Sample records for earth doped integrated

  1. Masters Project Integrated Optical Microsystems Group (IOMS) Optical Characterization of Rare Earth Doped Waveguides and Lasers

    E-print Network

    Al Hanbali, Ahmad

    such as Al2O3 and Y2O3 doped with rare earth elements are potentially capable of providing the requiredMasters Project ­ Integrated Optical Microsystems Group (IOMS) Optical Characