value of the temporal delay, depending on the distance betwe...

  4. Trapping of Atoms by the Counter-Propagating Stochastic Light Waves

    CERN Document Server

    Romanenko, Victor I

    2016-01-01

    We show that the field of counter-propagating stochastic light waves, one of which repeats the other, can form an one-dimension trap for atoms. The confinement of an ensemble of atoms in the trap and their simultaneous cooling can be achieved without using auxiliary fields. The temperature of the atomic ensemble depends on the autocorrelation time of the waves, their intensity and the detuning of the carrier frequency of the waves from the atomic transition frequency. The numerical simulation is carried out for sodium atoms.

  5. Influence of carbon dioxide on numbers of Culicoides midges collected with suction light traps in South Africa.

    Science.gov (United States)

    Venter, G J; Boikanyo, S N B; Majatladi, D M; Morey, L

    2016-03-01

    To implement risk management against diseases transmitted by species of Culicoides Latreille, 1809 (Diptera: Ceratopogonidae), it is essential to identify all potential vectors. Light traps are the most commonly used tool for the collection of Culicoides midges. Given the indiscriminate artificial attraction of light, traps will collect all night-flying insects rather than only livestock-associated Culicoides midges. Factors that may increase the efficacy of traps, especially for livestock-associated Culicoides midges, require investigation. In the present study, results obtained with Centers for Disease Control (CDC) and Onderstepoort light traps baited with carbon dioxide (CO2 ) were compared with those of unbaited controls. Comparisons were made using two replicates of a 4 × 4 randomized Latin square design. With both trap types, the mean numbers of Culicoides midges collected in 16 baited traps were higher than those caught in 16 unbaited traps. Although exceptionally low numbers were collected with the CDC traps, the increases in the numbers and frequency of collection of Culicoides imicola Kieffer, 1913 were more pronounced in the CDC traps compared with the Onderstepoort traps. These results indicate that the addition of CO2 may increase the efficiency of these traps for the collection of C. imicola and other livestock-associated Culicoides species. PMID:26522279

  6. Low cost and high performance light trapping structure for thin-film solar cells

    CERN Document Server

    Wang, DongLin; Su, Gang

    2015-01-01

    Nano-scaled dielectric and metallic structures are popular light tapping structures in thin-film solar cells. However, a large parasitic absorption in those structures is unavoidable. Most schemes based on such structures also involve the textured active layers that may bring undesirable degradation of the material quality. Here we propose a novel and cheap light trapping structure based on the prism structured SiO2 for thin-film solar cells, and a flat active layer is introduced purposefully. Such a light trapping structure is imposed by the geometrical shape optimization to gain the best optical benefit. By examining our scheme, it is disclosed that the conversion efficiency of the flat a-Si:H thin-film solar cell can be promoted to exceed the currently certified highest value. As the cost of SiO2-based light trapping structure is much cheaper and easier to fabricate than other materials, this proposal would have essential impact and wide applications in thin-film solar cells.

  7. Optical trapping of cold neutral atoms using a two-color evanescent light field around a carbon nanotube

    International Nuclear Information System (INIS)

    We suggest a new schema of trapping cold atoms using a two-color evanescent light field around a carbon nanotube. The two light fields circularly polarized sending through a carbon nanotube generates an evanescent wave around this nanotube. By evanescent effect, the wave decays away from the nanotube producing a set of trapping minima of the total potential in the transverse plane as a ring around the nanotube. This schema allows capture of atoms to a cylindrical shell around the nanotube. We consider some possible boundary conditions leading to the non-trivial bound state solution. Our result will be compared to some recent trapping models and our previous trapping models.

  8. The effect of high frequency sound on Culicoides numbers collected with suction light traps

    Directory of Open Access Journals (Sweden)

    Gert J. Venter

    2012-04-01

    Full Text Available Culicoides midges (Diptera: Ceratopogonidae, are involved in the transmission of various pathogens that cause important diseases of livestock worldwide. The use of insect repellents to reduce the attack rate of these insects on livestock could play an important role as part of an integrated control programme against diseases transmitted by these midges. The objective of this study was to determine whether high frequency sound has any repellent effect on Culicoides midges. The number of midges collected with 220 V Onderstepoort white light traps fitted with electronic mosquito repellents (EMRs, emitting 5-20 KHz multi-frequency sound waves, was compared with that of two untreated traps. Treatments were rotated in two replicates of a 4 x 4 randomised Latin square design. Although fewer midges were collected in the two traps fitted with EMRs, the average number collected over eight consecutive nights was not significantly different. The EMRs also had no influence on any of the physiological groups of Culicoides imicola Kieffer or the species composition of the Culicoides population as determined with light traps. The results indicate that high frequency sound has no repellent effect on Culicoides midges. There is therefore no evidence to support their promotion or use in the protection of animals against pathogens transmitted by Culicoides midges.

  9. Periodic molybdenum disc array for light trapping in amorphous silicon layer

    Science.gov (United States)

    Wang, Jiwei; Yang, Kang; Chen, Haiyan; Deng, Changkai; Li, Dongdong; Chen, Xiaoyuan; Ren, Wei

    2016-05-01

    We demonstrate the light trapping effect in amorphous silicon (a-Si:H) layer by inserting a layer of periodic molybdenum disc array (MDA) between the a-Si:H layer and the quartz substrate, which forms a three-layer structure of Si/MDA/SiO2. The MDA layer was fabricated by a new cost-effective method based on nano-imprint technology. Further light absorption enhancement was realized through altering the topography of MDA by annealing it at 700°C. The mechanism of light absorption enhancement in a-Si:H interfaced with MDA was analyzed, and the electric field distribution and light absorption curve of the different layers in the Si/MDA structure under light illumination of different wavelengths were simulated by employing numerical finite difference time domain (FDTD) solutions.

  10. Two-dimensional high efficiency thin-film silicon solar cells with a lateral light trapping architecture

    OpenAIRE

    Fang, Jia; Liu, Bofei; Zhao, Ying; Zhang, Xiaodan

    2014-01-01

    Introducing light trapping structures into thin-film solar cells has the potential to enhance their solar energy harvesting as well as the performance of the cells; however, current strategies have been focused mainly on harvesting photons without considering the light re-escaping from cells in two-dimensional scales. The lateral out-coupled solar energy loss from the marginal areas of cells has reduced the electrical yield indeed. We therefore herein propose a lateral light trapping structur...

  11. Light-trapping in solar cells by photonic nanostructures. The need for benchmarking and fabrication assessments

    Energy Technology Data Exchange (ETDEWEB)

    Lenzmann, F.O.; Salpakari, J.; Weeber, A.W.; Olson, C.L. [ECN Solar Energy, Petten (Netherlands)

    2013-07-15

    Light-trapping in solar cells by photonic nanostructures, e.g., nano-textured surfaces or metallic and nonmetallic nanoparticles is a research area of great promise. A large multitude of configurations is being explored and there is a rising need for (a set of) assessment elements that help to narrow in on the most viable ones. This paper discusses two examples: benchmark devices and the assessment of fabrication aspects for the nanostructures.

  12. Fabrication of the replica templated from butterfly wing scales with complex light trapping structures

    Science.gov (United States)

    Han, Zhiwu; Li, Bo; Mu, Zhengzhi; Yang, Meng; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

    2015-11-01

    The polydimethylsiloxane (PDMS) positive replica templated twice from the excellent light trapping surface of butterfly Trogonoptera brookiana wing scales was fabricated by a simple and promising route. The exact SiO2 negative replica was fabricated by using a synthesis method combining a sol-gel process and subsequent selective etching. Afterwards, a vacuum-aided process was introduced to make PDMS gel fill into the SiO2 negative replica, and the PDMS gel was solidified in an oven. Then, the SiO2 negative replica was used as secondary template and the structures in its surface was transcribed onto the surface of PDMS. At last, the PDMS positive replica was obtained. After comparing the PDMS positive replica and the original bio-template in terms of morphology, dimensions and reflectance spectra and so on, it is evident that the excellent light trapping structures of butterfly wing scales were inherited by the PDMS positive replica faithfully. This bio-inspired route could facilitate the preparation of complex light trapping nanostructure surfaces without any assistance from other power-wasting and expensive nanofabrication technologies.

  13. Loading a vapor cell magneto-optic trap using light-induced atom desorption

    CERN Document Server

    Anderson, B P

    2000-01-01

    Low intensity white light was used to increase the loading rate of $^{87}$Rb atoms into a vapor cell magneto-optic trap by inducing non-thermal desorption of Rb atoms from the stainless steel walls of the vapor cell. An increased Rb partial pressure reached a new equilibrium value in less than 10 seconds after switching on the broadband light source. After the source was turned off, the partial pressure returned to its previous value in $1/e$ times as short as 10 seconds.

  14. The effects of enhanced light trapping in tandem micromorph silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Krc, J.; Brecl, K.; Smole, F.; Topic, M. [Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, SI-1000 Ljubljana (Slovenia)

    2006-11-23

    Optical modelling is used to investigate the potential improvements in quantum efficiency and short-circuit current density of the top and bottom silicon cell in tandem micromorph configuration. The effects of enhanced haze parameter and different angular distribution functions of scattered light are presented and analysed. The role of an intermediate reflector (interlayer), located between the top and bottom cell, is studied from the optical point of view. The improvements in quantum efficiency of top cell are demonstrated for different types of interlayers. Potential thickness reductions due to enhanced light trapping in the solar cells are presented. (author)

  15. Enhancement of silicon solar cell performances due to light trapping by colloidal metal nanoparticles

    Science.gov (United States)

    Jana, Sourav Kanti; Le Donne, Alessia; Binetti, Simona

    2012-02-01

    Photovoltaics is the most promising technology for the future of green energy production. To fully realize the potential use of photovoltaic technology, low manufacturing cost and high working photoconversion efficiency must be obtained. Light trapping by metal nanoparticles is an attractive strategy in thin film as well as in bulk silicon solar cells aimed to confine light within the active layer to promote the photon absorption and therefore achieving higher efficiency. In this paper, we tested the deposition of silver and gold nanoparticles on bulk silicon solar cells by colloidal technique in order to enhance their photovoltaic conversion efficiency by means of Plasmonic Light Scattering by metal nanoparticles. The feasible Plasmonic Light Scattering related enhancement was examined using spectral response and I-V measurements. Relative increases of the total delivered power under simulated solar irradiation were observed for cells both with and without antireflection coating using silver and gold nanoparticles.

  16. Active control of light trapping by means of local magnetic coupling.pdf

    CERN Document Server

    Burresi, Matteo; van Oosten, Dries; Prangsma, Jord C; Song, Bong-Shik; Noda, Susumo; Kuipers, Laurens

    2009-01-01

    The ability to actively tune the properties of a nanocavity is crucial for future applications in photonics and quantum information. Two important man-made classes of materials have emerged to mold the flow of electromagnetic waves. Firstly, photonic crystals are dielectric nanostructures that can be used to confine and slow down light and control its emission. They act primarily on the electric component of the light field. More recently, a novel class of metallo-dielectric nanostructures has emerged. These so-called metamaterials enable fascinating phenomena, such as negative refraction, super-focusing and cloaking. This second class of materials realizes light control through effective interactions with both electric and magnetic component. In this work, we combine both concepts to gain an active and reversible control of light trapping on subwavelength length scales. By actuating a nanoscale magnetic coil close to a photonic crystal nanocavity, we interact with the rapidly varying magnetic field and accom...

  17. Discerning and selectively manipulating laser-trapped atoms using non-paraxial light

    CERN Document Server

    Mitsch, R; Albrecht, B; Schneeweiss, P; Rauschenbeutel, A

    2014-01-01

    We demonstrate that the non-paraxial character of a strongly confined light field can be used to spectrally discern and selectively manipulate two initially equivalent atomic ensembles of the same species. The technique is implemented with two symmetric linear arrays of cesium atoms, trapped on opposite sides of an optical nanofiber and separated by less than a micron. The nanofiber provides an evanescent field interface between the atoms and the guided light, where the latter exhibits a strongly position-dependent polarization. In the case of resonant interaction, this allows us to optically pump the ensembles into two distinct Zeeman states. In the case of dispersive interaction, the strong gradient of the light-induced fictitious magnetic field permits us to selectively address the ensembles with microwave radiation, thereby preparing them in distinct hyperfine states. This results in a composite fiber-coupled atomic medium with high potential for nonlinear optics at ultra-low light levels.

  18. Light Absorption in Arctic Sea Ice - Black Carbon vs Chlorophyll

    Science.gov (United States)

    Ogunro, O. O.; Wingenter, O. W.; Elliott, S.; Hunke, E. C.; Flanner, M.; Wang, H.; Dubey, M. K.; Jeffery, N.

    2015-12-01

    The fingerprint of climate change is more obvious in the Arctic than any other place on Earth. This is not only because the surface temperature there has increased at twice the rate of global mean temperature but also because Arctic sea ice extent has reached a record low of 49% reduction relative to the 1979-2000 climatology. Radiation absorption through black carbon (BC) deposited on Arctic snow and sea ice surface is one of the major hypothesized contributors to the decline. However, we note that chlorophyll-a absorption owing to increasing biology activity in this region could be a major competitor during boreal spring. Modeling of sea-ice physical and biological processes together with experiments and field observations promise rapid progress in the quality of Arctic ice predictions. Here we develop a dynamic ice system module to investigate discrete absorption of both BC and chlorophyll in the Arctic, using BC deposition fields from version 5 of Community Atmosphere Model (CAM5) and vertically distributed layers of chlorophyll concentrations from Sea Ice Model (CICE). To this point, our black carbon mixing ratios compare well with available in situ data. Both results are in the same order of magnitude. Estimates from our calculations show that sea ice and snow around the Canadian Arctic Archipelago and Baffin Bay has the least black carbon absorption while values at the ice-ocean perimeter in the region of the Barents Sea peak significantly. With regard to pigment concentrations, high amounts of chlorophyll are produced in Arctic sea ice by the bottom microbial community, and also within the columnar pack wherever substantial biological activity takes place in the presence of moderate light. We show that the percentage of photons absorbed by chlorophyll in the spring is comparable to the amount attributed to BC, especially in areas where the total deposition rates are decreasing with time on interannual timescale. We expect a continuous increase in

  19. Broadband light trapping based on periodically textured ZnO thin films

    Science.gov (United States)

    Liu, Bofei; Liang, Xuejiao; Liang, Junhui; Bai, Lisha; Gao, Haibo; Chen, Ze; Zhao, Ying; Zhang, Xiaodan

    2015-05-01

    Transparent conductive front electrodes (TCFEs) deployed in photovoltaic devices have been extensively studied for their significance in transporting carriers, coupling and trapping the incident photons in high-performing solar cells. The trade-off between the light-transmission, electrical, and scattering properties for TCFEs to achieve a broadband improvement in light absorption in solar cells while maintaining a high electrical performance has become the key issue to be tackled. In this paper, we employ self-assembled polystyrene (PS) spheres based on a sauna-like method as a template, followed by a double-layer deposition and then successfully fabricate highly-transparent, well-conductive, and large-scale periodically-textured ZnO TCFEs with broadband light trapping properties. A sheet resistance below 15 Ω sq-1 was achieved for the periodically-textured ZnO TCFEs, with a concomitant average transmission of 81% (including the glass substrate) in the 400-1100 nm spectral range, a haze improvement in a broadband spectral range, and a wider scattering angular domain. The proposed approach affords a promising alternative method to prepare periodically-textured TCFEs, which are essential for many optoelectronic device semiconductors, such as photovoltaic and display applications.Transparent conductive front electrodes (TCFEs) deployed in photovoltaic devices have been extensively studied for their significance in transporting carriers, coupling and trapping the incident photons in high-performing solar cells. The trade-off between the light-transmission, electrical, and scattering properties for TCFEs to achieve a broadband improvement in light absorption in solar cells while maintaining a high electrical performance has become the key issue to be tackled. In this paper, we employ self-assembled polystyrene (PS) spheres based on a sauna-like method as a template, followed by a double-layer deposition and then successfully fabricate highly-transparent, well

  20. Light trapping in a 30-nm organic photovoltaic cell for efficient carrier collection and light absorption

    CERN Document Server

    Tsai, Cheng-Chia; Banerjee, Ashish; Osgood, Richard M; Englund, Dirk

    2012-01-01

    We describe surface patterning strategies that permit high photon-collection efficiency together with high carrier-collection efficiency in an ultra-thin planar heterojunction organic photovoltaic cell. Optimized designs reach up to 50% photon collection efficiency in a P3HT layer of only 30 nm, representing a 3- to 5-fold improvement over an unpatterned cell of the same thickness. We compare the enhancement of light confinement in the active layer with an ITO top layer for TE and TM polarized light, and demonstrate that the light absorption can increase by a factor of 2 due to a gap-plasmon mode in the active layer.

  1. High Energy Laboratory Astrophysics Experiments using electron beam ion traps and advanced light sources

    Science.gov (United States)

    Brown, Gregory V.; Beiersdorfer, Peter; Bernitt, Sven; Eberle, Sita; Hell, Natalie; Kilbourne, Caroline; Kelley, Rich; Leutenegger, Maurice; Porter, F. Scott; Rudolph, Jan; Steinbrugge, Rene; Traebert, Elmar; Crespo-Lopez-Urritia, Jose R.

    2015-08-01

    We have used the Lawrence Livermore National Laboratory's EBIT-I electron beam ion trap coupled with a NASA/GSFC microcalorimeter spectrometer instrument to systematically address problems found in the analysis of high resolution X-ray spectra from celestial sources, and to benchmark atomic physics codes employed by high resolution spectral modeling packages. Our results include laboratory measurements of transition energies, absolute and relative electron impact excitation cross sections, charge exchange cross sections, and dielectronic recombination resonance strengths. More recently, we have coupled to the Max-Plank Institute for Nuclear Physics-Heidelberg's FLASH-EBIT electron beam ion trap to third and fourth generation advanced light sources to measure photoexcitation and photoionization cross sections, as well as, natural line widths of X-ray transitions in highly charged iron ions. Selected results will be presented.

  2. Towards high efficiency thin-film crystalline silicon solar cells: The roles of light trapping and non-radiative recombinations

    Science.gov (United States)

    Bozzola, A.; Kowalczewski, P.; Andreani, L. C.

    2014-03-01

    Thin-film solar cells based on silicon have emerged as an alternative to standard thick wafers technology, but they are less efficient, because of incomplete absorption of sunlight, and non-radiative recombinations. In this paper, we focus on the case of crystalline silicon (c-Si) devices, and we present a full analytic electro-optical model for p-n junction solar cells with Lambertian light trapping. This model is validated against numerical solutions of the drift-diffusion equations. We use this model to investigate the interplay between light trapping, and bulk and surface recombination. Special attention is paid to surface recombination processes, which become more important in thinner devices. These effects are further amplified due to the textures required for light trapping, which lead to increased surface area. We show that c-Si solar cells with thickness of a few microns can overcome 20% efficiency and outperform bulk ones when light trapping is implemented. The optimal device thickness in presence of light trapping, bulk and surface recombination, is quantified to be in the range of 10-80 μm, depending on the bulk quality. These results hold, provided the effective surface recombination is kept below a critical level of the order of 100 cm/s. We discuss the possibility of meeting this requirement, in the context of state-of-the-art techniques for light trapping and surface passivation. We show that our predictions are within the capability of present day silicon technologies.

  3. Development of a novel trap for the collection of black flies of the Simulium ochraceum complex.

    Directory of Open Access Journals (Sweden)

    Mario A Rodríguez-Pérez

    Full Text Available BACKGROUND: Human landing collections are currently the standard method for collecting onchocerciasis vectors in Africa and Latin America. As part of the efforts to develop a trap to replace human landing collections for the monitoring and surveillance of onchocerciasis transmission, comprehensive evaluations of several trap types were conducted to assess their ability to collect Simulium ochraceum sensu lato, one of the principal vectors of Onchocerca volvulus in Latin America. METHODOLOGY/PRINCIPAL FINDINGS: Diverse trap designs with numerous modifications and bait variations were evaluated for their abilities to collect S. Ochraceum s.l. females. These traps targeted mostly host seeking flies. A novel trap dubbed the "Esperanza window trap" showed particular promise over other designs. When baited with CO2 and BG-lure (a synthetic blend of human odor components a pair of Esperanza window traps collected numbers of S. Ochraceum s.l. females similar to those collected by a team of vector collectors. CONCLUSIONS/SIGNIFICANCE: The Esperanza window trap, when baited with chemical lures and CO2 can be used to collect epidemiologically significant numbers of Simulium ochraceum s.l., potentially serving as a replacement for human landing collections for evaluation of the transmission of O. volvulus.

  4. Light trapping in thin film solar cells using photonic engineering device concepts

    Science.gov (United States)

    Mutitu, James Gichuhi

    In this era of uncertainty concerning future energy solutions, strong reservations have arisen over the continued use and pursuit of fossil fuels and other conventional sources of energy. Moreover, there is currently a strong and global push for the implementation of stringent measures, in order to reduce the amount of green house gases emitted by every nation. As a consequence, there has emerged a sudden and frantic rush for new renewable energy solutions. In this world of renewable energy technologies is where we find photovoltaic (PV) technology today. However, as is, there are still many issues that need to be addressed before solar energy technologies become economically viable and available to all people, in every part of the world. This renewed interest in the development of solar electricity, has led to the advancement of new avenues that address the issues of cost and efficiency associated with PV. To this end, one of the prominent approaches being explored is thin film solar cell (TFSC) technology, which offers prospects of lower material costs and enables larger units of manufacture than conventional wafer based technology. However, TFSC technologies suffer from one major problem; they have lower efficiencies than conventional wafer based solar cell technologies. This lesser efficiency is based on a number of reasons, one of which is that with less material, there is less volume for the absorption of incident photons. This shortcoming leads to the need for optical light trapping; which is concerned with admitting the maximum amount of light into the solar cell and keeping the light within the structure for as long as possible. In this thesis, I present the fundamental scientific ideas, practice and methodology behind the application of photonic engineering device concepts to increase the light trapping capacity of thin film solar cells. In the introductory chapters, I develop the basic ideas behind light trapping in a sequential manner, where the effects

  5. Plasmonic light trapping in an ultrathin photovoltaic layer with film-coupled metamaterial structures

    International Nuclear Information System (INIS)

    A film-coupled metamaterial structure is numerically investigated for enhancing the light absorption in an ultrathin photovoltaic layer of crystalline gallium arsenide (GaAs). The top subwavelength concave grating and the bottom metallic film could not only effectively trap light with the help of wave interference and magnetic resonance effects excited above the bandgap, but also practically serve as electrical contacts for photon-generated charge collection. The energy absorbed by the active layer is greatly enhanced with the help of the film-coupled metamaterial structure, resulting in significant improvement on the short-circuit current density by three times over a free-standing GaAs layer at the same thickness. The performance of the proposed light trapping structure is demonstrated to be little affected by the grating ridge width considering the geometric tolerance during fabrication. The optical absorption at oblique incidences also shows direction-insensitive behavior, which is highly desired for efficiently converting off-normal sunlight to electricity. The results would facilitate the development of next-generation ultrathin solar cells with lower cost and higher efficiency

  6. Light trapping and near-unity solar absorption in a three-dimensional photonic-crystal.

    Science.gov (United States)

    Kuang, Ping; Deinega, Alexei; Hsieh, Mei-Li; John, Sajeev; Lin, Shawn-Yu

    2013-10-15

    We report what is to our knowledge the first observation of the effect of parallel-to-interface-refraction (PIR) in a three-dimensional, simple-cubic photonic-crystal. PIR is an acutely negative refraction of light inside a photonic-crystal, leading to light-bending by nearly 90 deg over broad wavelengths (λ). The consequence is a longer path length of light in the medium and an improved light absorption beyond the Lambertian limit. As an illustration of the effect, we show near-unity total absorption (≥98%) in λ=520-620 nm and an average absorption of ~94% over λ=400-700 nm for our α-Si:H photonic-crystal sample of an equivalent bulk thickness of t˜=450 nm. Furthermore, we have achieved an ultra-wide angular acceptance of light over θ=0°-80°. This demonstration opens up a new door for light trapping and near-unity solar absorption over broad λs and wide angles.

  7. Electrically Tunable Absorption Enhancement with Spectral and Polarization Selectivity through Graphene Plasmonic Light Trapping

    Directory of Open Access Journals (Sweden)

    Wenbin Liu

    2016-08-01

    Full Text Available In this paper, anisotropic graphene plasmonic structures are explored for light trapping and absorption enhancement in surrounding media. It is shown that electrically tunable and versatile spectral and polarization selectivity can be realized. Particularly, it is possible to control absorption of the incident light’s polarization component at a specific wavelength by varying the Fermi energy with suitable geometric designs. It may find applications for new types of infrared and THz photodetectors and will promote the research of other novel polarization devices.

  8. Light traps fail to estimate reliable malaria mosquito biting rates on Bioko Island, Equatorial Guinea

    Directory of Open Access Journals (Sweden)

    Overgaard Hans J

    2012-02-01

    Full Text Available Abstract Background The human biting rate (HBR, an important parameter for assessing malaria transmission and evaluating vector control interventions, is commonly estimated by human landing collections (HLC. Although intense efforts have been made to find alternative non-exposure mosquito collection methods, HLC remains the standard for providing reliable and consistent HBRs. The aim of this study was to assess the relationship between human landing and light trap collections (LTC, in an attempt to estimate operationally feasible conversion factors between the two. The study was conducted as part of the operational research component of the Bioko Island Malaria Control Project (BIMCP, Equatorial Guinea. Methods Malaria mosquitoes were collected indoors and outdoors by HLCs and LTCs in three villages on Bioko Island, Equatorial Guinea during five bimonthly collections in 2009. Indoor light traps were suspended adjacent to occupied long-lasting, insecticide-treated bed nets. Outdoor light traps were placed close to the outer wall under the roof of the collection house. Collected specimens were subjected to DNA extraction and diagnostic PCR to identify species within the Anopheles gambiae complex. Data were analysed by simple regression of log-transformed values and by Bayesian regression analysis. Results There was a poor correlation between the two collection methods. Results varied by location, venue, month, house, but also by the statistical method used. The more robust Bayesian analyses indicated non-linear relationships and relative sampling efficiencies being density dependent for the indoor collections, implying that straight-forward and simple conversion factors could not be calculated for any of the locations. Outdoor LTC:HLC relationships were weak, but could be estimated at 0.10 and 0.07 for each of two locations. Conclusions Light trap collections in combination with bed nets are not recommended as a reliable method to assess human

  9. Disorder-induced light trapping enhanced by pulse collisions in one-dimensional nonlinear photonic crystals

    CERN Document Server

    Novitsky, Denis

    2015-01-01

    We use numerical simulations to study interaction of co- and counter-propagating pulses in disordered multilayers with noninstantaneous Kerr nonlinearity. We propose a statistical argument for existence of the disorder-induced trapping which implies the dramatic rise of the probability of realization with low output energy in the structure with a certain level of disorder. This effect is much more pronounced in the case of two interacting pulses than in the single-pulse regime and does not occur in the strictly ordered system at the same intensity of the pulses. Therefore it cannot be explained simply as a result of increase in strength of nonlinear light-matter interaction.

  10. Testing and optical modeling of novel concentrating solar receiver geometries to increase light trapping and effective solar absorptance

    Science.gov (United States)

    Yellowhair, Julius; Ho, Clifford K.; Ortega, Jesus D.; Christian, Joshua M.; Andraka, Charles E.

    2015-09-01

    Concentrating solar power receivers are comprised of panels of tubes arranged in a cylindrical or cubical shape on top of a tower. The tubes contain heat-transfer fluid that absorbs energy from the concentrated sunlight incident on the tubes. To increase the solar absorptance, black paint or a solar selective coating is applied to the surface of the tubes. However, these coatings degrade over time and must be reapplied, which reduces the system performance and increases costs. This paper presents an evaluation of novel receiver shapes and geometries that create a light-trapping effect, thereby increasing the effective solar absorptance and efficiency of the solar receiver. Several prototype shapes were fabricated from Inconel 718 and tested in Sandia's solar furnace at an irradiance of ~30 W/cm2. Photographic methods were used to capture the irradiance distribution on the receiver surfaces. The irradiance profiles were compared to results from raytracing models. The effective solar absorptance was also evaluated using the ray-tracing models. Results showed that relative to a flat plate, the new geometries could increase the effective solar absorptance from 86% to 92% for an intrinsic material absorptance of 86%, and from 60% to 73% for an intrinsic material absorptance of 60%.

  11. Physics and Chemistry in Laser—Trapped Single Microparticles Studied by Light Scattering

    Institute of Scientific and Technical Information of China (English)

    W.Kiefer; M.Lankers; 等

    1995-01-01

    In this lecture various physical and chemical aspects are discussed when single particles of the size of the faserwavelength are trapped in strongly focused laser beams.First,we describe varius possibilities for the trapping techniques and micro-Raman setups.Then we discuss Raman-Mie-scattering and morphology dependent resonances which occur in dielectric spherical microparticles.These particles react as microresonators and influence the Raman spectra senerating input and output resonances.The electric field distribution inside and outside the dielectric microsphere in and out of resonance have been calcuated quantitatively to explain the input resonances.We also report on observed fast temperature jumps when microdroplets undergo an input resonance.Applications of these combined inelastic/elastic light scattring studies will be shown for microdroplet evaporation and for chemical studies such as simple acid/base reactions in a microdroplet,Furthermore we show results of recent studies on the emulsion polymerization process of styrene by applying a gradient force trap in a microscope.

  12. Plasmonic Light Trapping in an Ultrathin Photovoltaic Layer with Film-Coupled Metamaterial Structures

    CERN Document Server

    Wang, Hao

    2014-01-01

    A film-coupled metamaterial structure is numerically investigated for enhancing the light absorption in an ultrathin photovoltaic layer of crystalline gallium arsenide (GaAs). The top subwavelength concave grating and the bottom metallic film could not only effectively trap light with the help of wave interference and magnetic resonance effects excited above the bandgap, but also practically serve as electrical contacts for photon-generated charge collection. The energy absorbed by the active layer is greatly enhanced in the film-coupled metamaterial structure, resulting in significant enhancement on the short-circuit current density by three times over a free-standing GaAs layer at the same thickness. The results would facilitate the development of next-generation ultrathin solar cells with lower cost and higher efficiency.

  13. Control of light trapping in a large atomic system by a static magnetic field

    CERN Document Server

    Skipetrov, S E; Havey, M D

    2016-01-01

    We propose to control light trapping in a large ensemble of cold atoms by an external, static magnetic field. For an appropriate choice of frequency and polarization of the exciting pulse, the field is expected to speed up the fluorescence of a dilute atomic system but can significantly slow it down in a dense ensemble. The slowing down of fluorescence is due to the excitation of spatially localized collective atomic states that appear only under a strong magnetic field and have exponentially long lifetimes. The control of fluorescence by the magnetic field may be of interest for use in future quantum-information processing devices. It also paves a way towards the experimental observation of the disorder-induced localization of light in cold atomic systems.

  14. Unexpected Attraction of Polarotactic Water-Leaving Insects to Matt Black Car Surfaces: Mattness of Paintwork Cannot Eliminate the Polarized Light Pollution of Black Cars

    OpenAIRE

    Miklos Blaho; Tamas Herczeg; Gyorgy Kriska; Adam Egri; Denes Szaz; Alexandra Farkas; Nikolett Tarjanyi; Laszlo Czinke; Andras Barta; Gabor Horvath

    2014-01-01

    The horizontally polarizing surface parts of shiny black cars (the reflection-polarization characteristics of which are similar to those of water surfaces) attract water-leaving polarotactic insects. Thus, shiny black cars are typical sources of polarized light pollution endangering water-leaving insects. A new fashion fad is to make car-bodies matt black or grey. Since rough (matt) surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt ...

  15. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, Y. [Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, High Tech Campus, Building 21, 5656 AE Eindhoven (Netherlands); Department of Applied Physics, Plasma & Materials Processing, Eindhoven University of Technology (TUE), P.O. Box 513, 5600 MB Eindhoven (Netherlands); Lare, M. C. van; Polman, A. [Center for Nanophotonics, FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam (Netherlands); Veldhuizen, L. W.; Schropp, R. E. I., E-mail: r.e.i.schropp@tue.nl [Department of Applied Physics, Plasma & Materials Processing, Eindhoven University of Technology (TUE), P.O. Box 513, 5600 MB Eindhoven (Netherlands); Rath, J. K. [Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, High Tech Campus, Building 21, 5656 AE Eindhoven (Netherlands)

    2015-11-14

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  16. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    International Nuclear Information System (INIS)

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials

  17. Light trapping above the light cone in one-dimensional array of dielectric spheres

    CERN Document Server

    Bulgakov, Evgeny N

    2015-01-01

    We demonstrate bound states in the first TE and TM diffraction continua (BSC) in a linear periodic array of dielectric spheres in air above the light cone. We classify the BSCs according to the symmetry specified by the azimuthal number $m$, the Bloch wave vector $\\beta$ directed along the array, and polarization. The most simple symmetry protected TE and TM polarized BSCs have $m=0$ and $\\beta=0$ and occur in a wide range of the radius of the spheres and dielectric constant. More complicated BSCs with $m\

  18. Spectral and directional dependence of light-trapping in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ulbrich, Carolin

    2011-02-17

    This thesis investigates the directional and spectral dependence of light-incoupling and light-trapping in solar cells. The light-trapping does not notably change under increased angles of incidence. To enhance the incoupling at the front of the solar cell, the effects of a textured surface structure on the cover glass of the solar cell are investigated. The texture reduces the reflectance at the air-glass interface and, additionally, reduces the reflection losses originating at the interface between the glass and the transparent conductive oxide (TCO) as well as the TCO and the silicon (Si) absorber due to the randomization of light. On samples without a textured TCO/Si interface, the textured foil induces additional light-trapping in the photovoltaically active absorber material. This effect is not observed for samples with a textured TCO/Si interface. In this case, using tandem solar cells, a redistribution of light absorption in the top and bottom subcells is detected. The antireflective texture increases the short circuit current density in thin film silicon tandem solar cells by up to 1 mA/cm{sup 2}, and the conversion efficiency by up to 0.7 % absolute. The increase in the annual yield of solar cells is estimated to be up to 10 %. Further, the spectral dependence of the efficiency and annual yield of a tandem solar cell was investigated. The daily variation of the incident spectrum causes a change in the current matching of the serial connected subcells. Simulations determine the optimum subcell layer thicknesses of tandem solar cells. The thicknesses optimized in respect to the annual yield overlap in a wide range for both investigated locations with those for the AM1.5g standard spectrum. Though, a slight top limitation is favorable. Matching the short circuit currents of the subcells maximizes the overall current, but minimizes the fill factor. This thesis introduces a new definition for the matching condition of tandem solar cells. This definition

  19. Resonant scattering of light in a near-black-hole metric

    CERN Document Server

    Stadnik, Y V; Flambaum, V V; Berengut, J C

    2012-01-01

    We show that low-energy photon scattering from a body with radius $R$ slightly larger than its Schwarzschild radius $r_s$ resembles black-hole absorption. This absorption occurs via capture to one of the many long-lived, densely packed resonances that populate the continuum. The lifetimes and density of these meta-stable states tend to infinity in the limit $r_s \\to R$. We determine the energy averaged cross-section for particle capture into these resonances and show that it is equal to the absorption cross-section for a Schwarzschild black hole. Thus, a non-singular static metric may trap photons for arbitrarily long times, making it appear completely `black' before the actual formation of a black hole.

  20. Designing dye-nanochannel antenna hybrid materials for light harvesting, transport and trapping.

    Science.gov (United States)

    Calzaferri, Gion; Méallet-Renault, Rachel; Brühwiler, Dominik; Pansu, Robert; Dolamic, Igor; Dienel, Thomas; Adler, Pauline; Li, Huanrong; Kunzmann, Andreas

    2011-02-25

    We discuss artificial photonic antenna systems that are built by incorporating chromophores into one-dimensional nanochannel materials and by organizing the latter in specific ways. Zeolite L (ZL) is an excellent host for the supramolecular organization of different kinds of molecules and complexes. The range of possibilities for filling its one-dimensional channels with suitable guests has been shown to be much larger than one might expect. Geometrical constraints imposed by the host structure lead to supramolecular organization of the guests in the channels. The arrangement of dyes inside the ZL channels is what we call the first stage of organization. It allows light harvesting within the volume of a dye-loaded ZL crystal and also the radiationless transport of energy to either the channel ends or center. One-dimensional FRET transport can be realized in these guest-host materials. The second stage of organization is realized by coupling either an external acceptor or donor stopcock fluorophore at the ends of the ZL channels, which can then trap or inject electronic excitation energy. The third stage of organization is obtained by interfacing the material to an external device via a stopcock intermediate. A possibility to achieve higher levels of organization is by controlled assembly of the host into ordered structures and preparation of monodirectional materials. The usually strong light scattering of ZL can be suppressed by refractive-index matching and avoidance of microphase separation in hybrid polymer/dye-ZL materials. The concepts are illustrated and discussed in detail on a bidirectional dye antenna system. Experimental results of two materials with a donor-to-acceptor ratio of 33:1 and 52:1, respectively, and a three-dye system illustrate the validity and challenges of this approach for synthesizing dye-nanochannel hybrid materials for light harvesting, transport, and trapping.

  1. Characterization and FDTD simulation analysis on light trapping structures of amorphous silicon thin films by laser irradiation

    Science.gov (United States)

    Huang, Lu; Jin, Jing; Yuan, Zhijun; Yang, Weiguang; Wang, Linjun; Shi, Weimin; Zhou, Jun; Lou, Qihong

    2016-05-01

    The effect of laser energy density on the light-trapping structures of amorphous silicon (α-Si) thin films is studied both theoretically and experimentally. The thin films are irradiated by a frequency-doubled (λ = 532 nm) Nd:YAG pulsed nanosecond laser. An effective finite difference time domain (FDTD) model is built to find the optimized laser energy density (EL) for the light trapping structures of α-Si. Based on the simulation analysis, it shows the variation of reflection spectra with laser energy density. The optimized reflection spectra at EL = 1000 mJ/cm2 measured by UV-visible spectroscopy confirms to agree well with that corresponding to the depth to diameter ratio (h/D) in the FDTD simulation. The surface morphology characterization by optical microscope (OM) and scanning electron microscope (SEM) accords fairly well to of light-trapping modeling in the simulation.

  2. Dipolar and Quadrupolar Modes of Si02/Au Nanoshell Enhanced Light Trapping in Thin Film Solar Cells

    Institute of Scientific and Technical Information of China (English)

    BAI Yi-Ming; WANG Jun; CHEN Nuo-Fu; YAO Jian-Xi; ZHANG Xing-Wang; YIN Zhi-Gang; ZHANG Han; HUANG Tian-Mao

    2011-01-01

    @@ Dipolar and quadrupolar resonance wavelengths of SiO2/Au nanoshell surface plasmons are designed at 560nm to enhance the light trapping in thin film solar cells.In order to quantitatively describe the light trapping effect,the forward-scattering efficiency(FSE)and the light trapping efficiency(LTE) are proposed by considering the light scattering direction of SiO2/Au nanoshells.Based on the Mie theory, the FSE and the LTE are calculated for SiO2/Au nanoshells of different dimensions, and the contributions of the dipolar and quadrupolar modes to the light trapping effect are analyzed in detail.When the surface coverage of nanoshells is 5%, the LTEs are 21.7% and 46.9% for SiO2/Au nanoshells with sizes of(31 nm, 69nm) and(53nm, 141 nm), respectively.The results indicate that the SiO2/Au nanoshell whose quadrupolar mode peak is designed to the strongest solar energy flux density of the solar spectrum facilitates the further enhancement of light harvesting in thin film solar cells.

  3. Controlled transportation of mesoscopic particles by enhanced spin orbit interaction of light in an optical trap

    CERN Document Server

    Roy, Basudev; Panigrahi, Prasanta K; Roy, Soumyajit; Banerjee, Ayan

    2012-01-01

    Optical spin orbit interaction (SOI) causes an intrinsic coupling between the polarization and position of light and is manifested as a sub-wavelength effect in isotropic and inhomogeneous (stratified) media. We investigate the effects of SOI in an optical trap and demonstrate that the SOI for a tightly focused polarized laser beam in stratified media (as is found in an optical trap) depends on the thickness of the media, and can be magnified significantly by choosing slightly thicker cover slips than that used conventionally. A polarization analysis of the stratified media in the sample chamber shows the presence of spatially varying linear diattenuation terms in the Mueller matrix that result in a polarization dependent intensity profile. It is thus possible to controllably transport asymmetric particles having a well-defined optic axis by simply changing the polarization angle of a linearly polarized input beam. Pea-pod shaped single soft oxometalate (SOM) particles of dimension around 1 $\\mu$m have been m...

  4. Fiber-comb-stabilized light source at 556 nm for magneto-optical trapping of ytterbium

    CERN Document Server

    Yasuda, Masami; Inaba, Hajime; Nakajima, Yoshiaki; Hosaka, Kazumoto; Onae, Atsushi; Hong, Feng-Lei

    2010-01-01

    A frequency-stabilized light source emitting at 556 nm is realized by frequency-doubling a 1112-nm laser, which is phase-locked to a fiber-based optical frequency comb. The 1112-nm laser is either an ytterbium (Yb)-doped distributed feedback fiber laser or a master-slave laser system that uses an external cavity diode laser as a master laser. We have achieved the continuous frequency stabilization of the light source over a five-day period. With the light source, we have completed the second-stage magneto-optical trapping (MOT) of Yb atoms using the 1S0 - 3P1 intercombination transition. The temperature of the ultracold atoms in the MOT was 40 uK when measured using the time-of-flight method, and this is sufficient for loading the atoms into an optical lattice. The fiber-based frequency comb is shown to be a useful tool for controlling the laser frequency in cold-atom experiments.

  5. Light-trapping design for thin-film silicon-perovskite tandem solar cells

    Science.gov (United States)

    Foster, Stephen; John, Sajeev

    2016-09-01

    Using finite-difference time-domain simulations, we investigate the optical properties of tandem silicon/perovskite solar cells with a photonic crystal architecture, consisting of a square-lattice array of inverted pyramids with a center-to-center spacing of 2.5 μm. We demonstrate that near-perfect light-trapping and absorption can be achieved over the 300-1100 nm wavelength range with this architecture, using less than 10 μm (equivalent bulk thickness) of crystalline silicon. Using a one-diode model, we obtain projected efficiencies of over 30% for the two-terminal tandem cell under a current-matching condition, well beyond the current record for single-junction silicon solar cells. The architecture is amenable to mass fabrication through wet-etching and uses a fraction of the silicon of traditional designs, making it an attractive alternative to other silicon-perovskite tandem designs.

  6. Light trapping in an ensemble of pointlike impurity centers in a Fabry-Perot cavity

    Science.gov (United States)

    Kuraptsev, A. S.; Sokolov, I. M.

    2016-08-01

    We report the development of quantum microscopic theory of quasiresonant dipole-dipole interaction in the ensembles of impurity atoms imbedded into transparent dielectric and located in a Fabry-Perot cavity. On the basis of the general approach we study the simultaneous influence of the cavity and resonant dipole-dipole interaction on the shape of the line of atomic transition as well as on light trapping in dense impurity ensembles. We analyze this influence depending on the size of the ensemble, its density, as well as on rms deviation of the transition frequency shifts caused by the symmetry disturbance of the internal fields of the dielectric medium. Obtained results are compared with the case when the cavity is absent. We show that the cavity can essentially modify cooperative polyatomic effects.

  7. Light trapping in an ensemble of point-like impurity centers in Fabry-Perot cavity

    CERN Document Server

    Kuraptsev, A S

    2016-01-01

    We report the development of quantum microscopic theory of quasi-resonant dipole-dipole interaction in the ensembles of impurity atoms imbedded into transparent dielectric and located into Fabry-Perot cavity. On the basis of the general approach we study the simultaneous influence of the cavity and resonant dipole-dipole interaction on the shape of the line of atomic transition as well as on light trapping in dense impurity ensembles. We analyze this influence depending on the size of the ensemble, its density, as well as on r.m.s. deviation of the transition frequency shifts caused by the symmetry disturbance of the internal fields of the dielectric medium. Obtained results are compared with the case when the cavity is absent. We show that the cavity can essentially modify cooperative polyatomic effects.

  8. Printed light-trapping nanorelief Cu electrodes for full-solution-processed flexible organic solar cells

    Science.gov (United States)

    Li, Kan; Zhang, Yaokang; Zhen, Hongyu; Niu, Liyong; Fang, Xu; Liu, Zhike; Yan, Feng; Shen, Weidong; Li, Haifeng; Zheng, Zijian

    2016-07-01

    Light-trapping nanorelief metal electrodes have been proven to be an effective approach to improve the absorption performance of flexible organic solar cells (FOSCs). These nanorelief electrodes have been made by conventional vacuum deposition techniques, which are difficult to integrate with roll-to-roll fabrication processes. To address this challenge, this paper reports, for the first time, the fabrication of highly conductive nanorelief Cu electrodes on the flexible substrates through solution printing and polymer-assisted metal deposition at room temperature in the air. FOSCs made with these printed nanorelief Cu electrodes possess not only much improved power conversion efficiency, by 13.5%, but also significant enhancement in flexibility when compared with those made with flat Cu electrodes. Because of the low material and fabrication cost, these printed nanorelief Cu electrodes show great promise in roll-to-roll fabrication of FOSCs in the future.

  9. Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates

    Science.gov (United States)

    de Jong, M. M.

    2013-01-01

    In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic substrates can be a solution. In this thesis, we investigate the possibilities of depositing thin film solar cells directly onto cheap plastic substrates. Micro-textured glass and sheets, which have a wide range of applications, such as in green house, lighting etc, are applied in these solar cells for light trapping. Thin silicon films can be produced by decomposing silane gas, using a plasma process. In these types of processes, the temperature of the growing surface has a large influence on the quality of the grown films. Because plastic substrates limit the maximum tolerable substrate temperature, new methods have to be developed to produce device-grade silicon layers. At low temperature, polysilanes can form in the plasma, eventually forming dust particles, which can deteriorate device performance. By studying the spatially resolved optical emission from the plasma between the electrodes, we can identify whether we have a dusty plasma. Furthermore, we found an explanation for the temperature dependence of dust formation; Monitoring the formation of polysilanes as a function of temperature using a mass-spectrometer, we observed that the polymerization rate is indeed influenced by the substrate temperature. For solar cell substrate material, our choice was polycarbonate (PC), because of its low cost, its excellent transparency and its relatively high glass transition temperature of 130-140°C. At 130°C we searched for deposition recipes for device quality silicon, using a very high frequency plasma enhanced chemical deposition process. By diluting the feedstock silane with hydrogen gas, the silicon quality can be improved for amorphous silicon (a-Si), until we reach the

  10. Perfect light trapping in nanoscale thickness semiconductor films with resonant back reflector and spectrum-splitting structures

    CERN Document Server

    Liu, Jiang-Tao; Yang, Wen; Li, Jun

    2014-01-01

    The optical absorption of nanoscale thickness semiconductor films on top of light-trapping structures based on optical interference effects combined with spectrum-splitting structures is theoretically investigated. Nearly perfect absorption over a broad spectrum range can be achieved in $<100$ nm thick films on top of one-dimensional photonic crystal or metal films. This phenomenon can be attributed to interference induced photonic localization, which enhances the absorption and reduces the reflection of the films. Perfect solar absorption and low carrier thermalization loss can be achieved when the light-trapping structures with wedge-shaped spacer layer or semiconductor films are combined with spectrum-splitting structures.

  11. Light trapping in ultrathin 25  μm exfoliated Si solar cells.

    Science.gov (United States)

    Hilali, Mohamed M; Saha, Sayan; Onyegam, Emmanuel; Rao, Rajesh; Mathew, Leo; Banerjee, Sanjay K

    2014-09-20

    The optical absorption in 25-μm-thick, single-crystal Si foils fabricated using a novel exfoliation technique for solar cells is studied and improved in this work. Various light-trapping and optical absorption enhancement schemes implemented show that it is possible to substantially narrow the gap in optical absorption loss between the 25 μm Si foils and industry-standard 180-μm-thick Si wafer solar cells. An improvement of absorption by 58% in the near-infrared (740-1200 nm) range is observed for the 25 μm monocrystalline Si substrates with the use of antireflective coating and texturing. The back reflectance of the metal foil that provides mechanical support to the ultrathin Si semiconductor-on-metal foils is extracted to be ∼51.5%, based on the reflectance matching with the simulated escape reflectance in the sub-bandgap region. The back reflectance is enhanced to ∼58% by incorporating an intermediate silicon nitride layer on the back between the Si and the metal. The incorporation of Al as an improved metal reflector on top of the silicon nitride at the backside of the solar cell results in a 5.8 times enhancement in optical path length as a consequence of the improved effective back reflectance of ∼95%. A thin Si foil solar cell with an unoptimized amorphous Si/crystalline Si heterojunction with intrinsic-thin-layer design with implementation of such light-trapping schemes shows an efficiency of 13.28% with a short-circuit current density (JSC) of 35.97  mA/cm2, which approaches the JSC of industrial wafer-based Si solar cells. PMID:25322089

  12. OZONE UPTAKE OF DIFFERENT-SIZED BLACK CHERRY TREES IN HIGH- AND LOW-LIGHT ENVIRONMENTS

    Science.gov (United States)

    Ozone uptake rates of different-sized black cherry trees located in both high and low light environments were calculated from measurements of ambient ozone concentration and stomatal conductance. he objective of the study was to determine how tree size and light conditions may di...

  13. The Effects on Visually Impaired Children of Viewing Fluorescent Stimuli under Black-Light Conditions.

    Science.gov (United States)

    LaGrow, S. J.; Leung, J-P.; Leung, S.; Yeung, P.

    1998-01-01

    This study compared effects of four visual conditions of stimuli and light on the visual performance of 30 children with low vision (divided into high, and low, visual-acuity groups). Orange stimuli viewed under black light resulted in the best overall performance, benefitted the low-acuity group more than the high-acuity group, and was the…

  14. Glad nanostructured arrays with enhanced carrier collection and light trapping for photoconductive and photovoltaic device applications

    Science.gov (United States)

    Cansizoglu, Hilal

    Solar energy harvesting has been of great interest for researchers over the past 50 years. Main emphasis has been on developing high quality materials with low defect density and proper band gaps. However, high cost of bulk materials and insufficient light absorption in thin films led to utilization of semiconductor nanostructures in photovoltaics and photonics. Light trapping abilities of nanostructures can provide high optical absorption whereas core/shell nanostructured arrays can allow enhanced charge carrier collection. However, most of the nanofabrication methods that can produce uniform nanostructure geometries are limited in materials, dimensions, and not compatible with industrial production systems. Therefore, it is essential to develop innovative low-cost fabrication approaches that can address these issues. The primary goal of this project is to investigate light trapping and carrier collection properties of glancing angle deposited (GLAD) nanostructured arrays for high-efficiency, low-cost photoconductive and photovoltaic devices using characterization techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy and time resolved photocurrent measurements. Indium sulfide (In2S3) has been chosen as a model material system in this study. GLAD nanostructured arrays of vertical rods, screws, springs, zigzags and tilted rods were fabricated and characterized. A strong dependence of optical absorption on the shapes of nanostructures is observed from UV-vis-NIR spectroscopy. A simulation study using finite difference time domain (FDTD) shows that introducing 3D geometry results in diffuse scattering of light and leads to high optical absorption. Monte Carlo simulations were conducted to determine a simple and scalable fabrication technique for conformal and uniform shell coatings. The results suggest that an atomic flux with angular distribution, which can be

  15. The Eye of the Storm: Light from the Inner Plunging Region of Black Hole Accretion Discs

    CERN Document Server

    Zhu, Yucong; Narayan, Ramesh; Kulkarni, Akshay K; Penna, Robert F; McClintock, Jeffrey E

    2012-01-01

    It is generally thought that the light coming from the inner plunging region of black hole accretion discs contributes negligibly to the disc's overall spectrum, i.e. the plunging fluid is swallowed by the black hole before it has time to radiate. In the standard disc model used to fit X-ray observations of accretion discs, the plunging region is assumed to be perfectly dark. However, numerical simulations that include the full physics of the magnetized flow predict that a small fraction of the disc's total luminosity emanates from this plunging region. In this work, we investigate the observational consequences of this neglected inner light. We compute radiative transfer based disc spectra that correspond to 3D general relativistic magnetohydrodynamic simulated discs (which produce light inside their plunging regions). In the context of black hole spin estimation, we find that this neglected inner light only has a modest effect (this bias is less than typical observational systematic errors). For rapidly spi...

  16. Coupled optical-thermal-fluid and structural analyses of novel light-trapping tubular panels for concentrating solar power receivers

    Science.gov (United States)

    Ortega, Jesus D.; Christian, Joshua M.; Yellowhair, Julius E.; Ho, Clifford K.

    2015-09-01

    Traditional tubular receivers used in concentrating solar power are formed using tubes connected to manifolds to form panels; which in turn are arranged in cylindrical or rectangular shapes. Previous and current tubular receivers, such as the ones used in Solar One, Solar Two, and most recently the Ivanpah solar plants, have used a black paint coating to increase the solar absorptance of the receiver. However, these coatings degrade over time and must be reapplied, increasing the receiver maintenance cost. This paper presents the thermal efficiency evaluation of novel receiver tubular panels that have a higher effective solar absorptance due to a light-trapping effect created by arranging the tubes in each panel into unique geometric configurations. Similarly, the impact of the incidence angle on the effective solar absorptance and thermal efficiency is evaluated. The overarching goal of this work is to achieve effective solar absorptances of ~90% and thermal efficiencies above 85% without using an absorptance coating. Several panel geometries were initially proposed and were down-selected based on structural analyses considering the thermal and pressure loading requirements of molten salt and supercritical carbon-dioxide receivers. The effective solar absorptance of the chosen tube geometries and panel configurations were evaluated using the ray-tracing modeling capabilities of SolTrace. The thermal efficiency was then evaluated by coupling computational fluid dynamics with the ray-tracing results using ANSYS Fluent. Compared to the base case analysis (flat tubular panel), the novel tubular panels have shown an increase in effective solar absorptance and thermal efficiency by several percentage points.

  17. 3D micromanipulation at low numerical aperture with a single light beam: the focused-Bessel trap.

    Science.gov (United States)

    Ayala, Yareni A; Arzola, Alejandro V; Volke-Sepúlveda, Karen

    2016-02-01

    Full-three-dimensional (3D) manipulation of individual glass beads with radii in the range of 2-8 μm is experimentally demonstrated by using a single Bessel light beam focused through a low-numerical-aperture lens (NA=0.40). Although we have a weight-assisted trap with the beam propagating upward, we obtain a stable equilibrium position well away from the walls of the sample cell, and we are able to move the particle across the entire cell in three dimensions. A theoretical analysis for the optical field and trapping forces along the lateral and axial directions is presented for the focused-Bessel trap. This trap offers advantages for 3D manipulation, such as an extended working distance, a large field of view, and reduced aberrations. PMID:26907437

  18. Long-wave UV light fluorescence for identification of black-pigmented Bacteroides spp.

    OpenAIRE

    Slots, J; Reynolds, H S

    1982-01-01

    Black-pigmented Bacteroides strains were grown on blood agar, and the colonies were evaluated for fluorescence from long-wave UV light. Most test strains of Bacteroides melaninogenicus subsp. intermedius exhibited a brilliant red fluorescence. B. melaninogenicus subsp. melaninogenicus fluoresced mostly red-orange. Bacteroides asaccharolyticus showed a yellow or red fluorescence. The intensity of the Bacteroides fluorescence weakened when the black pigment of the colonies developed. In contras...

  19. Black holes and closed trapped surfaces a revision of a classic theorem

    CERN Document Server

    Claudel, C M

    2000-01-01

    It is standard assertion in relativity that, subject to an energy condition and the cosmic censorship hypothesis, closed trapped surfaces are not visible from future null infinity. A proof given by Hawking & Ellis in ''The Large Scale Structure of Space-Time'' is flawed since it is formulated in terms of an inadequate definition of a weakly asymptotically simple and empty space-time. A new proof is given based on a more restrictive definition of a weakly asymptotically simple and empty space-time.

  20. Light trapping and absorption optimization in certain thin-film photonic crystal architectures

    Science.gov (United States)

    Chutinan, Alongkarn; John, Sajeev

    2008-08-01

    We demonstrate two orders of magnitude enhancement of light absorption in certain thin-film photonic crystal (PC) architectures due to strong resonances arising from parallel interface refraction (PIR). This anomalous type of refraction is acutely negative and usually out of the plane of incidence. Over a wide range of frequencies, light impinging on idealized two-dimensional (2D) thin-film photonic crystals, over a cone of at least 20° in off-normal directions, couples to Bloch modes propagating nearly parallel to the thin-film-to-air interface. For realistic three-dimensional PC films of cubic symmetry, synthesized by photoelectrochemical etching, the PIR effect persists over a spectral range of at least 15% relative to the center frequency and within a cone of 50° of incident angles, normal to the film. This leads to anomalously long optical path lengths and long dwell times before the light beam exits the thin film. This near continuum of high-quality-factor optical resonances, associated with “transverse optical slow modes” in a spectral range of high electromagnetic density of states, can be much more effective for trapping and absorbing light than that of the previously reported longitudinal slow-group-velocity effects. The parallel interface refraction effect is general and can be found in specific spectral ranges of both 2D and 3D photonic crystals with cubic or other appropriate symmetries. In the presence of weak optical absorption within the PC backbone, energy conversion enhancement is interpreted using a simple temporal mode-coupling model. It is shown that absorption is optimized when the structural quality factor (in the absence of absorption) of the transverse optical slow modes is comparable to ωτabs , where ω is the optical frequency and τabs is the absorption time scale of the film material. Quantitative numerical results for light harvesting efficiency are obtained by finite-difference time-domain simulations of the electromagnetic

  1. Black lead molybdate nanoparticles: Facile synthesis and photocatalytic properties responding to visible light

    Energy Technology Data Exchange (ETDEWEB)

    Du, Weimin, E-mail: duweimin75@gmail.com [College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000 (China); Liu, Lixin; Zhou, Keke; Ma, Xiaodan; Hao, Yaming [College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000 (China); Qian, Xuefeng [School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-02-15

    Graphical abstract: - Highlights: • Black lead molybdate (PbMoO{sub 4}) nanoparticles were first synthesized. • A novel energy band structure leads to better absorption of visible light. • Black PbMoO{sub 4} nanoparticles have better visible-light-responsive photocatalytic activities. • It has better applied prospects in conversion and utilization of solar energy. - Abstract: Black lead molybdate (PbMoO{sub 4}) nanoparticles were first synthesized by the glycol–solvothermal method. Phase, morphology, crystal lattice, and specific surface of products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller nitrogen adsorption–desorption, respectively. Results revealed that the as-synthesized PbMoO{sub 4} nanoparticles are the scheelite-type tetragonal structure with 30–50 nm in size. Also, glycol played a dual function in present synthetic system: solvent and surface modification agent. Optical properties reveal glycol-modification on the surface of PbMoO{sub 4} nanoparticles can generate new energy level between the original conduction band and valence band, leading to better absorption of visible light and the black appearance. Photocatalytic experimental results demonstrate that black PbMoO{sub 4} nanoparticles synthesized in glycol medium have pretty visible-light-responsive photocatalytic degradation performance on methylene blue and phenol solution. Reaction mechanism investigations show that the excellent photocatalytic activities of black PbMoO{sub 4} nanoparticles derive from the novel energy band structure, smaller size, and larger specific surface area. Hence one can see that black PbMoO{sub 4} nanoparticles are a type of visible-light-responsive photocatalysts with excellent photocatalytic activities and potentially applied prospects in dye wastewater treatment and environmental protection. Meanwhile, the present work provides an innovative strategy for adjusting

  2. Black lead molybdate nanoparticles: Facile synthesis and photocatalytic properties responding to visible light

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Black lead molybdate (PbMoO4) nanoparticles were first synthesized. • A novel energy band structure leads to better absorption of visible light. • Black PbMoO4 nanoparticles have better visible-light-responsive photocatalytic activities. • It has better applied prospects in conversion and utilization of solar energy. - Abstract: Black lead molybdate (PbMoO4) nanoparticles were first synthesized by the glycol–solvothermal method. Phase, morphology, crystal lattice, and specific surface of products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller nitrogen adsorption–desorption, respectively. Results revealed that the as-synthesized PbMoO4 nanoparticles are the scheelite-type tetragonal structure with 30–50 nm in size. Also, glycol played a dual function in present synthetic system: solvent and surface modification agent. Optical properties reveal glycol-modification on the surface of PbMoO4 nanoparticles can generate new energy level between the original conduction band and valence band, leading to better absorption of visible light and the black appearance. Photocatalytic experimental results demonstrate that black PbMoO4 nanoparticles synthesized in glycol medium have pretty visible-light-responsive photocatalytic degradation performance on methylene blue and phenol solution. Reaction mechanism investigations show that the excellent photocatalytic activities of black PbMoO4 nanoparticles derive from the novel energy band structure, smaller size, and larger specific surface area. Hence one can see that black PbMoO4 nanoparticles are a type of visible-light-responsive photocatalysts with excellent photocatalytic activities and potentially applied prospects in dye wastewater treatment and environmental protection. Meanwhile, the present work provides an innovative strategy for adjusting the energy band structure of wide band

  3. Evolution of light trapped by a soliton in a microstructured fiber

    CERN Document Server

    Hill, S; Leonhardt, U; Koenig, F

    2009-01-01

    We observe the dynamics of pulse trapping in a microstructured fiber. Few-cycle pulses create a system of two pulses: a Raman shifting soliton traps a pulse in the normal dispersion regime. When the soliton approaches a wavelength of zero group velocity dispersion the Raman shifting abruptly terminates and the trapped pulse is released. In particular, the trap is less than 4ps long and contains a 1ps pulse. After being released, this pulse asymmetrically expands to more than 10ps. Additionally, there is no disturbance of the trapping dynamics at high input pulse energies as the supercontinuum develops further.

  4. Unexpected attraction of polarotactic water-leaving insects to matt black car surfaces: mattness of paintwork cannot eliminate the polarized light pollution of black cars.

    Science.gov (United States)

    Blaho, Miklos; Herczeg, Tamas; Kriska, Gyorgy; Egri, Adam; Szaz, Denes; Farkas, Alexandra; Tarjanyi, Nikolett; Czinke, Laszlo; Barta, Andras; Horvath, Gabor

    2014-01-01

    The horizontally polarizing surface parts of shiny black cars (the reflection-polarization characteristics of which are similar to those of water surfaces) attract water-leaving polarotactic insects. Thus, shiny black cars are typical sources of polarized light pollution endangering water-leaving insects. A new fashion fad is to make car-bodies matt black or grey. Since rough (matt) surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt the concerned surface. Consequently, matt black/grey cars may not induce polarized light pollution, which would be an advantageous feature for environmental protection. To test this idea, we performed field experiments with horizontal shiny and matt black car-body surfaces laid on the ground. Using imaging polarimetry, in multiple-choice field experiments we investigated the attractiveness of these test surfaces to various water-leaving polarotactic insects and obtained the following results: (i) The attractiveness of black car-bodies to polarotactic insects depends in complex manner on the surface roughness (shiny, matt) and species (mayflies, dolichopodids, tabanids). (ii) Non-expectedly, the matt dark grey car finish is much more attractive to mayflies (being endangered and protected in many countries) than matt black finish. (iii) The polarized light pollution of shiny black cars usually cannot be reduced with the use of matt painting. On the basis of these, our two novel findings are that (a) matt car-paints are highly polarization reflecting, and (b) these matt paints are not suitable to repel polarotactic insects. Hence, the recent technology used to make matt the car-bodies cannot eliminate or even can enhance the attractiveness of black/grey cars to water-leaving insects. Thus, changing shiny black car painting to matt one is a disadvantageous fashion fad concerning the reduction of polarized light pollution of black vehicles. PMID:25076137

  5. Unexpected attraction of polarotactic water-leaving insects to matt black car surfaces: mattness of paintwork cannot eliminate the polarized light pollution of black cars.

    Directory of Open Access Journals (Sweden)

    Miklos Blaho

    Full Text Available The horizontally polarizing surface parts of shiny black cars (the reflection-polarization characteristics of which are similar to those of water surfaces attract water-leaving polarotactic insects. Thus, shiny black cars are typical sources of polarized light pollution endangering water-leaving insects. A new fashion fad is to make car-bodies matt black or grey. Since rough (matt surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt the concerned surface. Consequently, matt black/grey cars may not induce polarized light pollution, which would be an advantageous feature for environmental protection. To test this idea, we performed field experiments with horizontal shiny and matt black car-body surfaces laid on the ground. Using imaging polarimetry, in multiple-choice field experiments we investigated the attractiveness of these test surfaces to various water-leaving polarotactic insects and obtained the following results: (i The attractiveness of black car-bodies to polarotactic insects depends in complex manner on the surface roughness (shiny, matt and species (mayflies, dolichopodids, tabanids. (ii Non-expectedly, the matt dark grey car finish is much more attractive to mayflies (being endangered and protected in many countries than matt black finish. (iii The polarized light pollution of shiny black cars usually cannot be reduced with the use of matt painting. On the basis of these, our two novel findings are that (a matt car-paints are highly polarization reflecting, and (b these matt paints are not suitable to repel polarotactic insects. Hence, the recent technology used to make matt the car-bodies cannot eliminate or even can enhance the attractiveness of black/grey cars to water-leaving insects. Thus, changing shiny black car painting to matt one is a disadvantageous fashion fad concerning the reduction of polarized light pollution of black vehicles.

  6. Dual gratings for enhanced light trapping in thin-film solar cells by a layer-transfer technique.

    Science.gov (United States)

    Schuster, Christian S; Kowalczewski, Piotr; Martins, Emiliano R; Patrini, Maddalena; Scullion, Mark G; Liscidini, Marco; Lewis, Liam; Reardon, Christopher; Andreani, Lucio C; Krauss, Thomas F

    2013-05-01

    Thin film solar cells benefit significantly from the enhanced light trapping offered by photonic nanostructures. The thin film is typically patterned on one side only due to technological constraints. The ability to independently pattern both sides of the thin film increases the degrees of freedom available to the designer, as different functions can be combined, such as the reduction of surface reflection and the excitation of quasiguided modes for enhanced light absorption. Here, we demonstrate a technique based on simple layer transfer that allows us to independently pattern both sides of the thin film leading to enhanced light trapping. We used a 400 nm thin film of amorphous hydrogenated silicon and two simple 2D gratings for this proof-of-principle demonstration. Since the technique imposes no restrictions on the design parameters, any type of structure can be made.

  7. Light trapping in amorphous silicon solar cells with periodic grating structures

    Energy Technology Data Exchange (ETDEWEB)

    Lia, Haihua; Wang, Qingkang; Chen, Jian [National Key Laboratory of Micro /Nano Fabrication Technology, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240 (China); Krc, J. [University of Ljubljana, Faculty of Electrical Engineering, Trzaska25, 1000 Ljubljana (Slovenia); Soppe, W.J. [Energy research Center of the Netherlands ECN, P. O. Box 1, 1755 ZG Pettern (Netherlands)

    2012-03-15

    We report on the design of amorphous silicon solar cells with the periodic grating structures. It is a combination of an anti-reflection structure and the metallic reflection grating. Optical coupling and light trapping in thin-film solar cells are studied numerically using the Rigorous Coupled Wave Analysis enhanced by the Modal Transmission Line theory. The impact of the structure parameters of the gratings is investigated. The results revealed that within the incident angles of - 40{sup 0} to + 40{sup 0} the reflectivity of the cell with a period of 0.5 {mu}m, a filling factor of 0.1 and a groove depth of 0.4 {mu}m is 4%-22.7% in the wavelength range of 0.3-0.6 {mu}m and 1%-20.8% in the wavelength range of 0.6-0.84 {mu}m, the absorption enhancement of the a-Si layer is 0.4%-10.8% and 20%-385%, respectively.

  8. Engineering inverse woodpile and woodpile photonic crystal solar cells for light trapping

    Science.gov (United States)

    Wang, Baomin; Chen, Kevin P.; Leu, Paul W.

    2016-06-01

    We demonstrate that inverse woodpile and woodpile photonic crystal nanocrystalline silicon structures may be engineered for light trapping in solar cells. We use finite-difference tim-domain simulations to show that the geometry of these photonic crystals may be varied such that absorption in the infrared, visible, and ultraviolet parts of the spectrum may all be improved. The short-circuit current density and ultimate efficiency are also improved. We found a 77.1% and 106% absorption enhancement in the optimized inverse woodpile and woodpile structures respectively, compared to a nanocrystalline silicon thin film of the equivalent thickness. The inverse woodpile structures may be approximated as a thin film with effective index of refraction, whereas the woodpile structures exhibit resonances from the coupling of TE and TM leaky modes in the stacked cylinders. Woodpile photonic crystal structures exhibit improved performance compared to inverse woodpile structures over a range of equivalent thicknesses and incidence angles. The performance of woodpile structures is also generally insensitive to the diameter, pitch and number of layers, whereas inverse woodpile structures are much more sensitive to morphology.

  9. Ultraviolet broadband light scattering for optically-trapped submicron-sized aerosol particles.

    Science.gov (United States)

    David, Grégory; Esat, Kıvanç; Ritsch, Irina; Signorell, Ruth

    2016-02-21

    We describe a broadband light scattering setup for the characterization of size and refractive index of single submicron-to-micron sized aerosol particles. Individual particles are isolated in air by a quadruple Bessel beam optical trap or a counter-propagating optical tweezer. The use of very broadband radiation in the wavelength range from 320 to 700 nm covering the ultraviolet region allows to size submicron particles. We show that a broad wavelength range is required to determine the particle radius and the refractive index with an uncertainty of several nanometers and ∼ 0.01, respectively. The smallest particle radius that can be accurately determined lies around 300 nm. Wavelength-dependent refractive index data over a broad range are obtained, including the ultraviolet region where corresponding data are rare. Four different applications are discussed: (1) the sizing of submicron polystyrene latex spheres, (2) the evaporation of binary glycerol water droplets, (3) hydration/dehydration cycling of aqueous potassium carbonate droplets, and (4) photochemical reactions of oleic acid droplets. PMID:26863396

  10. Fractal-like receiver geometries and features for increased light trapping and thermal efficiency

    Science.gov (United States)

    Ho, Clifford K.; Christian, Joshua M.; Yellowhair, Julius; Ortega, Jesus; Andraka, Charles

    2016-05-01

    Novel designs to increase light trapping and thermal efficiency of concentrating solar receivers at multiple length scales have been conceived and tested. The fractal-like geometries and features are introduced at both macro (meters) and meso (millimeters to centimeters) scales. Advantages include increased solar absorptance, reduced thermal emittance, and increased thermal efficiency. Radial and linear structures at the meso (tube shape and geometry) and macro (total receiver geometry and configuration) scales redirect reflected solar radiation toward the interior of the receiver for increased absorptance. Hotter regions within the interior of the receiver can reduce thermal emittance due to reduced local view factors to the environment, and higher concentration ratios can be employed with similar surface irradiances to reduce the effective optical aperture, footprint, and thermal losses. Coupled optical/fluid/thermal models have been developed to evaluate the performance of these designs relative to conventional designs, and meso-scale tests have been performed. Results show that fractal-like structures and geometries can increase the thermal efficiency by several percentage points at both the meso and macro scales, depending on factors such as intrinsic absorptance. The impact was more pronounced for materials with lower intrinsic solar absorptances (<0.9). The goal of this work is to increase the effective solar absorptance of oxidized substrate materials from ~0.9 to 0.95 or greater using these fractal-like geometries without the need for coatings.

  11. Numerical Analysis of Lamellar Gratings for Light-Trapping in Amorphous Silicon Solar Cells

    CERN Document Server

    Gablinger, David I

    2015-01-01

    In this paper, we calculate the material specific absorption accurately using a modal method by determining the integral of the Poynting vector around the boundary of a specific material. Given that the accuracy of our method is only determined by the number of modes included, the material specific absorption can be used as a quality measure for the light-trapping performance. We use this method to investigate metallic gratings and find nearly degenerate plasmons at the interface between metal and amorphous silicon (a-Si). The plasmons cause large undesired absorption in the metal part of a grating as used in a-Si cells. We explore ways to alleviate the parasitic absorption in the metal by appropriate choice of the geometry. Separating the diffraction grating from the back reflector helps, lining silver or aluminum with a dielectric helps as well. Gratings with depth > 60nm are preferred, and periods > 600nm are not useful. Maximum absorption in silicon can occur for less thick a-Si than is standard. We also ...

  12. Magneto-optical trap formed by elliptically polarised light waves for Mg atoms

    Science.gov (United States)

    Prudnikov, O. N.; Brazhnikov, D. V.; Taichenachev, A. V.; Yudin, V. I.; Goncharov, A. N.

    2016-07-01

    We consider a magneto-optical trap (MOT) formed by elliptically polarised waves for 24Mg atoms on a closed optical 3P2 → 3D3 (λ = 383.8 nm) transition in the ɛ - θ - ɛ¯ configuration of the field. Compared with a known MOT formed by circularly polarised waves (σ+ - σ- configuration), the suggested configuration of the trap formed by fields of ɛ - θ - ɛ¯ configuration allows deeper sub-Doppler cooling of trapped 24Mg atoms, which cannot be implemented in a conventional trap formed by fields of σ+ - σ- configuration.

  13. Shedding light on the black hole mass spectrum

    CERN Document Server

    Spera, Mario; Mapelli, Michela

    2016-01-01

    The mass spectrum of stellar black holes (BHs) is highly uncertain. Theoretical models of BH formation strongly depend on the efficiency of stellar winds of the progenitor star and on the supernova (SN) explosion mechanism. We discuss the BH mass spectrum we obtain using SEVN, a new public population-synthesis code that includes up-to-date stellar-wind prescriptions and several SN explosion models. Our models indicate a sub-solar metallicity environment for the progenitors of the gravitational wave source GW150914. We show that our models predict substantially larger BH masses (up to ~100 Msun) than other population synthesis codes, at low metallicity. In this proceeding, we also discuss the impact of pair-instability SNe on our previously published models.

  14. Non-occurrence of trapped surfaces and Black Holes in spherical gravitational collapse An abridged version

    CERN Document Server

    Mitra, A

    2000-01-01

    We have shown in an absolutely exact manner that for arbitrary EOS and radiation transport properties, (even) the idealized spherical gravitational collapse DOES NOT lead to the formation of trapped surfaces: 2GM(r,t)/R 0 if indeed R->0. Actually, this M,R->0 state would occur only after infinite proper time indicating that GTR is indeed the only naturally singularity free theory (as was cherished by Einstein). This M->0 state would materialize after the body radiates its entire initial mass-energy. We have shown that the final state corresponds to a zero mass BH state which may also be called a ``marginally naked'' singularity. Thus there is no event horizon at any finite R or M, and, therefore all the great theoretical confusions like whether there could be (i) White Holes, (ii) whether t (R) becomes spacelike (timelike) inside the EH (iii) Worm Holes, (iv) Time Machines, (v) Loss of information in gravitational collapse, get resolved. At any finite proper time, the collapsed object would be either static (...

  15. Comparative investigation of 39K and 40K trap loss rates alternative loss channel at low light intensities

    CERN Document Server

    Modugno, G; Inguscio, M; Dos Santos, M S; Telles, G D; Marcassa, L G; Bagnato, V S

    2001-01-01

    We report a comparative investigation of trap loss rates in a magneto-optical trap for two potassium isotopes, 39K and 40K, as a function of trap light intensity. The isotopes present a quite similar behavior for the loss rates at high intensities, and a sudden increase of the loss rates at low intensities is present in both cases. While for 39K such increase can be explained assuming that the major contribution to the losses comes from Hyperfine Changing Collisions, a different loss mechanism must be considered for 40K, which has an inverted ground state hyperfine structure. The experimental results of both isotopes are well reproduced by an alternative model based on radiative escape as the dominant loss mechanism.

  16. Optical Trapping-Formed Colloidal Assembly with Horns Extended to the Outside of a Focus through Light Propagation.

    Science.gov (United States)

    Kudo, Tetsuhiro; Wang, Shun-Fa; Yuyama, Ken-Ichi; Masuhara, Hiroshi

    2016-05-11

    We report optical trapping and assembling of colloidal particles at a glass/solution interface with a tightly focused laser beam of high intensity. It is generally believed that the particles are gathered only in an irradiated area where optical force is exerted on the particles by laser beam. Here we demonstrate that, the propagation of trapping laser from the focus to the outside of the formed assembly leads to expansion of the assembly much larger than the irradiated area with sticking out rows of linearly aligned particles like horns. The shape of the assembly, its structure, and the number of horns can be controlled by laser polarization. Optical trapping study utilizing the light propagation will open a new avenue for assembling and crystallizing quantum dots, metal nanoparticles, molecular clusters, proteins, and DNA. PMID:27104966

  17. Optical Trapping-Formed Colloidal Assembly with Horns Extended to the Outside of a Focus through Light Propagation.

    Science.gov (United States)

    Kudo, Tetsuhiro; Wang, Shun-Fa; Yuyama, Ken-Ichi; Masuhara, Hiroshi

    2016-05-11

    We report optical trapping and assembling of colloidal particles at a glass/solution interface with a tightly focused laser beam of high intensity. It is generally believed that the particles are gathered only in an irradiated area where optical force is exerted on the particles by laser beam. Here we demonstrate that, the propagation of trapping laser from the focus to the outside of the formed assembly leads to expansion of the assembly much larger than the irradiated area with sticking out rows of linearly aligned particles like horns. The shape of the assembly, its structure, and the number of horns can be controlled by laser polarization. Optical trapping study utilizing the light propagation will open a new avenue for assembling and crystallizing quantum dots, metal nanoparticles, molecular clusters, proteins, and DNA.

  18. Observation of Trapped Light Isotopes By The Detectors Nina and Nina-2

    Science.gov (United States)

    Sparvoli, R.; Wizard/NINA Collaboration

    The detector NINA aboard the satellite Resurs-01-N4, and the following experiment NINA-2 aboard the spacecraft MITA, detected hydrogen and helium isotopes geomag- netically trapped, while crossing the South Atlantic Anomaly. Deuterium and tritium at L-shellMITA altitudes (respectively 800 km and 400 km), and for energy greater than 10 MeV/n, is the interaction of trapped protons with residual atmospheric helium. In addition, the comparison between NINA and NINA-2 data shows how the flux of trapped particles decreases with the increase of the solar activity.

  19. Enhancement of efficiency in blue organic light-emitting devices with nanoscale barrier and trapping layers embedded in an emitting layer and a hole transport layer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dea Uk [Division of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Choo, Dong Chul [Research Institute of Information Display, Department of Information Display Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Tae Whan, E-mail: twk@hanyang.ac.k [Division of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Research Institute of Information Display, Department of Information Display Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Seo, Ji Hyun; Park, Jung Hyun; Kim, Young Kwan [Department of Information Display Engineering and COMID, Hong-ik University, Seoul 121-791 (Korea, Republic of)

    2009-07-01

    The electrical and the optical properties of the organic light-emitting diodes (OLEDs) utilizing a tetraphenylnaphthacene (rubrene) trapping layer and an 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBI) barrier layer with a nanoscale thickness were investigated. While the operating voltage of the OLED with a rubrene trapping layer in the HTL significantly increased because of a decrease in the hole mobility of the HTL, that of the OLED with a rubrene trapping layer in the EML slightly decreased resulting from an increase of the trapped electrons and holes in a rubrene trapping layer. The electroluminescence peak corresponding to the emission zone in the EML of OLEDs with a rubrene trapping layer and a TPBI barrier layer shifts to the EML center due to the existence of trapping layer in the EML.

  20. Light-trapping optimization in wet-etched silicon photonic crystal solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Eyderman, Sergey, E-mail: sergey.eyderman@utoronto.ca [Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7 (Canada); John, Sajeev [Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7 (Canada); Department of Physics, King Abdul-Aziz University, Jeddah (Saudi Arabia); Hafez, M.; Al-Ameer, S. S.; Al-Harby, T. S.; Al-Hadeethi, Y. [Department of Physics, King Abdul-Aziz University, Jeddah (Saudi Arabia); Bouwes, D. M. [iX-factory GmbH, Konrad Adenauer–Allee 11, 44263 Dortmund (Germany)

    2015-07-14

    We demonstrate, by numerical solution of Maxwell's equations, near-perfect solar light-trapping and absorption over the 300–1100 nm wavelength band in silicon photonic crystal (PhC) architectures, amenable to fabrication by wet-etching and requiring less than 10 μm (equivalent bulk thickness) of crystalline silicon. These PhC's consist of square lattices of inverted pyramids with sides comprised of various (111) silicon facets and pyramid center-to-center spacing in the range of 1.3–2.5 μm. For a wet-etched slab with overall height H = 10 μm and lattice constant a = 2.5 μm, we find a maximum achievable photo-current density (MAPD) of 42.5 mA/cm{sup 2}, falling not far from 43.5 mA/cm{sup 2}, corresponding to 100% solar absorption in the range of 300–1100 nm. We also demonstrate a MAPD of 37.8 mA/cm{sup 2} for a thinner silicon PhC slab of overall height H = 5 μm and lattice constant a = 1.9 μm. When H is further reduced to 3 μm, the optimal lattice constant for inverted pyramids reduces to a = 1.3 μm and provides the MAPD of 35.5 mA/cm{sup 2}. These wet-etched structures require more than double the volume of silicon, in comparison to the overall mathematically optimum PhC structure (consisting of slanted conical pores), to achieve the same degree of solar absorption. It is suggested these 3–10 μm thick structures are valuable alternatives to currently utilized 300 μm-thick textured solar cells and are suitable for large-scale fabrication by wet-etching.

  1. INFLUENCE OF FILM STRUCTURE AND LIGHT ON CHARGE TRAPPING AND DISSIPATION DYNAMICS IN SPUN-CAST ORGANIC THIN-FILM TRANSISTORS MEASURED BY SCANNING KELVIN PROBE MICROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Teague, L.; Moth, M.; Anthony, J.

    2012-05-03

    Herein, time-dependent scanning Kelvin probe microscopy of solution processed organic thin film transistors (OTFTs) reveals a correlation between film microstructure and OTFT device performance with the location of trapped charge within the device channel. The accumulation of the observed trapped charge is concurrent with the decrease in I{sub SD} during operation (V{sub G}=-40 V, V{sub SD}= -10 V). We discuss the charge trapping and dissipation dynamics as they relate to the film structure and show that application of light quickly dissipates the observed trapped charge.

  2. Light bending in Reissner-Nordstrom-de Sitter black hole by Rindler-Ishak method

    Science.gov (United States)

    Heydari-Fard, M.; Mojahed, S.; Rokni, S. Y.

    2014-05-01

    We investigate the influence of the cosmological constant, Λ, on the bending of light by a charged black hole in a de Sitter spacetime. Despite vanishing of the cosmological constant in the second order null geodesic equation, considering the method introduced by Rindler and Ishak (2007), we obtain an expression for the deflection angle, consistent with previous results for Schwarzschild, Schwarzschild-de Sitter (SdS), and Reissner-Nordstrom (RN) spacetimes.

  3. Local relaxation and light-cone-like propagation of correlations in a trapped one-dimensional Bose gas

    CERN Document Server

    Geiger, Remi; Mazets, Igor; Schmiedmayer, Jörg

    2013-01-01

    We describe the relaxation dynamics of a coherently split one-dimensional (1D) Bose gas in the harmonic approximation. A dephased, prethermalized state emerges in a light-cone-like evolution which is connected to the spreading of correlations with a characteristic velocity. In our description we put special emphasis on the influence of the longitudinal trapping potential and the finite size of the system, both of which are highly relevant in experiments. In particular, we quantify their influence on the phase correlation properties and the characteristic velocity with which the prethermalized state is established. Finally, we show that the trapping potential has an important effect on the recurrences of coherence which are expected to appear in a finite size system.

  4. Testing dark energy and light particles via black hole evaporation at colliders

    International Nuclear Information System (INIS)

    We show that collider experiments have the potential to exclude a light scalar field as well as generic models of modified gravity as dark energy candidates. Our mechanism uses the spectrum radiated by black holes and can equally well be applied to determine the number of light degrees of freedom. We obtain the grey body factors for massive scalar particles and calculate the total emissivity. While the Large Hadron Collider (LHC) may not get to the desired accuracy, the measurement is within reach of next generation colliders. (orig.)

  5. General method for simultaneous optimization of light trapping and carrier collection in an ultra-thin film organic photovoltaic cell

    Science.gov (United States)

    Tsai, Cheng-Chia; Grote, Richard R.; Beck, Jonathan H.; Kymissis, Ioannis; Osgood, Richard M.; Englund, Dirk

    2014-07-01

    We describe a general method for maximizing the short-circuit current in thin planar organic photovoltaic (OPV) heterojunction cells by simultaneous optimization of light absorption and carrier collection. Based on the experimentally obtained complex refractive indices of the OPV materials and the thickness-dependence of the internal quantum efficiency of the OPV active layer, we analyze the potential benefits of light trapping strategies for maximizing the overall power conversion efficiency of the cell. This approach provides a general strategy for optimizing the power conversion efficiency of a wide range of OPV structures. In particular, as an experimental trial system, the approach is applied here to a ultra-thin film solar cell with a SubPc/C60 photovoltaic structure. Using a patterned indium tin oxide (ITO) top contact, the numerically optimized designs achieve short-circuit currents of 0.790 and 0.980 mA/cm2 for 30 nm and 45 nm SubPc/C60 heterojunction layer thicknesses, respectively. These values correspond to a power conversion efficiency enhancement of 78% for the 30 nm thick cell, but only of 32% for a 45 nm thick cell, for which the overall photocurrent is actually higher. Applied to other material systems, the general optimization method can elucidate if light trapping strategies can improve a given cell architecture.

  6. Inelastic scattering of light by a cold trapped atom: Effects of the quantum center-of-mass motion

    CERN Document Server

    Bienert, M; Morigi, G; Bienert, Marc; Merkel, Wolfgang; Morigi, Giovanna

    2005-01-01

    The light scattered by a cold trapped ion, which is in the stationary state of laser cooling, presents features due to the mechanical effects of atom-photon interaction. These features appear as additional peaks (sidebands) in the spectrum of resonance fluorescence. Among these sidebands the literature has discussed the Stokes and anti-Stokes components, namely the sidebands of the elastic peak. In this manuscript we show that the motion also gives rise to sidebands of the inelastic peaks. These are not always visible, but, as we show, can be measured in parameter regimes which are experimentally accessible.

  7. Time domain simulation of tandem silicon solar cells with optimal textured light trapping enabled by the quadratic complex rational function

    OpenAIRE

    Chung, H.; Jung, K. Y.; Tee, X. T.; Bermel, Peter

    2014-01-01

    Amorphous silicon/crystalline silicon (a-Si/c-Si) micromorph tandem cells, with best confirmed efficiency of 12.3%, have yet to fully approach their theoretical performance limits. In this work, we consider a strategy for improving the light trapping and charge collection of a-Si/c-Si micromorph tandem cells using random texturing with adjustable short-range correlations and long-range periodicity. In order to consider the full-spectrum absorption of a-Si and c-Si, a novel dispersion model kn...

  8. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2006-01-01

    Full Text Available Although the definition and measurement techniques for atmospheric 'black carbon' ('BC' or 'elemental carbon'' ('EC' have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black ('brown carbon, Cbrown' makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC in the atmosphere. Evidence for the atmospheric presence of Cbrown comes from (1 spectral aerosol light absorption measurements near specific combustion sources, (2 observations of spectral properties of water extracts of continental aerosol, (3 laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4 indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of 'BC' and 'EC' over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of Cbrown is high relative to that of soot carbon. Chemical measurements to determine 'EC' are biased by the refractory nature of Cbrown as well as by complex matrix interferences. Optical measurements of 'BC' suffer from a number of problems: (1 many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2 there is no unique conversion factor between light absorption and 'EC' or 'BC' concentration in ambient aerosols, and (3 the difference in spectral properties between the different types of LAC, as well as the chemical complexity of Cbrown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our

  9. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2006-05-01

    Full Text Available Although the definition and measurement methods of atmospheric ''black carbon'' (''BC'' have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black (''brown carbon, Cbrown'' makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC in the atmosphere. Evidence for the atmospheric presence of Cbrown comes directly from aerosol absorption measurements near specific combustion sources, from observations of spectral properties of water extracts of continental aerosol, from laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that these species may severely bias measurements of ''BC'' and ''EC'' over vast parts of the troposphere, where mass concentration of Cbrown is high relative to that of combustion soot. We also imply that due to the strongly skewed absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. The possible consequences of these effects on our understanding of tropospheric processes are discussed.

  10. Hidden in the light: Magnetically induced afterglow from trapped chameleon fields

    Science.gov (United States)

    Gies, Holger; Mota, David F.; Shaw, Douglas J.

    2008-01-01

    We propose an afterglow phenomenon as a unique trace of chameleon fields in optical experiments. The vacuum interaction of a laser pulse with a magnetic field can lead to a production and subsequent trapping of chameleons in the vacuum chamber, owing to their mass dependence on the ambient matter density. Magnetically induced reconversion of the trapped chameleons into photons creates an afterglow over macroscopic timescales that can conveniently be searched for by current optical experiments. We show that the chameleon parameter range accessible to available laboratory technology is comparable to scales familiar from astrophysical stellar energy-loss arguments. We analyze quantitatively the afterglow properties for various experimental scenarios and discuss the role of potential background and systematic effects. We conclude that afterglow searches represent an ideal tool to aim at the production and detection of cosmologically relevant scalar fields in the laboratory.

  11. LFN, QPO and fractal dimension of X-ray light curves from black hole binaries

    Science.gov (United States)

    Prosvetov, Art; Grebenev, Sergey

    The origin of the low frequency noise (LFN) and quasi-periodic oscillations (QPO) observed in X-ray flux of Galactic black hole binaries is still not recognized in spite of multiple studies and attempts to model this phenomenon. There are known correlations between the QPO frequency, X-ray power density, X-ray flux and spectral state of the system, but there is no model that can do these dependences understandable. For the low frequency (~1 Hz) QPO we still have no even an idea capable to explain their production and don't know even what part of an accretion disc is responsible for them. Here we attempted to measure the fractal dimension of X-ray light curves of several black hole X-ray binaries and to study its correlation with the frequency of quasi periodic oscillations observed in their X-ray light-curves. The fractal dimension is a measure of the space-filling capacity of the light curves' profile. To measure the fractal dimension we used R/S method, which is fast enough and has good reputation in financial analytic and materials sciences. We found that if no QPO were observed in X-ray flux from the particular source, the fractal dimension is equal to the unique value which is independent on the source, its luminosity or its spectral state. On the other hand if QPO were detected in the flux, the fractal dimension deviated from its usual value. Also, we found a clear correlation between the QPO frequency and the fractal dimension of the emission. The relationship between these two parameters is solid but nonlinear. We believe that the analysis of X-ray light curves of black hole binaries using the fractal dimension has a good scientific potential and may provide an addition information on the geometry of accretion flow and fundamental physical parameters of the system.

  12. Optical pumping of deep traps in AlGaN/GaN-on-Si HEMTs using an on-chip Schottky-on-heterojunction light-emitting diode

    Energy Technology Data Exchange (ETDEWEB)

    Li, Baikui; Tang, Xi; Chen, Kevin J., E-mail: eekjchen@ust.hk [Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2015-03-02

    In this work, by using an on-chip integrated Schottky-on-heterojunction light-emitting diode (SoH-LED) which is seamlessly integrated with the AlGaN/GaN high electron mobility transistor (HEMT), we studied the effect of on-chip light illumination on the de-trapping processes of electrons from both surface and bulk traps. Surface trapping was generated by applying OFF-state drain bias stress, while bulk trapping was generated by applying positive substrate bias stress. The de-trapping processes of surface and/or bulk traps were monitored by measuring the recovery of dynamic on-resistance R{sub on} and/or threshold voltage V{sub th} of the HEMT. The results show that the recovery processes of both dynamic R{sub on} and threshold voltage V{sub th} of the HEMT can be accelerated by the on-chip SoH-LED light illumination, demonstrating the potentiality of on-chip hybrid opto-HEMTs to minimize the influences of traps during dynamic operation of AlGaN/GaN power HEMTs.

  13. A novel photocatalytic conversion of Tryptophan to Kynurenine using black light as a light source

    NARCIS (Netherlands)

    Hamdy Mohamed Saad, M.S.; Scott, E.L.; Carr, R.H.; Sanders, J.P.M.

    2012-01-01

    The photocatalytic conversion of an aqueous solution of l-tryptophan (Trp) to kynurenine (KN) was investigated under the illumination of different light sources. Results show that Trp converted to KN with a selectivity of 64% under the illumination of a medium pressure (MP) Hg lamp. KN selectivity w

  14. Tandem photonic-crystal thin films surpassing Lambertian light-trapping limit over broad bandwidth and angular range

    CERN Document Server

    Oskooi, Ardavan; Noda, Susumu

    2013-01-01

    The maximum absorption of solar radiation over the broadest range of frequencies and incident angles using the thinnest material possible has important applications for renewable-energy generation. Complete random texturing of an optically-thick film's surface to increase the path length of scattered light rays, first proposed nearly thirty years ago, has thus far remained the most effective approach for photon absorption over the widest set of conditions. Recent thin-film nanostructured designs involving resonant wave effects of photons have explored the possibility of superior performance though as of yet no proposal satisfying the dual requirements of enhanced and robust absorption over a large fraction of the solar spectrum has been made. Here using recent advances in computational electrodynamics we describe a general strategy for the design of a silicon thin film applicable to photovoltaic cells based on a quasi-resonant approach to light trapping where two partially-disordered photonic-crystal slabs, s...

  15. Self-rolling and light-trapping in flexible quantum well–embedded nanomembranes for wide-angle infrared photodetectors

    Science.gov (United States)

    Wang, Han; Zhen, Honglou; Li, Shilong; Jing, Youliang; Huang, Gaoshan; Mei, Yongfeng; Lu, Wei

    2016-01-01

    Three-dimensional (3D) design and manufacturing enable flexible nanomembranes to deliver unique properties and applications in flexible electronics, photovoltaics, and photonics. We demonstrate that a quantum well (QW)–embedded nanomembrane in a rolled-up geometry facilitates a 3D QW infrared photodetector (QWIP) device with enhanced responsivity and detectivity. Circular geometry of nanomembrane rolls provides the light coupling route; thus, there are no external light coupling structures, which are normally necessary for QWIPs. This 3D QWIP device under tube-based light-trapping mode presents broadband enhancement of coupling efficiency and omnidirectional detection under a wide incident angle (±70°), offering a unique solution to high-performance focal plane array. The winding number of these rolled-up QWIPs provides well-tunable blackbody photocurrents and responsivity. 3D self-assembly of functional nanomembranes offers a new path for high conversion efficiency between light and electricity in photodetectors, solar cells, and light-emitting diodes. PMID:27536723

  16. Self-rolling and light-trapping in flexible quantum well-embedded nanomembranes for wide-angle infrared photodetectors.

    Science.gov (United States)

    Wang, Han; Zhen, Honglou; Li, Shilong; Jing, Youliang; Huang, Gaoshan; Mei, Yongfeng; Lu, Wei

    2016-08-01

    Three-dimensional (3D) design and manufacturing enable flexible nanomembranes to deliver unique properties and applications in flexible electronics, photovoltaics, and photonics. We demonstrate that a quantum well (QW)-embedded nanomembrane in a rolled-up geometry facilitates a 3D QW infrared photodetector (QWIP) device with enhanced responsivity and detectivity. Circular geometry of nanomembrane rolls provides the light coupling route; thus, there are no external light coupling structures, which are normally necessary for QWIPs. This 3D QWIP device under tube-based light-trapping mode presents broadband enhancement of coupling efficiency and omnidirectional detection under a wide incident angle (±70°), offering a unique solution to high-performance focal plane array. The winding number of these rolled-up QWIPs provides well-tunable blackbody photocurrents and responsivity. 3D self-assembly of functional nanomembranes offers a new path for high conversion efficiency between light and electricity in photodetectors, solar cells, and light-emitting diodes. PMID:27536723

  17. 黑箱法应用于蚊虫监测的效果研究%Mosquito-trapping effects of black box method for mosquito surveillance

    Institute of Scientific and Technical Information of China (English)

    任文军; 熊建菁; 冷培恩; 刘洪霞; 黄瑾; 陈天民; 陈仁朝; 张锦生

    2012-01-01

    Objective To compare the mosquito-trapping effects of black boxes with different opening directions, and to explore the operation guidelines for black box method in mosquito surveillance. Methods The black boxes with different opening directions were used, and 24 h night-and-day observation method was adopted. Results There were significant differences in trapped mosquito number among the black boxes with different opening directions (f2=44.82, P0.05), but there was significant difference in mosquito sex (f2= 121.13, P<0.05). Conclusion The black box toward the west is the best for trapping mosquitoes, and can be used for regular mosquito surveillance and the evaluation of mosquito control in special areas.%目的 比较不同开口方向放置黑箱的捕蚊效果,探讨蚊虫黑箱法的操作规范.方法 不同开口朝向放置法以及24h昼夜观察法.结果 不同开口朝向黑箱的捕蚊数差异有统计学意义(f2=44.82,P<0.05),开口朝西的黑箱捕蚊最多;24 h昼夜观察捕获结果表明,蚊虫入箱高峰主要出现在清晨(05:00--07:00)和傍晚(18:00--20:00),各个时段均以开口朝西的黑箱捕获蚊虫最多,且差异有统计学意义(f2=259.56,P<0.05);人工小时法和黑箱法成蚊季节消长趋势一致,具有相关性和一致性(r=0.696,P<0.01);黑箱法和人工小时法监测的蚊种构成差异无统计学意义(f2=4.54,P>0.05),蚊虫性别比差异有统计学意义(f2=121.13,P<0.05).结论 黑箱开口朝西具有较好的诱捕效果,可适用于常规蚊虫监测以及特定场所蚊虫控制评估.

  18. Lifetime of Nano-Structured Black Silicon for Photovoltaic Applications

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk;

    2016-01-01

    In this work, we present recent results of lifetime optimization for nano-structured black silicon and its photovoltaic applications. Black silicon nano-structures provide significant reduction of silicon surface reflection due to highly corrugated nanostructures with excellent light trapping...

  19. Time domain simulation of tandem silicon solar cells with optimal textured light trapping enabled by the quadratic complex rational function.

    Science.gov (United States)

    Chung, H; Jung, K-Y; Tee, X T; Bermel, P

    2014-05-01

    Amorphous silicon/crystalline silicon (a-Si/c-Si) micromorph tandem cells, with best confirmed efficiency of 12.3%, have yet to fully approach their theoretical performance limits. In this work, we consider a strategy for improving the light trapping and charge collection of a-Si/c-Si micromorph tandem cells using random texturing with adjustable short-range correlations and long-range periodicity. In order to consider the full-spectrum absorption of a-Si and c-Si, a novel dispersion model known as a quadratic complex rational function (QCRF) is applied to photovoltaic materials (e.g., a-Si, c-Si and silver). It has the advantage of accurately modeling experimental semiconductor dielectric values over the entire relevant solar bandwidth from 300-1000 nm in a single simulation. This wide-band dispersion model is then used to model a silicon tandem cell stack (ITO/a-Si:H/c-Si:H/silver), as two parameters are varied: maximum texturing height h and correlation parameter f. Even without any other light trapping methods, our front texturing method demonstrates 12.37% stabilized cell efficiency and 12.79 mA/cm² in a 2 μm-thick active layer. PMID:24922389

  20. The influence of light on small hive beetle (Aethina tumida) behavior and trap capture

    OpenAIRE

    Duehl, Adrian; Arbogast, Richard; Sheridan, Audrey; Teal, Peter

    2012-01-01

    International audience The small hive beetle (Aethina tumida, Murray) is a major pest of honeybee (Apis mellifera) colonies, particularly in the Southeastern USA. We evaluated the small hive beetle's (SHB) response to different wavelengths of the light spectrum and found that SHB larvae and adults were most attracted to the 390 nm wavelength. Early instar larvae were not significantly attracted to light, while wandering larvae and adults exhibited strong positive phototaxis. The light resp...

  1. Energy Spectra of Geomagnetically Trapped Light Isotopes Measured by NINA-2 Instrument

    Science.gov (United States)

    Mikhailov, V. V.; Bakaldin, A.; Galper, A.; Koldashov, S.; Korotkov, M.; Leonov, A.; Voronov, S.; Bidoli, V.; Caoslino, M.; De Pascale, M.; Furano, G.; Iannucci, A.; Morselli, A.; Picozza, P.; Sparvoli, R.; Boezio, M.; Bonvincini, V.; Vacchi, A.; Zampa, N.; Ambriola, M.; Bellotti, R.; Cafagna, F.; Circella, M.; De Marzo, C.; Adriani, O.; Papini, P.; Spillantini, P.; Straulino, S.; Vannuccini, E.; Ricci, M.; Castellini, G.

    2003-07-01

    This paper reports about the energy spectrum of geomagnetically trapped protons, deuterons, tritons and He isotop es measured by the instrument NINA2 at the low boundary of the South Atlantic Anomaly. NINA-2 on board the satellite MITA has been in orbit from 15 July 2000 to 10 August 2001, flying with circular polar orbit (87° inclination), at an altitude between 300-440 km. Differential energy spectra were measured at L-shell ˜ 1.2 and local magnetic field b< 0.22 G. Data from NINA-2 are compared with measurements made onboard Resurs-01 N4 satellite with NINA instrument. Possible solar modulation effects are discussed.

  2. An Artificial Light Source Influences Mating and Oviposition of Black Soldier Flies, Hermetia illucens

    OpenAIRE

    Zhang, Jibin; Huang, Ling; He, Jin; Tomberlin, Jeffery K; Li, Jianhong; Lei, Chaoliang; Sun, Ming; Liu, Ziduo; Yu, Ziniu

    2010-01-01

    Current methods for mass-rearing black soldier flies, Hermetia illucens (L.) (Diptera: Stratiomyidae), in the laboratory are dependent on sunlight. Quartz-iodine lamps and rare earth lamps were examined as artificial light sources for stimulating H. illucens to mate and lay eggs. Sunlight was used as the control. Adults in the quartz-iodine lamp treatment had a mating rate of 61% of those in the sunlight control. No mating occurred when the rare earth lamp was used as a substitute. Egg hatch ...

  3. Nobel Prize in Physics 1997 "for development of methods to cool and trap atoms with laser light" : Steven Chu, Claude Cohen-Tannoudji and William D. Phillips

    CERN Multimedia

    1998-01-01

    Prof.S. Chu presents "the manipulation of atoms and bio-molecules by laser light" : a brief history of the laser cooling and trapping of atoms developed over the past 15 years will be presented. The cooling and trapping technology is already being applied in numerous areas of science and engineering. Applications to be discussed include atomic clocks, atom interferometers, as well as studies in polymer dynamics and protein motion.

  4. Fiber-comb-stabilized light source at 556 nm for magneto-optical trapping of ytterbium

    OpenAIRE

    Yasuda, Masami; Kohno, Takuya; Inaba, Hajime; Nakajima, Yoshiaki; Hosaka, Kazumoto; Onae, Atsushi; Hong, Feng-Lei

    2010-01-01

    A frequency-stabilized light source emitting at 556 nm is realized by frequency-doubling a 1112-nm laser, which is phase-locked to a fiber-based optical frequency comb. The 1112-nm laser is either an ytterbium (Yb)-doped distributed feedback fiber laser or a master-slave laser system that uses an external cavity diode laser as a master laser. We have achieved the continuous frequency stabilization of the light source over a five-day period. With the light source, we have completed the second-...

  5. Broadband perfect light trapping in the thinnest monolayer graphene-MoS2 photovoltaic cell: the new application of spectrum-splitting structure.

    Science.gov (United States)

    Wu, Yun-Ben; Yang, Wen; Wang, Tong-Biao; Deng, Xin-Hua; Liu, Jiang-Tao

    2016-01-01

    The light absorption of a monolayer graphene-molybdenum disulfide photovoltaic (GM-PV) cell in a wedge-shaped microcavity with a spectrum-splitting structure is investigated theoretically. The GM-PV cell, which is three times thinner than the traditional photovoltaic cell, exhibits up to 98% light absorptance in a wide wavelength range. This rate exceeds the fundamental limit of nanophotonic light trapping in solar cells. The effects of defect layer thickness, GM-PV cell position in the microcavity, incident angle, and lens aberration on the light absorptance of the GM-PV cell are explored. Despite these effects, the GM-PV cell can still achieve at least 90% light absorptance with the current technology. Our proposal provides different methods to design light-trapping structures and apply spectrum-splitting systems. PMID:26864749

  6. Broadband perfect light trapping in the thinnest monolayer graphene-MoS2 photovoltaic cell: the new application of spectrum-splitting structure.

    Science.gov (United States)

    Wu, Yun-Ben; Yang, Wen; Wang, Tong-Biao; Deng, Xin-Hua; Liu, Jiang-Tao

    2016-02-11

    The light absorption of a monolayer graphene-molybdenum disulfide photovoltaic (GM-PV) cell in a wedge-shaped microcavity with a spectrum-splitting structure is investigated theoretically. The GM-PV cell, which is three times thinner than the traditional photovoltaic cell, exhibits up to 98% light absorptance in a wide wavelength range. This rate exceeds the fundamental limit of nanophotonic light trapping in solar cells. The effects of defect layer thickness, GM-PV cell position in the microcavity, incident angle, and lens aberration on the light absorptance of the GM-PV cell are explored. Despite these effects, the GM-PV cell can still achieve at least 90% light absorptance with the current technology. Our proposal provides different methods to design light-trapping structures and apply spectrum-splitting systems.

  7. Light-trapping and recycling for extraordinary power conversion in ultra-thin gallium-arsenide solar cells.

    Science.gov (United States)

    Eyderman, Sergey; John, Sajeev

    2016-01-01

    We demonstrate nearly 30% power conversion efficiency in ultra-thin (~200 nm) gallium arsenide photonic crystal solar cells by numerical solution of the coupled electromagnetic Maxwell and semiconductor drift-diffusion equations. Our architecture enables wave-interference-induced solar light trapping in the wavelength range from 300-865 nm, leading to absorption of almost 90% of incoming sunlight. Our optimized design for 200 nm equivalent bulk thickness of GaAs, is a square-lattice, slanted conical-pore photonic crystal (lattice constant 550 nm, pore diameter 600 nm, and pore depth 290 nm), passivated with AlGaAs, deposited on a silver back-reflector, with ITO upper contact and encapsulated with SiO2. Our model includes both radiative and non-radiative recombination of photo-generated charge carriers. When all light from radiative recombination is assumed to escape the structure, a maximum achievable photocurrent density (MAPD) of 27.6 mA/cm(2) is obtained from normally incident AM 1.5 sunlight. For a surface non-radiative recombination velocity of 10(3) cm/s, this corresponds to a solar power conversion efficiency of 28.3%. When all light from radiative recombination is trapped and reabsorbed (complete photon recycling) the power conversion efficiency increases to 29%. If the surface recombination velocity is reduced to 10 cm/sec, photon recycling is much more effective and the power conversion efficiency reaches 30.6%. PMID:27334045

  8. Effective Light Trapping in Thin Film Silicon Solar Cells with Nano- and Microscale Structures on Glass Substrate.

    Science.gov (United States)

    Bong, Sungjae; Ahn, Shihyun; Anh, Le Huy Tuan; Kim, Sunbo; Park, Hyeongsik; Shin, Chonghoon; Park, Jinjoo; Lee, Younjung; Yi, Junsin

    2016-05-01

    For thin film silicon-based solar cells, effective light trapping at a broad range of wavelengths (400-1100 nm) is necessary. Normally, etching is only carried out with TCOs, such as SnO2:F and impurity doped ZnO, to form nano-sized craters in the surface morphology to confer a light trapping effect. However, in this study, prior to ZnO:Al etching, periodic structures on the glass substrates were made by photolithography and wet etching to increase the light scattering and internal reflection. The use of periodic structures on the glass substrate resulted in higher haze ratios in the range from 550 nm to 1100 nm, which is the optical absorption wavelength region for thin film silicon solar cells, than obtained by simple ZnO:Al etching. The periodically textured glass with micro-sized structures compensates for the low haze ratio at the middle and long wavelengths of wet etched ZnO:Al. ZnO:Al was deposited on the periodically textured glass, after which the ZnO:Al surface was also etched randomly using a mixed acid solution to form nano-sized craters. The thin film silicon solar cells with 350-nm-thick amorphous silicon absorber layer deposited on the periodic structured glass and etched ZnO:Al generated up to 10.68% more photocurrent, with 11.2% increase of the conversion efficiency compared to the cell deposited on flat glass and etched ZnO:Al. PMID:27483855

  9. Wafer-Scale Integration of Inverted Nanopyramid Arrays for Advanced Light Trapping in Crystalline Silicon Thin Film Solar Cells.

    Science.gov (United States)

    Zhou, Suqiong; Yang, Zhenhai; Gao, Pingqi; Li, Xiaofeng; Yang, Xi; Wang, Dan; He, Jian; Ying, Zhiqin; Ye, Jichun

    2016-12-01

    Crystalline silicon thin film (c-Si TF) solar cells with an active layer thickness of a few micrometers may provide a viable pathway for further sustainable development of photovoltaic technology, because of its potentials in cost reduction and high efficiency. However, the performance of such cells is largely constrained by the deteriorated light absorption of the ultrathin photoactive material. Here, we report an efficient light-trapping strategy in c-Si TFs (~20 μm in thickness) that utilizes two-dimensional (2D) arrays of inverted nanopyramid (INP) as surface texturing. Three types of INP arrays with typical periodicities of 300, 670, and 1400 nm, either on front, rear, or both surfaces of the c-Si TFs, are fabricated by scalable colloidal lithography and anisotropic wet etch technique. With the extra aid of antireflection coating, the sufficient optical absorption of 20-μm-thick c-Si with a double-sided 1400-nm INP arrays yields a photocurrent density of 39.86 mA/cm(2), which is about 76 % higher than the flat counterpart (22.63 mA/cm(2)) and is only 3 % lower than the value of Lambertian limit (41.10 mA/cm(2)). The novel surface texturing scheme with 2D INP arrays has the advantages of excellent antireflection and light-trapping capabilities, an inherent low parasitic surface area, a negligible surface damage, and a good compatibility for subsequent process steps, making it a good alternative for high-performance c-Si TF solar cells. PMID:27071681

  10. Light-trapping and recycling for extraordinary power conversion in ultra-thin gallium-arsenide solar cells

    Science.gov (United States)

    Eyderman, Sergey; John, Sajeev

    2016-01-01

    We demonstrate nearly 30% power conversion efficiency in ultra-thin (~200 nm) gallium arsenide photonic crystal solar cells by numerical solution of the coupled electromagnetic Maxwell and semiconductor drift-diffusion equations. Our architecture enables wave-interference-induced solar light trapping in the wavelength range from 300–865 nm, leading to absorption of almost 90% of incoming sunlight. Our optimized design for 200 nm equivalent bulk thickness of GaAs, is a square-lattice, slanted conical-pore photonic crystal (lattice constant 550 nm, pore diameter 600 nm, and pore depth 290 nm), passivated with AlGaAs, deposited on a silver back-reflector, with ITO upper contact and encapsulated with SiO2. Our model includes both radiative and non-radiative recombination of photo-generated charge carriers. When all light from radiative recombination is assumed to escape the structure, a maximum achievable photocurrent density (MAPD) of 27.6 mA/cm2 is obtained from normally incident AM 1.5 sunlight. For a surface non-radiative recombination velocity of 103 cm/s, this corresponds to a solar power conversion efficiency of 28.3%. When all light from radiative recombination is trapped and reabsorbed (complete photon recycling) the power conversion efficiency increases to 29%. If the surface recombination velocity is reduced to 10 cm/sec, photon recycling is much more effective and the power conversion efficiency reaches 30.6%. PMID:27334045

  11. Light-trapping and recycling for extraordinary power conversion in ultra-thin gallium-arsenide solar cells

    Science.gov (United States)

    Eyderman, Sergey; John, Sajeev

    2016-06-01

    We demonstrate nearly 30% power conversion efficiency in ultra-thin (~200 nm) gallium arsenide photonic crystal solar cells by numerical solution of the coupled electromagnetic Maxwell and semiconductor drift-diffusion equations. Our architecture enables wave-interference-induced solar light trapping in the wavelength range from 300-865 nm, leading to absorption of almost 90% of incoming sunlight. Our optimized design for 200 nm equivalent bulk thickness of GaAs, is a square-lattice, slanted conical-pore photonic crystal (lattice constant 550 nm, pore diameter 600 nm, and pore depth 290 nm), passivated with AlGaAs, deposited on a silver back-reflector, with ITO upper contact and encapsulated with SiO2. Our model includes both radiative and non-radiative recombination of photo-generated charge carriers. When all light from radiative recombination is assumed to escape the structure, a maximum achievable photocurrent density (MAPD) of 27.6 mA/cm2 is obtained from normally incident AM 1.5 sunlight. For a surface non-radiative recombination velocity of 103 cm/s, this corresponds to a solar power conversion efficiency of 28.3%. When all light from radiative recombination is trapped and reabsorbed (complete photon recycling) the power conversion efficiency increases to 29%. If the surface recombination velocity is reduced to 10 cm/sec, photon recycling is much more effective and the power conversion efficiency reaches 30.6%.

  12. Charge trapping and luminance mechanisms of organic light-emitting devices with a 5,6,11,12-tetraphenylnaphthacene emission layer.

    Science.gov (United States)

    Park, Su Hyeong; Lee, Dae Uk; Kim, Tae Whan

    2011-08-01

    The electrical and the optical properties of the organic light-emitting devices fabricated utilizing a 5,6,11,12-tetraphenylnaphthacene (rubrene) emission layer (EML) were investigated to clarify their charge trapping and luminance mechanisms. The increase in the thickness of the rubrene EML extended the width of the recombination zone, resulting in the enhancement of the efficiency and in the variation of the shoulder peak intensity of the electroluminescence spectra. The charge trapping and luminance mechanisms were affected by the total thickness of the rubrene layer, regardless of the existence of the barrier layers. The charge trapping and luminance mechanisms are described on the basis of the experimental results. PMID:22103164

  13. Colored Sticky Traps to Selectively Survey Thrips in Cowpea Ecosystem.

    Science.gov (United States)

    Tang, L D; Zhao, H Y; Fu, B L; Han, Y; Liu, K; Wu, J H

    2016-02-01

    The bean flower thrips, Megalurothrips usitatus (Bagrall) (Thysanoptera: Thripidae), is an important pest of legume crops in South China. Yellow, blue, or white sticky traps are currently recommended for monitoring and controlling thrips, but it is not known whether one is more efficient than the other or if selectivity could be optimized by trap color. We investigated the response of thrips and beneficial insects to different-colored sticky traps on cowpea, Vigna unguiculata. More thrips were caught on blue, light blue, white, and purple traps than on yellow, green, pink, gray, red, or black traps. There was a weak correlation on the number of thrips caught on yellow traps and survey from flowers (r = 0.139), whereas a strong correlation was found for blue traps and thrips' survey on flowers (r = 0.929). On commercially available sticky traps (Jiaduo®), two and five times more thrips were caught on blue traps than on white and yellow traps, respectively. Otherwise, capture of beneficial insects was 1.7 times higher on yellow than on blue traps. The major natural enemies were the predatory ladybird beetles (63%) and pirate bugs Orius spp. (29%), followed by a number of less representative predators and parasitoids (8%). We conclude the blue sticky trap was the best to monitor thrips on cowpea in South China. PMID:26429578

  14. An artificial light source influences mating and oviposition of black soldier flies, Hermetia illucens.

    Science.gov (United States)

    Zhang, Jibin; Huang, Ling; He, Jin; Tomberlin, Jeffery K; Li, Jianhong; Lei, Chaoliang; Sun, Ming; Liu, Ziduo; Yu, Ziniu

    2010-01-01

    Current methods for mass-rearing black soldier flies, Hermetia illucens (L.) (Diptera: Stratiomyidae), in the laboratory are dependent on sunlight. Quartz-iodine lamps and rare earth lamps were examined as artificial light sources for stimulating H. illucens to mate and lay eggs. Sunlight was used as the control. Adults in the quartz-iodine lamp treatment had a mating rate of 61% of those in the sunlight control. No mating occurred when the rare earth lamp was used as a substitute. Egg hatch for the quartz-iodine lamp and sunlight treatments occurred in approximately 4 days, and the hatch rate was similar between these two treatments. Larval and pupal development under these treatments required approximately 18 and 15 days at 28°C, respectively. Development of methods for mass rearing of H. illucens using artificial light will enable production of this fly throughout the year without investing in greenhouse space or requiring sunlight. PMID:21268697

  15. A novel approach for enhanced visible light activity in doped nanosize titanium dioxide through the excitons trapping

    Science.gov (United States)

    Jaimy, Kanakkanmavudi B.; Baiju, K. V.; Ghosh, Swapankumar; Warrier, K. G. K.

    2012-02-01

    Titanium dioxide doped with iron oxide (0-10 mol%) has been synthesized by an aqueous sol-gel method. The extent of phase transformation is higher in presence of up to 1 mol% of Fe3+ ions in doped titania. A further increase in Fe3+ content was found to decrease the phase transformation. A composition which contains ∼90% rutile and the remaining anatase phase shows the highest photocatalytic activity. Even though surface area values are dramatically decreased by the modification of TiO2 by Fe3+ doping, crystallinity plays a major role in photocatalytic activity enhancement. UV-vis reflectance spectra indicate a red-shift in band gap energy and thus an enhanced photoactivity in visible light, suitable for application in photodegradation of toxic industrial effluents as well as other organic contaminants, is achieved. Low concentrations of Fe3+ ions act as excitons trapping centers, while higher concentrations act as recombination centers. The synergy between the rutile-anatase ratios and optimum amount of Fe3+ ions improve the interfacial charge transfer and trapping which enhanced the photochemical degradation of MB dye. The Fe3+ doped TiO2 composition has the highest photoactivity, having an apparent rate constant of 11.1×10-3 min-1, which is much higher than that of commercial P25 Degussa titania (6.03×10-3 min-1).

  16. The Enhanced Light Absorptance and Device Application of Nanostructured Black Silicon Fabricated by Metal-assisted Chemical Etching.

    Science.gov (United States)

    Zhong, Hao; Guo, Anran; Guo, Guohui; Li, Wei; Jiang, Yadong

    2016-12-01

    We use metal-assisted chemical etching (MCE) method to fabricate nanostructured black silicon on the surface of C-Si. The Si-PIN photoelectronic detector based on this type of black silicon shows excellent device performance with a responsivity of 0.57 A/W at 1060 nm. Silicon nanocone arrays can be created using MCE treatment. These modified surfaces show higher light absorptance in the near-infrared range (800 to 2500 nm) compared to that of C-Si with polished surfaces, and the variations in the absorption spectra of the nanostructured black silicon with different etching processes are obtained. The maximum light absorptance increases significantly up to 95 % in the wavelength range of 400 to 2500 nm. Our recent novel results clearly indicate that nanostructured black silicon made by MCE has potential application in near-infrared photoelectronic detectors. PMID:27368764

  17. Mismatched front and back gratings for optimum light trapping in ultra-thin crystalline silicon solar cells

    Science.gov (United States)

    Hsu, Wei-Chun; Tong, Jonathan K.; Branham, Matthew S.; Huang, Yi; Yerci, Selçuk; Boriskina, Svetlana V.; Chen, Gang

    2016-10-01

    The implementation of a front and back grating in ultra-thin photovoltaic cells is a promising approach towards improving light trapping. A simple design rule was developed using the least common multiple (LCM) of the front and back grating periods. From this design rule, several optimal period combinations can be found, providing greater design flexibility for absorbers of indirect band gap materials. Using numerical simulations, the photo-generated current (Jph) for a 10-μm-thick crystalline silicon absorber was predicted to be as high as 38 mA/cm2, which is 11.74% higher than that of a single front grating (Jph=34 mA/cm2).

  18. High Stability White Organic Light-Emitting Diode (WOLED Using Nano-Double-Ultra Thin Carrier Trapping Materials

    Directory of Open Access Journals (Sweden)

    Kan-Lin Chen

    2014-01-01

    Full Text Available The structure of indium tin oxide (ITO (100 nm/molybdenum trioxide (MoO3 (15 nm/N,N0-bis-(1-naphthyl-N,N0-biphenyl-1,10-biphenyl-4,40-diamine (NPB (40 nm/4,4′-Bis(2,2-diphenylvinyl-1,1′-biphenyl (DPVBi (10 nm/5,6,11,12-tetraphenylnaphthacene (Rubrene (0.2 nm/DPVBi (24 nm/Rubrene (0.2 nm/DPVBi (6 nm/4,7-diphenyl-1,10-phenanthroline (BPhen: cesium carbonate (Cs2Co3 (10 nm/Al (120 nm with high color purity and stability white organic light-emitting diode (WOLED was fabricated. The function of the multiple-ultra-thin material (MUTM, such as Rubrene, is as the yellow light-emitting layer and trapping layer. The results show that the MUTM has an excellent carrier capture effect, resulting in high color stability of the device at different applied voltages. The Commissions Internationale De L’Eclairage (CIE coordinate of this device at 3~7 V is few displacement and shows a very slight variation of (±0.01, ±0.01. The maximum brightness of 9986 cd/m2 and CIE coordinates of (0.346, 0.339 are obtained at 7 V. The enhanced performance of the device may result from the direct charge trapping in MUTM and it can be found in the electroluminescence (EL process.

  19. Efficient illumination of spatial light modulators for optical trapping and manipulation

    DEFF Research Database (Denmark)

    Bañas, Andrew Rafael; Kopylov, Oleksii; Raaby, Peter;

    shaping while maintaining the speckle-free, high-contrast qualities of amplitude masking. Compared to a hard truncated Gaussian, a GPC Light Shaper (LS) saves up to 93% of typical losses3. We experimentally demonstrated shaped illumination with ~80% efficiency, ~3x intensity gain, and ~90% energy savings4...

  20. Photonic light trapping in silicon nanowire arrays: deriving and overcoming the physical limitations

    CERN Document Server

    Schmitt, Sebastian W

    2016-01-01

    Hexagonally aligned, free-standing silicon nanowire (SiNW) arrays serve as photonic resonators which, as compared to a silicon (Si) thin film, do not only absorb more visible (VIS) and near-infrared (NIR) light, but also show an inherent photonic light concentration that enhances their performance as solar absorbers. Using numerical simulations we show, how light concentration is induced by high optical cross sections of the individual SiNWs but cannot be optimized independently of the SiNW array absorption. While an ideal spatial density exists, for which the SiNW array absorption for VIS and NIR wavelengths reaches a maximum, the spatial correlation of SiNWs in an array suppresses the formation of optical Mie modes responsible for light concentration. We show that different from SiNWs with straight sidewalls, arrays of inverted silicon nanocones (SiNCs) permit to avoid the mode suppression. In fact they give rise to an altered set of photonic modes which is induced by the spatial correlation of SiNCs in the...

  1. Three-dimensional simulations of super-critical black hole accretion disks --- luminosities, photon trapping and variability

    CERN Document Server

    Sadowski, Aleksander

    2015-01-01

    We present a set of four three-dimensional, general relativistic, radiation MHD simulations of black hole accretion at super-critical mass accretion rates, $\\dot{M} > \\dot{M}_{\\rm Edd}$. We use these simulations to study how disk properties are modified when we vary the black hole mass, the black hole spin, or the mass accretion rate. In the case of a non-rotating black hole, we find that the total efficiency is of order $3\\%\\dot M c^2$, approximately a factor of two less than the efficiency of a standard thin accretion disk. The radiation flux in the funnel along the axis is highly super-Eddington, but only a small fraction of the energy released by accretion escapes in this region. The bulk of the $3\\%\\dot M c^2$ of energy emerges farther out in the disk, either in the form of photospheric emission or as a wind. In the case of a black hole with a spin parameter of 0.7, we find a larger efficiency of about $8\\%\\dot M c^2$. By comparing the relative importance of advective and diffusive radiation transport, w...

  2. High efficiency preparation of single trapped atoms using blue detuned light assisted collisions

    CERN Document Server

    Carpentier, A V; Sompet, P; Hilliard, A J; Walker, T G; Andersen, M F

    2012-01-01

    We report on a procedure by which we obtain a 91% loading efficiency of single 85Rb atoms in an optical microtrap. This can be achieved within a total preparation time of 542 ms. We employ blue detuned light assisted collisions to realize a process in which only one of the collision partners is lost. We explain the mechanism for efficiently loading a single atom and discuss the factors that limit the final efficiency.

  3. Aggregates of plasmonic nanoparticles for broadband light trapping in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Metallic nanoparticles (NPs) have not been effective in improving the overall performance of the cells with micrometer-thick absorbing layers mainly due to the parasitic optical dissipation in the metal. Here, using both experiment and theory, we demonstrate that aggregates of metallic NPs enhance the light absorption of dye-sensitized solar cells of a few micrometer-thick light absorbing layers. The composite electrode containing the optimal concentration of 5 wt% Au@SiO2 aggregates shows the enhancement of 80% and 52% in external quantum efficiency and photocurrent density, respectively. The superior performance of the aggregates relative to NP is attributed to their larger scattering efficiency using full-wave optical simulations. This is further confirmed by optical spectroscopic measurements showing that a large fraction of the incident light couples into the diffused components because of the presence of these metallic aggregates. The optical absorption enhancement is broadband and it is particularly strong at wavelengths larger than 680 nm where the optical absorption of dye molecules is weak. (paper)

  4. Comparison of surveillance efficacy between black box and lamp trap methods%黑箱法与灯诱法蚊虫监测结果比较

    Institute of Scientific and Technical Information of China (English)

    冷培恩; 除友祥; 武峥嵘; 刘洪霞; 徐仁权

    2011-01-01

    Objective To evaluate the application of black box method in mosquito surveillance by comparing the results from black box and lamp trap methods. Methods Two lamps were set at each surveillance site and one black box was put at a 10 m interval from each lamp. Surveillance was conducted twice every month. Results The total number of captured mosquitoes and the number of female mosquitoes by the lamp trap method was 3.50 times and 3.75 times higer than those monitored by black box method, respectively. The seasonal fluctuation curves reflected by both methods were unimodal, with a peak in July. The monthly calculations of mosquitoes of the two methods were highly correlated. Mosquitoes captured by the black box method included Culex pipens pollens (84.64%), Cx. Tritaeriorhynchus (10.02%), and Anopheles sinensis (3.34%), and those by the lamp trap method were Cx. Pipens pollens (80.47%), Cx. Tritaeriorhynchw (11.79%), and An. Sinensis (6.88%). Only a few Aedes albopictus and Armigeres subalbatus were trapped. The male-female ratios were similar between the two methods, whereas great difference in the mosquito number was found in distinct environments. Black box method was more effective in parks and hospitals than the other, while lamp trap was more effective in pasture lands and farms. Two peaks of mosquito density were shown on 05: 00 and 19: 00 with environmental difference between day and night. The day and night peaks of density were also present in parks, farms and pasture lands except hospitals and residential areas where only one night peak was shown. Conclusion With fewer requirements for equipment, operation skills and power supply, the black box method is an effective alternative to the lamp trap approach. Deployment before the night peak of density and collection after the early morning peak is recommended for mosquito monitoring.%目的 比较黑箱法与灯诱法监测蚊虫密度的差异,探讨黑箱法在蚊虫监测中的作用.方法 在7个

  5. Limits of light-trapping efficiency of prototypical lamellar 1-d metal gratings for amorphous silicon PV cells

    CERN Document Server

    Gablinger, David I

    2014-01-01

    One-dimensional lamellar gratings allow a particularly efficient way for solving Maxwell's equations by expanding the electromagnetic field in the basis of exact eigenmodes of the Helmholtz equation. Then, the solution can be expressed analytically as a superposition of these eigenmodes and the accuracy depends only on the number of modes $N$ included. On this basis, we compute ideal limits of light-trapping performance for prototypical lamellar metal surface relief gratings in amorphous silicon (a-Si) PV cells assuming that light absorption in the metal and front surface reflection can be suppressed. We show that geometric asymmetry can increase absorption. For large enough $N$, convergence of absorption spectra for E polarisation is reached. For H polarisation it is reached for wavelengths $\\lambda<$680-700 nm, while the integrated AM1.5-weighted absorption varies by less than 1\\% at large $N$. For an a-Si layer with height 200 nm and normal incidence, we obtain upper limits of the total absorption of 79...

  6. Nanoscale aluminum concaves for light-trapping in organic thin-films

    Science.gov (United States)

    Goszczak, Arkadiusz Jarosław; Adam, Jost; Cielecki, Paweł Piotr; Fiutowski, Jacek; Rubahn, Horst-Günter; Madsen, Morten

    2016-07-01

    Anodic aluminum oxide (AAO) templates, fabricated from oxalic acid and phosphoric acid, lead to non-periodic nanoscale concave structures in their underlying aluminum layer, which are investigated for their field-enhancement properties by applying a thin-film polymer coating based laser ablation technique. Local ablation spots, corresponding to field enhancement on the ridge edges of the aluminum concave nanostructures, are observed in surface-covering polymer films, and confirmed with FDTD studies. The field enhancement leads to improved light absorption in the applied polymer layers, which may be used as an efficient method for enhancing the power conversion efficiency of organic solar cells.

  7. Enhancing energy absorption in quantum dot solar cells via periodic light-trapping microstructures

    Science.gov (United States)

    Miller, Christopher Wayne; Fu, Yulan; Lopez, Rene

    2016-09-01

    Colloidal quantum dot (CQD) solar cells prove to be promising devices for optoelectronic applications due to their tunable absorption range, deep infrared absorption capabilities, and straightforward processability. However, there remains a need to further enhance their device performance—particularly when one has to adhere to strict physical limitations on their physical structure. Here we present a three-dimensional numerical model of CQD solar cells in COMSOL Multiphysics based on the finite element method. With this model we have simulated the optical characteristics of several CQD solar cells across varying photonic structures and physical parameters to investigate how distinct photonic structures may enhance the light absorption and current output of CQD solar cells using identical physical parameters. Of the many cells simulated, one notable model increased the predicted current in the active layer PbS by 69.33% as compared to a flat solar cell with identical physical parameters, and produced a current of 24.18 mA cm‑2 by implementing a cross-shaped photonic structure built on top of a flat substrate of glass and ITO. This cross-shaped model serves as a key example of how unique photonic structures can be implemented to further enhance light absorption.

  8. Light trapping regimes in thin-film silicon solar cells with a photonic pattern.

    Science.gov (United States)

    Zanotto, Simone; Liscidini, Marco; Andreani, Lucio Claudio

    2010-03-01

    We present a theoretical study of crystalline and amorphous silicon thin-film solar cells with a periodic pattern on a sub-micron scale realized in the silicon layer and filled with silicon dioxide right below a properly designed antireflection (AR) coating. The study and optimization of the structure as a function of all the photonic lattice parameters, together with the calculation of the absorption in a single layer, allows to identify the different roles of the periodic pattern in determining an increase of the absorbance. From one side, the photonic crystal and the AR coating act as impedance matching layers, thus minimizing reflection of incident light over a particularly wide range of frequencies. Moreover a strong absorption enhancement is observed when the incident light is coupled into the quasi guided modes of the photonic slab. We found a substantial increase of the short-circuit current when the parameters are properly optimized, demonstrating the advantage of a wavelength-scale, photonic crystal based approach for patterning of thin-film silicon solar cells. PMID:20389438

  9. Vortical light bullets in second-harmonic-generating media supported by a trapping potential

    CERN Document Server

    Sakaguchi, Hidetsugu

    2013-01-01

    We introduce a three-dimensional (3D) model of optical media with the quadratic ($\\chi ^{(2)}$) nonlinearity and an effective 2D isotropic harmonic-oscillator (HO) potential. While it is well known that 3D \\chi^2 solitons with embedded vorticity ("vortical light bullets") are unstable in the free space, we demonstrate that they have a broad stability region in the present model, being supported by the HO potential against the splitting instability. The shape of the vortical solitons may be accurately predicted by the variational approximation (VA). They exist above a threshold value of the total energy (norm) and below another critical value, which determines a stability boundary. The existence threshold vanishes is a part of the parameter space, depending on the mismatch parameter, which is explained by means of the comparison with the 2D counterpart of the system. Above the stability boundary, the vortex features shape oscillations, periodically breaking its axisymmetric form and restoring it. Collisions be...

  10. Tailoring broadband light trapping of GaAs and Si substrates by self-organised nanopatterning

    Energy Technology Data Exchange (ETDEWEB)

    Martella, C.; Chiappe, D.; Mennucci, C.; Buatier de Mongeot, F. [Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146 Genova (Italy)

    2014-05-21

    We report on the formation of high aspect ratio anisotropic nanopatterns on crystalline GaAs (100) and Si (100) substrates exploiting defocused Ion Beam Sputtering assisted by a sacrificial self-organised Au stencil mask. The tailored optical properties of the substrates are characterised in terms of total reflectivity and haze by means of integrating sphere measurements as a function of the morphological modification at increasing ion fluence. Refractive index grading from sub-wavelength surface features induces polarisation dependent anti-reflection behaviour in the visible-near infrared (VIS-NIR) range, while light scattering at off-specular angles from larger structures leads to very high values of the haze functions in reflection. The results, obtained for an important class of technologically relevant materials, are appealing in view of photovoltaic and photonic applications aiming at photon harvesting in ultrathin crystalline solar cells.

  11. Enhanced light trapping with double-groove grating in thin-film amorphous silicon solar cells

    Science.gov (United States)

    Wu, Jun

    2016-05-01

    A design to enhance light absorption in thin-film amorphous silicon (a-Si) solar cells is proposed. It is achieved by patterning a double-groove grating with waveguide layer as the absorbing layer and coating a double-groove grating anti-reflective layer in the front window of the cell. The broadband absorption under normal incidence can be achieved for both TE and TM polarizations. It is shown that the averaged integrated absorptions have very large angle independence for the optimized solar cell. An qualitative understanding of such broadband enhanced absorption effect, which is attributed to the guided mode resonance, is presented. The conclusions can be exploited to guide the design of solar cells based on a grating structure.

  12. Generation of Antibunched Light by Excited Molecules in a Microcavity Trap

    Science.gov (United States)

    DeMartini, F.; DiGiuseppe, G.; Marrocco, M.

    1996-01-01

    The active microcavity is adopted as an efficient source of non-classical light. By this device, excited by a mode-locked laser at a rate of 100 MHz, single-photons are generated over a single field mode with a nonclassical sub-poissonian distribution. The process of adiabatic recycling within a multi-step Franck-Condon molecular optical-pumping mechanism, characterized in our case by a quantum efficiency very close to one, implies a pump self-regularization process leading to a striking n-squeezing effect. By a replication of the basic single-atom excitation process a beam of quantum photon (Fock states) can be created. The new process represents a significant advance in the modern fields of basic quantum-mechanical investigation, quantum communication and quantum cryptography.

  13. Nanostructured zinc oxide systems with gold nanoparticle pattern for efficient light trapping

    International Nuclear Information System (INIS)

    In this work we describe the design of a system consisting of a zinc oxide nanowire array and ITO glass nanostructured with gold NPs. Our goal was to create a more efficient system that could be used in various optical applications, such as photovoltaics or photodetectors. The impact of gold NPs of different shapes, single as well as arranged in a pattern, on the optical properties of the system was studied by using a finite integration technique. The absorptance and transmittance spectra of individual components of the system were calculated. Finally, the integrated spectral enhancement factors of the photons absorbed and transmitted by the electrode were estimated using the different geometrical parameters of the electrode. The results suggested that the most effective absorber of light should include zinc oxide nanowires (NWs), with smaller diameters and cylindrical shapes of single gold NPs, as well as in a pattern, while the highest transmittance is obtained for greater diameter of NWs and conical shapes of gold NPs in a pattern. Based on these results, the absorption current density (derived from the generation and collection of light-generated charge carriers) was calculated for the ZnO-CdTe core-shell NWs nanostructured with gold NPs arranged into a pattern. The results suggest that the most efficient electrode contains ZnO NWs with gold NPs in a conical shaped pattern. Our results confirm the importance of computational simulation in the design of the photonic and photovoltaic devices, making it possible to predict the most efficient systems. These results could be useful to further optimize photonic or photovoltaic devices based on plasmonic NPs and semiconductor nanostructures. (paper)

  14. Nanostructured zinc oxide systems with gold nanoparticle pattern for efficient light trapping

    Science.gov (United States)

    Robak, Elżbieta; Kotkowiak, Michał; Drozdowski, Henryk

    2016-02-01

    In this work we describe the design of a system consisting of a zinc oxide nanowire array and ITO glass nanostructured with gold NPs. Our goal was to create a more efficient system that could be used in various optical applications, such as photovoltaics or photodetectors. The impact of gold NPs of different shapes, single as well as arranged in a pattern, on the optical properties of the system was studied by using a finite integration technique. The absorptance and transmittance spectra of individual components of the system were calculated. Finally, the integrated spectral enhancement factors of the photons absorbed and transmitted by the electrode were estimated using the different geometrical parameters of the electrode. The results suggested that the most effective absorber of light should include zinc oxide nanowires (NWs), with smaller diameters and cylindrical shapes of single gold NPs, as well as in a pattern, while the highest transmittance is obtained for greater diameter of NWs and conical shapes of gold NPs in a pattern. Based on these results, the absorption current density (derived from the generation and collection of light-generated charge carriers) was calculated for the ZnO-CdTe core-shell NWs nanostructured with gold NPs arranged into a pattern. The results suggest that the most efficient electrode contains ZnO NWs with gold NPs in a conical shaped pattern. Our results confirm the importance of computational simulation in the design of the photonic and photovoltaic devices, making it possible to predict the most efficient systems. These results could be useful to further optimize photonic or photovoltaic devices based on plasmonic NPs and semiconductor nanostructures.

  15. Black Holes

    Science.gov (United States)

    Luminet, Jean-Pierre

    1992-09-01

    Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.

  16. Evidence for GR rotational frame-dragging in the light from the Sgr A* supermassive black hole

    CERN Document Server

    Aschenbach, Bernd Eduard

    2009-01-01

    The analysis of flare start-times confirms the periods found years ago (Aschenbach et al., 2004) in the near-infrared and X-ray light-curves related to the Sgr A* black hole. The assignment of the frequencies found to radial and vertical epicyclic frequencies $\

  17. DEET (N,N-diethyl-meta-toluamide)/PMD (para-menthane-3,8-diol) repellent-treated mesh increases Culicoides catches in light traps.

    Science.gov (United States)

    Murchie, A K; Clawson, S; Rea, I; Forsythe, I W N; Gordon, A W; Jess, S

    2016-09-01

    Biting midges (Culicoides spp.) are vectors of bluetongue and Schmallenberg viruses. Treatment of mesh barriers is a common method for preventing insect-vectored diseases and has been proposed as a means of limiting Culicoides ingression into buildings or livestock transporters. Assessments using animals are costly, logistically difficult and subject to ethical approval. Therefore, initial screening of test repellents/insecticides was made by applying treatments to mesh (2 mm) cages surrounding Onderstepoort light traps. Five commercial treatments were applied to cages as per manufacturers' application rates: control (water), bendiocarb, DEET/p-menthane-3,8-diol (PMD) repellent, Flygo (a terpenoid based repellent) and lambda-cyhalothrin. The experimental design was a 5 × 5 Latin square, replicated in time and repeated twice. Incongruously, the traps surrounded by DEET/PMD repellent-treated mesh caught three to four times more Obsoletus group Culicoides (the commonest midge group) than the other treatments. A proposed hypothesis is that Obsoletus group Culicoides are showing a dose response to DEET/PMD, being attracted at low concentrations and repelled at higher concentrations but that the strong light attraction from the Onderstepoort trap was sufficient to overcome close-range repellence. This study does not imply that DEET/PMD is an ineffective repellent for Culicoides midges in the presence of an animal but rather that caution should be applied to the interpretation of light trap bioassays. PMID:27179956

  18. Light-trapping for room temperature Bose-Einstein condensation in InGaAs quantum wells.

    Science.gov (United States)

    Vasudev, Pranai; Jiang, Jian-Hua; John, Sajeev

    2016-06-27

    , the strong light confinement results in light-matter coupling strength of ℏΩ = 13.7 meV. Assuming an exciton density per QW of (15aB)-2, well below the saturation density, in a 2-D box-trap with a side length of 10 to 500 µm, we predict thermal equilibrium Bose-Einstein condensation well above room temperature. PMID:27410564

  19. Light-trapping for room temperature Bose-Einstein condensation in InGaAs quantum wells.

    Science.gov (United States)

    Vasudev, Pranai; Jiang, Jian-Hua; John, Sajeev

    2016-06-27

    , the strong light confinement results in light-matter coupling strength of ℏΩ = 13.7 meV. Assuming an exciton density per QW of (15aB)-2, well below the saturation density, in a 2-D box-trap with a side length of 10 to 500 µm, we predict thermal equilibrium Bose-Einstein condensation well above room temperature.

  20. The Hard X-Ray Spectrum of NGC 1365: Scattered Light, Not Black Hole Spin

    Science.gov (United States)

    Miller, L.; Turner, T. J.

    2013-08-01

    Active galactic nuclei (AGNs) show excess X-ray emission above 10 keV compared with extrapolation of spectra from lower energies. Risaliti et al. have recently attempted to model the hard X-ray excess in the type 1.8 AGN NGC 1365, concluding that the hard excess most likely arises from Compton-scattered reflection of X-rays from an inner accretion disk close to the black hole. Their analysis disfavored a model in which the hard excess arises from a high column density of circumnuclear gas partially covering a primary X-ray source, despite such components being required in the NGC 1365 data below 10 keV. Using a Monte Carlo radiative transfer approach, we demonstrate that this conclusion is invalidated by (1) use of slab absorption models, which have unrealistic transmission spectra for partial covering gas, (2) neglect of the effect of Compton scattering on transmitted spectra, and (3) inadequate modeling of the spectrum of scattered X-rays. The scattered spectrum is geometry-dependent and, for high global covering factors, may dominate above 10 keV. We further show that, in models of circumnuclear gas, the suppression of the observed hard X-ray flux by reprocessing may be no larger than required by the "light bending" model invoked for inner disk reflection, and the expected emission line strengths lie within the observed range. We conclude that the time-invariant "red wing" in AGN X-ray spectra is probably caused by continuum transmitted through and scattered from circumnuclear gas, not by highly redshifted line emission, and that measurement of black hole spin is not possible.

  1. Light absorption and scattering by aggregates: Application to black carbon and snow grains

    International Nuclear Information System (INIS)

    under the condition of equal geometrical cross section area for both external and internal mixing states; however, nonspherical snowflakes scatter less light in forward directions than spheres, resulting in a substantial reduction of the asymmetry factor. We further demonstrate that small soot particles on the order of 1 μm internally mixed with snow grains could effectively reduce snow albedo by as much as 5-10%. Indeed, the depositions of black carbon would substantially reduce mountain-snow albedo, which would lead to surface warming and snowmelt, critical to regional climatic surface temperature amplification and feedback.

  2. The role of iron and black carbon in aerosol light absorption

    Directory of Open Access Journals (Sweden)

    Y. Derimian

    2008-07-01

    Full Text Available Iron is a major component of atmospheric aerosols, influencing the light absorption ability of mineral dust, and an important micronutrient that affects oceanic biogeochemistry. The regional distribution of the iron concentration in dust is important for climate studies; however, this is difficult to obtain since it requires in-situ aerosol sampling or simulation of complex natural processes. Simultaneous studies of aerosol chemical composition and radiometric measurements of aerosol optical properties, which were performed in the Negev desert of Israel continuously for about eight years, suggest a potential for deriving a relationship between chemical composition and light absorption properties, in particular the spectral single-scattering albedo.

    The two main data sets of the present study were obtained by a sun/sky radiometer and a stacked filter unit sampler that collects particles in coarse and fine size fractions. Analysis of chemical and optical data showed the presence of mixed dust and pollution aerosol in the study area, although their sources appear to be different. Spectral SSA showed an evident response to increased concentrations of iron, black carbon equivalent matter, and their mixing state. A relationship that relates the spectral SSA, the percentage of iron in total particulate mass, and the pollution components was derived. Results calculated, using this relationship, were compared with measurements from dust episodes in several locations around the globe. The comparison showed reasonable agreement between the calculated and the observed iron concentrations, and supported the validity of the suggested approach for the estimation of iron concentrations in mineral dust.

  3. Gravitational deflection of light and massive particles by a moving Kerr-Newman black hole

    Science.gov (United States)

    He, Guansheng; Lin, Wenbin

    2016-05-01

    The gravitational deflection of test particles including light, due to a radially moving Kerr-Newman (KN) black hole with an arbitrary constant velocity that is perpendicular to its angular momentum, is investigated. In harmonic coordinates, we derive the second post-Minkowskian (2PM) equations of motion for test particles, and solve them by high-accuracy numerical calculations. We then concentrate on discussing the kinematical corrections caused by the motion of the gravitational source to second-order deflection. The analytical formula of the light-deflection angle up to the second order by a moving lens is obtained. For a massive particle moving with a relativistic velocity, there are two different analytical results for the Schwarzschild deflection angle up to the second order reported in the previous works, i.e. α (w)=2≤ft(1+\\tfrac{1}{{w}2}\\right)\\tfrac{M}{b}+3π ≤ft(\\tfrac{1}{4}+\\tfrac{1}{{w}2}\\right)\\tfrac{{M}2}{{b}2} and α (w)=2≤ft(1+\\tfrac{1}{{w}2}\\right)\\tfrac{M}{b}+≤ft[3π ≤ft(\\tfrac{1}{4}+\\tfrac{1}{{w}2}\\right)+2≤ft(1-\\tfrac{1}{{w}4}\\right)\\right]\\tfrac{{M}2}{{b}2}, where M, b, and w are the mass of the lens, the impact parameter, and the particle’s initial velocity, respectively. Our numerical result is in perfect agreement with the former result. Furthermore, the analytical formula for massive particle deflection up to the second order in the Kerr geometry is achieved. Finally, the possibilities of detecting the motion effects on the second-order deflection are also analyzed.

  4. Black Carbon and Kerosene Lighting: An Opportunity for Rapid Action on Climate Change and Clean Energy for Development

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Arne [Humboldt State Univ., MN (United States). Schatz Energy Research Center; Bond, Tami C. [Univ. of Illinois at Urbana-Champaign, IL (United States). Dept. of Civil and Environmental Engineering; Lam, Nicholoas L. [Univ. of California, Berkeley, CA (United States). Dept. of Environmental Health Sciences; Hultman, Nathan [The Brookings Institution, Washington, DC (United States)

    2013-04-15

    Replacing inefficient kerosene lighting with electric lighting or other clean alternatives can rapidly achieve development and energy access goals, save money and reduce climate warming. Many of the 250 million households that lack reliable access to electricity rely on inefficient and dangerous simple wick lamps and other kerosene-fueled light sources, using 4 to 25 billion liters of kerosene annually to meet basic lighting needs. Kerosene costs can be a significant household expense and subsidies are expensive. New information on kerosene lamp emissions reveals that their climate impacts are substantial. Eliminating current annual black carbon emissions would provide a climate benefit equivalent to 5 gigatons of carbon dioxide reductions over the next 20 years. Robust and low-cost technologies for supplanting simple wick and other kerosene-fueled lamps exist and are easily distributed and scalable. Improving household lighting offers a low-cost opportunity to improve development, cool the climate and reduce costs.

  5. Light Fraction Carbon and Water-Stable Aggregates in Black Soils

    Institute of Scientific and Technical Information of China (English)

    SHI Yi; CHEN Xin; SHEN Shan-Min

    2007-01-01

    The distribution of light fraction carbon (LF-C) in the various size classes of aggregates and its relationship to waterstable aggregates as well as the influence of cultivation on the organic components in virgin and cultivated black soils were studied by wet sieving and density separation methods. The total organic carbon (TOC) and LF-C were significantly higher (P ≤ 0.05) in the virgin soils than in the cultivated soils. The LF-C in aggregates of different size classes varied from 0.9 to 2.5 g kg-1 in the cultivated soils and from 2.5 to 7.1 g kg-1 in the virgin soils, whereas the ratio of LF-C to TOC varied from 1.9% to 7.3% and from 5.0% to 12.2%, respectively. After being incubated under constant temperature and controlled humidity for three months, the contribution of LF-C to TOC sharply decreased to an amount (1.7%-8.5%)close to the level in soils that had been cultivated for 20 to 25 years (1.3%-8.8%). As a result, the larger water-stable macro-aggregates (especially > 1 mm) decreased sharply, indicating that the LF-C pool in virgin soils declined quickly after cultivation, which reduced the water stability of soil aggregates.

  6. Simultaneous broadband light trapping and fill factor enhancement in crystalline silicon solar cells induced by Ag nanoparticles and nanoshells.

    Science.gov (United States)

    Fahim, Narges F; Jia, Baohua; Shi, Zhengrong; Gu, Min

    2012-09-10

    Crystalline silicon solar cells are predominant and occupying more than 89% of the global solar photovoltaic market. Despite the boom of the innovative solar technologies, few can provide a low-cost radical solution to dramatically boost the efficiency of crystalline silicon solar cells, which has reached plateau in the past ten years. Here, we present a novel strategy to simultaneously achieve dramatic enhancement in the short-circuit current and the fill factor through the integration of Ag plasmonic nanoparticles and nanoshells on the antireflection coating and the screen-printed fingers of monocrystalline silicon solar cells, respectively, by a single step and scalable modified electroless displacement method. As a consequence, up to 35.2% enhancement in the energy conversion efficiency has been achieved due to the plasmonic broadband light trapping and the significant reduction in the series resistance. More importantly, this method can further increase the efficiency of the best performing textured solar cells from 18.3% to 19.2%, producing the highest efficiency cells exceeding the state-of-the-art efficiency of the standard screen-printed solar cells. The dual functions of the Ag nanostructures, reported for the first time here, present a clear contrast to the previous works, where plasmonic nanostructures were integrated into solar cells to achieve the short-circuit current enhancement predominately. Our method offers a facile, cost-effective and scalable pathway for metallic nanostructures to be used to dramatically boost the overall efficiency of the optically thick crystalline silicon solar cells. PMID:23037536

  7. Dynamics of black holes

    OpenAIRE

    Hayward, Sean A.

    2008-01-01

    This is a review of current theory of black-hole dynamics, concentrating on the framework in terms of trapping horizons. Summaries are given of the history, the classical theory of black holes, the defining ideas of dynamical black holes, the basic laws, conservation laws for energy and angular momentum, other physical quantities and the limit of local equilibrium. Some new material concerns how processes such as black-hole evaporation and coalescence might be described by a single trapping h...

  8. CAPTURE OF Tuta absoluta (Meyrick (LEPIDOPTERA: GELECHIIDAE WITH LIGHT TRAP IN TOMATO CROP CAPTURA DE Tuta absoluta (Meyrick (LEPIDOPTERA: GELECHIIDAE COM ARMADILHA LUMINOSA NA CULTURA DO TOMATEIRO TUTORADO

    Directory of Open Access Journals (Sweden)

    Aline Cavalcante Rodrigues de Oliveira

    2008-09-01

    Full Text Available

    The tomato leafminer (Tuta absoluta represents a serious problem for the tomato crop, not only due to the intensity of its attack, but also to its occurrence during all the crop cycle. In Brazil, this pest has been controlled almost exclusively with insecticides, what is undesirable for economic and environmental reasons. In order to get more information on the control of this pest this research was carried out, in Ouro Verde (Goiás State, Brazil, from September through October 2002, to evaluate the use of light  traps for capture of adult T. absoluta specimens. The treatments used were: 1 black lamp; 2 BLB lamp; 3 Grolux lamp; and 4 fluorescent daylight lamp. The experimental design used was randomized complete blocks with four replications. The parameter to evaluate treatment capture efficiency was the counting of the adult T. absoluta specimens trapped. The results showed that the BLB and ultraviolet lamps were the most efficient treatments. Therefore, both can help to control the tomato leafminer in integrated pest management programs.

    KEY-WORDS: Tomato pinworm; integrated pest management; tomato.

    A traça-do-tomateiro (Tuta absoluta representa um sério problema à tomaticultura, não somente pela intensidade de ataque, mas também por sua ocorrência durante todo o ciclo da cultura. No Brasil, esta praga tem sido controlada, quase exclusivamente, com inseticidas, o que é indesejável, tanto por motivos econômicos, quanto ambientais. Visando a obter maiores informa

  9. Screening of LED light source of the adapter solar trap lamp for trapping the citrus psyllid%适配太阳能诱虫器诱杀柑橘木虱LED光源的筛选

    Institute of Scientific and Technical Information of China (English)

    林雄杰; 范国成; 胡菡青; 阮传清; 蔡子坚; Xia Yulu; 杜云贵; 刘波

    2013-01-01

    The citrus psyllid is the vector of Huanglongbing.In order to control citrus psyllid and prevent disease,screening of LED light source adapter solar trap lamp for citrus psyllid by using reaction vessel of insect behavior was carried out in the laboratory.The results showed that the phototaxis of 1 800 1x and 4 310 lx blue and green light sources (wavelength 460 nm and 531 nm) were best on the illumination duration of 17 h.It was also found that the phototaxis of citrus psyllid adults was positively correlated with light intensity and light duration under the same wavelength condition.It might provide an effective theoretical basis for the LED light source for forecasting and trapping citrus psyllid in the field in the future.%柑橘木虱(Dia phorina citri)是柑橘黄龙病的传播媒介.为达到治虫防病的目的,在室内利用昆虫行为反应器开展适配太阳能诱虫器的LED光源筛选,结果表明:柑橘木虱成虫对光照强度分别为1 800 lx和4 310 lx的蓝光和绿光(波长分别为460 nm和531 nm)在光照时长为17 h时的趋光性最佳,相同波长条件下,其趋光性与光照强度和光照时长成正相关.该研究结果为进一步探索适宜田间柑橘木虱测报和高效诱杀的LED光源提供理论依据.

  10. Aerosol light absorption, black carbon, and elemental carbon at the Fresno Supersite, California

    Science.gov (United States)

    Chow, Judith C.; Watson, John G.; Doraiswamy, Prakash; Chen, Lung-Wen Antony; Sodeman, David A.; Lowenthal, Douglas H.; Park, Kihong; Arnott, W. Patrick; Motallebi, Nehzat

    2009-08-01

    Particle light absorption ( bap), black carbon (BC), and elemental carbon (EC) measurements at the Fresno Supersite during the summer of 2005 were compared to examine the equivalency of current techniques, evaluate filter-based bap correction methods, and determine the EC mass absorption efficiency (σ ap) and the spectral dependence of bap. The photoacoustic analyzer (PA) was used as a benchmark for in-situ bap. Most bap measurement techniques were well correlated ( r ≥ 0.95). Unadjusted Aethalometer (AE) and Particle Soot Absorption Photometer (PSAP) bap were up to seven times higher than PA bap at similar wavelengths because of absorption enhancement by backscattering and multiple scattering. Applying published algorithms to correct for these effects reduced the differences to 24 and 17% for the AE and PSAP, respectively, at 532 nm. The Multi-Angle Absorption Photometer (MAAP), which accounts for backscattering effects, overestimated bap relative to the PA by 51%. BC concentrations determined by the AE, MAAP, and Sunset Laboratory semi-continuous carbon analyzer were also highly correlated ( r ≥ 0.93) but differed by up to 57%. EC measured with the IMPROVE/STN thermal/optical protocols, and the French two-step thermal protocol agreed to within 29%. Absorption efficiencies determined from PA bap and EC measured with different analytical protocols averaged 7.9 ± 1.5, 5.4 ± 1.1, and 2.8 ± 0.6 m 2/g at 532, 670, and 1047 nm, respectively. The Angström exponent (α) determined from adjusted AE and PA bap ranged from 1.19 to 1.46. The largest values of α occurred during the afternoon hours when the organic fraction of total carbon was highest. Significant biases associated with filter-based measurements of bap, BC, and EC are method-specific. Correcting for these biases must take into account differences in aerosol concentration, composition, and sources.

  11. Cylinder light concentrator and absorber: theoretical description

    OpenAIRE

    Kildishev, Alexander V.; Prokopeva, Ludmila J.; Narimanov, Evgenii

    2010-01-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the d...

  12. A Comparison of Carbon Dioxide Sources for Mosquito Capture in Centers for Disease Control and Prevention Light Traps on the Florida Gulf Coast (1).

    Science.gov (United States)

    Hoel, David F; Dunford, James C; Kline, Daniel L; Irish, Seth R; Weber, Michael; Richardson, Alec G; Doud, Carl W; Wirtz, Robert A

    2015-09-01

    Traditional sources of carbon dioxide (CO₂), dry ice, and compressed gas, were tested against 3 combinations of food-grade reagents known to generate CO₂using a compact, lightweight generator delivery system with Centers for Disease Control and Prevention light traps. Three 6 × 6 Latin square trials were completed near the Florida Gulf Coast in the Lower Suwannee Wildlife Refuge during the summer of 2013, collecting a total of 31,632 female mosquitoes. Treatments included dry ice, compressed CO₂gas, a control trap (no CO₂), citric acid + sodium bicarbonate, vinegar + sodium bicarbonate, and yeast + sugar. Decreasing order of trap collections (treatment mean number of mosquitoes per trap night ± standard error) were dry ice 773.5 (± 110.1) > compressed gas 440.7 (± 42.3) > citric acid + sodium bicarbonate 197.6 (± 30.4), yeast + sugar 153.6 (± 27.4) > vinegar + sodium bicarbonate 109.6 (± 16.2) > control 82.4 (± 14.0). A 2-way Kruskal-Wallis analysis by treatment, site, and treatment × site interaction identified significant differences between all treatments. Although dry ice and compressed CO₂gas collected significantly more mosquitoes than other combinations (P < 0.05), use of citric acid and sodium bicarbonate or yeast and sugar greatly outperformed unbaited traps and offer a good alternative to dry ice and compressed gas in areas where these agents are not readily available or are difficult to obtain due to logistical constraints. An inexpensive, portable CO₂generator for use with food-grade reagents is described.

  13. Nonlinear time series analysis of the light curves from the black hole system GRS1915+105

    Institute of Scientific and Technical Information of China (English)

    K.P Harikrishnan; Ranjeev Misra; G.Ambika

    2011-01-01

    GRS 1915+105 is a prominent black hole system exhibiting variability over a wide range of time scales and its observed light curves have been classified into 12 temporal states. Here we undertake a complete analysis of these light curves from all the states using various quantifiers from nonlinear time series analysis, such as the correlation dimension (D2), the correlation entropy (K2), singular value decomposition (SVD) and the multifractal spectrum (f(α) spectrum). An important aspect of our analysis is that, for estimating these quantifiers, we use algorithmic schemes which we have recently proposed and successfully tested on synthetic as well as practical time series from various fields. Though the schemes are based on the conventional delay embedding technique, they are automated so that the above quantitative measures can be computed using conditions prescribed by the algorithm and without any intermediate subjective analysis. We show that nearly half of the 12 temporal states exhibit deviation from randomness and their complex temporal behavior could be approximated by a few (three or four) coupled ordinary nonlinear differential equations. These results could be important for a better understanding of the processes that generate the light curves and hence for modeling the temporal behavior of such complex systems.To our knowledge, this is the first complete analysis of an astrophysical object (let alone a black hole system) using various techniques from nonlinear dynamics.

  14. N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes

    Science.gov (United States)

    Baumgardt, H.

    2016-10-01

    We have determined the masses and mass-to-light ratios of 50 Galactic globular clusters by comparing their velocity dispersion and surface brightness profiles against a large grid of 900 N-body simulations of star clusters of varying initial concentration, size and central black hole mass fraction. Our models follow the evolution of the clusters under the combined effects of stellar evolution and two-body relaxation allowing us to take the effects of mass segregation and energy equipartition between stars self-consistently into account. For a subset of 16 well observed clusters we also derive their kinematic distances. We find an average mass-to-light ratio of Galactic globular clusters of =1.98 ± 0.03, which agrees very well with the expected M/L ratio if the initial mass function (IMF) of the clusters was a standard Kroupa or Chabrier mass function. We do not find evidence for a decrease of the average mass-to-light ratio with metallicity. The surface brightness and velocity dispersion profiles of most globular clusters are incompatible with the presence of intermediate-mass black holes (IMBHs) with more than a few thousand M⊙ in them. The only clear exception is ω Cen, where the velocity dispersion profile provides strong evidence for the presence of a ˜40,000 M⊙ IMBH in the centre of the cluster.

  15. Nobel Prize in Physics 1997 "for development of methods to cool and trap atoms with laser light" : Steven Chu, Claude Cohen-Tannoudji and William D. Phillips

    CERN Multimedia

    Audiovideo service

    1998-01-01

    Prof. C. Cohen-Tannoudji presents "manipulating atoms with light" . By using quasi-resonant exchanges of energy, linear and angular momentum between atoms and photons, it is possible to polarize atoms, to displace their energy levels and to control their position and their velocity. A few physical mechanisms allowing one to trap atoms and to cool them in the microKelvin, and even in the nanoKelvin range, will be described. Various possible applications of such ultracold atoms will be also reviewed.

  16. Shining Light on Quantum Gravity with Pulsar-Black Hole Binaries

    CERN Document Server

    Estes, John; Lippert, Matthew; Simonetti, John H

    2016-01-01

    Pulsars are some of the most accurate clocks found in nature, while black holes offer a unique arena for the study of quantum gravity. As such, pulsar-black hole (PSR-BH) binaries provide ideal astrophysical systems for detecting effects of quantum gravity. With the success of aLIGO and the advent of instruments like the SKA and eLISA, the prospects for discovery of such PSR-BH binaries are very promising. We argue that PSR-BH binaries can serve as ready-made testing grounds for proposed resolutions to the black hole information paradox. We propose using timing signals from a pulsar beam passing through the region near a BH event horizon as a probe of quantum gravitational effects. In particular, we demonstrate that fluctuations of the geometry outside a black hole lead to an increase in the measured root-mean-square deviation of arrival times of pulsar pulses traveling near the horizon. This allows for a clear observational test of the nonviolent nonlocality proposal for black hole information escape. For a ...

  17. Shining Light on Quantum Gravity with Pulsar-Black Hole Binaries

    OpenAIRE

    Estes, John; Kavic, Michael; Lippert, Matthew; Simonetti, John H.

    2016-01-01

    Pulsars are some of the most accurate clocks found in nature, while black holes offer a unique arena for the study of quantum gravity. As such, pulsar-black hole (PSR-BH) binaries provide ideal astrophysical systems for detecting effects of quantum gravity. With the success of aLIGO and the advent of instruments like the SKA and eLISA, the prospects for discovery of such PSR-BH binaries are very promising. We argue that PSR-BH binaries can serve as ready-made testing grounds for proposed reso...

  18. Near perfect light trapping in a 2D gold nanotrench grating at oblique angles of incidence and its application for sensing.

    Science.gov (United States)

    Guo, Junpeng; Li, Zhitong; Guo, Hong

    2016-07-25

    A two-dimensional nanotrench cavity grating on a thick gold film was fabricated by using e-beam lithography. Optical reflection spectra from the fabricated device were measured at oblique angles of incidence for TE and TM polarizations. Near perfect light absorption was observed at different wavelengths for TE and TM polarizations at oblique angles of incidence. The peak absorption wavelength of TM polarization red-shifts significantly as angle of incidence increases. The peak absorption wavelength of TE polarization blue-shifts slightly as incident angle increases. Using finite-difference time-domain (FDTD) simulations, two orders of magnitude magnetic field enhancement was revealed inside nanotrenches, indicating strong light trapping inside the nanostructure. The fabricated device was investigated as a refractive index chemical sensor. It was found that sensitivity increases for TM polarization and decreases for TE polarization when angle of incidence increases from zero. PMID:27464175

  19. Optimization of generalized dielectric nanostructures for enhanced light trapping in thin-film photovoltaics via boosting the local density of optical states.

    Science.gov (United States)

    Wang, Peng; Menon, Rajesh

    2014-01-13

    Recent work has shown that using a high-index cladding atop a lower-index photovoltaic absorber enables absorption of light beyond the ergodic (4n2) limit. In this paper, we propose a generalized optimization method for deriving optimal geometries that allow for such enhancement. Specifically, we adapted the direct-binary-search algorithm to optimize a complex 2-D multi-layer structure with the explicit goal of increasing photocurrent. We show that such an optimization results in enhancing the local density of optical states in an ultra-thin absorber, which forms a slot-waveguide geometry in the presence of a higher-index overcladding. Numerical simulations confirmed optical absorption approaching 100% and absorption-enhancement beyond the ergodic (4n2) limit for specific spectral bands of interest. Our method provides a direct, intuitive and computationally scalable approach for designing light-trapping nanostructures.

  20. Using chemical wet-etching methods of textured AZO films on a-Si:H solar cells for efficient light trapping

    International Nuclear Information System (INIS)

    In this paper, Al-doped ZnO (AZO) films are deposited on glasses substrate by RF magnetron sputtering. The optical, electrical and morphological properties of AZO films textured by wet-etching with different etchants, H3PO4, HCl, and HNO3 are studied. It is found that the textured structure could enhance the light scattering and light trapping ability of amorphous silicon solar cells. The textured AZO film etched with HNO3 exhibits optimized optical properties (T% ≧ 80% over entire wavelength, haze ratio > 40% at 550 nm wavelength) and excellent electrical properties (ρ = 5.86 × 10−4 Ωcm). Scanning electron microscopy and Atomic force microscopy are used to observe surface morphology and average roughness of each textured AZO films. Finally, the textured AZO films etched by H3PO4, HCl and HNO3 were applied to front electrode layer for p–i–n amorphous silicon solar cells. The highest conversion efficiency of amorphous silicon solar cell fabricated on HNO3-etched AZO film was 7.08% with open-circuit voltage, short-circuit current density and fill factor of 895 mV, 14.92 mA/cm2 and 0.56, respectively. It shows a significantly enhancement in the short-circuit current density and conversion efficiency by 16.2% and 20.2%, respectively, compared with the solar cell fabricated on as-grown AZO film. - Highlights: • The textured surface enhances light scattering and light trapping ability. • The HNO3-etched AZO film exhibits excellent optical and electrical properties. • The efficiency of a-Si:H solar cell fabricated on HNO3-etched AZO film was 7.08%. • The short-circuit current density enhances to 16.2%. • The conversion efficiency enhances to 20.2%

  1. ZnO/a-Si distributed Bragg reflectors for light trapping in thin film solar cells from visible to infrared range

    Science.gov (United States)

    Chen, Aqing; Yuan, Qianmin; Zhu, Kaigui

    2016-01-01

    Distributed Bragg reflectors (DBRs) consisting of ZnO and amorphous silicon (a-Si) were prepared by magnetron sputtering method for selective light trapping. The quarter-wavelength ZnO/a-Si DBRs with only 6 periods exhibit a peak reflectance of above 99% and have a full width at half maximum that is greater than 347 nm in the range of visible to infrared. The 6-pair reversed quarter-wavelength ZnO/a-Si DBRs also have a peak reflectance of 98%. Combination of the two ZnO/a-Si DBRs leads to a broader stopband from 686 nm to 1354 nm. Using the ZnO/a-Si DBRs as the rear reflector of a-Si thin film solar cells significantly increases the photocurrent in the spectrum range of 400-1000 nm, in comparison with that of the cells with Al reflector. The obtained results suggest that ZnO/a-Si DBRs are promising reflectors of a-Si thin-film solar cells for light trapping.

  2. Multi-scale and angular analysis of ray-optical light trapping schemes in thin-film solar cells: micro lens array, V-shaped configuration, and double parabolic trapper.

    Science.gov (United States)

    Cho, Changsoon; Lee, Jung-Yong

    2013-03-11

    An efficient light trapping scheme is a key to enhancing the power conversion efficiency (PCE) of thin-film photovoltaic (PV) cells by compensating for the insufficient light absorption. To handle optical components from nano-scale to micro-scale seamlessly, a multi-scale optical simulation is carefully designed in this study and is used to qualitatively analyze the light trapping performances of a micro lens array (MLA), a V-shaped configuration, and the newly proposed scheme, which is termed a double parabolic trapper (DPT) according to both daily and annual movement of the sun. DPT has the potential to enhance the PCE significantly, from 5.9% to 8.9%, for PCDTBT:PC(70)BM-based polymer solar cells by perfectly trapping the incident light between two parabolic PV cells.

  3. MT-1二氧化碳诱蚊器诱捕白纹伊蚊效果观察%Evaluation of the trapping effect of MT-1 carbon dioxide light-trap on adult Aedes albopictus

    Institute of Scientific and Technical Information of China (English)

    葛军旗; 张洪江; 王晨; 李书明

    2011-01-01

    Objective To evaluate the trapping effect of MT-1 carbon dioxide light-traps on adult Aedes albopictus. Methods A factorial design was conducted to compare six CO2 flow groups and one blank control at 7 sampled sites during 10 surveillance periods. The traps were placed at each sample site to collect mosquitoes, and were replaced with new devices with the flow rate adjusted every two hours between 02:00-22:00. Results (1) A total of 1122 adult mosquitoes were collected and identified as two species, including 939 Ae. Albopictus; (2) Mosquitoes were collected more efficiently in the CO2 flow groups (F=3.05, P=0.01), and the highest number of collected mosquitoes was observed at a flow rate of 6 L/min; (3) The numbers of captured Ae. Albopictus were statistically different in distinct surveillance periods (F=2.98, P=0.03), and most of them were captured during 18:00-20:00 and 04:00-06:00; (4) No difference was found in the captured Ae. Albopictus at the sample sites (F=0.47, P=0.80). Conclusion The MT-1 carbon dioxide light-traps could be used to collect adult Ae. Albopictus at a recommended CO2 flow rate of 6 L/min at dusk.%目的 评估MT-1二氧化碳(CO2)诱蚊器诱捕白纹伊蚊的效果.方法 采用析因设计方案,设6个CO2流量组和1个CO2空白对照组、10个监测时段和7个取样点,在每个取样点布放诱蚊灯,每2h调整诱蚊器的CO2流量并更换捕蚊笼,将采集到的蚊虫分类并计数,监测时间为02:00-22:00,探讨CO2流量、监测时段和取样点对MT-1 CO2诱蚊器诱捕白纹伊蚊效果的影响.结果 (1)共捕获蚊类1122只,其中白纹伊蚊占83.69%;(2)CO2流量组对白纹伊蚊的诱捕效果高于对照组(F=3.05,P=0.01),流量为6 L/min时捕获的白纹伊蚊最多;(3)不同监测时段对白纹伊蚊捕获数量的影响差异有统计学意义(F=2.98,P=0.03),18:00-20:00和04:00-06:00两个时段捕获的白纹伊蚊数量较多;(4)各取样点捕获的白纹伊蚊差异无统计学意义(F=0.47,P

  4. The trade-off of light trapping between top and bottom cell in micromorph tandem solar cells with sputtering ZnO:Al glass substrate

    Science.gov (United States)

    Bai, Lisha; Liu, Bofei; Fan, Jun; Zhang, Dekun; Wei, Changchun; Sun, Jian; Zhao, Ying; Zhang, Xiaodan

    2014-11-01

    A simulated and experimental investigation of the trade-off between light trapping and current matching in p-i-n structured a-Si:H/μc-Si:H tandem solar cells is presented, which aims to address the limited short circuit current density (Jsc) that results from the low long-wavelength light scattering of the fluorine-doped tin oxide (SnO2:F) substrates typically used. To this end, the mismatch of the Jsc between the top and bottom cells is reduced by utilizing a ZnO:Al substrate with optimized long-wavelength light scattering properties as the front contact, thereby improving the response of the bottom cell at the expense of the lower top cell's Jsc yet. A trade-off between the top and bottom cell's light response is subsequently found with SnO2 or ZnO:Al as a substrate, by introducing an n-type μc-SiOx intermediate reflector (IR) between the two component cells. An initial efficiency based on an approximate current matching of 11.90% is achieved for a-Si:H/μc-Si:H tandem solar cell by adopting a magnetron-sputtered and texture-etched ZnO:Al substrate and an optimized n-type μc-SiOx IR.

  5. Synergistic effect of single-electron-trapped oxygen vacancies and carbon species on the visible light photocatalytic activity of carbon-modified TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaodong, E-mail: donguser@henu.edu.cn; Xue, Xiaoxiao; Liu, Xiaogang; Xing, Xing; Li, Qiuye; Yang, Jianjun

    2015-03-01

    Carbon-modified TiO{sub 2} (CT) nanoparticles were prepared via a two-step method of heat treatment without the resorcinol-formaldehyde (RF) polymer. As-prepared CT nanoparticles were characterized by means of X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UV–Vis/DRS), transmission electron microscopy (TEM), N{sub 2} adsorption–desorption isotherms, thermal analysis (TA), electron spin resonance (ESR), and X-ray photoelectron spectroscopy (XPS). The visible light photocatalytic activities were evaluated on the basis of the degradation of methyl orange (MO). The synergistic effect of single-electron-trapped oxygen vacancies (SETOVs) and the carbon species on the visible light photocatalytic activities of the CT nanoparticles were discussed. It was found that the crystalline phase, the morphology, and particle size of the CT nanoparticles depended on the second heat-treatment temperature instead of the first heat-treatment temperature. The visible light photocatalytic activities were attributed to the synergistic effect of SETOVs and the carbon species, and also depended on the specific surface area of the photocatalysts. - Highlights: • Carbon-modified TiO{sub 2} particles have been prepared without RF polymer. • The visible light photocatalytic activities of the particles have been evaluated. • The band gap energy structure of the carbon-modified TiO{sub 2} has been proposed. • Synergistic effect of SETOVs and carbon species has been discussed. • The activities also depend on the specific surface area of the catalysts.

  6. Null Trajectories and Bending of Light in Charged Black Holes with Quintessence

    Science.gov (United States)

    Fernando, Sharmanthie; Meadows, Scott; Reis, Kevon

    2015-10-01

    We have studied null geodesics of the charged black hole surrounded by quintessence. Quintessence is a candidate for dark energy and is represented by a scalar field. Here, we have done a detailed study of the photon trajectories. The exact solutions for the trajectories are obtained in terms of the Jacobi-elliptic integrals for all possible energy and angular momentum of the photons. We have also studied the bending angle using the Rindler and Ishak method.

  7. Null trajectories and bending of light in charged black holes with quintessence

    CERN Document Server

    Fernando, Sharmanthie; Reis, Kevon

    2014-01-01

    We have studied null geodesics of the charged black hole surrounded by quintessence. Quintessence is a candidate for dark energy and is represented by a scalar field. Here, we have done a detailed study of the photon trajectories. The exact solutions for the trajectories are obtained in terms of the Jacobi-elliptic integrals for all possible energy and angular momentum of the photons. We have also studied the bending angle using the Rindler and Ishak method.

  8. Lamp-lit bridges as dual light-traps for the night-swarming mayfly, Ephoron virgo: interaction of polarized and unpolarized light pollution.

    Directory of Open Access Journals (Sweden)

    Denes Szaz

    Full Text Available Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99% adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a supernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently attracted to both unpolarized and polarized light sources, that both types of photopollution are being produced at the bridge, and that spatial patterns of swarming and oviposition are consistent with evolved behaviors being triggered maladaptively by these two types of light pollution. We suggest solutions to bridge and lighting design that should prevent or mitigate the impacts of such scenarios in the future. The detrimental impacts of such scenarios may extend beyond Ephoron virgo.

  9. Lamp-Lit Bridges as Dual Light-Traps for the Night-Swarming Mayfly, Ephoron virgo: Interaction of Polarized and Unpolarized Light Pollution

    OpenAIRE

    Denes Szaz; Gabor Horvath; Andras Barta; Robertson, Bruce A.; Alexandra Farkas; Adam Egri; Nikolett Tarjanyi; Gergely Racz; Gyorgy Kriska

    2015-01-01

    Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a ...

  10. Lamp-lit bridges as dual light-traps for the night-swarming mayfly, Ephoron virgo: interaction of polarized and unpolarized light pollution.

    Science.gov (United States)

    Szaz, Denes; Horvath, Gabor; Barta, Andras; Robertson, Bruce A; Farkas, Alexandra; Egri, Adam; Tarjanyi, Nikolett; Racz, Gergely; Kriska, Gyorgy

    2015-01-01

    Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99% adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a supernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently attracted to both unpolarized and polarized light sources, that both types of photopollution are being produced at the bridge, and that spatial patterns of swarming and oviposition are consistent with evolved behaviors being triggered maladaptively by these two types of light pollution. We suggest solutions to bridge and lighting design that should prevent or mitigate the impacts of such scenarios in the future. The detrimental impacts of such scenarios may extend beyond Ephoron virgo. PMID:25815748

  11. N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes

    CERN Document Server

    Baumgardt, Holger

    2016-01-01

    We have determined the masses and mass-to-light ratios of 50 Galactic globular clusters by comparing their velocity dispersion and surface brightness profiles against a large grid of 900 N-body simulations of star clusters of varying initial concentration, size and central black hole mass fraction. Our models follow the evolution of the clusters under the combined effects of stellar evolution and two-body relaxation allowing us to take the effects of mass segregation and energy equipartition between stars self-consistently into account. For a subset of 16 well observed clusters we also derive their kinematic distances. We find an average mass-to-light ratio of Galactic globular clusters of $=1.98 \\pm 0.03$, which agrees very well with the expected M/L ratio if the initial mass function of the clusters was a standard Kroupa or Chabrier mass function. We do not find evidence for a decrease of the average mass-to-light ratio with metallicity. The surface brightness and velocity dispersion profiles of most globul...

  12. The secondary maxima in black hole X-ray nova light curves - Clues toward a complete picture

    Science.gov (United States)

    Chen, Wan; Livio, Mario; Gehrels, Neil

    1993-01-01

    We study the secondary maxima observed commonly in the X-ray/optical light curves of black hole X-ray novae and show that they can play an important role in our understanding of the X-ray nova phenomenon. We discuss the observational characteristics of the secondary maxima and possible mechanisms to produce them. We propose a complete scenario for black hole X-ray nova events. The main outburst is caused by a disk instability. The second maximum is caused by X-ray evaporation of the matter near the inner Lagrangian (L1) region when the disk becomes optically thin. The third maximum (or the final minioutburst) is due to a mass transfer instability caused by hard X-ray heating of the subphotospheric layers of the secondary during the outburst. We predict that the newly discovered X-ray nova GRO J0422 + 32 may develop a final minioutburst in early 1993 and that its binary orbital period is less than 7 hr.

  13. The Effect of Spatial Gradients in Stellar Mass-to-Light Ratio on Black Hole Mass Measurements

    CERN Document Server

    McConnell, Nicholas J; Ma, Chung-Pei; Greene, Jenny E; Lauer, Tod R; Gebhardt, Karl

    2013-01-01

    We have tested the effect of spatial gradients in stellar mass-to-light ratio (Y) on measurements of black hole masses (MBH) derived from stellar orbit superposition models. Such models construct a static gravitational potential for a galaxy and its central black hole, but typically assume spatially uniform Y. We have modeled three giant elliptical galaxies with gradients alpha = d(log Y)/d(log r) from -0.2 to +0.1. Color and line strength gradients suggest mildly negative alpha in these galaxies. Introducing a negative (positive) gradient in Y increases (decreases) the enclosed stellar mass near the center of the galaxy and leads to systematically smaller (larger) MBH measurements. For models with alpha = -0.2, the best-fit values of MBH are 28%, 27%, and 17% lower than the constant-Y case, in NGC 3842, NGC 6086, and NGC 7768, respectively. For alpha = +0.1, MBH are 14%, 22%, and 17% higher than the constant-Y case for the three respective galaxies. For NGC 3842 and NGC 6086, this bias is comparable to the s...

  14. Trapped and marginally trapped surfaces in Weyl-distorted Schwarzschild solutions

    CERN Document Server

    Pilkington, Terry; Fitzgerald, Joseph; Booth, Ivan

    2011-01-01

    To better understand the allowed range of black hole geometries, we study Weyl-distorted Schwarzschild solutions. They always contain trapped surfaces, a singularity and an isolated horizon and so should be understood to be (geometric) black holes. However we show that for large distortions the isolated horizon is neither a future outer trapping horizon (FOTH) nor even a marginally trapped surface: slices of the horizon cannot be infinitesimally deformed into (outer) trapped surfaces. We consider the implications of this result for popular quasilocal definitions of black holes.

  15. Characterizing optical dipole trap via fluorescence of trapped cesium atoms

    Institute of Scientific and Technical Information of China (English)

    LIU; Tao; GENG; Tao; YAN; Shubin; LI; Gang; ZHANG; Jing; WANG; Junmin; PENG; Kunchi; ZHANG; Tiancai

    2006-01-01

    Optical dipole trap (ODT) is becoming an important tool of manipulating neutral atoms. In this paper ODT is realized with a far-off resonant laser beam strongly focused in the magneto-optical trap (MOT) of cesium atoms. The light shift is measured by simply monitoring the fluorescence of the atoms in the magneto-optical trap and the optical dipole trap simultaneously. The advantages of our experimental scheme are discussed, and the effect of the beam waist and power on the potential of dipole trap as well as heating rate is analyzed.

  16. Optical and Magnetic Trapping of Potassium 39

    Science.gov (United States)

    Ensher, Jason; Cornell, Eric; Cataliotti, Francesco; Fort, Chiara; Marin, Francesco; Prevedelli, Marco; Inguscio, Massimo; Ricci, Leonardo; Tino, Guglielmo

    1998-05-01

    We present measurments of optical trapping and cooling and magnetic trapping of ^39K in a double-MOT apparatus. (Optics Lett. 21, 290(1996)) We have measured light-assisted collisional loss rates from our second MOT over a range of trap light intensities. At an intensity of 10 mW/cm^2 we find a loss rate parameter β of 2 x 10-11 cc/s. β increases with trap light intensity and is consistent with the values measured by Williamson and Walker (JOSA B 12, 1393 (1995)). We also present studies of the temperature of atoms in a MOT of ^39K. Under certain conditions of repump light intensity and trap light detuning we measure temperatures nearly as low as the Doppler Limit. Finally, we report on prelimiary results of magnetic trapping in which we have trapped several 10^7 atoms in a quadrupole magnetic trap.

  17. Using chemical wet-etching methods of textured AZO films on a-Si:H solar cells for efficient light trapping

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Guo-Sheng; Li, Chien-Yu; Huang, Kuo-Chan; Houng, Mau-Phon, E-mail: mphoung@eembox.ncku.edu.tw

    2015-06-15

    In this paper, Al-doped ZnO (AZO) films are deposited on glasses substrate by RF magnetron sputtering. The optical, electrical and morphological properties of AZO films textured by wet-etching with different etchants, H{sub 3}PO{sub 4}, HCl, and HNO{sub 3} are studied. It is found that the textured structure could enhance the light scattering and light trapping ability of amorphous silicon solar cells. The textured AZO film etched with HNO{sub 3} exhibits optimized optical properties (T% ≧ 80% over entire wavelength, haze ratio > 40% at 550 nm wavelength) and excellent electrical properties (ρ = 5.86 × 10{sup −4} Ωcm). Scanning electron microscopy and Atomic force microscopy are used to observe surface morphology and average roughness of each textured AZO films. Finally, the textured AZO films etched by H{sub 3}PO{sub 4}, HCl and HNO{sub 3} were applied to front electrode layer for p–i–n amorphous silicon solar cells. The highest conversion efficiency of amorphous silicon solar cell fabricated on HNO{sub 3}-etched AZO film was 7.08% with open-circuit voltage, short-circuit current density and fill factor of 895 mV, 14.92 mA/cm{sup 2} and 0.56, respectively. It shows a significantly enhancement in the short-circuit current density and conversion efficiency by 16.2% and 20.2%, respectively, compared with the solar cell fabricated on as-grown AZO film. - Highlights: • The textured surface enhances light scattering and light trapping ability. • The HNO{sub 3}-etched AZO film exhibits excellent optical and electrical properties. • The efficiency of a-Si:H solar cell fabricated on HNO{sub 3}-etched AZO film was 7.08%. • The short-circuit current density enhances to 16.2%. • The conversion efficiency enhances to 20.2%.

  18. Constructing and Using a Light Trap Harvester: Rural Technology for Mass Collection of Agoro Termites (Macrotermes subhylanus

    Directory of Open Access Journals (Sweden)

    M.A. Ayieko

    2011-02-01

    Full Text Available Entomophagy is now a growing industry in many parts of the world especially in the developing countries. Entrepreneurs in several parts of the world are making edible insects both palatable and marketable for income generation. The traditional use of insects as food continues to be widespread in tropical and subtropical countries and to provide significant nutritional, economic and ecological benefits for rural communities. Consumption of insects is considered to be a more efficient use of the world's resources to feed the growing population. Insect consumption is growing in many parts of the world and the winged termite in particular is consumed widely in various part of East Africa especially in the western part of Kenya. The traditional methods of collecting these termites vary considerably from one region to another. This paper highlights the indigenous ways of collecting Macrotermes subhylanus locally known as Agoro in the Lake Victoria region. The method was developed by integrating modern technology and the indigenous technological knowledge. The variation in the yield of the sample of Agoro mounds selected and the traps used are presented and discussed.

  19. Hawking radiation from an acoustic black hole on an ion ring.

    Science.gov (United States)

    Horstmann, B; Reznik, B; Fagnocchi, S; Cirac, J I

    2010-06-25

    In this Letter we propose to simulate acoustic black holes with ions in rings. If the ions are rotating with a stationary and inhomogeneous velocity profile, regions can appear where the ion velocity exceeds the group velocity of the phonons. In these regions phonons are trapped like light in black holes, even though we have a discrete field theory and a nonlinear dispersion relation. We study the appearance of Hawking radiation in this setup and propose a scheme to detect it. PMID:20867352

  20. 某国四发动机冒黑烟市场问题攻关%China four light truck black smoke problem research

    Institute of Scientific and Technical Information of China (English)

    许高杰

    2016-01-01

    Four emissions of light trucks in particular conditions will appear black smoke. After investigation, research, and successfully solve the market problems.%某国四排放的轻卡在特定工况时会出现冒黑烟的情况。经过调查,攻关,顺利解决市场问题。

  1. Etching process optimization using NH{sub 4}Cl aqueous solution to texture ZnO:Al films for efficient light trapping in flexible thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, S., E-mail: susanamaria.fernandez@ciemat.es [CIEMAT, Departamento de Energias Renovables, Madrid (Spain); Abril, O. de [ISOM and Departamento de Fisica Aplicada, Escuela Tecnica Superior de Ingenieros de Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Naranjo, F.B. [Grupo de Ingenieria Fotonica, Universidad de Alcala, Departamento de Electronica, Alcala de Henares, Madrid (Spain); Gandia, J.J. [CIEMAT, Departamento de Energias Renovables, Madrid (Spain)

    2012-04-02

    0.5 {mu}m-thick aluminum-doped zinc oxide (ZnO:Al) films were deposited at 100 Degree-Sign C on polyethylene terephthalate substrates by Radio Frequency magnetron sputtering. The as-deposited films were compact and dense, showing grain sizes of 32.0 {+-} 6.4 nm and resistivities of (8.5 {+-} 0.7) Multiplication-Sign 10{sup -4} {Omega} cm. The average transmittance in the visible wavelength range of the structure ZnO:Al/PET was around 77%. The capability of a novel two-step chemical etching using diluted NH{sub 4}Cl aqueous solution to achieve efficient textured surfaces for light trapping was analyzed. The results indicated that both the aqueous solution and the etching method resulted appropriated to obtain etched surfaces with a surface roughness of 32 {+-} 5 nm, haze factors at 500 nm of 9% and light scattering at angles up to 50 Degree-Sign . To validate all these results, a commercially ITO coated PET substrate was used for comparison.

  2. Etching process optimization using NH4Cl aqueous solution to texture ZnO:Al films for efficient light trapping in flexible thin film solar cells

    International Nuclear Information System (INIS)

    0.5 μm-thick aluminum-doped zinc oxide (ZnO:Al) films were deposited at 100 °C on polyethylene terephthalate substrates by Radio Frequency magnetron sputtering. The as-deposited films were compact and dense, showing grain sizes of 32.0 ± 6.4 nm and resistivities of (8.5 ± 0.7) × 10−4 Ω cm. The average transmittance in the visible wavelength range of the structure ZnO:Al/PET was around 77%. The capability of a novel two-step chemical etching using diluted NH4Cl aqueous solution to achieve efficient textured surfaces for light trapping was analyzed. The results indicated that both the aqueous solution and the etching method resulted appropriated to obtain etched surfaces with a surface roughness of 32 ± 5 nm, haze factors at 500 nm of 9% and light scattering at angles up to 50°. To validate all these results, a commercially ITO coated PET substrate was used for comparison.

  3. Impact of brown and clear carbon on light absorption enhancement, single scatter albedo and absorption wavelength dependence of black carbon

    Directory of Open Access Journals (Sweden)

    D. A. Lack

    2010-01-01

    Full Text Available The presence of clear coatings on atmospheric black carbon (BC particles is known to enhance the magnitude of light absorption by the BC cores. Based on calculations using core/shell Mie theory, we demonstrate the enhancement of light absorption (EAbs by atmospheric black carbon (BC when coated in mildly absorbing material (CBrown is reduced, relative to the enhancement by non-absorbing coatings (CClear. This reduction, sensitive to CBrown shell thickness and imaginary refractive index (RI, can be up to 50% for 400 nm radiation and 25% averaged across the visible radiation spectrum for reasonable core/shell diameters. The enhanced direct radiative forcing possible due to the enhancement effect of CClear is therefore reduced if the coating is absorbing. Additionally, the need to explicitly treat BC as an internal, as opposed to external, mixture with CBrown is shown to be important to the calculated single scatter albedo only whensub models treat BC as large spherical cores (>50 nm. For smaller BC cores (or fractal agglomerates consideration of the BC and CBrown as an external mixture leads to relatively small errors in the particle single scatter albedo of <0.03. It is often assumed that observation of an absorption Angstrom exponent (AAE >1 indicates non-BC absorption. Here, it is shown that BC cores coated in CClearcan reasonably have an AAE of up to 1.6, a result that complicates the attribution of observed light absorption to CBrown within ambient particles. However, an AAE<1.6 does not exclude the possibility of CBrown, rather CBrown cannot be confidently assigned unless AAE>1.6. Comparison of these results to some ambient AAE data shows that large-scale attribution of CBrown is a challenging task using current in-situ measurement methods. We suggest that coincident measurements of particle core and

  4. Novel EUV mask black border suppressing EUV and DUV OoB light reflection

    Science.gov (United States)

    Ito, Shin; Kodera, Yutaka; Fukugami, Norihito; Komizo, Toru; Maruyama, Shingo; Watanabe, Genta; Yoshida, Itaru; Kotani, Jun; Konishi, Toshio; Haraguchi, Takashi

    2016-05-01

    EUV lithography is the most promising technology for semiconductor device manufacturing of the 10nm node and beyond. The image border is a pattern free dark area around the die on the photomask serving as transition area between the parts of the mask that is shielded from the exposure light by the Reticle Masking (REMA) blades and the die. When printing a die at dense spacing on an EUV scanner, the reflection from the image border overlaps edges of neighboring dies, affecting CD and contrast in this area. This is related to the fact that EUV absorber stack reflects 1-3% of actinic EUV light. To reduce this effect several types of image border with reduced EUV reflectance (budget including impact of OOB light in the die edge area is evaluated which shows that the OOB impact from HBB becomes comparable with other CDU contributors in this area. Finally, we state that HBB is a promising technology allowing for CD control at die edges.

  5. PEDOT:PSS with embedded TiO2 nanoparticles as light trapping electrode for organic photovoltaics

    Science.gov (United States)

    Park, Yoonseok; Müller-Meskamp, Lars; Vandewal, Koen; Leo, Karl

    2016-06-01

    The performance of organic optoelectronic devices can be improved by employing a suitable optical cavity design beyond the standard plane layer approach, e.g., by the inclusion of periodically or randomly textured structures which increase light incoupling or extraction. One of the simplest approaches is to add an additional layer containing light scattering particles into the device stack. Solution processed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films are promising for replacing the brittle and expensive indium tin oxide transparent electrode. We use a blend of 100 nm TiO2 scattering particles in PEDOT:PSS solution to fabricate transparent electrode films which also functions as a scattering layer. When utilized in an organic photovoltaic device, a power conversion efficiency of 7.92% is achieved, which is an 8.6% relative improvement compared to a device with a neat PEDOT:PSS electrode without the nanoparticles. This improvement is caused by an increase in short-circuit current due to an improved photon harvesting in the 320 nm-700 nm spectral wavelength range.

  6. The hard X-ray spectrum of NGC 1365: scattered light, not black hole spin

    CERN Document Server

    Miller, L

    2013-01-01

    Active Galactic Nuclei (AGN) show excess X-ray emission above 10 keV compared with extrapolation of spectra from lower energies. Risaliti et al. have recently attempted to model the hard X-ray excess in the type 1.8 AGN NGC 1365, concluding that the hard excess most likely arises from Compton-scattered reflection of X-rays from an inner accretion disk close to the black hole. Their analysis disfavored a model in which the hard excess arises from a high column density of circumnuclear gas partially covering a primary X-ray source, despite such components being required in the NGC 1365 data below 10 keV. Using a Monte Carlo radiative transfer approach, we demonstrate that this conclusion is invalidated by (i) use of slab absorption models, which have unrealistic transmission spectra for partial covering gas, (ii) neglect of the effect of Compton scattering on transmitted spectra and (iii) inadequate modeling of the expected spectrum of scattered X-rays. The scattered spectrum is geometry dependent and, for high...

  7. Temporal Windowing of Trapped States

    CERN Document Server

    Castellano, L M

    2001-01-01

    Trapped state definition for 3-level atoms in Lambda configuration, is a very restrictive one, and for the case of unpolarized beams, this definition no longer holds.We introduce a more general definition by using a reference frame rotating with the frequency of the control field, obtaining a temporal windowing for the trapped population.This amounts to a time quantization of the coherent population transfer, making possible to study the phase coherence in trapped light.

  8. Tight control of light trapping in surface addressable photonic crystal membranes: application to spectrally and spatially selective optical devices (Conference Presentation)

    Science.gov (United States)

    Letartre, Xavier; Blanchard, Cédric; Grillet, Christian; Jamois, Cécile; Leclercq, Jean-Louis; Viktorovitch, Pierre

    2016-04-01

    Surface addressable Photonic Crystal Membranes (PCM) are 1D or 2D photonic crystals formed in a slab waveguides where Bloch modes located above the light line are exploited. These modes are responsible for resonances in the reflection spectrum whose bandwidth can be adjusted at will. These resonances result from the coupling between a guided mode of the membrane and a free-space mode through the pattern of the photonic crystal. If broadband, these structures represent an ideal mirror to form compact vertical microcavity with 3D confinement of photons and polarization selectivity. Among numerous devices, low threshold VCSELs with remarkable and tunable modal properties have been demonstrated. Narrow band PCMs (or high Q resonators) have also been extensively used for surface addressable optoelectronic devices where an active material is embedded into the membrane, leading to the demonstration of low threshold surface emitting lasers, nonlinear bistables, optical traps... In this presentation, we will describe the main physical rules which govern the lifetime of photons in these resonant modes. More specifically, it will be emphasized that the Q factor of the PCM is determined, to the first order, by the integral overlap between the electromagnetic field distributions of the guided and free space modes and of the dielectric periodic perturbation which is applied to the homogeneous membrane to get the photonic crystal. It turns out that the symmetries of these distributions are of prime importance for the strength of the resonance. It will be shown that, by molding in-plane or vertical symmetries of Bloch modes, spectrally and spatially selective light absorbers or emitters can be designed. First proof of concept devices will be also presented.

  9. Enhancing Light-Trapping Properties of Amorphous Si Thin-Film Solar Cells Containing High-Reflective Silver Conductors Fabricated Using a Nonvacuum Process

    Directory of Open Access Journals (Sweden)

    Jun-Chin Liu

    2014-01-01

    Full Text Available We proposed a low-cost and highly reflective liquid organic sheet silver conductor using back contact reflectors in amorphous silicon (a-Si single junction superstrate configuration thin-film solar cells produced using a nonvacuum screen printing process. A comparison of silver conductor samples with vacuum-system-sputtered silver samples indicated that the short-circuit current density (Jsc of sheet silver conductor cells was higher than 1.25 mA/cm2. Using external quantum efficiency measurements, the sheet silver conductor using back contact reflectors in cells was observed to effectively enhance the light-trapping ability in a long wavelength region (between 600 nm and 800 nm. Consequently, we achieved an optimal initial active area efficiency and module conversion efficiency of 9.02% and 6.55%, respectively, for the a-Si solar cells. The results indicated that the highly reflective sheet silver conductor back contact reflector layer prepared using a nonvacuum process is a suitable candidate for high-performance a-Si thin-film solar cells.

  10. Broadband and Low-Loss Plasmonic Light Trapping in Dye-Sensitized Solar Cells Using Micrometer-Scale Rodlike and Spherical Core-Shell Plasmonic Particles.

    Science.gov (United States)

    Malekshahi Byranvand, Mahdi; Nemati Kharat, Ali; Taghavinia, Nima; Dabirian, Ali

    2016-06-29

    Dielectric scattering particles have widely been used as embedded scattering elements in dye-sensitized solar cells (DSCs) to improve the optical absorption of the device. Here we systematically study rodlike and spherical core-shell silica@Ag particles as more effective alternatives to the dielectric scattering particles. The wavelength-scale silica@Ag particles with sufficiently thin Ag shell support hybrid plasmonic-photonic resonance modes that have low parasitic absorption losses and a broadband optical response. Both of these features lead to their successful deployment in light trapping in high-efficiency DSCs. Optimized rodlike silica@Ag@silica particles improve the power conversion efficiency of a DSC from 6.33 to 8.91%. The dimension, surface morphology, and concentration of these particles are optimized to achieve maximal efficiency enhancement. The rodlike silica particles are prepared in a simple one-pot synthesis process and then are coated with Ag in a liquid-phase deposition process by reducing an Ag salt. The aspect ratio of silica rods is tuned by adjusting the temperature and duration of the growth process, whereas the morphology of Ag shell is tailored by controlling the reduction rate of Ag salt, where slower reduction in a polyol process gives a smoother Ag shell. Using optical calculations, the superior performance of the plasmonic core-shell particles is related to the large number of hybrid photonic-plasmonic resonance modes that they support. PMID:27300764

  11. Comment on "Towards high efficiency thin-film crystalline silicon solar cells: The roles of light trapping and non-radiative recombinations" [J. Appl. Phys. 115, 094501 (2014)

    Science.gov (United States)

    Abenante, L.

    2015-01-01

    In the above paper, an analytical approach including a new solution to the differential diffusion equation in illuminated quasi-neutral regions (QNR) is exploited to calculate the short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and efficiency (η) of light-trapping (LT) c-Si solar cells with a given structure. Comparisons with numerical results calculated by the Silvaco ATLAS device simulator in the same LT cells show that the analytical results are systematically overestimated. According to the authors, the inaccuracies in Jsc, Voc, and η are due to the fact that assuming ideal collection from space-charge region (SCR) and using the superposition approximation introduce systematic errors into analytical models. In this comment, an analytical approach using reported solutions to the transport equations in QNR and SCR, where ideal collection from SCR is assumed and the superposition approximation is used, is shown to agree with both the Silvaco and PC1d numerical approaches in calculating Jsc, Voc, and η, in the same LT devices as considered in the commented paper. Reasons for the inaccuracies detected in the commented paper are suggested.

  12. Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates

    Energy Technology Data Exchange (ETDEWEB)

    Springer, J. [Forschungszentrum Julich GmbH, Julich (Germany). Institute of Photovoltaics; Academy of Sciences of the Czech Republic, Prague (Czech Republic). Institute of Physics; Rech, B.; Reetz, W.; Muller, J. [Forschungszentrum Julich GmbH, Julich (Germany). Institute of Photovoltaics; Vanecek, M. [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Institute of Physics

    2005-01-01

    Influence of front TCO thickness, surface texture and different back reflectors on short-circuit current density and fill factor of thin film silicon solar cells were investigated. For the front TCO studies, we used ZnO layers of different thickness and applied wet chemical etching in diluted HCl. This approach allowed us to adjust ZnO texture and thickness almost independently. Additionally, we used optical modeling to calculate optical absorption losses in every layer. Results show that texture and thickness reduction of front ZnO increase quantum efficiency over the whole spectral range. The major gain is in the red/IR region. However, the higher sheet resistance of the thin ZnO causes a reduction in fill factor. In the back reflector studies, we compared four different back reflectors: ZnO/Ag, Ag, ZnO/Al and Al. ZnO/Ag yielded the best, Al the worst light trapping properties. Furthermore, the Ag back contact turned out to be superior to ZnO/Al for microcrystalline cells. Finally, the smooth ZnO/Ag back contact showed a higher reflectivity than the rough one. We prepared pin cells with rough and smooth ZnO/Ag interface, leaving the roughness of all other interfaces unchanged. (author)

  13. General Laws of Black-Hole Dynamics

    OpenAIRE

    Hayward, Sean A.

    1993-01-01

    A general definition of a black hole is given, and general `laws of black-hole dynamics' derived. The definition involves something similar to an apparent horizon, a trapping horizon, defined as a hypersurface foliated by marginal surfaces of one of four non-degenerate types, described as future or past, and outer or inner. If the boundary of an inextendible trapped region is suitably regular, then it is a (possibly degenerate) trapping horizon. The future outer trapping horizon provides the ...

  14. Black to Black

    DEFF Research Database (Denmark)

    Langkjær, Michael Alexander

    2012-01-01

    Pop musicians performing in black stage costume take advantage of cultural traditions relating to matters black. Stylistically, black is a paradoxical color: although a symbol of melancholy, pessimism, and renunciation, black also expresses minimalist modernity and signifies exclusivity (as...

  15. Black light visualized solar lentigines on the shoulders and upper back are associated with objectively measured UVR exposure and cutaneous malignant melanoma

    DEFF Research Database (Denmark)

    Idorn, Luise Winkel; Datta, Pameli; Heydenreich, Jakob;

    2015-01-01

    and graded into 3 categories using black light photographs to show sun damage. Current UVR exposure in healthy controls was assessed by personal electronic UVR dosimeters that measured time-related UVR and by corresponding exposure diaries during a summer season. Sunburn history was assessed by interviews......, as well as time spent outdoors around noon on holidays and beach trips during a summer season, most likely reflecting past UVR exposure, and that solar lentigines are a risk factor for CMM....

  16. Trapping molecules on chips

    CERN Document Server

    Santambrogio, Gabriele

    2015-01-01

    In the last years, it was demonstrated that neutral molecules can be loaded on a microchip directly from a supersonic beam. The molecules are confined in microscopic traps that can be moved smoothly over the surface of the chip. Once the molecules are trapped, they can be decelerated to a standstill, for instance, or pumped into selected quantum states by laser light or microwaves. Molecules are detected on the chip by time-resolved spatial imaging, which allows for the study of the distribution in the phase space of the molecular ensemble.

  17. 3D characterization of the forces in optical traps based on counter-propagation beams shaped by a spatial light modulator

    DEFF Research Database (Denmark)

    Kristensen, M. V.; Lindballe, T.; Kylling, A.;

    2010-01-01

    An experimental characterization of the 3D forces, acting on a trapped polystyrene bead in a counter-propagating beam geometry, is reported. Using a single optical trap with a large working distance (in the BioPhotonics Workstation), we simultaneously measure the transverse and longitudinal...... trapping force constants. Two different methods were used: The Drag force method and the Equipartition method. We show that the counterpropagating beams traps are simple harmonic for small displacements. The force constants reveal a transverse asymmetry as - = 9.7 pN/µm and + = 11.3 pN/µm (at a total laser...... power of 2x35 mW) for displacements in opposite directions. The Equipartition method is limited by mechanical noise and is shown to be applicable only when the total laser power in a single 10 µm counter-propagating trap is below 2x20 mW....

  18. Cylinder light concentrator and absorber: theoretical description.

    Science.gov (United States)

    Kildishev, Alexander V; Prokopeva, Ludmila J; Narimanov, Evgenii E

    2010-08-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications--from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the desired ray-optical performance, can provide absorption efficiencies comparable to those of ideal devices with a smooth gradient in index. PMID:20721056

  19. A reliable light scattering computing for black carbon-containing particles: Hybrid discrete dipole approximation (h-DDA)

    Science.gov (United States)

    Moteki, N.

    2015-12-01

    Black carbon (BC) is a light-absorbing carbonaceous aerosol emitted from combustions of fossil fuels and biomasses and is estimated as the second most important contributor to positive climate forcing after the carbon dioxide. In the atmosphere, the fractal aggregate of BC-spherules may be mixed with non-absorbing (or weakly absorbing) compounds that forms morphologically complex "BC-containing particle". A reliable scattering code for BC-containing particles is necessary for predicting mass absorption efficiency of BC and designing/evaluating optical techniques for estimating microphysical properties (i.e., size distribution, mixing state, shape, refractive index) of BC-containing particles. The computational methods that derived from the volume-integral form of the Maxwell equation, such as discrete dipole approximation (DDA), are method of choice for morphologically complex object like BC-containing particles. In ordinary DDA, the entire particle volume is approximated as a collection of tiny cubical dipoles (with side length d) placed on a 3D cubic lattice. For several model BC-containing particles, the comparisons with numerically exact T-matrix method reveals that the ordinary DDA suffered from persistent positive systematic error (up to +30%) in absorption even under d DDA error is identified to be the shape error in BC-spherules. To eliminate the shape error in BC-spherules, we propose a new DDA methodology which may be called hybrid DDA (h-DDA): each primary BC sphere is assumed as a spherical dipole, while remaining particle volume of coating material is approximated by a collection of tiny cubical dipoles on a 3D cubic lattice. Positive absorption bias up to +30% in ordinary DDA is suppressed to within 3% in h-DDA. In h-DDA code, an efficient FFT-based algorithm for solving the matrix equation has been implemented, by utilizing the multilevel block-Toeplitz property of the submatrix corresponding to inter-dipole interaction within coating material.

  20. Dynamic array of dark optical traps

    DEFF Research Database (Denmark)

    Daria, V.R.; Rodrigo, P.J.; Glückstad, J.

    2004-01-01

    A dynamic array of dark optical traps is generated for simultaneous trapping and arbitrary manipulation of multiple low-index microstructures. The dynamic intensity patterns forming the dark optical trap arrays are generated using a nearly loss-less phase-to-intensity conversion of a phase......-encoded coherent light source. Two-dimensional input phase distributions corresponding to the trapping patterns are encoded using a computer-programmable spatial light modulator, enabling each trap to be shaped and moved arbitrarily within the plane of observation. We demonstrate the generation of multiple dark...

  1. Responses of Neomegalotomus parvus (Hemiptera: Alydidae) to color and male-lured traps

    OpenAIRE

    Maurício Ursi Ventura; Antônio Ricardo Panizzi

    2004-01-01

    In 1998, the relative responses of Neomegalotomus parvus (Westwood) (Hemiptera: Alydidae) to colors in traps were assessed in the field. Colors were printed in white alkaline paper and covered with transparent plastic. Printed colors were black, green, yellow, red and blue. Treatments also included white paper and aluminum foil. Green traps captured more bugs than the other traps (except yellow). Yellow traps caught significantly more N. parvus males than blue, black and aluminum traps. White...

  2. A Black Hole Levitron

    CERN Document Server

    Arsiwalla, Xerxes D

    2009-01-01

    We study the problem of spatially stabilising four dimensional extremal black holes in background electric/magnetic fields. Whilst looking for stationary stable solutions describing black holes kept in external fields we find that taking a continuum limit of Denef et al's multi-center solutions provides a supergravity description of such backgrounds within which a black hole can be trapped in a given volume. This is realised by levitating a black hole over a magnetic dipole base. We comment on how such a construction resembles a mechanical Levitron.

  3. Relative Efficacy of CDC and UV Light-traps for Indoor Collection of Culex (Cx.) tritaeniorhychus in Yunnan, P.R.China%云南人房三带喙库蚊CDC和UV诱蚊灯捕捉效果观察

    Institute of Scientific and Technical Information of China (English)

    周红宁; Sarah Pettifor; Nigel Hill; 肖育江; 杜尊伟; 李鸿宾; 张再兴

    2004-01-01

    目的评估CDC和UV诱蚊灯夜间人房三带喙库蚊捕捉效果.方法根据拉丁方设计方案,把诱蚊灯置于寝室和客厅,每晚轮流置灯.结果共捕获库蚊属蚊虫6种624只.其中三带喙库蚊属于最常见的蚊种(419只);CDC和UV灯捕捉蚊虫效果差异无显著性,但当地降雨量与CDC捕捉效果存在较强的正相关关系,而与UV灯捕蚊效果呈弱的负相关.结论无论是CDC诱蚊灯还是UV诱蚊灯都可以作为云南省三带喙库蚊种群密度监测的有效方法.%Objective The efficacy of CDC and UV traps for the coll ection of Culex (Cx.) tritaeniorhynchus was evaluated in overnight in door c ollection. Method The traps were placed in bedrooms and sittin g rooms and rotated nightly approximately following a Latin square design. Results A total of 624 mosquitoes of the genera Culex were trapped comprising 6 species. Most common was Cx.tritaeniorhynchus with 419 individuals trapped. There was no significant difference in the efficiency of CDC and UV traps although there was a stronger positive correlati on between mosquitoes collected in CDC lamps and rainfall, whereas, there was a weak negative correlation between UV lamps and local rainfall. Conclusio n We suggest that either CDC or UV light traps provide an efficient met hod to monitor the population of Cx.tritaniorhychus in Yunnan province.

  4. Development of an apparatus for cooling 6Li-87Rb Fermi-Bose mixtures in a light-assisted magnetic trap

    CERN Document Server

    Brown-Hayes, M; Kim, W -J; Onofrio, R

    2007-01-01

    We describe an experimental setup designed to produce ultracold trapped gas clouds of fermionic 6Li and bosonic 87Rb. This combination of alkali metals has the potential to reach deeper Fermi degeneracy with respect to other mixtures since it allows for improved heat capacity matching which optimizes sympathetic cooling efficiency. Atomic beams of the two species are independently produced and then decelerated by Zeeman slowers. The slowed atoms are collected into a magneto-optical trap and then transferred into a quadrupole magnetic trap. An ultracold Fermi gas with temperature in the 10^-3 T_F range should be attainable through selective confinement of the two species via a properly detuned laser beam focused in the center of the magnetic trap.

  5. Trapping of photophoretic particles

    CERN Document Server

    Magiera, Martin P

    2014-01-01

    A trapping mechanism for self-propelled particles based on an inhomogeneous drive is presented and studied analytically as well as by computer simulations. In experiments this method can be realized using photophoretic Janus particles driven by a light source, which shines through a shading mask and leads to an accumulation of the swimmers in the shaded part. The mechanism can be traced back to a finite penetration depth of particles impinging from the illuminated part of the system into the shaded part.

  6. Light or heavy supermassive black hole seeds: the role of internal rotation in the fate of supermassive stars

    Science.gov (United States)

    Fiacconi, Davide; Rossi, Elena M.

    2016-10-01

    Supermassive black holes are a key ingredient of galaxy evolution. However, their origin is still highly debated. In one of the leading formation scenarios, a black hole of ˜100 M⊙ results from the collapse of the inner core of a supermassive star (≳ 104 - 5 M⊙), created by the rapid accumulation (≳ 0.1 M⊙ yr-1) of pristine gas at the centre of newly formed galaxies at z ˜ 15. The subsequent evolution is still speculative: the remaining gas in the supermassive star can either directly plunge into the nascent black hole, or part of it can form a central accretion disc, whose luminosity sustains a surrounding, massive, and nearly hydrostatic envelope (a system called a "quasi-star"). To address this point, we consider the effect of rotation on a quasi-star, as angular momentum is inevitably transported towards the galactic nucleus by the accumulating gas. Using a model for the internal redistribution of angular momentum that qualitative matches results from simulations of rotating convective stellar envelopes, we show that quasi-stars with an envelope mass greater than a few 105 M⊙ × black hole mass/100 M⊙)0.82 have highly sub-keplerian gas motion in their core, preventing gas circularisation outside the black hole's horizon. Less massive quasi-stars could form but last for only ≲ 104 years before the accretion luminosity unbinds the envelope, suppressing the black hole growth. We speculate that this might eventually lead to a dual black hole seed population: (i) massive (>104 M⊙) seeds formed in the most massive (>108 M⊙) and rare haloes; (ii) lighter (˜102 M⊙) seeds to be found in less massive and therefore more common haloes.

  7. Registros de Mantodea (Insecta coletados à luz no dossel da floresta, na torre do km 14 do núcleo ZF-2, Manaus, Brasil Records of Mantodea (Insecta collected with light trap at 45 meters height over an Amazon forest canopy, at ZF-2 nucleus, Manaus, Brazil

    Directory of Open Access Journals (Sweden)

    Yana Karlla Lessa Alves Dantas

    2008-01-01

    Full Text Available Foram realizadas coletas mensais de insetos de janeiro a dezembro de 2004, durante três noites de transição lunar minguante/nova, das 18:00 às 06:00 horas. Os espécimes foram capturados em um lençol iluminado com lâmpada de 250 watts, luz mista de vapor de mercúrio e lâmpada de 20 watts black light (BL e black light bulb (BLB. A armadilha foi montada a 45 metros de altura numa torre metálica de 50 metros, que ultrapassa a maioria das copas das árvores, num platô de terra firme, na bacia do rio Cuieiras, Manaus, Amazonas, Brasil. Foram coletados 23 espécies de Mantodea, sendo Chaeteessidae (1 espécie; Mantoididae (2; Mantidae (15; Thespidae (2 e Acanthopidae (3. Seis espécies são novas e serão descritas oportunamente nos seguintes gêneros: Cardioptera Burmeister, 1838, Phyllovates Kirby, 1904, Pseudovates Saussure, 1869, Stagmomantis Saussure, 1869, Stagmatoptera Burmeister, 1838 e Metilia Stal, 1877. Três espécies registradas para o Brasil sem uma região determinada estão sendo registradas para a Amazônia brasileira: Heterovates pardalina Saussure, 1872, Macromantis ovalifolia (Stoll, 1813 e Photina reticulata (Burmeister, 1838. Quatro registros são novos para o estado do Amazonas: Angela guianensis Rehn, 1906, Photina gracillis Giglio-Tos, 1915, Raptrix perspicua (Fabricius, 1787 e Vates festae Gigio-Tos, 1914. Os números de indivíduos, em cada coleta mensal, são apresentados para cada espécie.Insect collections were carried out monthly from January to December of 2004, during three nights of lunar transition third quarter moon/new moon from 18 p.m. to 6 a.m. They were collected over a vertical white sheet illuminated by a 250 watts mixed light and a 20 watts black light (BL and black light bulb (BLB lamps. The light trap was mounted at 45 meters height in a metallic tower of 50 meters height, in a "platô de terra firme", in the Cueiras River basin, in Manaus, Amazonas, Brazil. It was collected 23 species of

  8. Optical wire trap for cold neutral atoms

    CERN Document Server

    Schneeweiss, Philipp; Rauschenbeutel, Arno

    2014-01-01

    We propose a trap for cold neutral atoms using a fictitious magnetic field induced by a nanofiber-guided light field. In close analogy to magnetic side-guide wire traps realized with current-carrying wires, a trapping potential can be formed when applying a homogeneous magnetic bias field perpendicular to the fiber axis. We discuss this scheme in detail for laser-cooled cesium atoms and find trap depths and trap frequencies comparable to the two-color nanofiber-based trapping scheme but with one order of magnitude lower powers of the trapping laser field. Moreover, the proposed scheme allows one to bring the atoms closer to the nanofiber surface, thereby enabling efficient optical interfacing of the atoms with additional light fields. Specifically, optical depths per atom, $\\sigma_0/A_{\\rm eff}$, of more than 0.4 are predicted, making this system eligible for nanofiber-based nonlinear and quantum optics experiments.

  9. Permanent fixing or reversible trapping and release of DNA micropatterns on a gold nanostructure using continuous-wave or femtosecond-pulsed near-infrared laser light.

    Science.gov (United States)

    Shoji, Tatsuya; Saitoh, Junki; Kitamura, Noboru; Nagasawa, Fumika; Murakoshi, Kei; Yamauchi, Hiroaki; Ito, Syoji; Miyasaka, Hiroshi; Ishihara, Hajime; Tsuboi, Yasuyuki

    2013-05-01

    The use of localized surface plasmons (LSPs) for highly sensitive biosensors has already been investigated, and they are currently being applied for the optical manipulation of small nanoparticles. The objective of this work was the optical trapping of λ-DNA on a metallic nanostructure with femtosecond-pulsed (fs) laser irradiation. Continuous-wave laser irradiation, which is generally used for plasmon excitation, not only increased the electromagnetic field intensity but also generated heat around the nanostructure, causing the DNA to become permanently fixed on the plasmonic substrate. Using fs laser irradiation, on the other hand, the reversible trapping and release of the DNA was achieved by switching the fs laser irradiation on and off. This trap-and-release behavior was clearly observed using a fluorescence microscope. This technique can also be used to manipulate other biomolecules such as nucleic acids, proteins, and polysaccharides and will prove to be a useful tool in the fabrication of biosensors. PMID:23586869

  10. The effect of snow/sea ice type on the response of albedo and light penetration depth (e-folding depth) to increasing black carbon

    OpenAIRE

    A. A. Marks; M. D. King

    2014-01-01

    The optical properties of snow/sea ice vary with age and by the processes they were formed, giving characteristic types of snow and sea ice. The response of albedo and light penetration depth (e-folding depth) to increasing mass-ratio of black carbon is shown to depend on the snow and sea ice type and the thickness of the snow or sea ice. The response of albedo and e-folding depth of three different types of snow (cold polar snow, windpacked snow and melting...

  11. The effect of snow/sea ice type on the response of albedo and light penetration depth (e-folding depth) to increasing black carbon

    OpenAIRE

    A. A. Marks; M. D. King

    2014-01-01

    The optical properties of snow/sea ice vary with age and by the processes they were formed, giving characteristic types of snow and sea ice. The response of albedo and light penetration depth (e-folding depth) to increasing mass ratio of black carbon is shown to depend on the snow and sea ice type and the thickness of the snow or sea ice. The response of albedo and e-folding depth of three different types of snow (cold polar snow, wind-packed snow and meltin...

  12. Big Crunch-based omnidirectional light concentrators

    CERN Document Server

    Smolyaninov, Igor I

    2014-01-01

    Omnidirectional light concentration remains an unsolved problem despite such important practical applications as design of efficient mobile photovoltaic cells. Optical black hole designs developed recently offer partial solution to this problem. However, even these solutions are not truly omnidirectional since they do not exhibit a horizon, and at large enough incidence angles light may be trapped into quasi-stationary orbits around such imperfect optical black holes. Here we propose and realize experimentally another gravity-inspired design of a broadband omnidirectional light concentrator based on the cosmological Big Crunch solutions. By mimicking the Big Crunch spacetime via corresponding effective optical metric we make sure that every photon world line terminates in a single point.

  13. 太阳电池中陷光材料和结构的研究%Research on Light Trapping Materials and Structure for Solar Cells

    Institute of Scientific and Technical Information of China (English)

    张晓丹; 黄茜; 陈新亮; 陈永生

    2016-01-01

    The most effective way to promote the PV industry is to improve the efficiency of solar cells. Increasing optical utilization and spectral absorption can improve the efficiency of wide-spectrum thin film solar cells. In the former period, the main research contents of this project are focus on how to widen the optical transmittances, obtain high haze values and increase the optical utilization in the long wavelength region. Some typical research results are listed as follows:(1)Properties of high valence difference WZO have been investigated by means of plane wave pseudo-potential method based on the DFT and pulsed DC magnetron sputtering technique. The theoretical and practical results show that the Fermi level enters into the conduction band when doping W atoms into ZnO, indicating a typical n-type semiconductor characteristic and the optical band gap Eg increases significantly.(2) Influences of indium doping on the electrical, structural and optical properties of ZnO films prepared by ultrasonic spray pyrolysis have been investigated. Experimental results show that indium dopant can enhance the carrier mobility and (001) preferential orientation of ZnO thin films, which make the ZnO:In thin films more conductive and strong light-scattering.(3) The structural, electrical and optical properties of LPCVD-ZnO:B thin films have been ameliorated through using the ZnO buffer layer. The experimental results show that the "rich oxygen" buffer layer effectively increased the near infrared optical transmittance.(4) A double-period structure to improve light absorption and trapping has been proposed by combining MS ZnO and LPCVD-grown ZnO:B films. This kind of mutiscale-tpye ZnO films as front electrodes are preliminarily used in tandem solar cells.(5)A high-performance ZnO electrode with high conductivity, transmittance and haze radio has been prepared by magnetron sputtering and post wet-etching. Effective textured surface with large crater and small crater compound is

  14. Trapped antihydrogen

    CERN Document Server

    Butler, E; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Cesar, C L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hydomako, R; Jenkins, M J; Jonsell, S; Jørgensen, L V; Kemp, S L; Kurchaninov, L; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Seif el Nasr, S; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki,Y

    2012-01-01

    Precision spectroscopic comparison of hydrogen and antihydrogen holds the promise of a sensitive test of the Charge-Parity-Time theorem and matter-antimatter equivalence. The clearest path towards realising this goal is to hold a sample of antihydrogen in an atomic trap for interrogation by electromagnetic radiation. Achieving this poses a huge experimental challenge, as state-of-the-art magnetic-minimum atom traps have well depths of only ∼1 T (∼0.5 K for ground state antihydrogen atoms). The atoms annihilate on contact with matter and must be ‘born’ inside the magnetic trap with low kinetic energies. At the ALPHA experiment, antihydrogen atoms are produced from antiprotons and positrons stored in the form of non-neutral plasmas, where the typical electrostatic potential energy per particle is on the order of electronvolts, more than 104 times the maximum trappable kinetic energy. In November 2010, ALPHA published the observation of 38 antiproton annihilations due to antihydrogen atoms that had been ...

  15. 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...

  16. Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.; Aziz, Michael J.; Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Rekemeyer, Paul H.; Gradečak, Silvija [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-12-14

    Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.

  17. Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

    International Nuclear Information System (INIS)

    Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon

  18. Weyl-Conformally Invariant Light-Like p-Brane Theories: New Aspects in Black Hole Physics and Kaluza-Klein Dynamics

    CERN Document Server

    Guendelman, E I; Nissimov, E; Pacheva, S

    2005-01-01

    We introduce and study in some detail the properties of a novel class of Weyl-conformally invariant p-brane theories which describe intrinsically light-like branes for any odd world-volume dimension. Their dynamics significantly differs from that of the ordinary (conformally non-invariant) Nambu-Goto p-branes. We present explicit solutions of the WILL-brane (Weyl-Invariant Light-Like brane)equations of motion in various gravitational models of physical relevance exhibiting various new phenomena. In D=4 the WILL-membrane serves as a material and charged source for gravity and electromagnetism in the coupled Einstein-Maxwell-WILL-membrane system; it automatically positions itself on (``straddles'') the common event horizon of the corresponding matching black hole solutions, thus providing an explicit dynamical realization of the membrane paradigm in black hole physics. In product spaces of interest in Kaluza-Klein theories the WILL-brane wrappes non-trivially around the compact (internal)dimensions and still de...

  19. Fabrication of 3 D Mesoporous Black TiO2 /MoS2 /TiO2 Nanosheets for Visible-Light-Driven Photocatalysis.

    Science.gov (United States)

    Liu, Xuefeng; Xing, Zipeng; Zhang, Hang; Wang, Wenmei; Zhang, Yan; Li, Zhenzi; Wu, Xiaoyan; Yu, Xiujuan; Zhou, Wei

    2016-05-23

    A novel 3 D mesoporous black TiO2 (MBT)/MoS2 /MBT sandwich-like nanosheet was successfully fabricated using a facile mechanochemical process combined with an in situ solid-state chemical reduction approach, followed by mild calcination (350 °C) under an argon atmosphere. The MBT/MoS2 /MBT exhibits a 3 D sandwich-like nanosheet structure and heterojunctions are formed at the interfaces between MoS2 and black TiO2 . The significantly narrowed band gap of MBT/MoS2 /MBT is attributed to the introduction of MoS2 and the formed Ti(3+) species in the frameworks. The visible-light photocatalytic degradation rate of methyl orange and the hydrogen production rate are as high as 89.86 % and 0.56 mmol h(-1)  g(-1) , respectively. The introduction of MoS2 and Ti(3+) in the frameworks favors the visible-light absorption and the separation of photogenerated charges, and the 3 D sandwich-like heterojunction structure facilitates the transfer of photogenerated charges.

  20. Fabrication of 3 D Mesoporous Black TiO2 /MoS2 /TiO2 Nanosheets for Visible-Light-Driven Photocatalysis.

    Science.gov (United States)

    Liu, Xuefeng; Xing, Zipeng; Zhang, Hang; Wang, Wenmei; Zhang, Yan; Li, Zhenzi; Wu, Xiaoyan; Yu, Xiujuan; Zhou, Wei

    2016-05-23

    A novel 3 D mesoporous black TiO2 (MBT)/MoS2 /MBT sandwich-like nanosheet was successfully fabricated using a facile mechanochemical process combined with an in situ solid-state chemical reduction approach, followed by mild calcination (350 °C) under an argon atmosphere. The MBT/MoS2 /MBT exhibits a 3 D sandwich-like nanosheet structure and heterojunctions are formed at the interfaces between MoS2 and black TiO2 . The significantly narrowed band gap of MBT/MoS2 /MBT is attributed to the introduction of MoS2 and the formed Ti(3+) species in the frameworks. The visible-light photocatalytic degradation rate of methyl orange and the hydrogen production rate are as high as 89.86 % and 0.56 mmol h(-1)  g(-1) , respectively. The introduction of MoS2 and Ti(3+) in the frameworks favors the visible-light absorption and the separation of photogenerated charges, and the 3 D sandwich-like heterojunction structure facilitates the transfer of photogenerated charges. PMID:27111114

  1. Black holes new horizons

    CERN Document Server

    Hayward, Sean Alan

    2013-01-01

    Black holes, once just fascinating theoretical predictions of how gravity warps space-time according to Einstein's theory, are now generally accepted as astrophysical realities, formed by post-supernova collapse, or as supermassive black holes mysteriously found at the cores of most galaxies, powering active galactic nuclei, the most powerful objects in the universe. Theoretical understanding has progressed in recent decades with a wider realization that local concepts should characterize black holes, rather than the global concepts found in textbooks. In particular, notions such as trapping h

  2. Multiple scattering of light by water cloud droplets with external and internal mixing of black carbon aerosols

    Institute of Scientific and Technical Information of China (English)

    Wang Hai-Hua; Sun Xian-Ming

    2012-01-01

    The mixture of water cloud droplets with black carbon impurities is modeled by external and internal mixing models.The internal mixing model is modeled with a two-layered sphere(water cloud droplets containing black carbon(BC)inclusions),and tihe single scattering and absorption characteristics are calculated at the visible wavelength of 0.55 μm by using the Lorenz Mie theory.The external mixing model is developed assuming that the same amount of BC particles are mixed with the water droplets externally.The multiple scattering characteristics we computed by using the Monte Carlo method.The results show that when the size of the BC aerosol is small,the reflection intensity of the internal mixing model is bigger than that of the external mixing model.However,if the size of the BC aerosol is big,the absorption of the internal mixing model will be larger than that of the external mixing model.

  3. Theoretical study of stimulated and spontaneous Hawking effects from an acoustic black hole in a hydrodynamically flowing fluid of light

    OpenAIRE

    Grisins, Pjotrs; Nguyen, Hai Son; Bloch, Jacqueline; Amo, Alberto; Carusotto, Iacopo

    2016-01-01

    We propose an experiment to detect and characterize the analog Hawking radiation in an analog model of gravity consisting of a flowing exciton-polariton condensate. Under a suitably designed coherent pump configuration, the condensate features an acoustic event horizon for sound waves that at the semiclassical level is equivalent to an astrophysical black hole horizon. We show that a continuous-wave pump-and-probe spectroscopy experiment allows to measure the analog Hawking temperature from t...

  4. Culicoides (Diptera: Ceratopogonidae) host preferences and biting rates in the Netherlands : comparing cattle, sheep and the black-light suction trap

    NARCIS (Netherlands)

    Elbers, A.R.W.; Meiswinkel, R.

    2014-01-01

    Host preference is an important determinant of feeding behaviour in biting insects and a critical component in the transmission of vector-borne diseases. The aim of the study was to quantify Culicoides (Diptera: Ceratopogonidae) host preferences and biting rates using tethered livestock at pasture (

  5. The Connection Between Entropy and the Absorption Spectra of Schwarzschild Black Holes for Light and Massless Scalar Fields

    Directory of Open Access Journals (Sweden)

    Sergio Mendoza

    2009-01-01

    Full Text Available We present heuristic arguments suggesting that if EM waves with wavelengths somewhat larger than the Schwarzschild radius of a black hole were fully absorbed by it, the second law of thermodynamics would be violated, under the Bekenstein interpretation of the area of a black hole as a measure of its entropy. Thus, entropy considerations make the well known fact that large wavelengths are only marginally absorbed by black holes, a natural consequence of thermodynamics. We also study numerically the ingoing radial propagation of a scalar field wave in a Schwarzschild metric, relaxing the standard assumption which leads to the eikonal equation, that the wave has zero spatial extent. We find that if these waves have wavelengths larger that the Schwarzschild radius, they are very substantially reflected, fully to numerical accuracy. Interestingly, this critical wavelength approximately coincides with the one derived from entropy considerations of the EM field, and is consistent with well known limit results of scattering in the Schwarzschild metric. The propagation speed is also calculated and seen to differ from the value c, for wavelengths larger than Rs, in the vicinity of Rs. As in all classical wave phenomena, whenever the wavelength is larger or comparable to the physical size of elements in the system, in this case changes in the metric, the zero extent ’particle’ description fails, and the wave nature becomes apparent.

  6. Light or heavy supermassive black hole seeds: the role of internal rotation in the fate of supermassive stars

    CERN Document Server

    Fiacconi, Davide

    2016-01-01

    Supermassive black holes are a key ingredient of galaxy evolution. However, their origin is still highly debated. In one of the leading formation scenarios, a black hole of $\\sim100$ M$_{\\odot}$ results from the collapse of the inner core of a supermassive star ($\\gtrsim 10^{4-5}$ M$_{\\odot}$), created by the rapid accumulation ($\\gtrsim 0.1 $ M$_{\\odot}$ yr$^{-1}$) of pristine gas at the centre of newly formed galaxies at $z\\sim 15$. The subsequent evolution is still speculative: the remaining gas in the supermassive star can either directly plunge into the nascent black hole, or part of it can form a central accretion disc, whose luminosity sustains a surrounding, massive, and nearly hydrostatic envelope (a system called a "quasi-star"). To address this point, we consider the effect of rotation on a quasi-star, as angular momentum is inevitably transported towards the galactic nucleus by the accumulating gas. Using a model for the internal redistribution of angular momentum that qualitative matches results ...

  7. Light

    CERN Document Server

    Ditchburn, R W

    2011-01-01

    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. Optimizing Trap Design and Trapping Protocols for Drosophila suzukii (Diptera: Drosophilidae).

    Science.gov (United States)

    Renkema, Justin M; Buitenhuis, Rosemarije; Hallett, Rebecca H

    2014-12-01

    Drosophila suzukii Matsumura (Diptera: Drosophilidae) is a recent invasive pest of fruit crops in North America and Europe. Carpophagous larvae render fruit unmarketable and may promote secondary rot-causing organisms. To monitor spread and develop programs to time application of controls, further work is needed to optimize trap design and trapping protocols for adult D. suzukii. We compared commercial traps and developed a new, easy-to-use plastic jar trap that performed well compared with other designs. For some trap types, increasing the entry area led to increased D. suzukii captures and improved selectivity for D. suzukii when populations were low. However, progressive entry area enlargement had diminishing returns, particularly for commercial traps. Unlike previous studies, we found putting holes in trap lids under a close-fitting cover improved captures compared with holes on sides of traps. Also, red and black traps outperformed yellow and clear traps when traps of all colors were positioned 10-15 cm apart above crop foliage. In smaller traps, attractant surface area and entry area, but not other trap features (e.g., headspace volume), appeared to affect D. suzukii captures. In the new, plastic jar trap, tripling attractant volume (360 vs 120 ml) and weekly attractant replacement resulted in the highest D. suzukii captures, but in the larger commercial trap these measures only increased by-catch of large-bodied Diptera. Overall, the plastic jar trap with large entry area is affordable, durable, and can hold high attractant volumes to maximize D. suzukii capture and selectivity. PMID:26470076

  9. Comparison of various configurations of CDC-type traps for the collection of Phlebotomus papatasi (Scopoli) in southern Israel

    Science.gov (United States)

    We conducted 2 experiments to determine the best configuration of CDC-trap for catching male and female Phlebotomus papatasi. Darker traps caught significantly more male sand flies; significantly more females were captured by traps with either all black or a combination of black and white features. ...

  10. Magnetic trapping of ultracold neutrons

    OpenAIRE

    Brome, C. R.; Butterworth, J. S.; Dzhosyuk, S. N.; Mattoni, C. E. H.; McKinsey, D. N.; Doyle, J. M.; Huffman, P. R.; Dewey, M. S.; Wietfeldt, F. E.; Golub, R.; Habicht, K.; Greene, G. L.; Lamoreaux, S. K.; Coakley, K. J.

    2001-01-01

    Three-dimensional magnetic confinement of neutrons is reported. Neutrons are loaded into an Ioffe-type superconducting magnetic trap through inelastic scattering of cold neutrons with 4He. Scattered neutrons with sufficiently low energy and in the appropriate spin state are confined by the magnetic field until they decay. The electron resulting from neutron decay produces scintillations in the liquid helium bath that results in a pulse of extreme ultraviolet light. This light is frequency dow...

  11. Influence of near-ultraviolet light enhancement and photosynthetic photon flux density during photoperiod extension on the morphology and lignin content of black spruce seedlings

    International Nuclear Information System (INIS)

    When containerized black spruce seedlings (Picea mariana (Mill.) B.S.P.) are grown rapidly in greenhouse culture, they sometimes bend over, grow horizontally and become deformed. This phenomenon has been known to affect between 5% and 10% of a winter greenhouse crop. In this study, near-ultraviolet lamps were used to supplement the artificial light received from high-pressure sodium lamps and the effects on seedling morphology and lignin contents were examined. Neither height to diameter ratios nor lignin concentrations were significantly affected by UV radiation flux density. However, seedling biomass, height, root collar diameter, lignin content, and lignin to cellulose ratios of stems were significantly correlated with total photosynthetic photon flux density (PPFD) received during photoperiod extension. Height to diameter ratios were negatively correlated with PPFD during photoperiod enhancement because of a greater relative increase in diameter growth compared with height growth. Neither UV nor PAR flux density affected the percentage of black spruce seedlings having stem deformations greater than 30 ° from the vertical

  12. The New Black

    OpenAIRE

    Lettman-Hicks, Sharon

    2014-01-01

    The New Black is a documentary that tells the story of how the African American community is grappling with the gay rights issue in light of the recent gay marriage movement and the fight over Civil Rights. The film documents activities, families and clergy on both sides of the campaign to legalize gay marriage and examines homophobia in the Black community's institutional pillar, the Black church, and reveals the Christian right wing's strategy of exploiting this phenomenon in order to pursu...

  13. An Integrated Mirror and Surface Ion Trap with a Tunable Trap Location

    CERN Document Server

    Van Rynbach, Andre; Kim, Jungsang

    2016-01-01

    We report a demonstration of a surface ion trap fabricated directly on a highly reflective mirror surface, which includes a secondary set of radio frequency (RF) electrodes allowing for translation of the quadrupole RF null location. We introduce a position-dependent photon scattering rate for a $^{174}$Yb$^+$ ion in the direction perpendicular to the trap surface using a standing wave of retroreflected light off the mirror surface directly below the trap. Using this setup, we demonstrate the capability of fine-tuning the RF trap location with nanometer scale precision and characterize the charging effects of the dielectric mirror surface upon exposure to ultra-violet light.

  14. Annual Trapping Proposal 1985

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Annual Trapping Plan for the 1984-1985 trapping season at Clarence Cannon NWR outlines rules and regulations for the trapping of beaver and muskrat on the...

  15. Advances in the use of trapping systems for Rhynchophorus ferrugineus (Coleoptera: Curculionidae): traps and attractants.

    Science.gov (United States)

    Vacas, S; Primo, J; Navarro-Llopis, V

    2013-08-01

    Given the social importance related to the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae), efforts are being made to develop new control methods, such as the deployment of trapping systems. In this work, the efficacy of a new black pyramidal trap design (Picusan) has been verified in comparison with white and black buckets. In addition, the attractant and synergistic effect of ethyl acetate (EtAc) at different release levels has been evaluated under field conditions. The results show that Picusan traps captured 45% more weevils than bucket-type traps, offering significantly better trapping efficacy. The addition of water to traps baited with palm tissues was found to be essential, with catches increasing more than threefold compared with dry traps. EtAc alone does not offer attractant power under field conditions, and the release levels from 57 mg/d to 1 g/d have no synergistic effect with ferrugineol. Furthermore, significantly fewer females were captured when EtAc was released at 2 g/d. The implications of using EtAc dispensers in trapping systems are discussed.

  16. Temperature and wavelength dependent trap filling in M{sub 2}Si{sub 5}N{sub 8}:Eu (M=Ca, Sr, Ba) persistent phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Smet, Philippe F., E-mail: philippe.smet@ugent.be [LumiLab, Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, 9000 Gent (Belgium); Center for Nano- and Biophotonics (NB-Photonics), Ghent University (Belgium); Van den Eeckhout, Koen [LumiLab, Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, 9000 Gent (Belgium); Center for Nano- and Biophotonics (NB-Photonics), Ghent University (Belgium); Bos, Adrie J.J.; Kolk, Erik van der; Dorenbos, Pieter [Delft University of Technology, Faculty of Applied Sciences, 2629 JB Delft (Netherlands)

    2012-03-15

    The evaluation of persistent phosphors is often focused on the processes right after the excitation, namely on the shape of the afterglow decay curve and the duration of the afterglow, in combination with thermoluminescence glow curve analysis. In this paper we study in detail the trap filling process in europium-doped alkaline earth silicon nitrides (Ca{sub 2}Si{sub 5}N{sub 8}:Eu, Sr{sub 2}Si{sub 5}N{sub 8}:Eu and Ba{sub 2}Si{sub 5}N{sub 8}:Eu), i.e., how the persistent luminescence can be induced. Both the temperature at which the phosphors are excited and the spectral distribution of the excitation light on the ability to store energy in the phosphors' lattices are investigated. We show that for these phosphors this storage process is thermally activated upon excitation in the lower 5d excited states of Eu{sup 2+}, with the lowest thermal barrier for europium doped Ca{sub 2}Si{sub 5}N{sub 8}. Also, the influence of co-doping with thulium on the trap filling and afterglow behavior is studied. Finally there exists a clear relation between the luminescence quenching temperature and the trap filling efficiency. The latter relation can be utilized to select new efficient 5d-4f based afterglow phosphors. - Highlights: Black-Right-Pointing-Pointer Orange afterglow in M{sub 2}Si{sub 5}N{sub 8}:Eu(Tm) studied with thermoluminescence spectroscopy. Black-Right-Pointing-Pointer Strong influences of excitation wavelength and temperature on trap filling. Black-Right-Pointing-Pointer Energy level scheme is presented. Black-Right-Pointing-Pointer Relation between trap filling with visible light and thermal quenching behavior.

  17. X-ray emission fluorescence (XRF) analysis of origin of raw materials of light dark reddish brown porcelain and porcelain with black flower on a white background of Dangyangyu kiln

    International Nuclear Information System (INIS)

    Dangyangyu kiln was an important civil porcelain production place in the North China during the Song Dynasty. In order to find out the source of raw materials of the porcelain body and glaze and their classification relationship so as to correctly distinguish them, we have used XRF to determine the major chemical elements of some porcelain samples with light brown and samples with black flower on a white background. Dynamic fuzzy cluster analysis was applied to the data. Results indicate that the origin of raw materials of light brown porcelain body samples is comparatively more concentrated, while that of the porcelain with black flower on a white background is scattered about. The origin of the body materials of those two kinds of porcelain samples is obviously different. The origin of raw materials of light brown porcelain samples is comparatively concentrated and stable, while that of the porcelain with black flower on a white background is scattered about, moreover, the origin of glaze raw materials and the formula of the two kinds are obviously different. The origin and formula of the light brown porcelain with white glaze in the interior are close to those of the white glaze of porcelain with black flower on a white background, but they are not entirely identical. (author)

  18. zTrap: zebrafish gene trap and enhancer trap database

    Directory of Open Access Journals (Sweden)

    Muto Akira

    2010-10-01

    Full Text Available Abstract Background We have developed genetic methods in zebrafish by using the Tol2 transposable element; namely, transgenesis, gene trapping, enhancer trapping and the Gal4FF-UAS system. Gene trap constructs contain a splice acceptor and the GFP or Gal4FF (a modified version of the yeast Gal4 transcription activator gene, and enhancer trap constructs contain the zebrafish hsp70l promoter and the GFP or Gal4FF gene. By performing genetic screens using these constructs, we have generated transgenic zebrafish that express GFP and Gal4FF in specific cells, tissues and organs. Gal4FF expression is visualized by creating double transgenic fish carrying a Gal4FF transgene and the GFP reporter gene placed downstream of the Gal4-recognition sequence (UAS. Further, the Gal4FF-expressing cells can be manipulated by mating with UAS effector fish. For instance, when fish expressing Gal4FF in specific neurons are crossed with the UAS:TeTxLC fish carrying the tetanus neurotoxin gene downstream of UAS, the neuronal activities are inhibited in the double transgenic fish. Thus, these transgenic fish are useful to study developmental biology and neurobiology. Description To increase the usefulness of the transgenic fish resource, we developed a web-based database named zTrap http://kawakami.lab.nig.ac.jp/ztrap/. The zTrap database contains images of GFP and Gal4FF expression patterns, and genomic DNA sequences surrounding the integration sites of the gene trap and enhancer trap constructs. The integration sites are mapped onto the Ensembl zebrafish genome by in-house Blat analysis and can be viewed on the zTrap and Ensembl genome browsers. Furthermore, zTrap is equipped with the functionality to search these data for expression patterns and genomic loci of interest. zTrap contains the information about transgenic fish including UAS reporter and effector fish. Conclusion zTrap is a useful resource to find gene trap and enhancer trap fish lines that express GFP

  19. The Aarhus Ion Micro-Trap Project

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; Nielsen, Otto; Poulsen, Gregers;

    As part of our involvement in the EU MICROTRAP project, we have designed, manufactured and assembled a micro-scale ion trap with integrated optical fibers. These prealigned fibers will allow delivering cooling laser light to single ions. Therefore, such a trap will not require any direct optical...... and installed in an ultra high vacuum chamber, which includes an ablation oven for all-optical loading of the trap [2]. The next steps on the project are to demonstrate the operation of the micro-trap and the cooling of ions using fiber delivered light. [1] D. Grant, Development of Micro-Scale Ion traps, Master...... Thesis (2008). [2] R.J. Hendricks, D.M. Grant, P.F. Herskind, A. Dantan and M. Drewsen, An all-optical ion-loading technique for scalable microtrap architectures, Applied Physics B, 88, 507 (2007)....

  20. A state-insensitive, compensated nanofiber trap

    CERN Document Server

    Lacroûte, C; Goban, A; Alton, D J; Ding, D; Stern, N P; Kimble, H J

    2011-01-01

    Laser trapping and interfacing of laser-cooled atoms in an optical fiber network is an important capability for quantum information science. Following the pioneering work of Balykin et al. and Vetsch et al., we propose a robust method of trapping single Cesium atoms with a two-color state-insensitive evanescent wave around a dielectric nanofiber. Specifically, we show that vector light shifts (i.e., effective inhomogeneous Zeeman broadening of the ground states) induced by the inherent ellipticity of the forward-propagating evanescent wave can be effectively canceled by a backward-propagating evanescent wave. Furthermore, by operating the trapping lasers at the magic wavelengths, we remove the differential scalar light shift between ground and excited states, thereby allowing for resonant driving of the optical D2 transition. This scheme provides a promising approach to trap and probe neutral atoms with long trap and coherence lifetimes with realistic experimental parameters.

  1. Time-resolved measurements of black carbon light absorption enhancement in urban and near-urban locations of Southern Ontario, Canada

    Directory of Open Access Journals (Sweden)

    T. W. Chan

    2010-08-01

    Full Text Available In this study a photoacoustic spectrometer (PA, a laser-induced incandescence instrument system (LII and an aerosol mass spectrometer were operated in parallel for in situ measurements of black carbon (BC light absorption enhancement. Results of a thermodenuder experiment using ambient particles in Toronto are presented first to show that LII measurements of BC are not influenced by particle coating while the PA response is enhanced and also that the nature of this enhancement is influenced by particle morphology. Comparisons of ambient PA and LII measurements at four different locations (suburban Toronto; a street canyon with heavy diesel bus traffic in Ottawa; adjacent to a commuter highway in Ottawa and; regional background air in and around Windsor, Ontario, show that the different meteorological conditions and atmospheric processes result in different particle light absorption enhancement and hence the specific attenuation coefficient (SAC. Depending upon location of measurement and the BC spherule diameter (primary particle size – PPS measurement from the LII, the SAC varies from 2.6±0.04 to 22.5±0.7 m2 g−1. Observations from this study also show the active surface area of the BC aggregate, inferred from PPS, is an important parameter for inferring the degree of particle collapse of a BC particle. The predictability of the overall BC light absorption enhancement in the atmosphere depends not only on the coating mass but also on the source of the BC and on our ability to predict or measure the change in particle morphology as particles evolve.

  2. Experimental study of driving micro-particles with double sources and double light traps%双光源双光阱法驱动微型粒子旋转的实验研究

    Institute of Scientific and Technical Information of China (English)

    朱艳英; 靳李丽; 许耀云; 陈志婷; 孟祥君; 李云涛

    2012-01-01

    在自行构建的双光源双光阱实验系统中,实现了双光阱法驱动微型粒子旋转的实验研究。其原理是利用双折射晶体微粒光致旋转产生的涡旋力带动一个被光镊捕获的普通微粒进行旋转。实验观测了CaCO3粒子的旋转通过液体传动使酵母菌细胞团旋转的实验现象,当两个光阱的激光功率一定时,两个光阱的距离必须选择合适,CaCO3粒子的旋转才会通过液体的传动带动酵母菌细胞团旋转。实验结果得到CaCO3粒子逆时针旋转频率为2.75Hz,带动酵母菌粒子团顺时针旋转频率为2.25Hz。%We build the double-optical-trapping and double-optical tweezer experiment system and achieve driving particles with double light traps method. The principle is that the vortex force generated by light rotation using birefringence crystal particles drives ordinary particles captured by optical tweezer rotating. The CaCO3 crystal rotation will produce vortex which can drive a yeast cell which is captured by light rotation. The rotation of the crystal particles and passive particle is observed by a CCD camera. The rotation characteristics of yeast cell which is driven by CaCO3 particles are analyzed and discussed. When the two laser power supplies are constant, the distance between two light sources must be suitable, the yeast will be driven by CaCO3 particles, and it rotates in the opposite direction of the motion of CaCO3 particles. Experimental results show that the frequency of counter-clockwise rotation of CaCO3 is 2.75 Hz and that of clockwise rotation of yeast cell mass is 2.25 Hz.

  3. Determination of wood burning and fossil fuel contribution of black carbon at Delhi, India using aerosol light absorption technique.

    Science.gov (United States)

    Tiwari, S; Pipal, A S; Srivastava, A K; Bisht, D S; Pandithurai, G

    2015-02-01

    A comprehensive measurement program of effective black carbon (eBC), fine particle (PM2.5), and carbon monoxide (CO) was undertaken during 1 December 2011 to 31 March 2012 (winter period) in Delhi, India. The mean mass concentrations of eBC, PM2.5, and CO were recorded as 12.1 ± 8.7 μg/m(3), 182.75 ± 114.5 μg/m(3), and 3.41 ± 1.6 ppm, respectively, during the study period. Also, the absorption Angstrom exponent (AAE) was estimated from eBC and varied from 0.38 to 1.29 with a mean value of 1.09 ± 0.11. The frequency of occurrence of AAE was ~17 % less than unity whereas ~83 % greater than unity was observed during the winter period in Delhi. The mass concentrations of eBC were found to be higher by ~34 % of the average value of eBC (12.1 μg/m(3)) during the study period. Sources of eBC were estimated, and they were ~94 % from fossil fuel (eBCff) combustion whereas only 6 % was from wood burning (eBCwb). The ratio between eBCff and eBCwb was 15, which indicates a higher impact from fossil fuels compared to biomass burning. When comparing eBCff during day and night, a factor of three higher concentrations was observed in nighttime than daytime, and it is due to combustion of fossil fuel (diesel vehicle emission) and shallow boundary layer conditions. The contribution of eBCwb in eBC was higher between 1800 and 2100 hours due to burning of wood/biomass. A significant correlation between eBC and PM2.5 (r = 0.78) and eBC and CO (r = 0.46) indicates the similarity in location sources. The mass concentration of eBC was highest (23.4 μg/m(3)) during the month of December when the mean visibility (VIS) was lowest (1.31 km). Regression analysis among wind speed (WS), VIS, soot particles, and CO was studied, and significant negative relationships were seen between VIS and eBC (-0.65), eBCff (-0.66), eBCwb (-0.34), and CO (-0.65); however, between WS and eBC (-0.68), eBCff (-0.67), eBCwb (-0.28), and CO (-0.53). The regression analysis indicated

  4. Shrew trap efficiency

    DEFF Research Database (Denmark)

    Gambalemoke, Mbalitini; Mukinzi, Itoka; Amundala, Drazo;

    2008-01-01

    We investigated the efficiency of four trap types (pitfall, Sherman LFA, Victor snap and Museum Special snap traps) to capture shrews. This experiment was conducted in five inter-riverine forest blocks in the region of Kisangani. The total trapping effort was 6,300, 9,240, 5,280 and 5,460 trap-ni...

  5. 黑光治疗银屑病的临床分析%The Clinical Analyze of Psoriasis by Black Light Treatment

    Institute of Scientific and Technical Information of China (English)

    刘秀英

    2014-01-01

    Objective To approach clinical result of psoriasis by black light treatment.Methods To analyze the 200 cases clinical data of psoriasis patients in our hospital dermatology from 2010.1 to 2013.12 ,which was to be divided into two grouo ,control group 100 cases and detection group 100 cases.The PASI score pretherapy and post of treatment of two groups psoriasis patients was detected ,clinical curative effect of two groups psoriasis patients was detected.Results The PASI score pretherapy of treatment two groups psoriasis patients were no difference ,the The PASI score post of detec-tion group was better than control group ,the clinical curative effect of detection group was higher than control group ,P<0.05 ,the difference were statistical significance.Conclusions The clinical symptoms of psoriasis by black light treat-ment was obviously ,the result was good ,which was to be used.%目的:探讨黑光治疗银屑病的临床治疗效果。方法对收治的200例银屑病患者临床资料,依据治疗措施不同进行分组,对照组100例和观察组100例。观察两组银屑病患者治疗前后PASI评分情况和两组银屑病患者临床治疗效果。结果两组银屑病患者治疗前PASI评分无明显差异,P>0.05,观察组银屑病患者治疗后PASI评分明显优于对照组,观察组银屑病患者临床治疗总有效率明显高于对照组,P<0.05,差异均有统计学意义。结论黑光治疗银屑病患者临床症状改善明显,效果良好,值得临床推广应用。

  6. Efficient Fiber Optic Detection of Trapped Ion Fluorescence

    OpenAIRE

    VanDevender, A. P.; Colombe, Y.; J. Amini; Leibfried, D.; Wineland, D. J.

    2010-01-01

    Integration of fiber optics may play a critical role in the development of quantum information processors based on trapped ions and atoms by enabling scalable collection and delivery of light and coupling trapped ions to optical microcavities. We trap 24Mg+ ions in a surface-electrode Paul trap that includes an integrated optical fiber for detecting 280-nm fluorescence photons. The collection numerical aperture is 0.37 and total collection efficiency is 2.1 %. The ion can be positioned betwee...

  7. Evanescent field trapping of nanoparticles using nanostructured ultrathin optical fibers.

    Science.gov (United States)

    Daly, Mark; Truong, Viet Giang; Chormaic, Síle Nic

    2016-06-27

    While conventional optical trapping techniques can trap objects with submicron dimensions, the underlying limits imposed by the diffraction of light generally restrict their use to larger or higher refractive index particles. As the index and diameter decrease, the trapping difficulty rapidly increases; hence, the power requirements for stable trapping become so large as to quickly denature the trapped objects in such diffraction-limited systems. Here, we present an evanescent field-based device capable of confining low index nanoscale particles using modest optical powers as low as 1.2 mW, with additional applications in the field of cold atom trapping. Our experiment uses a nanostructured optical micro-nanofiber to trap 200 nm, low index contrast, fluorescent particles within the structured region, thereby overcoming diffraction limitations. We analyze the trapping potential of this device both experimentally and theoretically, and show how strong optical traps are achieved with low input powers. PMID:27410600

  8. Geometry of black hole spacetimes

    CERN Document Server

    Andersson, Lars; Blue, Pieter

    2016-01-01

    These notes, based on lectures given at the summer school on Asymptotic Analysis in General Relativity, collect material on the Einstein equations, the geometry of black hole spacetimes, and the analysis of fields on black hole backgrounds. The Kerr model of a rotating black hole in vacuum is expected to be unique and stable. The problem of proving these fundamental facts provides the background for the material presented in these notes. Among the many topics which are relevant for the uniqueness and stability problems are the theory of fields on black hole spacetimes, in particular for gravitational perturbations of the Kerr black hole, and more generally, the study of nonlinear field equations in the presence of trapping. The study of these questions requires tools from several different fields, including Lorentzian geometry, hyperbolic differential equations and spin geometry, which are all relevant to the black hole stability problem.

  9. Instability of black hole formation in gravitational collapse

    International Nuclear Information System (INIS)

    We consider here the classic scenario given by Oppenheimer, Snyder, and Datt, for the gravitational collapse of a massive matter cloud, and examine its stability under the introduction of small tangential stresses. We show, by offering an explicit class of physically valid tangential stress perturbations, that an introduction of tangential pressure, however small, can qualitatively change the final fate of collapse from a black hole final state to a naked singularity. This shows instability of black hole formation in collapse and sheds important light on the nature of cosmic censorship hypothesis and its possible formulations. The key effect of these perturbations is to alter the trapped surface formation pattern within the collapsing cloud and the apparent horizon structure. This allows the singularity to be visible, and implications are discussed.

  10. Tachyon Physics with Trapped Ions

    CERN Document Server

    Lee, Tony E; Cheng, Xiao-Hang; Lamata, Lucas; Solano, Enrique

    2015-01-01

    It has been predicted that particles with imaginary mass, called tachyons, would be able to travel faster than the speed of light. So far, there has not been any experimental evidence for tachyons in either natural or engineered systems. Here, we propose how to experimentally simulate Dirac tachyons with trapped ions. Quantum measurement on a Dirac particle simulated by a trapped ion causes it to have an imaginary mass so that it may travel faster than the effective speed of light. We show that a Dirac tachyon must have spinor-motion entanglement in order to be superluminal. We also show that it exhibits significantly more Klein tunneling than a normal Dirac particle. We provide numerical simulations with realistic ion systems and show that our scheme is feasible with current technology.

  11. Singlet molecular oxygen generation by light-activated DHN-melanin of the fungal pathogen Mycosphaerella fijiensis in black Sigatoka disease of bananas.

    Directory of Open Access Journals (Sweden)

    Miguel J Beltrán-García

    Full Text Available In pathogenic fungi, melanin contributes to virulence, allowing tissue invasion and inactivation of the plant defence system, but has never been implicated as a factor for host cell death, or as a light-activated phytotoxin. Our research shows that melanin synthesized by the fungal banana pathogen Mycosphaerella fijiensis acts as a virulence factor through the photogeneration of singlet molecular oxygen O2 (1Δg. Using analytical tools, including elemental analysis, ultraviolet/infrared absorption spectrophometry and MALDI-TOF mass spectrometry analysis, we characterized both pigment content in mycelia and secreted to the culture media as 1,8-dihydroxynaphthalene (DHN-melanin type compound. This is sole melanin-type in M. fijiensis. Isolated melanins irradiated with a Nd:YAG laser at 532 nm produced monomol light emission at 1270 nm, confirming generation of O2 (1Δg, a highly reactive oxygen specie (ROS that causes cellular death by reacting with all cellular macromolecules. Intermediary polyketides accumulated in culture media by using tricyclazole and pyroquilon (two inhibitors of DHN-melanin synthesis were identified by ESI-HPLC-MS/MS. Additionally, irradiation at 532 nm of that mixture of compounds and whole melanized mycelium also generated O2 (1Δg. A pigmented-strain generated more O2 (1Δg than a strain with low melanin content. Banana leaves of cultivar Cavendish, naturally infected with different stages of black Sigatoka disease, were collected from field. Direct staining of the naturally infected leaf tissues showed the presence of melanin that was positively correlated to the disease stage. We also found hydrogen peroxide (H2O2 but we cannot distinguish the source. Our results suggest that O2 (1Δg photogenerated by DHN-melanin may be involved in the destructive effects of Mycosphaerella fijiensis on banana leaf tissues. Further studies are needed to fully evaluate contributions of melanin-mediated ROS to microbial pathogenesis.

  12. Singlet molecular oxygen generation by light-activated DHN-melanin of the fungal pathogen Mycosphaerella fijiensis in black Sigatoka disease of bananas.

    Science.gov (United States)

    Beltrán-García, Miguel J; Prado, Fernanda M; Oliveira, Marilene S; Ortiz-Mendoza, David; Scalfo, Alexsandra C; Pessoa, Adalberto; Medeiros, Marisa H G; White, James F; Di Mascio, Paolo

    2014-01-01

    In pathogenic fungi, melanin contributes to virulence, allowing tissue invasion and inactivation of the plant defence system, but has never been implicated as a factor for host cell death, or as a light-activated phytotoxin. Our research shows that melanin synthesized by the fungal banana pathogen Mycosphaerella fijiensis acts as a virulence factor through the photogeneration of singlet molecular oxygen O2 (1Δg). Using analytical tools, including elemental analysis, ultraviolet/infrared absorption spectrophometry and MALDI-TOF mass spectrometry analysis, we characterized both pigment content in mycelia and secreted to the culture media as 1,8-dihydroxynaphthalene (DHN)-melanin type compound. This is sole melanin-type in M. fijiensis. Isolated melanins irradiated with a Nd:YAG laser at 532 nm produced monomol light emission at 1270 nm, confirming generation of O2 (1Δg), a highly reactive oxygen specie (ROS) that causes cellular death by reacting with all cellular macromolecules. Intermediary polyketides accumulated in culture media by using tricyclazole and pyroquilon (two inhibitors of DHN-melanin synthesis) were identified by ESI-HPLC-MS/MS. Additionally, irradiation at 532 nm of that mixture of compounds and whole melanized mycelium also generated O2 (1Δg). A pigmented-strain generated more O2 (1Δg) than a strain with low melanin content. Banana leaves of cultivar Cavendish, naturally infected with different stages of black Sigatoka disease, were collected from field. Direct staining of the naturally infected leaf tissues showed the presence of melanin that was positively correlated to the disease stage. We also found hydrogen peroxide (H2O2) but we cannot distinguish the source. Our results suggest that O2 (1Δg) photogenerated by DHN-melanin may be involved in the destructive effects of Mycosphaerella fijiensis on banana leaf tissues. Further studies are needed to fully evaluate contributions of melanin-mediated ROS to microbial pathogenesis.

  13. Black holes and beyond

    International Nuclear Information System (INIS)

    Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for instance, the UK

  14. A model for direct laser interference patterning of ZnO:Al - predicting possible sample topographies to optimize light trapping in thin-film silicon solar cells

    Science.gov (United States)

    Dyck, Tobias; Haas, Stefan

    2016-04-01

    We present a novel approach to obtaining a quick prediction of a sample's topography after the treatment with direct laser interference patterning (DLIP) . The underlying model uses the parameters of the experimental setup as input, calculates the laser intensity distribution in the interference volume and determines the corresponding heat intake into the material as well as the subsequent heat diffusion within the material. The resulting heat distribution is used to determine the topography of the sample after the DLIP treatment . This output topography is in good agreement with corresponding experiments. The model can be applied in optimization algorithms in which a sample topography needs to be engineered in order to suit the needs of a given device. A prominent example for such an application is the optimization of the light scattering properties of the textured interfaces in a solar cell.

  15. Towards Quantum Simulations Using a Chip Ion Trap

    Science.gov (United States)

    Cao, Chenglin; Wright, Ken; Brennan, Daniel; Ji, Geoffrey; Monroe, Christopher

    2013-05-01

    We report our current experimental progress towards using chip ion traps for quantum simulation. Current progress is being made using a micro-fabricated symmetric trap from GTRI. This trap implements a novel two level design that combines the benefits of both surface traps and linear four-rod traps. The trap has 50 electrodes which allow for the fine control of the DC potential needed to create large anharmonic potentials, to join and split ion chains and to shuttle ions along the trapping axis similar to many surface traps. However this trap also has a much deeper trapping depth than conventional surface traps and improved optical access via an angled slot through the chip wide enough to accommodate higher power laser light which could cause surface charging or damage in a traditional chip trap. These advantages should allow trapping of long ion chains. We hope to use these features as the next step in increasing the size of current quantum simulations being done at Univ of Maryland, which are aimed at exploring quantum phenomena in spin systems in a regime inaccessible to classical simulation. This work is supported by grants from the U.S. Army Research Office with funding from the DARPA OLE program, IARPA, and the MURI program; and the NSF Physics Frontier Center at JQI. We acknowledge the GTRI team of J. Amini, K. Brown, A. Harter, F. Shaikh, R. Slusher, and C. Volin for the fabrication of the trap.

  16. 液晶空间光调制器产生可调三光学势阱*%Generation of the controllable triple-well optical trap by liquid-crystal spatial light modulator*

    Institute of Scientific and Technical Information of China (English)

    周巧巧; 徐淑武; 陆俊发; 周琦; 纪宪明; 印建平

    2013-01-01

      提出了产生三光学势阱的新方案,在该方案中用液晶空间光调制器制作相位型闪耀光栅,单色相干光照明,产生按等边三角形分布的三个光学势阱,三个光阱光强大小分布相同,调节空间光调制器的相位分布,可以改变光阱的相对位置,实现三光阱到单个光阱、两光阱合并为一个光阱等演变及其反向演变,调节过程简单、方便。根据现有空间光调制器性能和尺寸,模拟设计光栅,计算三光阱的光强分布和调控过程中光强的变化,结果表明:用一般功率的激光照明,能够得到具有较大峰值光强和较高光强梯度的可调三光阱,在原子和分子光学实验研究中有多种重要的应用。%A new scheme of generating the controllable triple-well optical trap is proposed, in which a liquid-crystal spatial light modulator (SLM) is used to fabricate the phase-type blazed grating and be illuminated with coherent monochromatic light. Three optical wells, each of which has the same intensity distribution, can be formed with relative position of the distribution of an equilateral triangle. The relative positions of the optical wells can be changed by simply and conveniently adjusting the phase distribution of the SLM to realize the evolution and reverse evolution from triple or dual wells to single well. The phase grating is designed by simulation according to the technical parameters of the SLM, and illuminated by the laser with ordinary power. The intensity distributions and intensity changes in the adjustment process for the triple wells are calculated. Results show that the controllable triple-well optical trap with very high peak value of intensity and intensity gradient can be obtained. It has many important applications in the experimental study of atomic and molecular optics.

  17. Small Mammal Trapping 2003

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Small mammal traps were placed in the Baring division and in the Edmunds division of Moosehom National Wildlife Refuge. There were a total of 98 traps set for up to...

  18. St. Croix trap study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data set contains detailed information about the catch from 600 trap stations around St. Croix. Data fields include species caught, size data, trap location...

  19. Nanofiber-based optical trapping of cold neutral atoms

    CERN Document Server

    Vetsch, Eugen; Mitsch, Rudolf; Reitz, Daniel; Schneeweiss, Philipp; Rauschenbeutel, Arno

    2012-01-01

    We present experimental techniques and results related to the optimization and characterization of our nanofiber-based atom trap [Vetsch et al., Phys. Rev. Lett. 104, 203603 (2010)]. The atoms are confined in an optical lattice which is created using a two-color evanescent field surrounding the optical nanofiber. For this purpose, the polarization state of the trapping light fields has to be properly adjusted. We demonstrate that this can be accomplished by analyzing the light scattered by the nanofiber. Furthermore, we show that loading the nanofiber trap from a magneto-optical trap leads to sub-Doppler temperatures of the trapped atomic ensemble and yields a sub-Poissonian distribution of the number of trapped atoms per trapping site.

  20. Excitons in Electrostatic Traps

    OpenAIRE

    Hammack, A. T.; Gippius, N. A.; Andreev, G. O.; Butov, L. V.; Hanson, M.; Gossard, A. C.

    2005-01-01

    We consider in-plane electrostatic traps for indirect excitons in coupled quantum wells, where the traps are formed by a laterally modulated gate voltage. An intrinsic obstacle for exciton confinement in electrostatic traps is an in-plane electric field that can lead to exciton dissociation. We propose a design to suppress the in-plane electric field and, at the same time, to effectively confine excitons in the electrostatic traps. We present calculations for various classes of electrostatic ...

  1. Trap designs for monitoring Drosophila suzukii (Diptera: Drosophilidae).

    Science.gov (United States)

    Lee, Jana C; Shearer, Peter W; Barrantes, Luz D; Beers, Elizabeth H; Burrack, Hannah J; Dalton, Daniel T; Dreves, Amy J; Gut, Larry J; Hamby, Kelly A; Haviland, David R; Isaacs, Rufus; Nielsen, Anne L; Richardson, Tamara; Rodriguez-Saona, Cesar R; Stanley, Cory A; Walsh, Doug B; Walton, Vaughn M; Yee, Wee L; Zalom, Frank G; Bruck, Denny J

    2013-12-01

    Drosophila suzukii (Matsumura), an invasive pest of small and stone fruits, has been recently detected in 39 states of the United States, Canada, Mexico, and Europe. This pest attacks ripening fruit, causing economic losses including increased management costs and crop rejection. Ongoing research aims to improve the efficacy of monitoring traps. Studies were conducted to evaluate how physical trap features affect captures of D. suzukii. We evaluated five colors, two bait surface areas, and a top and side position for the fly entry point. Studies were conducted at 16 sites spanning seven states and provinces of North America and nine crop types. Apple cider vinegar was the standard bait in all trap types. In the overall analysis, yellow-colored traps caught significantly more flies than clear, white, and black traps; and red traps caught more than clear traps. Results by color may be influenced by crop type. Overall, the trap with a greater bait surface area caught slightly more D. suzukii than the trap with smaller area (90 vs. 40 cm(2)). Overall, the two traps with a side-mesh entry, with or without a protective rain tent, caught more D. suzukii than the trap with a top-mesh entry and tent. PMID:24252375

  2. Duponchelia water-trap

    NARCIS (Netherlands)

    Deventer, van P.

    2008-01-01

    How can the harmful Duponchelia insect best be trapped for optimum detection? A water trap was found to be most effective in a field test by Plant Research International. Another advantage is the low maintenance required by this trap. The composition of the Duponchelia sex pheromone was identified j

  3. Do poverty traps exist ?

    OpenAIRE

    Kraay, Aart; McKenzie, David

    2014-01-01

    This paper reviews the empirical evidence on the existence of poverty traps, understood as self-reinforcing mechanisms through which poor individuals or countries remain poor. Poverty traps have captured the interest of many development policy makers, because poverty traps provide a theoretically coherent explanation for persistent poverty. They also suggest that temporary policy intervent...

  4. Ion trap simulation tools.

    Energy Technology Data Exchange (ETDEWEB)

    Hamlet, Benjamin Roger

    2009-02-01

    Ion traps present a potential architecture for future quantum computers. These computers are of interest due to their increased power over classical computers stemming from the superposition of states and the resulting capability to simultaneously perform many computations. This paper describes a software application used to prepare and visualize simulations of trapping and maneuvering ions in ion traps.

  5. The caddisfly fauna (Insecta, Trichoptera) of the rivers of the Black Sea basin in Kosovo with distributional data for some rare species

    OpenAIRE

    Halil Ibrahimi; Mladen Kučinić; Agim Gashi; Linda Grapci Kotori

    2012-01-01

    Abstract Adult caddisflies were collected from 12 stations in the Black Sea basin in Kosovo using UV light traps. Sixty-five of the seventy-six species reported in this paper are first records for the Kosovo caddisfly fauna. The unexpected discovery of several species during this investigation: Agapetus delicatulus McLachlan, 1884, Psychomyia klapaleki Malicky, 1995, Tinodes janssensi Jacquemart, 1957, Hydropsyche emarginata Navas, 1923, Drusus botosaneanui Kumanski, 1968, Potamophylax rotund...

  6. Optical trapping in liquid crystals

    Science.gov (United States)

    Simoni, F.; Lucchetti, L.; Criante, L.; Bracalente, F.; Aieta, F.

    2010-08-01

    Optical trapping and manipulation of micrometric silica particles dispersed in a nematic liquid crystal is reported. Several kind of samples are considered: homeotropic and planar undoped cells and homeotropic and planar cells doped by a small amount of the azo-dye Methyl-Red. The incident light intensity is over the threshold for optical reorientation of the molecular director. The refractive index of the dispersed particles is lower than the ones of the liquid crystal therefore the usual conditions for laser trapping and manipulation are not fulfilled. Nevertheless optical trapping is possible and is closely related to the optical nonlinearity of the hosting liquid crystal1. Trapping in doped and undoped cells are compared and it is shown that in the first case intensity lower by more than one order of magnitude is required as compared to the one needed in undoped samples. The effect is faster and the structural forces are of longer range. The formation of bubble-gum like defects in doped samples under certain experimental conditions is also reported and discussed.

  7. Trapping Horizons in Sultana-Dyer Space-Time

    Institute of Scientific and Technical Information of China (English)

    SUN Cheng-Yi

    2011-01-01

    The Sultana-Dyer space-time is suggested as a model describing a black hole embedded in an expanding universe.Recently, its global structure is analyzed and the trapping horizons are shown.In the paper, by directly calculating the expansions of the radial null vector fields normal to the space-like two-spheres foliating the trapping horizons, we find that the trapping horizon outside the event horizon in the Sultana-Dyer space-time is a past trapping horizon.Further, we find that the past trapping horizon is an outer, instantaneously degenerate or inner trapping horizon accordingly when the radial coordinate is less than, equal to or greater than some value.

  8. Superconducting microfabricated ion traps

    CERN Document Server

    Wang, Shannon X; Labaziewicz, Jaroslaw; Dauler, Eric; Berggren, Karl; Chuang, Isaac L

    2010-01-01

    We fabricate superconducting ion traps with niobium and niobium nitride and trap single 88Sr ions at cryogenic temperatures. The superconducting transition is verified and characterized by measuring the resistance and critical current using a 4-wire measurement on the trap structure, and observing change in the rf reflection. The lowest observed heating rate is 2.1(3) quanta/sec at 800 kHz at 6 K and shows no significant change across the superconducting transition, suggesting that anomalous heating is primarily caused by noise sources on the surface. This demonstration of superconducting ion traps opens up possibilities for integrating trapped ions and molecular ions with superconducting devices.

  9. Time-resolved measurements of black carbon light absorption enhancement in urban and near-urban locations of southern Ontario, Canada

    Directory of Open Access Journals (Sweden)

    T. W. Chan

    2011-10-01

    Full Text Available In this study a photoacoustic spectrometer (PA, a laser-induced incandescence instrument system (LII and an Aerosol Mass Spectrometer were operated in parallel for in-situ measurements of black carbon (BC light absorption enhancement. Results of a thermodenuder experiment using ambient particles in Toronto are presented first to show that LII measurements of BC are not influenced by the presence of non-refractory material thus providing true atmospheric BC mass concentrations. In contrast, the PA response is enhanced when the non-refractory material is internally mixed with the BC particles. Through concurrent measurements using the LII and PA the specific absorption cross-section (SAC can be quantified with high time resolution (1 min. Comparisons of ambient PA and LII measurements from four different locations (suburban Toronto; a street canyon with diesel bus traffic in Ottawa; adjacent to a commuter highway in Ottawa and; regional background air in and around Windsor, Ontario, show that different impacts from emission sources and/or atmospheric processes result in different particle light absorption enhancements and hence variations in the SAC. The diversity of measurements obtained, including those with the thermodenuder, demonstrated that it is possible to identify measurements where the presence of externally-mixed non-refractory particles obscures direct observation of the effect of coating material on the SAC, thus allowing this effect to be measured with more confidence. Depending upon the time and location of measurement (urban, rural, close to and within a lake breeze frontal zone, 30 min average SAC varies between 9 ± 2 and 43 ± 4 m2 g−1. Causes of this variation, which were determined through the use of meteorological and gaseous measurements (CO, SO2, O3, include the particle emission source, airmass source region, the degree of atmospheric processing. Observations from this study

  10. Black Consciousness

    Science.gov (United States)

    Hraba, Joseph; Siegman, Jack

    1974-01-01

    Black militancy is treated as an instance of class consciousness with criteria and scales developed to measure black consciousness and "self-placement" into black consciousness. These dimensions are then investigated with respect to the social and symbolic participation in the ideology of the black movement on the part of a sample of black…

  11. The Electronic McPhail Trap

    Directory of Open Access Journals (Sweden)

    Ilyas Potamitis

    2014-11-01

    Full Text Available Certain insects affect cultivations in a detrimental way. A notable case is the olive fruit fly (Bactrocera oleae (Rossi, that in Europe alone causes billions of euros in crop-loss/per year. Pests can be controlled with aerial and ground bait pesticide sprays, the efficiency of which depends on knowing the time and location of insect infestations as early as possible. The inspection of traps is currently carried out manually. Automatic monitoring traps can enhance efficient monitoring of flying pests by identifying and counting targeted pests as they enter the trap. This work deals with the hardware setup of an insect trap with an embedded optoelectronic sensor that automatically records insects as they fly in the trap. The sensor responsible for detecting the insect is an array of phototransistors receiving light from an infrared LED. The wing-beat recording is based on the interruption of the emitted light due to the partial occlusion from insect’s wings as they fly in the trap. We show that the recordings are of high quality paving the way for automatic recognition and transmission of insect detections from the field to a smartphone. This work emphasizes the hardware implementation of the sensor and the detection/counting module giving all necessary implementation details needed to construct it.

  12. Trap style influences wild pig behavior and trapping success

    Science.gov (United States)

    Williams, B.L.; Holtfreter, R.W.; Ditchkoff, S.S.; Grand, J.B.

    2011-01-01

    Despite the efforts of many natural resource professionals, wild pig (Sus scrofa) populations are expanding in many areas of the world. Although many creative techniques for controlling pig populations are being explored, trapping has been and still is themost commonly usedmethod of population control formany public and private land managers. We conducted an observational study to examine the efficiency of 2 frequently used trap styles: a small, portable box-style trap and a larger, semi-permanent, corral-style trap.We used game cameras to examine patterns of trap entry by wild pigs around each style of trap, and we conducted a trapping session to compare trapping success between trap styles. Adult female and juvenile wild pigs entered both styles of trap more readily than did adult males, and adult males seemed particularly averse to entering box traps. Less than 10% of adult male visits to box traps resulted in entries, easily the least percentage of any class at any style of trap. Adult females entered corral traps approximately 2.2 times more often per visit than box traps and re-entered corral traps >2 times more frequently. Juveniles entered and reentered both box and corral traps at similar rates. Overall (all-class) entry-per-visit rates at corral traps (0.71) were nearly double that of box traps (0.37). Subsequent trapping data supported these preliminary entry data; the capture rate for corral traps was >4 times that of box traps. Our data suggest that corral traps are temporally and economically superior to box traps with respect to efficiency; that is, corral traps effectively trap more pigs per trap night at a lower cost per pig than do box traps. ?? 2011 The Wildlife Society.

  13. Microfabricated ion trap array

    Science.gov (United States)

    Blain, Matthew G.; Fleming, James G.

    2006-12-26

    A microfabricated ion trap array, comprising a plurality of ion traps having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale ion traps to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The reduced electrode voltage enables integration of the microfabricated ion trap array with on-chip circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of the microfabricated ion trap array can be realized in truly field portable, handheld microanalysis systems.

  14. Black Droplets

    CERN Document Server

    Santos, Jorge E

    2014-01-01

    Black droplets and black funnels are gravitational duals to states of a large N, strongly coupled CFT on a fixed black hole background. We numerically construct black droplets corresponding to a CFT on a Schwarzchild background with finite asymptotic temperature. We find two branches of such droplet solutions which meet at a turning point. Our results suggest that the equilibrium black droplet solution does not exist, which would imply that the Hartle-Hawking state in this system is dual to the black funnel constructed in \\cite{Santos:2012he}. We also compute the holographic stress energy tensor and match its asymptotic behaviour to perturbation theory.

  15. Modular cryostat for ion trapping with surface-electrode ion traps

    CERN Document Server

    Vittorini, Grahame; Brown, Kenneth R; Harter, Alexa W; Doret, S Charles

    2013-01-01

    We present a simple cryostat purpose built for use with surface-electrode ion traps, designed around an affordable, large cooling power commercial pulse tube refrigerator. A modular vacuum enclosure with a single vacuum space facilitates interior access, and enables rapid turnaround and flexiblity for future modifications. Long rectangular windows provide nearly 360 degrees of optical access in the plane of the ion trap, while a circular bottom window near the trap enables NA 0.4 light collection without the need for in-vacuum optics. We evaluate the system's mechanical and thermal characteristics, and we quantify ion trapping performance by trapping 40Ca+, finding small stray electric fields, long ion lifetimes, and low ion heating rates.

  16. Large-area surveys for black carbon and other light-absorbing impurities in snow: Arctic, Antarctic, North America, China (Invited)

    Science.gov (United States)

    Warren, S. G.; Doherty, S. J.; Hegg, D.; Dang, C.; Zhang, R.; Grenfell, T. C.; Brandt, R. E.; Clarke, A. D.; Zatko, M.

    2013-12-01

    Absorption of radiation by ice is extremely weak at visible and near-UV wavelengths, so small amounts of light-absorbing impurities (LAI) in snow can dominate the absorption of sunlight at these wavelengths, reducing the albedo relative to that of pure snow and leading to earlier snowmelt. Snow samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean, on tundra, glaciers, ice caps, sea ice, and frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack was accessible for sampling. Snow was also collected at 67 sites in western North America. Expeditions from Lanzhou University obtained black carbon (BC) amounts at 84 sites in northeast and northwest China. BC was measured at 3 locations on the Antarctic Plateau, and at 5 sites on East Antarctic sea ice. The snow is melted and filtered; the filters are analyzed in a spectrophotometer. Median BC mixing ratios in snow range over 4 orders of magnitude from 0.2 ng/g in Antarctica to 1000 ng/g in northeast China. Chemical analyses, input to a receptor model, indicate that the major source of BC in most of the Arctic is biomass burning, but industrial sources dominate in Svalbard and the central Arctic Ocean. Non-BC impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. In northeast China BC is the dominant LAI, but in Inner Mongolia soil dominates. When the snow surface layer melts, much of the BC is left at the top of the snowpack rather than carried away in meltwater, thus causing a positive feedback on snowmelt. This process was quantified through field studies in Greenland, Alaska, and Norway, where we found that only 10-30% of the BC is removed with meltwater. The BC content of the Arctic atmosphere has declined markedly since 1989, according to the continuous measurements of near-surface air in Canada, Alaska, and Svalbard. Correspondingly, our recent BC

  17. Duponchelia water-trap

    OpenAIRE

    Deventer, van, S.J.H.

    2008-01-01

    How can the harmful Duponchelia insect best be trapped for optimum detection? A water trap was found to be most effective in a field test by Plant Research International. Another advantage is the low maintenance required by this trap. The composition of the Duponchelia sex pheromone was identified just over a year ago and now growers are using pheromone traps on a large scale for a timely detection of this difficult pest insect. The caterpillars of this moth cause damage in all sorts of crops...

  18. Radiation trapping inside a hollow-core photonic crystal fiber

    CERN Document Server

    Jen, H H; Lee, Kevin C J; Chen, Yi-Hsin; Yu, Ite A

    2014-01-01

    We report the radiation trapping effect inside a hollow-core photonic crystal fiber (PCF). An optical dipole trap was used to load and confine the atoms in the PCF without contacting the wall of the fiber. The transmission of a probe light propagating through the PCF was studied experimentally and theoretically. With the experimental results and theoretical predictions, we conclude that the radiation trapping can play a significant role and should be taken into account in the spectroscopic measurements inside the PCF.

  19. Black Eye

    Science.gov (United States)

    ... eyesight if not treated. If both eyes are black after a head injury, it could signify a skull fracture or other serious injury. Next Black Eye Symptoms Related Ask an Ophthalmologist Answers How ...

  20. An effort to trap mink in Maine to protect nesting Seabirds 1999

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report details and effort to trap mink and survey black guillemots on islands in outer Penobscot Bay Otter, Roberts, Little Roberts, Carvers, Hay, and...

  1. Plasmon enhanced optical tweezers with gold-coated black silicon

    Science.gov (United States)

    Kotsifaki, D. G.; Kandyla, M.; Lagoudakis, P. G.

    2016-05-01

    Plasmonic optical tweezers are a ubiquitous tool for the precise manipulation of nanoparticles and biomolecules at low photon flux, while femtosecond-laser optical tweezers can probe the nonlinear optical properties of the trapped species with applications in biological diagnostics. In order to adopt plasmonic optical tweezers in real-world applications, it is essential to develop large-scale fabrication processes without compromising the trapping efficiency. Here, we develop a novel platform for continuous wave (CW) and femtosecond plasmonic optical tweezers, based on gold-coated black silicon. In contrast with traditional lithographic methods, the fabrication method relies on simple, single-step, maskless tabletop laser processing of silicon in water that facilitates scalability. Gold-coated black silicon supports repeatable trapping efficiencies comparable to the highest ones reported to date. From a more fundamental aspect, a plasmon-mediated efficiency enhancement is a resonant effect, and therefore, dependent on the wavelength of the trapping beam. Surprisingly, a wavelength characterization of plasmon-enhanced trapping efficiencies has evaded the literature. Here, we exploit the repeatability of the recorded trapping efficiency, offered by the gold-coated black silicon platform, and perform a wavelength-dependent characterization of the trapping process, revealing the resonant character of the trapping efficiency maxima. Gold-coated black silicon is a promising platform for large-scale parallel trapping applications that will broaden the range of optical manipulation in nanoengineering, biology, and the study of collective biophotonic effects.

  2. 'Black holes': escaping the void.

    Science.gov (United States)

    Waldron, Sharn

    2013-02-01

    The 'black hole' is a metaphor for a reality in the psyche of many individuals who have experienced complex trauma in infancy and early childhood. The 'black hole' has been created by an absence of the object, the (m)other, so there is no internalized object, no (m)other in the psyche. Rather, there is a 'black hole' where the object should be, but the infant is drawn to it, trapped by it because of an intrinsic, instinctive need for a 'real object', an internalized (m)other. Without this, the infant cannot develop. It is only the presence of a real object that can generate the essential gravity necessary to draw the core of the self that is still in an undeveloped state from deep within the abyss. It is the moving towards a real object, a (m)other, that relativizes the absolute power of the black hole and begins a reformation of its essence within the psyche.

  3. Black hole evaporation: a paradigm

    International Nuclear Information System (INIS)

    A paradigm describing black hole evaporation in non-perturbative quantum gravity is developed by combining two sets of detailed results: (i) resolution of the Schwarzschild singularity using quantum geometry methods and (ii) time evolution of black holes in the trapping and dynamical horizon frameworks. Quantum geometry effects introduce a major modification in the traditional spacetime diagram of black hole evaporation, providing a possible mechanism for recovery of information that is classically lost in the process of black hole formation. The paradigm is developed directly in the Lorentzian regime and necessary conditions for its viability are discussed. If these conditions are met, much of the tension between expectations based on spacetime geometry and structure of quantum theory would be resolved

  4. Wormholes as Black Hole Foils

    CERN Document Server

    Damour, Thibault

    2007-01-01

    We study to what extent wormholes can mimic the observational features of black holes. It is surprisingly found that many features that could be thought of as ``characteristic'' of a black hole (endowed with an event horizon) can be closely mimicked by a globally static wormhole, having no event horizon. This is the case for: the apparently irreversible accretion of matter down a hole, no-hair properties, quasi-normal-mode ringing, and even the dissipative properties of black hole horizons, such as a finite surface resistivity equal to 377 Ohms. The only way to distinguish the two geometries on an observationally reasonable time scale would be through the detection of Hawking's radiation, which is, however, too weak to be of practical relevance for astrophysical black holes. We point out the existence of an interesting spectrum of quantum microstates trapped in the throat of a wormhole which could be relevant for storing the information ``lost'' during a gravitational collapse.

  5. Evaluation of Trap Designs and Deployment Strategies for Capturing Halyomorpha halys (Hemiptera: Pentatomidae).

    Science.gov (United States)

    Morrison, William R; Cullum, John P; Leskey, Tracy C

    2015-08-01

    Halyomorpha halys (Stål) is an invasive pest that attacks numerous crops. For growers to make informed management decisions against H. halys, an effective monitoring tool must be in place. We evaluated various trap designs baited with the two-component aggregation pheromone of H. halys and synergist and deployed in commercial apple orchards. We compared our current experimental standard trap, a black plywood pyramid trap 1.22 m in height deployed between border row apple trees with other trap designs for two growing seasons. These included a black lightweight coroplast pyramid trap of similar dimension, a smaller (29 cm) pyramid trap also ground deployed, a smaller limb-attached pyramid trap, a smaller pyramid trap hanging from a horizontal branch, and a semipyramid design known as the Rescue trap. We found that the coroplast pyramid was the most sensitive, capturing more adults than all other trap designs including our experimental standard. Smaller pyramid traps performed equally in adult captures to our experimental standard, though nymphal captures were statistically lower for the hanging traps. Experimental standard plywood and coroplast pyramid trap correlations were strong, suggesting that standard plywood pyramid traps could be replaced with lighter, cheaper coroplast pyramid traps. Strong correlations with small ground- and limb-deployed pyramid traps also suggest that these designs offer promise as well. Growers may be able to adopt alternative trap designs that are cheaper, lighter, and easier to deploy to monitor H. halys in orchards without a significant loss in sensitivity. PMID:26470309

  6. LIME GREEN LIGHT-EMITTING DIODE EQUIPPED YELLOW STICKY CARD TRAPS FOR MONITORING WHITEFLIES, APHIDS AND FUNGUS GNATS IN GREENHOUSES%应用附加绿黄色光二极管的黄色胶片监测温室中的粉虱、蚜虫和蕈蚊

    Institute of Scientific and Technical Information of China (English)

    朱昌祺; Alvin M. Simmons; 陈天业; Patrick J. Alexander; Thomas J. Henneerry

    2004-01-01

    绿黄色光二极管(LED)附加在塑胶杯和胶片捕捉器可增加捕捉实验室和温室中昆虫的数量.附加有530nm绿黄色LED的塑胶杯捕捉器比没有附加的捕捉到更多的Trialeurodes vaporariorum(Westwood)和Bemisia tabaci(Gennadius)B生态型.在温室中昆虫笼以四季豆和棉花试验,附加有530nm绿黄色LED的黄色胶片(YC)和透明塑胶片(CS)分别缩写为LED-YC和LED-CS)比每一种没有附加的捕捉器捕捉到更多的T. vaporariorum,B.tabaci B生态型,Ahis gossypii(Glover)和Bradysia coprophila(Lintner)成虫.绿黄色LED-YC在温室中有用为监测和控制的潜在性.%Light-emitting diodes (LEDs) were attached to plastic cup and sticky card traps to improve Pest insect catches in the laboratory and in greenhouses. Plastic cup traps equipped with 530 nm lime green LEDs caught more adult Trialeurodes vaporariorum (Westwood) and Bemisia tabaci (Gennadius) biotype B compared with plastic cup traps alone. Yellow sticky card (YC) and clear plastic sticky card (CS) traps equipped with lime green LEDs (LED-YC and LED-CS, respectively) caught more adult T. vaporariorum, B. tabaci biotype B, Aphis gossypii (Glover) and Bradysia coprophila (Lintner) compared with unlit traps of each type in greenhouse cage studies with shell beans, Phaseolus vulgaris (L.) and cotton, Gossypium hirsutum (L.). The lime green LED equipped YC traps have potential for use in greenhouses for insect detection,monitoring, and control.

  7. Nonlinear integrable ion traps

    Energy Technology Data Exchange (ETDEWEB)

    Nagaitsev, S.; /Fermilab; Danilov, V.; /SNS Project, Oak Ridge

    2011-10-01

    Quadrupole ion traps can be transformed into nonlinear traps with integrable motion by adding special electrostatic potentials. This can be done with both stationary potentials (electrostatic plus a uniform magnetic field) and with time-dependent electric potentials. These potentials are chosen such that the single particle Hamilton-Jacobi equations of motion are separable in some coordinate systems. The electrostatic potentials have several free adjustable parameters allowing for a quadrupole trap to be transformed into, for example, a double-well or a toroidal-well system. The particle motion remains regular, non-chaotic, integrable in quadratures, and stable for a wide range of parameters. We present two examples of how to realize such a system in case of a time-independent (the Penning trap) as well as a time-dependent (the Paul trap) configuration.

  8. Nonlinear Integrable Ion Traps

    CERN Document Server

    Nagaitsev, S

    2011-01-01

    Quadrupole ion traps can be transformed into nonlinear traps with integrable motion by adding special electrostatic potentials. This can be done with both stationary potentials (electrostatic plus a uniform magnetic field) and with time-dependent electric potentials. These potentials are chosen such that the single particle Hamilton-Jacobi equations of motion are separable in some coordinate systems. The electrostatic potentials have several free adjustable parameters allowing for a quadrupole trap to be transformed into, for example, a double-well or a toroidal-well system. The particle motion remains regular, non-chaotic, integrable in quadratures, and stable for a wide range of parameters. We present two examples of how to realize such a system in case of a time-independent (the Penning trap) as well as a time-dependent (the Paul trap) configuration.

  9. Pyrolytic carbon coated black silicon.

    Science.gov (United States)

    Shah, Ali; Stenberg, Petri; Karvonen, Lasse; Ali, Rizwan; Honkanen, Seppo; Lipsanen, Harri; Peyghambarian, N; Kuittinen, Markku; Svirko, Yuri; Kaplas, Tommi

    2016-01-01

    Carbon is the most well-known black material in the history of man. Throughout the centuries, carbon has been used as a black material for paintings, camouflage, and optics. Although, the techniques to make other black surfaces have evolved and become more sophisticated with time, carbon still remains one of the best black materials. Another well-known black surface is black silicon, reflecting less than 0.5% of incident light in visible spectral range but becomes a highly reflecting surface in wavelengths above 1000 nm. On the other hand, carbon absorbs at those and longer wavelengths. Thus, it is possible to combine black silicon with carbon to create an artificial material with very low reflectivity over a wide spectral range. Here we report our results on coating conformally black silicon substrate with amorphous pyrolytic carbon. We present a superior black surface with reflectance of light less than 0.5% in the spectral range of 350 nm to 2000 nm. PMID:27174890

  10. 1985-86 Trapping Proposal

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Annual Trapping Plan for the 1985-1986 trapping season at Clarence Cannon NWR outlines rules and regulations for the trapping of beaver and muskrat on the...

  11. Optimal Proton Trapping

    CERN Document Server

    Coakley, K J

    2006-01-01

    In a neutron lifetime experiment conducted at the National Institute of Standards and Technology, protons produced by neutron decay events are confined in a Penning trap. In each run of the experiment, there is a trapping stage of duration $\\tau$. After the trapping stage, protons are purged from the trap. A proton detector provides incomplete information because it goes dead after detecting the first of any purged protons. Further, there is a dead time $\\delta$ between the end of the trapping stage in one run and the beginning of the next trapping stage in the next run. Based on the fraction of runs where a proton is detected, I estimate the trapping rate $\\lambda$ by the method of maximum likelihood. I show that the expected value of the maximum likelihood estimate is infinite. To obtain a maximum likelihood estimate with a finite expected value and a well-defined and finite variance, I restrict attention to a subsample of all realizations of the data. This subsample excludes an exceedingly rare realization...

  12. New Horizons for Black Holes and Branes

    CERN Document Server

    Emparan, Roberto; Niarchos, Vasilis; Obers, Niels A

    2009-01-01

    We initiate a systematic scan of the landscape of black holes in any spacetime dimension using the recently proposed blackfold effective worldvolume theory. We focus primarily on asymptotically flat stationary vacuum solutions, where we uncover large classes of new black holes. These include helical black strings and black rings, black odd-spheres, for which the horizon is a product of a large and a small sphere, and non-uniform black cylinders. More exotic possibilities are also outlined. The blackfold description recovers correctly the ultraspinning Myers-Perry black holes as ellipsoidal even-ball configurations where the velocity field approaches the speed of light at the boundary of the ball. Helical black ring solutions provide the first instance of asymptotically flat black holes in more than four dimensions with a single spatial U(1) isometry. They also imply infinite rational non-uniqueness in ultraspinning regimes, where they maximize the entropy among all stationary single-horizon solutions. Moreove...

  13. Doppler cooling of an optically dense cloud of trapped atoms

    CERN Document Server

    Schmidt, P O; Werner, J; Binhammer, T; Görlitz, A; Pfau, T; Schmidt, Piet O.; Hensler, Sven; Binhammer, Thomas; G\\"{o}rlitz, Axel; Pfau, Tilman

    2002-01-01

    We have studied a general technique for laser cooling a cloud of polarized trapped atoms down to the Doppler temperature. A one-dimensional optical molasses using polarized light cools the axial motional degree of freedom of the atoms in the trap. Cooling of the radial degrees of freedom can be modelled by reabsorption of scattered photons in the optically dense cloud. We present experimental results for a cloud of chromium atoms in a magnetic trap. A simple model based on rate equations shows quantitative agreement with the experimental results. This scheme allows us to readily prepare a dense cloud of atoms in a magnetic trap with ideal starting conditions for evaporative cooling.

  14. In-trap fluorescence detection of atoms in a microscopic dipole trap

    CERN Document Server

    Hilliard, A J; Sompet, P; Carpentier, A V; Andersen, M F

    2015-01-01

    We investigate fluorescence detection using a standing wave of blue-detuned light of one or more atoms held in a deep, microscopic dipole trap. The blue-detuned standing wave realizes a Sisyphus laser cooling mechanism so that an atom can scatter many photons while remaining trapped. When imaging more than one atom, the blue detuning limits loss due to inelastic light-assisted collisions. Using this standing wave probe beam, we demonstrate that we can count from one to the order of 100 atoms in the microtrap with sub-poissonian precision.

  15. The nature of the TRAP-Anti-TRAP complex.

    Science.gov (United States)

    Watanabe, Masahiro; Heddle, Jonathan G; Kikuchi, Kenichi; Unzai, Satoru; Akashi, Satoko; Park, Sam-Yong; Tame, Jeremy R H

    2009-02-17

    Tryptophan biosynthesis is subject to exquisite control in species of Bacillus and has become one of the best-studied model systems in gene regulation. The protein TRAP (trp RNA-binding attenuation protein) predominantly forms a ring-shaped 11-mer, which binds cognate RNA in the presence of tryptophan to suppress expression of the trp operon. TRAP is itself regulated by the protein Anti-TRAP, which binds to TRAP and prevents RNA binding. To date, the nature of this interaction has proved elusive. Here, we describe mass spectrometry and analytical centrifugation studies of the complex, and 2 crystal structures of the TRAP-Anti-TRAP complex. These crystal structures, both refined to 3.2-A resolution, show that Anti-TRAP binds to TRAP as a trimer, sterically blocking RNA binding. Mass spectrometry shows that 11-mer TRAP may bind up to 5 AT trimers, and an artificial 12-mer TRAP may bind 6. Both forms of TRAP make the same interactions with Anti-TRAP. Crystallization of wild-type TRAP with Anti-TRAP selectively pulls the 12-mer TRAP form out of solution, so the crystal structure of wild-type TRAP-Anti-TRAP complex reflects a minor species from a mixed population. PMID:19164760

  16. Black phosphorus nonvolatile transistor memory

    Science.gov (United States)

    Lee, Dain; Choi, Yongsuk; Hwang, Euyheon; Kang, Moon Sung; Lee, Seungwoo; Cho, Jeong Ho

    2016-04-01

    We demonstrated nanofloating gate transistor memory devices (NFGTMs) using mechanically-exfoliated few-layered black phosphorus (BP) channels and gold nanoparticle (AuNPs) charge trapping layers. The resulting BP-NFGTMs exhibited excellent memory performances, including the five-level data storage, large memory window (58.2 V), stable retention (104 s), and cyclic endurance (1000 cycles).We demonstrated nanofloating gate transistor memory devices (NFGTMs) using mechanically-exfoliated few-layered black phosphorus (BP) channels and gold nanoparticle (AuNPs) charge trapping layers. The resulting BP-NFGTMs exhibited excellent memory performances, including the five-level data storage, large memory window (58.2 V), stable retention (104 s), and cyclic endurance (1000 cycles). Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02078j

  17. SURVEY OF THE ENTOMOFAUNA THROUGH LUMINOUS TRAP

    Directory of Open Access Journals (Sweden)

    V. R. Andrade Neto

    2014-09-01

    Full Text Available The demand for forest-based raw materials for energy, construction, paper pulp and the pressure to comply with legal requirements concerning environmental legislation, for example, the replacement of the permanent preservation area, legal reserve and recovery of degraded area, leads to encourage the production of healthy seedlings in a health status to do not compromise their future production. The present study aimed to survey the entomofauna population using the “Luiz de Queiroz” model of luminous trap, with white and red fluorescent lamps. The experiment was conducted at the nursery “Flora Sinop” in Sinop – MT. The survey was conducted weekly between the months of April to July 2010, totaling 4 months sand, 32 samples collected. The orders Hemiptera and Coleoptera showed the highest number of individuals captured, either in attraction with white or red light. It was captured 10.089 individuals, 9.339 collected under the influence of white light, representing 92,56%, and 750 with red light, only 7,44% of the total. The white light luminous trap possessed greater efficiency in the attraction of insects when compared with the red light trap.

  18. Local temperature for dynamical black holes

    CERN Document Server

    Hayward, Sean A; Nadalini, M; Vanzo, L; Zerbini, S

    2009-01-01

    A local Hawking temperature was recently derived for any future outer trapping horizon in spherical symmetry, using a Hamilton-Jacobi tunneling method, and is given by a dynamical surface gravity as defined geometrically. Descriptions are given of the operational meaning of the temperature, in terms of what observers measure, and its relation to the usual Hawking temperature for static black holes. Implications for the final fate of an evaporating black hole are discussed.

  19. Local temperature for dynamical black holes

    Science.gov (United States)

    Hayward, Sean A.; di Criscienzo, R.; Nadalini, M.; Vanzo, L.; Zerbini, S.

    2009-05-01

    A local Hawking temperature was recently derived for any future outer trapping horizon in spherical symmetry, using a Hamilton-Jacobi tunneling method, and is given by a dynamical surface gravity as defined geometrically. Descriptions are given of the operational meaning of the temperature, in terms of what observers measure, and its relation to the usual Hawking temperature for static black holes. Implications for the final fate of an evaporating black hole are discussed.

  20. Conservation laws for dynamical black holes

    OpenAIRE

    Hayward, Sean A.

    2006-01-01

    An essentially complete new paradigm for dynamical black holes in terms of trapping horizons is presented, including dynamical versions of the physical quantities and laws which were considered important in the classical paradigm for black holes in terms of Killing or event horizons. Three state functions are identified as surface integrals over marginal surfaces: irreducible mass, angular momentum and charge. There are three corresponding conservation laws, expressing the rate of change of t...

  1. Black holes and relativitic gravity theories

    Science.gov (United States)

    Fennelly, A. J.; Pavelle, R.

    1977-01-01

    All presently known relativistic gravitation theories were considered which have a Riemannian background geometry and possess exact static, spherically symmetric solutions which are asymptotically flat. Each theory predicts the existence of trapped surfaces (black holes). For a general static isotropic metric, MACSYMA was used to compute the Newman-Penrose equations, the black hole radius, the impact parameter, and capture radius for photon accretion. These results were then applied to several of the better known gravitation theories.

  2. Elimination of charge carrier trapping in diluted semiconductors

    Science.gov (United States)

    Abbaszadeh, D.; Kunz, A.; Wetzelaer, G. A. H.; Michels, J. J.; Crăciun, N. I.; Koynov, K.; Lieberwirth, I.; Blom, P. W. M.

    2016-06-01

    In 1962, Mark and Helfrich demonstrated that the current in a semiconductor containing traps is reduced by N/Ntr, with N the amount of transport sites, Nt the amount of traps and r a number that depends on the trap energy distribution. For r > 1, the possibility opens that trapping effects can be nearly eliminated when N and Nt are simultaneously reduced. Solution-processed conjugated polymers are an excellent model system to test this hypothesis, because they can be easily diluted by blending them with a high-bandgap semiconductor. We demonstrate that in conjugated polymer blends with 10% active semiconductor and 90% high-bandgap host, the typical strong electron trapping can be effectively eliminated. As a result we were able to fabricate polymer light-emitting diodes with balanced electron and hole transport and reduced non-radiative trap-assisted recombination, leading to a doubling of their efficiency at nearly ten times lower material costs.

  3. Comment on Hawking radiation and trapping horizons

    CERN Document Server

    Baier, Rudolf

    2015-01-01

    We consider dynamical black hole formation from a collapsing fluid described by a symmetric and flat FRW metric. Using the Hamilton-Jacobi method the local Hawking temperature for the formed trapping/apparent horizon is calculated. The local Hawking temperature depends on the tunneling path, which we take to be along a null direction $(\\Delta s=0)$. We find that the local Hawking temperature depends directly on the equation of state of the collapsing fluid. We argue that Hawking radiation by quantum tunnelling from future inner and future outer trapping horizons is possible. However, only radiation from a space-like dynamical horizon has a chance to be observed by an external observer. Some comparison to existing literature is made.

  4. Optothermal Molecule Trap

    OpenAIRE

    Duhr, Stefan; Braun, Dieter

    2006-01-01

    Thermophoresis moves molecules along temperature gradients, typically from hot to cold. We superpose fluid flow with thermophoretic molecule flow under well defined microfluidic conditions, imaged by fluorescence microscopy. DNA is trapped and accumulated 16-fold in regions where both flows move in opposite directions. Strong 800-fold accumulation is expected, however with slow trapping kinetics. The experiment is equally described by a three-dimensional and one-dimensional analytical model. ...

  5. An Improved Antihydrogen Trap

    OpenAIRE

    Kalra, Rita Rani

    2015-01-01

    The recent demonstration of trapped atomic antihydrogen for 15 to 1000 seconds is a milestone towards precise spectroscopy for tests of CPT invariance. The confinement of a total of 105±21 atoms in a quadrupole magnetic trap was made possible by several improved methods. Improved accumulation techniques give us the largest numbers of constituent particles yet: up to 10 million antiprotons and several billion positrons. A novel cooling protocol leads to 3.5 K antiprotons, the coldest ever obse...

  6. Fractal Poverty Traps

    OpenAIRE

    Barrett, Christopher B.; Swallow, Brent M.

    2003-01-01

    This paper offers an informal theory of fractal poverty traps that lead to chronic poverty at multiple scales of socio-spatial aggregation. Poverty traps result from nonlinear processes at individual, household, community, national and international scales that cause the coexistence of high and low equilibrium levels of productivity and income and high and low rates of economic growth. Multiple equilibria result from key threshold effects that exist at all scales due to market failures and no...

  7. Structural traps 2

    Energy Technology Data Exchange (ETDEWEB)

    Beaumont, E.A.; Foster, N.H.

    1990-01-01

    This book contains studies of fields that exist because of the presence of tectonic faulting. Tectonic faulting occurs because of the release of crustal stresses. Nontectonic faulting is due to other factors, such as salt solution and collapse or detachment from sedimentary loading and slumping. The traps responsible for the fields in this volume are related either directly or indirectly to a fault block. The traps of Amposta, Cano Limon, Ninian, Renqiu, and Sarir are directly related to a fault block. Brent and Magnus fields are the result of traps formed by an unconformity truncation and a tilted fault block. Mobeetie field is the result of a trap indirectly related to a fault block. The anticline associated with the trap formed by differential compaction over a basement fault block. Red Oak field comprises traps both in a fault block and in an overlying anticline formed by differential compaction over the same fault block. With the exception of Cano Limon, all the fault blocks associated with these fields formed mainly under tensional stresses. The fault block associated with Cano Limon field formed by shearing in a strike-slip environment. Another aspect described in each field study is the history of its exploration and development.

  8. Ultratrace determination of lead by hydride generation in-atomizer trapping atomic absorption spectrometry: Optimization of plumbane generation and analyte preconcentration in a quartz trap-and-atomizer device

    Energy Technology Data Exchange (ETDEWEB)

    Kratzer, Jan, E-mail: jkratzer@biomed.cas.cz

    2012-05-15

    A compact trap-and-atomizer device and a preconcentration procedure based on hydride trapping in excess of oxygen over hydrogen in the collection step, both constructed and developed previously in our laboratory, were employed to optimize plumbane trapping in this device and to develop a routine method for ultratrace lead determination subsequently. The inherent advantage of this preconcentration approach is that 100% preconcentration efficiency for lead is reached in this device which has never been reported before using quartz or metal traps. Plumbane is completely retained in the trap-and-atomizer device at 290 Degree-Sign C in oxygen-rich atmosphere and trapped species are subsequently volatilized at 830 Degree-Sign C in hydrogen-rich atmosphere. Effect of relevant experimental parameters on plumbane trapping and lead volatilization are discussed, and possible trapping mechanisms are hypothesized. Plumbane trapping in the trap-and-atomizer device can be routinely used for lead determination at ultratrace levels reaching a detection limit of 0.21 ng ml{sup -1} Pb (30 s preconcentration, sample volume 2 ml). Further improvement of the detection limit is feasible by reducing the blank signal and increasing the trapping time. - Highlights: Black-Right-Pointing-Pointer In-atomizer trapping HG-AAS was optimized for Pb. Black-Right-Pointing-Pointer A compact quartz trap-and-atomizer device was employed. Black-Right-Pointing-Pointer Generation, preconcentration and atomization steps were investigated in detail. Black-Right-Pointing-Pointer 100% preconcentration efficiency for lead was reached. Black-Right-Pointing-Pointer Routine analytical method was developed for Pb determination (LOD of 0.2 ng ml{sup -1} Pb).

  9. Black Culture

    Directory of Open Access Journals (Sweden)

    Angela Khristin Brown

    2013-07-01

    Full Text Available The migration of blacks in North America through slavery became united.  The population of blacks past downs a tradition of artist through art to native born citizens. The art tradition involved telling stories to each generation in black families. The black culture elevated by tradition created hope to determine their personal freedom to escape from poverty of enslavement and to establish a way of life through tradition. A way of personal freedoms was through getting a good education that lead to a better foundation and a better way of life. 

  10. Comparision of carbon dioxide-baited trapping systems for sampling outdoor mosquito populations in Tanzania

    NARCIS (Netherlands)

    Mboera, L.E.G.; Knols, B.G.J.; Braks, M.A.H.; Takken, W.

    2000-01-01

    For collecting mosquitoes (Diptera: Culicidae) the outdoor catching efficiency of four types of trapping devices baited with carbon dioxide (CO2, 300 ml/min) was evaluated and compared in two areas of Tanzania. The types of traps employed were: the CDC miniature trap with the incandescent light bulb

  11. Black holes and beyond

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for

  12. Spectral gaps for normally hyperbolic trapping

    CERN Document Server

    Dyatlov, Semyon

    2014-01-01

    We establish a resonance free strip for codimension 2 symplectic normally hyperbolic trapped sets with smooth incoming/outgoing tails. An important application is wave decay on Kerr and Kerr-de Sitter black holes. We recover the optimal size of the strip and give an $o(h^{-2})$ resolvent bound there. We next show existence of deeper resonance free strips under the $r$-normal hyperbolicity assumption and a pinching condition. We also give a lower bound on one-sided cutoff resolvent on the real line.

  13. Turbulent black holes.

    Science.gov (United States)

    Yang, Huan; Zimmerman, Aaron; Lehner, Luis

    2015-02-27

    We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids.

  14. Turbulent black holes.

    Science.gov (United States)

    Yang, Huan; Zimmerman, Aaron; Lehner, Luis

    2015-02-27

    We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids. PMID:25768746

  15. Deep dyeing properties and light fastness of black ultrafine polyester for automotive textiles%黑色细旦汽车内饰面料染深性和耐光性

    Institute of Scientific and Technical Information of China (English)

    葛元宇; 闵洁; 代烨珉

    2012-01-01

    研究了细旦面料分散黑染色显色性及其耐光色牢度,以及添加耐光牢度提升剂后对细旦织物的表观得色和耐光色牢度的影响.研究结果表明,在染料用量3%-15%(omf)范围内,细旦纤维上染料浓度递增能直接引起纤维颜色深度的递增;当染料用量较低时,耐光牢度提升剂和分散染料在向涤纶纤维迁移过程中的相互影响较小;而当染料用量较大时,两者之间的竞染效应凸显,使染色织物K/S值下降;相同氙弧曝光条件下,细旦纤维上染料含量越高,其耐受光照的性能越优异.%Deep dyeing and light fastness of the black ultra-fine automotive textiles mainly depend on dye depth. Effects of dye-stuff dosage and light fastness promoter on the color value and light fastness are investigated. Results show that the color value increases along with the increase in dye depth ranging from 3% to 15%omf. There is little interaction between light fastness promoters and disperse dyes at low concentration during dye migration. When dye quantity is high, the competition between the light fastness promoters and dyes will lead to lower K/S value. The higher the content of dyes in the ultra-fine fibers is, the better the light fastness will be.

  16. The Formation of Supermassive Black Holes in the First Galaxies

    NARCIS (Netherlands)

    Schleicher, Dominik R. G.; Banerjee, Robi; Sur, Sharanya; Glover, Simon C. O.; Spaans, Maarten; Klessen, Ralf S.; Whalen, Daniel J.; Bromm, Volker; Yoshida, Naoki

    2010-01-01

    We discuss the formation of supermassive black holes in the early universe, and how to probe their subsequent evolution with the upcoming mm/sub-mm telescope ALMA. We first focus on the chemical and radiative conditions for black hole formation, in particular considering radiation trapping and molec

  17. Comparative efficacy of three suction traps for collecting phlebotomine sand flies (Diptera: Psychodidae) in open habitats.

    Science.gov (United States)

    Faiman, Roy; Cuño, Ruben; Warburg, Alon

    2009-06-01

    The efficacy of three suction traps for trapping phlebotomine sand flies (Diptera: Psychodidae) was compared. Traps were baited with Co(2) and used without any light source. CO(2)-baited CDC traps were evaluated either in their standard downdraft orientation or inverted (iCDC traps). Mosquito Magnet-X (MMX) counterflow geometry traps were tested in the updraft orientation only. Both updraft traps (iCDC and MMX) were deployed with their opening ∼10 cm from the ground while the opening of the downdraft (CDC) trap was ∼40 cm above ground. Comparisons were conducted in two arid locations where different sand fly species prevail. In the Jordan Valley, 3,367 sand flies were caught, 2,370 of which were females. The predominant species was Phlebotomus (Phlebotomus) papatasi, Scopoli 1786 (>99%). The updraft-type traps iCDC and MMX caught an average of 118 and 67.1 sand flies per trap night, respectively. The CDC trap caught 32.9 sand flies on average per night, significantly less than the iCDC traps. In the Judean desert, traps were arranged in a 3 × 3 Latin square design. A total of 565 sand flies were caught, 345 of which were females. The predominant species was P. (Paraphlebotomus) sergenti Parrot 1917 (87%). The updraft traps iCDC and MMX caught an average of 25.6 and 17.9 sand flies per trap per night, respectively. The CDC trap caught 7.8 sand flies on average per night, significantly less than the iCDC traps. The female to male ratio was 1.7 on average for all trap types. In conclusion, updraft traps deployed with their opening close to the ground are clearly more effective for trapping sand flies than downdraft CDC traps in open habitats.

  18. Using insect traps to increase weaver ant (Oecophylla longinoda) prey capture

    DEFF Research Database (Denmark)

    Lynegaard, Gina; Offenberg, Joachim; Fast, Thora;

    2014-01-01

    estimated the amount of insects caught by simple traps (cost per trap = 3.9 USD), and whether O. longinoda was able to collect insects from them. On average, a trap caught 110 insects per month without catching any weaver ants. The number of insects found in traps with ant access was 25% lower than in...... by O. longinoda under natural conditions (without traps), potentially increasing to 14% if ants learn to extract all insects. Thus, prey intake may be increased with 5-14% per 3.9 USD invested in traps. These numbers increased to 38 and 78%, respectively, when light was used to attract insects during...

  19. Slowly balding black holes

    International Nuclear Information System (INIS)

    The 'no-hair' theorem, a key result in general relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the no-hair theorem is not formally applicable for black holes formed from the collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively ''frozen in'' the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes NB=eΦ∞/(πc(ℎ/2π)), where Φ∞≅2π2BNSRNS3/(PNSc) is the initial magnetic flux through the hemispheres of the progenitor and out to infinity. We test this theoretical result via 3-dimensional general relativistic plasma simulations of rotating black holes that start with a neutron star dipole magnetic field with no currents initially present outside the event horizon. The black hole's magnetosphere subsequently relaxes to the split-monopole magnetic field geometry with self-generated currents outside the event horizon. The dissipation of the resulting equatorial current sheet leads to a slow loss of the anchored flux tubes, a process that balds the black hole on long resistive time scales rather than the short light-crossing time scales expected from the vacuum no-hair theorem.

  20. Slowly balding black holes

    Science.gov (United States)

    Lyutikov, Maxim; McKinney, Jonathan C.

    2011-10-01

    The “no-hair” theorem, a key result in general relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the no-hair theorem is not formally applicable for black holes formed from the collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively “frozen in” the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes NB=eΦ∞/(πcℏ), where Φ∞≈2π2BNSRNS3/(PNSc) is the initial magnetic flux through the hemispheres of the progenitor and out to infinity. We test this theoretical result via 3-dimensional general relativistic plasma simulations of rotating black holes that start with a neutron star dipole magnetic field with no currents initially present outside the event horizon. The black hole’s magnetosphere subsequently relaxes to the split-monopole magnetic field geometry with self-generated currents outside the event horizon. The dissipation of the resulting equatorial current sheet leads to a slow loss of the anchored flux tubes, a process that balds the black hole on long resistive time scales rather than the short light-crossing time scales expected from the vacuum no-hair theorem.

  1. Optimising camera traps for monitoring small mammals.

    Science.gov (United States)

    Glen, Alistair S; Cockburn, Stuart; Nichols, Margaret; Ekanayake, Jagath; Warburton, Bruce

    2013-01-01

    Practical techniques are required to monitor invasive animals, which are often cryptic and occur at low density. Camera traps have potential for this purpose, but may have problems detecting and identifying small species. A further challenge is how to standardise the size of each camera's field of view so capture rates are comparable between different places and times. We investigated the optimal specifications for a low-cost camera trap for small mammals. The factors tested were 1) trigger speed, 2) passive infrared vs. microwave sensor, 3) white vs. infrared flash, and 4) still photographs vs. video. We also tested a new approach to standardise each camera's field of view. We compared the success rates of four camera trap designs in detecting and taking recognisable photographs of captive stoats (Mustelaerminea), feral cats (Felis catus) and hedgehogs (Erinaceuseuropaeus). Trigger speeds of 0.2-2.1 s captured photographs of all three target species unless the animal was running at high speed. The camera with a microwave sensor was prone to false triggers, and often failed to trigger when an animal moved in front of it. A white flash produced photographs that were more readily identified to species than those obtained under infrared light. However, a white flash may be more likely to frighten target animals, potentially affecting detection probabilities. Video footage achieved similar success rates to still cameras but required more processing time and computer memory. Placing two camera traps side by side achieved a higher success rate than using a single camera. Camera traps show considerable promise for monitoring invasive mammal control operations. Further research should address how best to standardise the size of each camera's field of view, maximise the probability that an animal encountering a camera trap will be detected, and eliminate visible or audible cues emitted by camera traps.

  2. Comparison of three trap types for adult catching of whitefly Bemisia tabaci and its parasitoid Eretmocerus mundus in tomato greenhouse

    OpenAIRE

    Nombela, Gloria; Chu, CC.; Heneberry, T.; Muñiz, M.

    2003-01-01

    The attractiveness of three trap types to Bemisia tabaci (Gennadius) B-biotype (= Bemisia argentifolii Bellows & Perring) and Eretmocerus mundus Mercet adult was compared in two choice experiments in a greenhouse at the Centro de Ciencias Medioambientales, Madrid, Spain.  Yellow sticky cards equipped with light-emitting-diodes (LED-YC) caught more adults per trap per day than yellow sticky card (YC) traps.YC traps caught significantly more B. tabaci and E. mundus adults than plastic cup traps...

  3. Evanescent optical trapping of nanoscale particles using slotted tapered optical fibres

    CERN Document Server

    Daly, Mark; Chormaic, Síle Nic

    2016-01-01

    While conventional optical trapping techniques can trap objects with submicron dimensions, the underlying limits imposed by the diffraction of light generally restrict their use to larger, or higher refractive index particles. As the index and diameter decrease, the trapping difficulty rapidly increases; hence, the power requirements for stable trapping become so large as to quickly denature the trapped objects in such diffraction-limited systems. Here, we present an evanescent field-based device capable of confining low index nanoscale particles using modest optical powers as low as 1.2 mW, with additional applications in the field of cold atom trapping. Our experiment uses a nanostructured optical micro-nanofibre to trap 200 nm, low-index, fluorescent particles within the structured region, thereby overcoming diffraction limitations. We analyse the trapping potential of this device both experimentally and theoretically, and show how strong optical traps are achieved with low input powers.

  4. Evolving Black Hole Horizons in General Relativity and Alternative Gravity

    Directory of Open Access Journals (Sweden)

    Valerio Faraoni

    2013-09-01

    Full Text Available From the microscopic point of view, realistic black holes are time-dependent and the teleological concept of the event horizon fails. At present, the apparent or trapping horizon seem to be its best replacements in various areas of black hole physics. We discuss the known phenomenology of apparent and trapping horizons for analytical solutions of General Relativity and alternative theories of gravity. These specific examples (we focus on spherically symmetric inhomogeneities in a background cosmological spacetime are useful as toy models for research on various aspects of black hole physics.

  5. Evolving black hole horizons in General Relativity and alternative gravity

    CERN Document Server

    Faraoni, Valerio

    2013-01-01

    From the microscopic point of view, realistic black holes are time-dependent and the teleological concept of event horizon fails. At present, the apparent or the trapping horizon seem its best replacements in various areas of black hole physics. We discuss the known phenomenology of apparent and trapping horizons for analytical solutions of General Relativity and alternative theories of gravity. These specific examples (we focus on spherically symmetric inhomogeneities in a background cosmological spacetime) may be useful as toy models for research on various aspects of black hole physics.

  6. Penning trap at IGISOL

    Energy Technology Data Exchange (ETDEWEB)

    Szerypo, J. E-mail: jerzy.szerypo@phys.jyu.fi; Jokinen, A.; Kolhinen, V.S.; Nieminen, A.; Rinta-Antila, S.; Aeystoe, J

    2002-04-22

    The IGISOL facility at the Department of Physics of the University of Jyvaeskylae (JYFL) is delivering radioactive beams of short-lived exotic nuclei, in particular the neutron-rich isotopes from the fission reaction. These nuclei are studied with the nuclear spectroscopy methods. In order to substantially increase the quality and sensitivity of such studies, the beam should undergo beam handling: cooling, bunching and isobaric purification. The first two processes are performed with the use of an RFQ cooler/buncher. The isobaric purification will be made by a Penning trap placed after the RF-cooler element. This contribution describes the current status of the Penning trap project and its future prospects. The latter comprise the precise nuclear mass measurements, nuclear spectroscopy in the Penning trap interior as well as the laser spectroscopy on the extracted beams.

  7. .Investigation the  Zero-Valent Iron (ZVI Performance in the Presence of UV light and Hydrogen Peroxide on Removal of Azo Dyes Acid Orange 7 and Reactive Black 5 from Aquatic Solutions

    Directory of Open Access Journals (Sweden)

    Mansur Zarrabi

    2013-02-01

    Full Text Available Background and Objectives: Colored wastewaters are known as one of the most important sources of environmental pollutants. Having toxic chemicals and aesthetic problems has made treatment of these wastewaters very crucial. So far a number of methods such as electrochemical treatment, coagulation and flocculation, and adsorption have been used for treatment of textile industries wastewater. Hence,  the efficiency of zero-valent iron powder in the presence of UV light and hydrogen peroxide to remove Acid Orange 7 and Reactive Black 5 from the synthetic solutions was investigated.Materials and Methods: Conducting all experiments in a batch reactor, we examined different parameters including initial concentration of the color (25, 50, 75 mg/L, contact time (30,  60, 120 min, pH (3, 7, 11, the amount of iron powder (0.6, 1.3,  2  g/l, and hydrogen peroxide concentration (10, 15, 20  ml/l.Result: The results showed that dye removal efficiency was increased by increasing contact time, the amount of iron powder and hydrogen peroxide concentration. On the other hand, with the increasing pH and initial concentration of dye, removal efficiency decreased in both AO7and RB5 dyes.Conclusion: We found that the integrated ZVI/UV/H2O2 method has  high efficiency in removing azo dyes Acid Orange 7 and Reactive Black 5.

  8. Camera traps can be heard and seen by animals.

    Science.gov (United States)

    Meek, Paul D; Ballard, Guy-Anthony; Fleming, Peter J S; Schaefer, Michael; Williams, Warwick; Falzon, Greg

    2014-01-01

    Camera traps are electrical instruments that emit sounds and light. In recent decades they have become a tool of choice in wildlife research and monitoring. The variability between camera trap models and the methods used are considerable, and little is known about how animals respond to camera trap emissions. It has been reported that some animals show a response to camera traps, and in research this is often undesirable so it is important to understand why the animals are disturbed. We conducted laboratory based investigations to test the audio and infrared optical outputs of 12 camera trap models. Camera traps were measured for audio outputs in an anechoic chamber; we also measured ultrasonic (n = 5) and infrared illumination outputs (n = 7) of a subset of the camera trap models. We then compared the perceptive hearing range (n = 21) and assessed the vision ranges (n = 3) of mammals species (where data existed) to determine if animals can see and hear camera traps. We report that camera traps produce sounds that are well within the perceptive range of most mammals' hearing and produce illumination that can be seen by many species.

  9. Quantum interference from remotely trapped ions

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, S; Rotter, D; Hennrich, M; Blatt, R [Institute for Experimental Physics, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck (Austria); Rohde, F; Schuck, C; Almendros, M; Gehr, R; Dubin, F; Eschner, J [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Av del Canal OlImpic, E-08860 Castelldefels (Spain)], E-mail: francois.dubin@icfo.es

    2009-01-15

    We observe quantum interference of photons emitted by two continuously laser-excited single ions, independently trapped in distinct vacuum vessels. High contrast two-photon interference is observed in two experiments with different ion species, Ca{sup +} and Ba{sup +}. Our experimental findings are quantitatively reproduced by Bloch equation calculations. In particular, we show that the coherence of the individual resonance fluorescence light field is determined from the observed interference.

  10. Redesigning octopus traps

    Directory of Open Access Journals (Sweden)

    Eduarda Gomes

    2014-06-01

    In order to minimise the identified problems in the actual traps, the present work proposes a new design with the aim of reducing the volume and weight during transport, and also during onshore storage. Alternative materials to avoid corrosion and formation of encrustations were also proposed.

  11. The Honey Trap

    DEFF Research Database (Denmark)

    Wagner, Michael

    Michael F. Wagner: The Honey Trap –The democratization of leisure through automobilism The automobile has achieved a central position in modern everyday life as an essential artefact to mobility. This raises the question how automobiles have been mediated for mass consumption? The central thesis...

  12. The Universal Trap.

    Science.gov (United States)

    Goodman, Paul

    The compulsory system of education is criticized on the grounds that it has become a regimented "universal trap" antithetical to democracy. In contrast to the Jeffersonian concept of education in the service of citizen initiative for the preservation of freedom, current compulsory education is a tool of industrialism and of a rigidly stratified…

  13. Black psyllium

    Science.gov (United States)

    ... block your throat or esophagus and may cause choking. Do not take this product if you have ... take enough water. Otherwise, black psyllium might cause choking. Take at least 150 mL water for each ...

  14. Black tea

    Science.gov (United States)

    ... product containing black tea extract plus green tea extract, asparagus, guarana, kidney bean, and mate along with a combination of kidney bean pods, garcinia, and chromium yeast for 12 weeks does not reduce body weight ...

  15. Black tea

    Science.gov (United States)

    ... heartburn, dizziness, ringing in the ears, convulsions, and confusion. Also, people who drink black tea or other ... glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide ( ...

  16. Responses of Neomegalotomus parvus (Hemiptera: Alydidae to color and male-lured traps

    Directory of Open Access Journals (Sweden)

    Maurício Ursi Ventura

    2004-08-01

    Full Text Available In 1998, the relative responses of Neomegalotomus parvus (Westwood (Hemiptera: Alydidae to colors in traps were assessed in the field. Colors were printed in white alkaline paper and covered with transparent plastic. Printed colors were black, green, yellow, red and blue. Treatments also included white paper and aluminum foil. Green traps captured more bugs than the other traps (except yellow. Yellow traps caught significantly more N. parvus males than blue, black and aluminum traps. White, red and blue traps captured significantly more N. parvus males than black traps. In 1999, the same treatments were used and additionally included the factor presence (X absence of males in cages in the traps. Four males were confined in the cages together with pigeon pea seeds and water. Control traps received only pigeon pea seeds and water. No responses were found for color comparisons. Male-lured traps captured significantly more males than control traps.Em 1998, as respostas relativas de Neomegalotomus parvus (Westwood (Hemiptera: Alydidae a cores em armadilhas foram avaliadas no campo. As cores foram impressas (preto, verde, amarelo, vermelho e azul, em papel alcalino branco e coberto com plástico transparente. Também se incluiu papel branco e folha de alumínio, como tratamentos. Armadilhas verdes capturaram mais insetos que outras armadilhas (exceto amarelo. Armadilhas amarelas capturaram significativamente mais machos de N. parvus do que armadilhas azuis, pretas e alumínio. Armadilhas brancas, vermelhas e azuis capturaram significativamente mais machos de N. parvus do que armadilhas pretas. Em 1999, os mesmos tratamentos foram usados e também se incluiu fator presença (X ausência de machos em gaiolas nas armadilhas. Quatro machos foram confinados nas gaiolas junto com sementes de guandu e água. Testemunhas receberam somente sementes de guandu e água. Não foram obtidas respostas significativas à cores. Armadilhas com machos capturaram

  17. View of the VO prototype made of two sectors of scintillating counters. WLS fibers embedded within connectors appear in green color. Beams of optical fibers inside black sheath collect and transport the emitted light to photo-multipliers a few meters apart.

    CERN Multimedia

    2004-01-01

    View of the VO prototype made of two sectors of scintillating counters. WLS fibers embedded within connectors appear in green color. Beams of optical fibers inside black sheath collect and transport the emitted light to photo-multipliers a few meters apart.

  18. Optical trapping of gold aerosols

    DEFF Research Database (Denmark)

    Schmitt, Regina K.; Pedersen, Liselotte Jauffred; Taheri, S. M.;

    2015-01-01

    Aerosol trapping has proven challenging and was only recently demonstrated.1 This was accomplished by utilizing an air chamber designed to have a minimum of turbulence and a laser beam with a minimum of aberration. Individual gold nano-particles with diameters between 80 nm and 200 nm were trapped...... in air using a 1064 nm laser. The positions visited by the trapped gold nano-particle were quantified using a quadrant photo diode placed in the back focal plane. The time traces were analyzed and the trapping stiffness characterizing gold aerosol trapping determined and compared to aerosol trapping...... of nanometer sized silica and polystyrene particles. Based on our analysis, we concluded that gold nano-particles trap more strongly in air than similarly sized polystyrene and silica particles. We found that, in a certain power range, the trapping strength of polystyrene particles is linearly decreasing...

  19. Cosmological Constraints from Primordial Black Holes

    OpenAIRE

    Liddle, Andrew R.; Green, Anne M.

    1998-01-01

    Primordial black holes may form in the early Universe, for example from the collapse of large amplitude density perturbations predicted in some inflationary models. Light black holes undergo Hawking evaporation, the energy injection from which is constrained both at the epoch of nucleosynthesis and at the present. The failure as yet to unambiguously detect primordial black holes places important constraints. In this article, we are particularly concerned with the dependence of these constrain...

  20. Optical trapping of absorbing particles

    CERN Document Server

    Rubinsztein-Dunlop, H; Friese, M E J; Heckenberg, N R

    1998-01-01

    Radiation pressure forces in a focussed laser beam can be used to trap microscopic absorbing particles against a substrate. Calculations based on momentum transfer considerations show that stable trapping occurs before the beam waist, and that trapping is more effective with doughnut beams. Such doughnut beams can transfer angular momentum leading to rotation of the trapped particles. Energy is also transferred, which can result in heating of the particles to temperatures above the boiling point of the surrounding medium.

  1. Highly uniform holographic microtrap arrays for single atom trapping using a feedback optimization of in-trap fluorescence measurements.

    Science.gov (United States)

    Tamura, Hikaru; Unakami, Tomoyuki; He, Jun; Miyamoto, Yoko; Nakagawa, Ken'ichi

    2016-04-18

    We report on the novel optimization method to realize highly uniform microtrap arrays for single atom trapping with a spatial light modulator (SLM). This method consists of two iterative feedback loops with the measurements of both diffracted light intensities and in-trap fluorescence intensities from each microtrap. By applying this method to the single 87Rb atom trapping, we can reduce the variance of trap depths from 20.8% to 1.7% for 4 × 4 square arrays and less than 4% for various arrays with up to 62 sites. The detection error of individual single atoms is also reduced from 1.7% to 0.0054% on average. PMID:27137252

  2. Orthogonal trapping and sensing with long working distance optics [invited

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin; Tauro, Sandeep

    2010-01-01

    will enable us to strongly expand the field of laser manipulation and diagnostics of the motion and structure of macromolecular systems. In particular, combining our new spatial light modulating techniques with the unique properties of ultrashort laser pulses we aim at constructing a multi-purpose Bio...... university this has been illustrated by CARS and fluorescence spectroscopy of trapped polystyrene beads where the side view geometry opens intriguing possibilities for accessing trapped particles with optical as well as other types of probe methods independent from the trapping process2....

  3. Low-mass black holes as the remnants of primordial black hole formation.

    Science.gov (United States)

    Greene, Jenny E

    2012-01-01

    Bridging the gap between the approximately ten solar mass 'stellar mass' black holes and the 'supermassive' black holes of millions to billions of solar masses are the elusive 'intermediate-mass' black holes. Their discovery is key to understanding whether supermassive black holes can grow from stellar-mass black holes or whether a more exotic process accelerated their growth soon after the Big Bang. Currently, tentative evidence suggests that the progenitors of supermassive black holes were formed as ∼10(4)-10(5) M(⊙) black holes via the direct collapse of gas. Ongoing searches for intermediate-mass black holes at galaxy centres will help shed light on this formation mechanism. PMID:23250434

  4. Low-mass black holes as the remnants of primordial black hole formation.

    Science.gov (United States)

    Greene, Jenny E

    2012-01-01

    Bridging the gap between the approximately ten solar mass 'stellar mass' black holes and the 'supermassive' black holes of millions to billions of solar masses are the elusive 'intermediate-mass' black holes. Their discovery is key to understanding whether supermassive black holes can grow from stellar-mass black holes or whether a more exotic process accelerated their growth soon after the Big Bang. Currently, tentative evidence suggests that the progenitors of supermassive black holes were formed as ∼10(4)-10(5) M(⊙) black holes via the direct collapse of gas. Ongoing searches for intermediate-mass black holes at galaxy centres will help shed light on this formation mechanism.

  5. Singlet Molecular Oxygen Generation by Light-Activated DHN-Melanin of the Fungal Pathogen Mycosphaerella fijiensis in Black Sigatoka Disease of Bananas

    OpenAIRE

    Miguel J Beltrán-García; Prado, Fernanda M.; Marilene S Oliveira; David Ortiz-Mendoza; Alexsandra C Scalfo; Adalberto Pessoa; Medeiros, Marisa H. G.; White, James F.; Paolo Di Mascio

    2014-01-01

    In pathogenic fungi, melanin contributes to virulence, allowing tissue invasion and inactivation of the plant defence system, but has never been implicated as a factor for host cell death, or as a light-activated phytotoxin. Our research shows that melanin synthesized by the fungal banana pathogen Mycosphaerella fijiensis acts as a virulence factor through the photogeneration of singlet molecular oxygen O2 (1Δg). Using analytical tools, including elemental analysis, ultraviolet/infrared absor...

  6. Heating rate and electrode charging measurements in a scalable, microfabricated, surface-electrode ion trap

    CERN Document Server

    Allcock, D T C; Janacek, H A; Linke, N M; Ballance, C J; Steane, A M; Lucas, D M; Jarecki, R L; Habermehl, S D; Blain, M G; Stick, D; Moehring, D L

    2011-01-01

    We characterise the performance of a surface-electrode ion "chip" trap fabricated using established semiconductor integrated circuit and micro-electro-mechanical-system (MEMS) microfabrication processes which are in principle scalable to much larger ion trap arrays, as proposed for implementing ion trap quantum information processing. We measure rf ion micromotion parallel and perpendicular to the plane of the trap electrodes, and find that on-package capacitors reduce this to <~ 10 nm in amplitude. We also measure ion trapping lifetime, charging effects due to laser light incident on the trap electrodes, and the heating rate for a single trapped ion. The performance of this trap is found to be comparable with others of the same size scale.

  7. Beauty is attractive: Moduli trapping at enhanced symmetry points

    International Nuclear Information System (INIS)

    We study quantum effects on moduli dynamics arising from the production of particles which are light at special points in moduli space. The resulting forces trap the moduli at these points, which often exhibit enhanced symmetry. Moduli trapping occurs in time-dependent quantum field theory, as well as in systems of moving D-branes, where it leads the branes to combine into stacks. Trapping also occurs in an expanding universe, though the range over which the moduli can roll is limited by Hubble friction. We observe that a scalar field trapped on a steep potential can induce a stage of acceleration of the universe, which we call trapped inflation. Moduli trapping ameliorates the cosmological moduli problem and may affect vacuum selection. In particular, rolling moduli are most powerfully attracted to the points with the largest number of light particles, which are often the points of greatest symmetry. Given suitable assumptions about the dynamics of the very early universe, this effect might help to explain why among the plethora of possible vacuum states of string theory, we appear to live in one with a large number of light particles and (spontaneously broken) symmetries. In other words, some of the surprising properties of our world might arise not through pure chance or miraculous cancellations, but through a natural selection mechanism during dynamical evolution. (author)

  8. Coherence in Microchip Traps

    CERN Document Server

    Treutlein, P; Steinmetz, T; Hänsch, T W; Reichel, J; Treutlein, Philipp; Hommelhoff, Peter; Steinmetz, Tilo; H\\"ansch, Theodor W.; Reichel, Jakob

    2003-01-01

    We report the coherent manipulation of internal states of neutral atoms in a magnetic microchip trap. Coherence lifetimes exceeding 1 s are observed with atoms at distances of $4-130 \\mu$m from the microchip surface. The coherence lifetime in the microtrap is independent of atom-surface distance and agrees well with the results of similar measurements in macroscopic magnetic traps. Due to the absence of surface-induced decoherence, a miniaturized atomic clock with a relative stability in the $10^{-13}$ range can be realized. For applications in quantum information processing, we propose to use microwave near-fields in the proximity of chip wires to create potentials that depend on the internal state of the atoms.

  9. Detection of Trapped Antihydrogen

    CERN Document Server

    Hydomako, Richard Allan

    The ALPHA experiment is an international effort to produce, trap, and perform precision spectroscopic measurements on antihydrogen (the bound state of a positron and an antiproton). Based at the Antiproton Decelerator (AD) facility at CERN, the ALPHA experiment has recently magnetically confined antihydrogen atoms for the first time. A crucial element in the observation of trapped antihydrogen is ALPHA’s silicon vertexing detector. This detector contains sixty silicon modules arranged in three concentric layers, and is able to determine the three-dimensional location of the annihilation of an antihydrogen atom by reconstructing the trajectories of the produced annihilation products. This dissertation focuses mainly on the methods used to reconstruct the annihilation location. Specifically, the software algorithms used to identify and extrapolate charged particle tracks are presented along with the routines used to estimate the annihilation location from the convergence of the identified tracks. It is shown...

  10. Phosphorous trapped within buckminsterfullerene

    Science.gov (United States)

    Larsson, J. A.; Greer, J. C.; Harneit, W.; Weidinger, A.

    2002-05-01

    Under normal circumstances, when covalent molecules form, electrons are exchanged between atoms to form bonds. However, experiment and theoretical computations reveal exactly the opposite effect for the formation of group V elements nitrogen and phosphorous encapsulated within a buckminsterfullerene molecule. The C60 carbon cage remains intact upon encapsulation of the atom, whereas the electronic charge cloud of the N or P atom contracts. We have studied the chemical, spin, and thermodynamic properties of endohedral phosphorous (P@C60) and have compared our results with earlier findings for N@C60. From a combined experimental and theoretical vantage, we are able to elucidate a model for the interaction between the trapped group V atom and the fullerene cage. A picture emerges for the electronic structure of these complexes, whereby an atom is trapped within a fullerene, and interacts weakly with the molecular orbitals of the C60 cage.

  11. Synthesis of visible light driven cobalt tailored Ag2O/TiON nanophotocatalyst by reverse micelle processing for degradation of Eriochrome Black T

    KAUST Repository

    Hussain, Syed Tajammul

    2013-02-01

    An ultra efficient cobalt tailored silver and nitrogen co-doped titania (TiON/Ag2O/Co) visible nanophotocatalyst is successfully synthesized using modified reverse micelle processing. Composition, phase, distribution of dopants, functional group analysis, optical properties and morphology of synthesized materials are investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) based techniques and others. Charge states of titanium (Ti) and silver are explored through core-loss electron energy loss spectroscopy (EELS) analysis and X ray photoelectron spectroscopy (XPS). Our characterization results showed that the synthesized nanophotocatalyst consisted of anatase phased qausispherical nanoparticles that exhibited homogeneous distribution of dopants, large surface area, high quantum efficiency and enhanced optical properties. At lower content of doped Co ions, the TiON/Ag2O responded with extraordinary photocatalytic properties. The cobalt tailored nanophotocatalyst showed remarkable activity against Eriochrome Black T (EBT). Moreover, comparative degradation behavior of EBT with TiON, Ag2O/TiON and Co/Ag2O/TiON is also investigated. © 2012 Elsevier Ltd.

  12. Architecture for a scalable ion-trap quantum computer

    International Nuclear Information System (INIS)

    A scalable architecture for quantum information processing with trapped ions depends, among other things, on the ability to store and manipulate large numbers of ions within a single processing unit, i.e. the ion trap. To reliably control the ions these traps must be stable and well characterised. Furthermore, reliable ways of sharing the information between the ions have to be developed. This work presents the development of and the results from two segmented-trap experiments. First, the ions are used as electrical field probes which serves as the basis for a novel diagnostic tool. With these probes light-induced charging of trap structures was observed with a sensitivity of 40 elementary charges per root Hz. Second, a way to share quantum information in a multiplexed trap structure by direct coupling between two trapping sites is presented. A coherent exchange of the motional states between two ions, separated by 54 microns, was observed. The coupling strength between these two trap sites was increased using additional ions as near-field antennae. (author)

  13. Black holes

    CERN Document Server

    Chrúsciel, P T

    2002-01-01

    This paper is concerned with several not-quantum aspects of black holes, with emphasis on theoretical and mathematical issues related to numerical modeling of black hole space-times. Part of the material has a review character, but some new results or proposals are also presented. We review the experimental evidence for existence of black holes. We propose a definition of black hole region for any theory governed by a symmetric hyperbolic system of equations. Our definition reproduces the usual one for gravity, and leads to the one associated with the Unruh metric in the case of Euler equations. We review the global conditions which have been used in the Scri-based definition of a black hole and point out the deficiencies of the Scri approach. Various results on the structure of horizons and apparent horizons are presented, and a new proof of semi-convexity of horizons based on a variational principle is given. Recent results on the classification of stationary singularity-free vacuum solutions are reviewed. ...

  14. Indonesia : Avoiding the Trap

    OpenAIRE

    World Bank

    2014-01-01

    Within the next two decades Indonesia aspires to generate prosperity, avoid a middle-income trap and leave no one behind as it tries to catch up with high-income economies. These are ambitious goals. Realizing them requires sustained high growth and job creation, as well as reduced inequality. Can Indonesia achieve them? This report argues that the country has the potential to rise and bec...

  15. Comparison of sex pheromone traps for monitoring pink hibiscus mealybug (Hemiptera: Pseudococcidae).

    Science.gov (United States)

    Vitullo, Justin; Wang, Shifa; Zhang, Aijun; Mannion, Catharine; Bergh, J Christopher

    2007-04-01

    The pink hibiscus mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), is a highly polyphagous pest that invaded Florida in 2002 and has recently been reported from several locations in Louisiana. Although identification of its sex pheromone in 2004 improved monitoring capabilities tremendously, the effectiveness and efficiency of different pheromone trap designs for capturing males has not been evaluated. We deployed green Delta, Pherocon IlB, Pherocon V, Jackson, and Storgard Thinline traps in Homestead, FL, and compared the number of male M. hirsutus captured per trap, the number captured per unit of trapping surface area, the amount of extraneous material captured, and the time taken to count trapped mealybugs. Pheromone-baited traps with larger trapping surfaces (green Delta, Pherocon IIB, and Pherocon V) captured more males per trap than those with smaller surfaces (Jackson and Storgard Thinline), and fewest males were captured by Storgard Thinline traps. However, Jackson traps captured as many or more males per square centimeter of trapping surface as those with larger surfaces, and the time required to count males in Jackson traps was significantly less than in green Delta, Pherocon IIB, and Pherocon V traps. Although all trap designs accumulated some debris and nontarget insects, it was rated as light to moderate for all designs. Based on our measures of effectiveness and efficiency, the Jackson trap is most suitable for monitoring M. hirsutus populations. Additionally, unlike the other traps evaluated, which must be replaced entirely or inspected in the field and then redeployed, only the sticky liners of Jackson traps require replacement, enhancing the efficiency of trap servicing.

  16. Water-Trapped Worlds

    CERN Document Server

    Menou, Kristen

    2013-01-01

    Although tidally-locked habitable planets orbiting nearby M-dwarf stars are among the best astronomical targets to search for extrasolar life, they may also be deficient in volatiles and water. Climate models for this class of planets show atmospheric transport of water from the dayside to the nightside, where it is precipitated as snow and trapped as ice. Since ice only slowly flows back to the dayside upon accumulation, the resulting hydrological cycle can trap a large amount of water in the form of nightside ice. Using ice sheet dynamical and thermodynamical constraints, I illustrate how planets with less than about a quarter the Earth's oceans could trap most of their surface water on the nightside. This would leave their dayside, where habitable conditions are met, potentially dry. The amount and distribution of residual liquid water on the dayside depend on a variety of geophysical factors, including the efficiency of rock weathering at regulating atmospheric CO2 as dayside ocean basins dry-up. Water-tr...

  17. Space, time, and black holes

    Energy Technology Data Exchange (ETDEWEB)

    Darling, D.

    1980-10-01

    A discussion of Einstein's General Relativity and how it can explain black holes is included. The key idea of general relativity being that gravitational forces are a direct outcome of local curvature of space-time. The more mass something has the deeper the depression or well it causes in space-time. Black holes are supermassive objects, hence their gravity well is so steep even light can't escape. The three properties associated with a black hole are mass angular momentum, and electric charge. Non-rotating, Schwarzchild, and rotating, Kerr, black holes are studied. A Kruskal-Szekeres diagram for each type is given and explained. (SC)

  18. Black hole accretion disc impacts

    Science.gov (United States)

    Pihajoki, P.

    2016-04-01

    We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength λ = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.

  19. Black hole accretion disc impacts

    CERN Document Server

    Pihajoki, Pauli

    2015-01-01

    We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength {\\lambda} = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.

  20. Chiral discrimination in optical trapping and manipulation

    Science.gov (United States)

    Bradshaw, David S.; Andrews, David L.

    2014-10-01

    When circularly polarized light interacts with chiral molecules or nanoscale particles powerful symmetry principles determine the possibility of achieving chiral discrimination, and the detailed form of electrodynamic mechanisms dictate the types of interaction that can be involved. The optical trapping of molecules and nanoscale particles can be described in terms of a forward-Rayleigh scattering mechanism, with trapping forces being dependent on the positioning within the commonly non-uniform intensity beam profile. In such a scheme, nanoparticles are commonly attracted to local potential energy minima, ordinarily towards the centre of the beam. For achiral particles the pertinent material response property usually entails an electronic polarizability involving transition electric dipole moments. However, in the case of chiral molecules, additional effects arise through the engagement of magnetic counterpart transition dipoles. It emerges that, when circularly polarized light is used for the trapping, a discriminatory response can be identified between left- and right-handed polarizations. Developing a quantum framework to accurately describe this phenomenon, with a tensor formulation to correctly represent the relevant molecular properties, the theory leads to exact analytical expressions for the associated energy landscape contributions. Specific results are identified for liquids and solutions, both for isotropic media and also where partial alignment arises due to a static electric field. The paper concludes with a pragmatic analysis of the scope for achieving enantiomer separation by such methods.

  1. Synthesis of visible light driven cobalt tailored Ag{sub 2}O/TiON nanophotocatalyst by reverse micelle processing for degradation of Eriochrome Black T

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Syed Tajammul, E-mail: dr_tajammul@yahoo.ca [Nano Science and Catalysis Div. National Centre For Physics, Quaid-i-Azam University Complex, Islamabad 4400 (Pakistan); Rashid [Nano Science and Catalysis Div. National Centre For Physics, Quaid-i-Azam University Complex, Islamabad 4400 (Pakistan); Department of Chemistry, Quaid-i-Azam University, Islamabad (Pakistan); Anjum, Dalaver [Imaging and Characterization Lab, Blg 3 L0/room 232, 4700, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Siddiqa, Asima [Nano Science and Catalysis Div. National Centre For Physics, Quaid-i-Azam University Complex, Islamabad 4400 (Pakistan); Badshah, Amin [Department of Chemistry, Quaid-i-Azam University, Islamabad (Pakistan)

    2013-02-15

    Graphical abstract: Cobalt tailored Ag{sub 2}O/TiON nanophotocatalyst is synthesized using reverse micelle technique and it showed extraordinary photocatalytic activity. Display Omitted Highlights: ► TiON/Ag{sub 2}O/Co nanophotocatalyst is synthesized using microemulsion technique. ► Low temperature anatase phase and outstanding photocatlytic activity is observed. ► Effect of temperature and inert atmosphere on materials phase is investigated. ► Homogeneous dopants distribution and oxygen vacancies are examined. ► Enhancement in surface area, quantum efficiency and optical properties is observed. -- Abstract: An ultra efficient cobalt tailored silver and nitrogen co-doped titania (TiON/Ag{sub 2}O/Co) visible nanophotocatalyst is successfully synthesized using modified reverse micelle processing. Composition, phase, distribution of dopants, functional group analysis, optical properties and morphology of synthesized materials are investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) based techniques and others. Charge states of titanium (Ti) and silver are explored through core-loss electron energy loss spectroscopy (EELS) analysis and X ray photoelectron spectroscopy (XPS). Our characterization results showed that the synthesized nanophotocatalyst consisted of anatase phased qausispherical nanoparticles that exhibited homogeneous distribution of dopants, large surface area, high quantum efficiency and enhanced optical properties. At lower content of doped Co ions, the TiON/Ag{sub 2}O responded with extraordinary photocatalytic properties. The cobalt tailored nanophotocatalyst showed remarkable activity against Eriochrome Black T (EBT). Moreover, comparative degradation behavior of EBT with TiON, Ag{sub 2}O/TiON and Co/Ag{sub 2}O/TiON is also investigated.

  2. Light Water Reactor Sustainability Program Support and Modeling for the Boiling Water Reactor Station Black Out Case Study Using RELAP and RAVEN

    Energy Technology Data Exchange (ETDEWEB)

    Diego Mandelli; Curtis Smith; Thomas Riley; John Schroeder; Cristian Rabiti; Aldrea Alfonsi; Joe Nielsen; Dan Maljovec; Bie Wang; Valerio Pascucci

    2013-09-01

    The existing fleet of nuclear power plants is in the process of extending its lifetime and increasing the power generated. In order to evaluate the impact of these two factors on the safety of the plant, the Risk Informed Safety Margin Characterization (RISMC) project aims to provide insight to decision makers through a series of simulations of the plant dynamics for different initial conditions (e.g., probabilistic analysis and uncertainty quantification). This report focuses, in particular, on the impact of power uprate on the safety of a boiled water reactor system. The case study considered is a loss of off-site power followed by the loss of diesel generators, i.e., a station black out (SBO) event. Analysis is performed by using a thermo-hydraulic code, i.e. RELAP-5, and a stochastic analysis tool currently under development at INL, i.e. RAVEN. Starting from the event tree models contained in SAPHIRE, we built the input file for RELAP-5 that models in great detail system dynamics under SBO conditions. We also interfaced RAVEN with RELAP-5 so that it would be possible to run multiple RELAP-5 simulation runs by changing specific keywords of the input file. We both employed classical statistical tools, i.e. Monte-Carlo, and more advanced machine learning based algorithms to perform uncertainty quantification in order to quantify changes in system performance and limitations as a consequence of power uprate. We also employed advanced data analysis and visualization tools that helped us to correlate simulation outcome such as maximum core temperature with a set of input uncertain parameters. Results obtained gave a detailed overview of the issues associated to power uprate for a SBO accident scenario. We were able to quantify how timing of safety related events were impacted by a higher reactor core power. Such insights can provide useful material to the decision makers to perform risk-infomed safety margins management.

  3. High contrast atomic magnetometer based on coherent population trapping

    International Nuclear Information System (INIS)

    We present an experimental and theoretical investigation of the coherent population trapping (CPT) resonance excited on the D1 line of 87Rb atoms by bichromatic linearly polarized laser light. The experimental results show that a lin ‖ lin transition scheme is a promising alternative to the conventional circular—circular transition scheme for an atomic magnetometer. Compared with the circular light transition scheme, linear light accounts for high-contrast transmission resonances, which makes this excitation scheme promising for high-sensitivity magnetometers. We also use linear light and circular light to detect changes of a standard magnetic field, separately. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  4. How Black Are Black Hole Candidates?

    CERN Document Server

    Robertson, S L; Robertson, Stanley L.; Leiter, Darryl J.

    2002-01-01

    In previous work we found that many of the spectral properties of x-ray binaries, including both galactic black hole candiates (GBHC) and neutron stars, were consistent with the existence of intrinsically magnetized central objects. Here we review and extend the observational evidence for the existence of intrinsically magnetized GBHC and show that their existence is consistent with a new class of solutions of the Einstein field equations of General Relativity. These solutions are based on a strict adherence to the Principle of Equivalence, which prevents the time-like geodesics of physical matter from becoming null on trapped surfaces of infinite red shift. The new solutions emerge from the fact that the structure and radiation transfer properties of the energy-momentum tensor on the right hand side of the Einstein field equations must have a form that is consistent with this Principle of Equivalence requirement. In this context, we show that the Einstein field equations allow the existence of highly red shi...

  5. Linearity Limits of Biased 1337 Trap Detectors

    CERN Document Server

    Balling, Petr

    2015-01-01

    The upper power limit of linear response of light trap detectors was recently measured [2,3]. We have completed this measurement with test of traps with bias voltage at several visible wavelengths using silicon photodiodes Hamamatsu S1337 1010 and made a brief test of S5227 1010. Bias extends the linearity limit by factor of more than 10 for very narrow beams and more than 30 for wide beams [5]. No irreversible changes were detected even for the highest irradiance of 33 W/cm2 at 406nm. Here we present measurement of minimal bias voltage necessary for 99%, 99.8% and 99.95% linearity for several beam sizes.

  6. Quantum state control of trapped Holmium atoms

    Science.gov (United States)

    Hostetter, James; Yip, Christopher; Milner, William; Booth, Donald; Collett, Jeffrey; Saffman, Mark

    2016-05-01

    Neutral Holmium with its large number of hyperfine ground states provides a promising approach for collective encoding of a multi-qubit register. A prerequisite for collective encoding is the ability to prepare different states in the 128 state hyperfine ground manifold. We report progress towards optical pumping and control of the hyperfine Zeeman state of trapped Ho atoms. Atoms are transferred from a 410.5 nm MOT into a 455 nm optical dipole trap. The atoms can be optically pumped using light driving the ground 6s2 , F = 11 to 6 s 6 p ,F' = 11 transition together with a F = 10 to F' = 11 repumper. Microwave fields are then used to drive transitions to hyperfine levels with 4 <= F <= 11 . Work supported by NSF award PHY-1404357.

  7. Magneto-Optical Trapping of Holmium Atoms

    CERN Document Server

    Miao, J; Stratis, G; Saffman, M

    2014-01-01

    We demonstrate sub-Doppler laser cooling and magneto-optical trapping of the rare earth element Holmium. Atoms are loaded from an atomic beam source and captured in six-beam $\\sigma_+ - \\sigma_-$ molasses using a strong $J=15/2 \\leftrightarrow J=17/2$ cycling transition at $\\lambda=410.5~\\rm nm$. Due to the small difference in hyperfine splittings and Land\\'e $g$-factors in the lower and upper levels of the cooling transition the MOT is self-repumped without additional repump light, and deep sub-Doppler cooling is achieved with the magnetic trap turned on. We measure the leakage out of the cycling transition to metastable states and find a branching ratio $\\sim 10^{-5}$ which is adequate for state resolved measurements on hyperfine encoded qubits.

  8. Schwarzschild black holes can wear scalar wigs

    CERN Document Server

    Barranco, Juan; Degollado, Juan Carlos; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Núñez, Darío; Sarbach, Olivier

    2012-01-01

    We study the evolution of a massive scalar field surrounding a Schwarzschild black hole and find configurations that can survive for arbitrarily long times, provided the black hole or the scalar field mass is small enough. In particular, both ultra-light scalar field dark matter around supermassive black holes and axion-like scalar fields around primordial black holes can survive for cosmological times. Moreover, these results are quite generic, in the sense that fairly arbitrary initial data evolves, at late times, as a combination of those long-lived configurations.

  9. Strong Gravitational Lensing by Kiselev Black Hole

    CERN Document Server

    Younas, Azka; Jamil, Mubasher

    2015-01-01

    We investigate the gravitational lensing scenario due to Schwarzschild-like black hole surrounded by quintessence (Kiselev black hole). We discuss here these special cases of Kiselev black hole: non-extreme, extreme and naked singularity. We present the detailed derivation for the bending angles of light as it traverses in the equatorial plane of the black hole. We also calculate the approximate bending angle and compare it with exact bending angle expressions. In the weak field approximation we calculate the expression for relativistic images.

  10. Locking information in black holes.

    Science.gov (United States)

    Smolin, John A; Oppenheim, Jonathan

    2006-03-01

    We show that a central presumption in the debate over black-hole information loss is incorrect. Ensuring that information not escape during evaporation does not require that it all remain trapped until the final stage of the process. Using the recent quantum information-theoretic result of locking, we show that the amount of information that must remain can be very small, even as the amount already radiated is negligible. Information need not be additive: A small system can lock a large amount of information, making it inaccessible. Only if the set of initial states is restricted can information leak. PMID:16606164

  11. Laboratory and field testing of bednet traps for mosquito (Diptera: Culicidae) sampling in West Java, Indonesia.

    Science.gov (United States)

    Stoops, Craig A; Gionar, Yoyo R; Rusmiarto, Saptoro; Susapto, Dwiko; Andris, Heri; Elyazar, Iqbal R F; Barbara, Kathryn A; Munif, Amrul

    2010-06-01

    Surveillance of medically important mosquitoes is critical to determine the risk of mosquito-borne disease transmission. The purpose of this research was to test self-supporting, exposure-free bednet traps to survey mosquitoes. In the laboratory we tested human-baited and unbaited CDC light trap/cot bednet (CDCBN) combinations against three types of traps: the Mbita Trap (MIBITA), a Tent Trap (TENT), and a modified Townes style Malaise trap (TSM). In the laboratory, 16 runs comparing MBITA, TSM, and TENT to the CDCBN were conducted for a total of 48 runs of the experiment using 13,600 mosquitoes. The TENT trap collected significantly more mosquitoes than the CDCBN. The CDCBN collected significantly more than the MBITA and there was no difference between the TSM and the CDCBN. Two field trials were conducted in Cibuntu, Sukabumi, West Java, Indonesia. The first test compared human-baited and unbaited CDCBN, TENT, and TSM traps during six nights over two consecutive weeks per month from January, 2007 to September, 2007 for a total of 54 trapnights. A total of 8,474 mosquitoes representing 33 species were collected using the six trapping methods. The TENT-baited trap collected significantly more mosquitoes than both the CDCBN and the TSM. The second field trial was a comparison of the baited and unbaited TENT and CDCBN traps and Human Landing Collections (HLCs). The trial was carried out from January, 2008 to May, 2008 for a total of 30 trap nights. A total of 11,923 mosquitoes were collected representing 24 species. Human Landing Collections captured significantly more mosquitoes than either the TENT or the CDCBN. The baited and unbaited TENT collected significantly more mosquitoes than the CDCBN. The TENT trap was found to be an effective, light-weight substitute for the CDC light-trap, bednet combination in the field and should be considered for use in surveys of mosquito-borne diseases such as malaria, arboviruses, and filariasis.

  12. Fischer Black

    OpenAIRE

    Robert C. Merton; Myron S. Scholes

    2013-01-01

    ReprintThis article was originally published by Wiley for the American Finance Association (Merton RC, Scholes MS. 1995. Fischer Black. J. Finance 50(5):1359–70). It is reprinted with permission from John Wiley and Sons © 1995. Reference formatting was updated to facilitate linking.

  13. Quantum simulations with cold trapped ions

    Science.gov (United States)

    Blatt, Rainer

    2016-05-01

    The quantum toolbox of the Innsbruck ion-trap quantum computer is applied to simulate the dynamics and to investigate the propagation of entanglement in a quantum many-body system represented by long chains of trapped-ion qubits. Quantum dynamics can be described by particle-like carriers of information that emerge in the collective behavior of the underlying system, the so-called quasiparticles. These elementary excitations are predicted to distribute quantum information in a fashion determined by the system's interactions. First, we observe the entanglement distributed by quasiparticles as they trace out light-cone-like wavefronts. Second, using the ability to tune the interaction range in our system, we observe information propagation in an experimental regime where the effective-lightcone picture does not apply. Moreover, a spectroscopic technique is presented to study artificial quantum matter and use it for characterizing quasiparticles in a many-body system of trapped atomic ions. Our approach is to excite combinations of the system's fundamental quasiparticle eigenmodes, given by delocalized spin waves. By observing the dynamical response to superpositions of such eigenmodes, we extract the system dispersion relation, magnetic order, and even detect signatures of quasiparticle interactions. In the second part of the talk, it will be shown how strings of trapped ions can be used for quantum simulations of a lattice gauge field theory. As an example, we map the real-time evolution of the Schwinger mechanism to a string of trapped ions in a few-qubit quantum computer, simulating the spontaneous creation of electron-positron pairs.

  14. Retrospective accident dosimetry using trapped charges

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. I.; Kim, J. L.; Chang, I.; Kim, B. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Dicentric chromosome aberrations technique scoring of aberrations in metaphases prepared from human lymphocytes is most commonly used. This is considered as a reliable technique because the sample is extracted from the individual human body itself. There are other techniques in biological dosimetry such as Fluorescence In Situ Hybridization (FISH) using translocations, premature chromosome condensation (PCC) and micronucleus assay. However the minimum detectable doses (MDD) are relatively high and sample preparation time is also relatively longer. Therefore, there is limitation in use of these techniques for the purpose of triage in a short time in case of emergency situation relating large number of persons. Electronic paramagnetic resonance (EPR) technique is based on the signal from unpaired electrons such as free radicals in irradiated materials especially tooth enamel, however it has also limitation for the purpose of triage because of difficulty of sample taking and its high MDD. Recently as physical methods, thermoluminescence (TL) and optically stimulated luminescence (OSL) technique have been attracted due to its lower MDD and simplicity of sample preparation. Density of the trapped charges is generally proportional to the radiation dose absorbed and the intensity of emitting light is also proportional to the density of trapped charges, thus it can be applied to measure radiation dose retrospectively. In this presentation, TL and OSL techniques are going to introduced and discussed as physical methods for retrospective accident dosimetry using trapped charges especially in electronic component materials. As a tool for dose reconstruction for emergency situation, thermoluminescece and optically stimulated luminescence techniques which are based on trapped charges during exposure of material are introduced. These techniques have several advantages such as high sensitivity, fast evaluation and ease to sample collection over common biological dosimetry and EPR

  15. An Atomic Abacus: Trapped ion quantum computing experiments at NIST

    Science.gov (United States)

    Demarco, Brian

    2003-03-01

    Trapped atomic ions are an ideal system for exploring quantum information science because deterministic state preparation and efficient state detection are possible and coherent manipulation of atomic systems is relatively advanced. In our experiment, a few singly charged Be ions are confined by static and radio-frequency electric fields in a micro-machined linear Paul trap. The internal and motional states of the ions are coherently manipulated using applied laser light. Our current work focuses on demonstrating the necessary ingredients to produce a scalable quantum computing scheme and on simplifying and improving quantum logic gates. I will speak about a new set of experiments that was made possible by recent improvements in trap technology. A novel trap with multiple trapping regions was used to demonstrate the first steps towards a fully scalable quantum computing scheme. Single ions were ``shuttled" between trapping regions without disturbing the ion's motional and internal state, and two ions were separated from a single to two different trapping zones. Improvements in the trap manufacturing process has led to a reduction of nearly two orders of magnitude in the ion's motional heating rate, making possible two new improved logic gates. The first gate utilizes the wave-packet nature of the ions to tune the laser-atom interaction and achieve a controlled-NOT gate between a single ion's spin and motional states. The second, a two-ion phase gate, uses phase-space dynamics to produce a state-sensitive geometric phase. I will end with a quick look at experiments using a Mg ion to sympathetically cool a simultaneously trapped Be ion and a glimpse of the next generation of ions traps currently under construction.

  16. Nonresonance adiabatic photon trap

    CERN Document Server

    Popov, S S; Burdakov, A V; Ushkova, M Yu

    2016-01-01

    Concept of high efficiency photon storage based on adiabatic confinement between concave mirrors is presented and experimentally investigated. The approach is insensitive to typical for Fabri-Perot cells requirements on quality of accumulated radiation, tolerance of resonator elements and their stability. Experiments have been carried out with the trap, which consists from opposed concave cylindrical mirrors and conjugated with them spherical mirrors. In result, high efficiency for accumulation of radiation with large angular spread and spectrum width has been confirmed. As radiation source a commercial fiber laser has been used.

  17. Atom trap trace analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Z.-T.; Bailey, K.; Chen, C.-Y.; Du, X.; Li, Y.-M.; O' Connor, T. P.; Young, L.

    2000-05-25

    A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. The atom counts are free of contamination from other isotopes, elements,or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications.

  18. Atomic Coherent Trapping and Properties of Trapped Atom

    Institute of Scientific and Technical Information of China (English)

    YANG Guo-Jian; XIA Li-Xin; XIE Min

    2006-01-01

    Based on the theory of velocity-selective coherent population trapping, we investigate an atom-laser system where a pair of counterpropagating laser fields interact with a three-level atom. The influence of the parametric condition on the properties of the system such as velocity at which the atom is selected to be trapped, time needed for finishing the coherent trapping process, and possible electromagnetically induced transparency of an altrocold atomic medium,etc., is studied.

  19. Hydrogen solubility, diffusivity and trapping in a tempered Fe-C-Cr martensitic steel under various mechanical stress states

    Energy Technology Data Exchange (ETDEWEB)

    Frappart, S., E-mail: simon.frappart@univ-lr.fr [V and M France - VRA, 60 route de Leval, F-59620 Aulnoye-Aymeries (France); Laboratoire d' Etudes des Materiaux en Milieux Agressifs, F.R.E.D.D, CNRS FR-3097, Universite de la Rochelle, Avenue Michel Crepeau, F-17042 La Rochelle Cedex 01 (France); Feaugas, X.; Creus, J. [Laboratoire d' Etudes des Materiaux en Milieux Agressifs, F.R.E.D.D, CNRS FR-3097, Universite de la Rochelle, Avenue Michel Crepeau, F-17042 La Rochelle Cedex 01 (France); Thebault, F.; Delattre, L.; Marchebois, H. [V and M France - VRA, 60 route de Leval, F-59620 Aulnoye-Aymeries (France)

    2012-02-01

    Highlights: Black-Right-Pointing-Pointer Engineering elasticity is divided into three mechanical behaviours. Black-Right-Pointing-Pointer Apparent diffusion coefficient is affected in the generalized plasticity domain. Black-Right-Pointing-Pointer Plasticity increases irreversibly trapped H related to dislocation creation. Black-Right-Pointing-Pointer A local elastic distortion seems to affect hydrogen lattice concentration. Black-Right-Pointing-Pointer Elastic field around precipitates seems to be reversible trapping sites. - Abstract: Electrochemical permeation test under stress conditions was carried out to determine the consequences of lattice distortion and defects on hydrogen solubility, diffusivity and trapping in a quenched and tempered martensitic steel. We focused our attention within the 'engineering' elastic domain which can be divided into three domains: elasticity, micro-plasticity and generalized plasticity. The local elastic distortion associated with hydrogen atoms in lattice sites and residual vacancies seems to affect hydrogen lattice concentration. The hydrogen trapped in elastic fields shows a complex behaviour as a function of stress related to a possible internal relaxation of stresses around precipitates with the occurrence of plasticity. The plastic deformation caused a substantial increase of irreversible trapping sites in relation with the dislocation multiplication. Apparent diffusion coefficient decreased in this deformation domain in agreement with classical trapping models.

  20. Efficacy of commercial mosquito traps in capturing phlebotomine sand flies (Diptera: Psychodidae) in Egypt.

    Science.gov (United States)

    Hoel, D F; Kline, D L; Hogsette, J A; Bernier, U R; El-Hossary, S S; Hanafi, H A; Watany, N; Fawaz, E Y; Furman, B D; Obenauer, P J; Szumlas, D E

    2010-11-01

    Four types of commercial mosquito control traps, the Mosquito Magnet Pro (MMP), the Sentinel 360 (S360), the BG-Sentinel (BGS), and the Mega-Catch Ultra (MCU), were compared with a standard Centers for Disease Control and Prevention (CDC) light trap for efficacy in collecting phlebotomine sand flies (Diptera: Psychodidae) in a small farming village in the Nile River Valley 10 km north of Aswan, Egypt. Each trap was baited with either carbon dioxide (CO2) from combustion of butane gas (MMP), dry ice (CDC and BGS traps), light (MCU and S360), or dry ice and light (CDC). Traps were rotated through five sites in a5 x 5 Latin square design, repeated four times during the height of the sand fly season (June, August, and September 2007) at a site where 94% of sand flies in past collections were Phlebotomus papatasi (Scopoli). A total of 6,440 sand flies was collected, of which 6,037 (93.7%) were P. papatasi. Of the CO2-baited traps, the BGS trap collected twice as many P. papatasi as the MMP and CDC light traps, and at least three times more P. papatasi than the light-only MCU and S360 traps (P MMP 56.8 (+/- 9.0) > CDC 52.3 (+/- 6.1) > MCU 38.2 (+/- 6.4) > S360 12.6 (+/- 1.8). Results indicate that several types of commercial traps are suitable substitutes for the CDC light trap in sand fly surveillance programs.

  1. An electromagnetic black hole made of metamaterials

    CERN Document Server

    Cheng, Qiang

    2009-01-01

    Traditionally, a black hole is a region of space with huge gravitational field in the means of general relativity, which absorbs everything hitting it including the light. In general relativity, the presence of matter-energy densities results in the motion of matter propagating in a curved spacetime1, which is similar to the electromagnetic-wave propagation in a curved space and in an inhomogeneous metamaterial2. Hence one can simulate the black hole using electromagnetic fields and metamaterials. In a recent theoretical work, an optical black hole has been proposed based on metamaterials, in which the numerical simulations showed a highly efficient light absorption3. Here we report the first experimental demonstration of electromagnetic black hole in the microwave frequencies. The proposed black hole is composed of non-resonant and resonant metamaterial structures, which can absorb electromagnetic waves efficiently coming from all directions due to the local control of electromagnetic fields. Hence the elect...

  2. Magnetic traps with a spherical separatrix: Tornado traps

    International Nuclear Information System (INIS)

    A review is given on the features of magnetic traps with a spherical separatrix, with special emphasis on Tornado spiral coil configurations. The confinement and heating of static plasms in Tornado traps is treated, including the topology of the magnetic field structure, the magneto-mechanical properties of the magnetic coil system, as well as the particle orbits and plasma behaviour in these traps. In addition, the mode of rotating plasma operation by crossed electric and magnetic fields is described. The results of experiments on static and rotating plasmas are summarized, and conclusions are drawn about future possibilities of Tornado traps in the creation and containment of hot plasmas. (orig.)

  3. Wormholes as black hole foils

    Science.gov (United States)

    Damour, Thibault; Solodukhin, Sergey N.

    2007-07-01

    We study to what extent wormholes can mimic the observational features of black holes. It is surprisingly found that many features that could be thought of as “characteristic” of a black hole (endowed with an event horizon) can be closely mimicked by a globally static wormhole, having no event horizon. This is the case for the apparently irreversible accretion of matter down a hole, no-hair properties, quasi-normal-mode ringing, and even the dissipative properties of black hole horizons, such as a finite surface resistivity equal to 377 Ohms. The only way to distinguish the two geometries on an observationally reasonable time scale would be through the detection of Hawking’s radiation, which is, however, too weak to be of practical relevance for astrophysical black holes. We point out the existence of an interesting spectrum of quantum microstates trapped in the throat of a wormhole which could be relevant for storing the information lost during a gravitational collapse.

  4. Abundância e sazonalidade das espécies de Hydropsychidae (Insecta, Trichoptera capturadas em armadilha luminosa no Estado do Paraná, Brasil Abundance and seasonality of Hydropsychidae species (Insccta, Trichoptera collected with light trap at Paraná State, Brazil

    Directory of Open Access Journals (Sweden)

    Luciane Marinoni

    2000-03-01

    Full Text Available During one year of the project called "Survey of the Entomological Fauna in Paraná State" (henceforth PROFAUPAR, 126,340 adult specimens of Trichoptera were collected with light trap. The individuais of the family Hydropsychidae were identified and a list of species is presented. Eighteen species in four genera were identified. From this, S. (R. discalis Flint, 1972,5. (R. paramnsis Flint, 1983;S (R. spinulosa Flint, 1972 are for the first time registered for Brazil and Leptonema sparsum (Ulmer, 1905, Macrostemum hyalinum (Pictet, 1836, S. (Smicridea albosignata Ulmer, 1907; S. (Rhyacophylax dentifera Flint, 1983; S. (R. iguazu Flint, 1983; S. (R. piraya Flint, 1983; S. (R. unguiculaia Flint, 1983; S. (R. vermiculata Flint, 1978 and S. (R. weidneri Flint, 1972, for Paraná State. Discussion about the individuais abundance and species seasonality is presented.

  5. Abundância e sazonalidade das espécies de Leptoceridae (Insecta, Trichoptera capturadas com armadilha luminosa no Estado do Paraná, Brasil Abundance and seasonality of Leptoceridae species (Insecta, Trichoptera captured with light trap at Paraná State, Brazil

    Directory of Open Access Journals (Sweden)

    Gisele Luziane de Almeida

    2000-06-01

    Full Text Available From 126,340 adult specimens of Trichoptera captured with light trap during one year of the project called "Survey of the Entomological Fauna in Paraná State" (Paraná, Brazil, 6,375 belong to the family Leptoceridae. The individuals of the family were identified and a list of species is presented. The following species are recorded for the first time to Paraná State: Achoropsyche duodecimpunctata (Navas. 1916; Nectopsyche aureovittala Flint, 1983; Nectopsyche fuscomaculata Flint, 1983; Nectopsyche muhni (Navas, 1916; Nectopsyche separata (Banks, 1920; Nectopsyche ortizi Holzenthal, 1995; Nectopsyche splendida (Navas, 1917 and Tripleclides gracilis (Burmeister, 1839. Discussion on individual abundance and species seasonality are also presented.

  6. Optimization of the Esperanza window trap for the collection of the African onchocerciasis vector Simulium damnosum sensu lato.

    Science.gov (United States)

    Toé, Laurent D; Koala, Lassane; Burkett-Cadena, Nathan D; Traoré, Bizini M; Sanfo, Moussa; Kambiré, Sié Roger; Cupp, Eddie W; Traoré, Soungalo; Yameogo, Laurent; Boakye, Daniel; Rodríguez-Pérez, Mario A; Unnasch, Thomas R

    2014-09-01

    A simple inexpensive trap (Esperanza window trap) was shown recently to collect significant numbers of Simulium ochraceum sensu lato, a major vector of Onchocerca volvulus in Mesoamerica. Here, we report studies optimizing this trap for the collection of Simulium damnosum s.l., the major vector of O. volvulus in Africa. A shortened, blue and black striped version of the Esperanza window trap, when baited with a combination of CO2 and worn trousers, rivalled human landing collections in the number of S. damnosum s.l. females collected. Traps baited with a commercially available human skin lure and CO2 resulted in collections that were not significantly different than those obtained from traps baited with worn trousers and CO2. This suggests that the Esperanza window trap may offer a replacement for human landing collections for monitoring onchocerciasis transmission in Africa. PMID:24794201

  7. Revealing a hard X-ray spectral component reverberating within one light hour of the central Supermassive Black Hole in Ark 564

    CERN Document Server

    Giustini, M; Reeves, J N; Miller, L; Legg, E; Kraemer, S B; George, I M

    2015-01-01

    Ark 564 (z=0.0247) is an X-ray bright NLS1. By using advanced X-ray timing techniques, Legg et al. (2012) discovered an excess of "delayed" emission in the hard X-ray band (4-7.5 keV) following about 1000 seconds after "flaring" light in the soft X-ray band (0.4-1 keV). We report on the X-ray spectral analysis of eight XMM-Newton and one Suzaku observation of Ark 564. High-resolution spectroscopy was performed with the RGS in the soft X-ray band, while broad-band spectroscopy was performed with the EPIC-pn and XIS/PIN instruments. We analysed time-averaged, flux-selected, and time-resolved spectra. Despite the large variability in flux, the broad band spectral shape of Ark 564 is not dramatically varying and can be reproduced either by a superposition of a power law and a blackbody emission, or by a Comptonized power law emission model. High resolution spectroscopy revealed the presence of ionised gas along the line of sight at the systemic redshift of the source, with a low column density and a range of ioni...

  8. Inhomogeneous broadening of optical transitions of 87Rb atoms in an optical nanofiber trap

    CERN Document Server

    Lee, J; Hoffman, J E; Orozco, L A; Rolston, S L

    2014-01-01

    We experimentally demonstrate optical trapping of 87Rb atoms using a two-color evanescent field around an optical nanofiber. In our trapping geometry, a blue-detuned traveling wave whose polarization is nearly parallel to the polarization of a red-detuned standing wave produce significant vector light shifts that lead to broadening of the absorption profile of a near-resonant beam at the trapping site. A model that includes scalar, vector, and tensor light shifts of the probe transition $5S_{1/2}$-$5P_{3/2}$ from the trapping beams; weighted by the temperature-dependent position of the atoms in the trap qualitatively describe the observed asymmetric profile, and explained differences with previous experiments that used Cs atoms. The model provides a consistent way to extract the number of atoms in the trap.

  9. Are we getting the full picture? Animal responses to camera traps and implications for predator studies.

    Science.gov (United States)

    Meek, Paul; Ballard, Guy; Fleming, Peter; Falzon, Greg

    2016-05-01

    Camera trapping is widely used in ecological studies. It is often considered nonintrusive simply because animals are not captured or handled. However, the emission of light and sound from camera traps can be intrusive. We evaluated the daytime and nighttime behavioral responses of four mammalian predators to camera traps in road-based, passive (no bait) surveys, in order to determine how this might affect ecological investigations. Wild dogs, European red foxes, feral cats, and spotted-tailed quolls all exhibited behaviors indicating they noticed camera traps. Their recognition of camera traps was more likely when animals were approaching the device than if they were walking away from it. Some individuals of each species retreated from camera traps and some moved toward them, with negative behaviors slightly more common during the daytime. There was no consistent response to camera traps within species; both attraction and repulsion were observed. Camera trapping is clearly an intrusive sampling method for some individuals of some species. This may limit the utility of conclusions about animal behavior obtained from camera trapping. Similarly, it is possible that behavioral responses to camera traps could affect detection probabilities, introducing as yet unmeasured biases into camera trapping abundance surveys. These effects demand consideration when utilizing camera traps in ecological research and will ideally prompt further work to quantify associated biases in detection probabilities.

  10. Trapped-space-charge-limited currents in organics

    Energy Technology Data Exchange (ETDEWEB)

    Paasch, Gernot [IFW Dresden (Germany); Blom, Paul; Mandoc, Magda; Boer, Bert de [University of Groningen (Netherlands)

    2007-07-01

    The Mott-Gurney law for space charge limited current (SCLC) has been modified early to account for the presence of exponentially distributed traps. This expression has been widely used to analyse transport in organic light emitting diodes. However, the theory fails to describe the rather weak temperature dependence observed for electron transport, for instance in PPV derivatives. There we have shown that the trap-limited SCLC law is essentially modified if the density of transport states is of Gaussian type. Here, we discuss the origin of this modification and present a detailed analysis of the modified law. In addition, we derive further modifications for different combinations of densities of states of both the transport states and the trap distribution. As a result, rather different dependencies of the current on voltage, layer thickness and temperature are possible. Consequently, one has to exercise care in order to obtain reliable trap parameters from SCLC.

  11. Track and trap in 3D

    Science.gov (United States)

    Glückstad, Jesper; Rodrigo, Peter J.; Nielsen, Ivan P.; Alonzo, Carlo A.

    2007-04-01

    Three-dimensional light structures can be created by modulating the spatial phase and polarization properties of an an expanded laser beam. A particularly promising technique is the Generalized Phase Contrast (GPC) method invented and patented at Risø National Laboratory. Based on the combination of programmable spatial light modulator devices and an advanced graphical user-interface the GPC method enables real-time, interactive and arbitrary control over the dynamics and geometry of synthesized light patterns. Recent experiments have shown that GPC-driven micro-manipulation provides a unique technology platform for fully user-guided assembly of a plurality of particles in a plane, control of particle stacking along the beam axis, manipulation of multiple hollow beads, and the organization of living cells into three-dimensional colloidal structures. Here we present GPC-based optical micromanipulation in a microfluidic system where trapping experiments are computer-automated and thereby capable of running with only limited supervision. The system is able to dynamically detect living yeast cells using a computer-interfaced CCD camera, and respond to this by instantly creating traps at positions of the spotted cells streaming at flow velocities that would be difficult for a human operator to handle.

  12. Some results on dynamical black holes

    CERN Document Server

    Vanzo, L

    2008-01-01

    We give indications that outer future trapping horizons play a role in the particular semi-classical instability of an evolving black hole that produces the Hawking's radiation. These are obtained with the use of the Hamilton-Jacobi tunneling method. It automatically selects one special expression for the surface gravity of a changing horizon, the one defined a decade ago by Hayward using Kodama's theory of spherically symmetric gravitational fields. The method also applies to point masses embedded in an expanding universe and to general, spherically symmetric black holes.

  13. Highly efficient white organic light-emitting devices consisting of undoped ultrathin yellow phosphorescent layer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shengqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Ma, Zhu; Zhao, Juan [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2013-02-15

    High-efficiency white organic light-emitting devices (WOLEDs) based on an undoped ultrathin yellow light-emitting layer and a doped blue light-emitting layer were demonstrated. While the thickness of blue light-emitting layer, formed by doping a charge-trapping phosphor, iridium(III) bis(4 Prime ,6 Prime -difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6) in a wide bandgap host, was kept constant, the thickness of neat yellow emissive layer of novel phosphorescent material, bis[2-(4-tertbutylphenyl)benzothiazolato-N,C{sup 2 Prime }]iridium (acetylacetonate) [(t-bt){sub 2}Ir(acac)] was varied to optimize the device performance. The optimized device exhibited maximum luminance, current efficiency and power efficiency of 24,000 cd/m{sup 2} (at 15.2 V), 79.0 cd/A (at 1550 cd/m{sup 2}) and 40.5 lm/W (at 1000 cd/m{sup 2}), respectively. Besides, the white-light emission covered a wide range of visible spectrum, and the Commission Internationale de l'Eclairage coordinates were (0.32, 0.38) with a color temperature of 5800 K at 8 V. Moreover, high external quantum efficiency was also obtained in the high-efficiency WOLEDs. The performance enhancement was attributed to the proper thickness of (t-bt){sub 2}Ir(acac) layer that enabled adequate current density and enough phosphorescent dye to trap electrons. - Highlights: Black-Right-Pointing-Pointer Highly efficient WOLEDs based on two complementary layers were fabricated. Black-Right-Pointing-Pointer The yellow emissive layer was formed by utilizing undoping system. Black-Right-Pointing-Pointer The blue emissive layer was made by host-guest doping system. Black-Right-Pointing-Pointer The thickness of the yellow emissive layer was varied to make device optimization. Black-Right-Pointing-Pointer The optimized device achieved high power efficiency of 40.5 lm/W.

  14. Photodetector with enhanced light absorption

    Science.gov (United States)

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  15. Trapped-Electron Runaway Effect

    CERN Document Server

    Nilsson, E; Fisch, N J; Peysson, Y

    2015-01-01

    In a tokamak, trapped electrons subject to a strong electric field cannot run away immediately, because their parallel velocity does not increase over a bounce period. However, they do pinch towards the tokamak center. As they pinch towards the center, the trapping cone becomes more narrow, so eventually they can be detrapped and run away. When they run away, trapped electrons will have very a different signature from circulating electrons subject to the Dreicer mechanism. The characteristics of what are called trapped-electron runaways are identified and quantified, including their distinguishable perpendicular velocity spectrum and radial extent.

  16. Slowly balding black holes

    CERN Document Server

    Lyutikov, Maxim

    2011-01-01

    The "no hair" theorem, a key result in General Relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the "no hair" theorem is not formally applicable for black holes formed from collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively "frozen-in" the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes $N_B = e \\Phi_\\infty /(\\pi c \\hbar)$, where $\\Phi_\\infty \\approx 2 \\pi^2 B_{NS} R_{NS}^3 /(P_{\\rm NS} c)$ is the initial magnetic flux through the hemisphere...

  17. Observation of cooperatively enhanced atomic dipole forces from NV centers in optically trapped nanodiamonds

    CERN Document Server

    Juan, M L; Besga, B; Brennen, G; Molina-Terriza, G; Volz, T

    2015-01-01

    Since the early work by Ashkin in 1970, optical trapping has become one of the most powerful tools for manipulating small particles, such as micron sized beads or single atoms. The optical trapping mechanism is based on the interaction energy of a dipole and the electric field of the laser light. In atom trapping, the dominant contribution typically comes from the allowed optical transition closest to the laser wavelength, whereas for mesoscopic particles it is given by the bulk polarizability of the material. These two different regimes of optical trapping have coexisted for decades without any direct link, resulting in two very different contexts of applications: one being the trapping of small objects mainly in biological settings, the other one being dipole traps for individual neutral atoms in the field of quantum optics. Here we show that for nanoscale diamond crystals containing artificial atoms, so-called nitrogen vacancy (NV) color centers, both regimes of optical trapping can be observed at the same...

  18. black cat

    Institute of Scientific and Technical Information of China (English)

    杜铁梅

    2016-01-01

    The black cat is a masterpiece of short fiction of Poe. He successfully solved the problem of creating of the horror effect by using scene description, symbol, repetition and first-person narrative methods. And created a complete and unified mysterious terror, achieved the effect of shocking. This paper aims to discuss the mystery in-depth and to enrich the research system in Poe’s novels.

  19. Influence of trap color and host volatiles on capture of the emerald ash borer (Coleoptera: Buprestidae).

    Science.gov (United States)

    Crook, Damon J; Khrimian, Ashot; Cossé, Allard; Fraser, Ivich; Mastro, Victor C

    2012-04-01

    Field trapping assays were conducted in 2009 and 2010 throughout western Michigan, to evaluate lures for adult emerald ash borer, A. planipennis Fairmaire (Coleoptera: Buprestidae). Several ash tree volatiles were tested on purple prism traps in 2009, and a dark green prism trap in 2010. In 2009, six bark oil distillate lure treatments were tested against manuka oil lures (used in 2008 by USDA APHIS PPQ emerald ash borer cooperative program). Purple traps baited with 80/20 (manuka/phoebe oil) significantly increased beetle catch compared with traps baited with manuka oil alone. In 2010 we monitored emerald ash borer attraction to dark green traps baited with six lure combinations of 80/20 (manuka/phoebe), manuka oil, and (3Z)-hexenol. Traps baited with manuka oil and (3Z)-hexenol caught significantly more male and total count insects than traps baited with manuka oil alone. Traps baited with manuka oil and (3Z)-hexenol did not catch more beetles when compared with traps baited with (3Z)-hexenol alone. When compared with unbaited green traps our results show that (3Z)-hexenol improved male catch significantly in only one of three field experiments using dark green traps. Dark green traps caught a high number of A. planipennis when unbaited while (3Z)-hexenol was seen to have a minimal (nonsignificant) trap catch effect at several different release rates. We hypothesize that the previously reported kairomonal attractancy of (3Z)-hexenol (for males) on light green traps is not as obvious here because of improved male attractancy to the darker green trap. PMID:22606813

  20. Understanding Persistence: A 3D Trap Map of an H2RG Imaging Sensor

    CERN Document Server

    Anderson, Rachel E; Valenti, Jeff; Bergeron, Eddie

    2014-01-01

    Several theories exist to explain persistence, most of which revolve around the distribution of traps. We aim to simulate persistence and illustrate this complex issue with a 3D trap map. For this experiment, we vary the detector voltage bias to simulate the change in the depletion region that occurs when the detector is exposed to light. This allows us to measure the distribution of traps in the depletion region. This paper will explore the results from this experiment and discuss the implications.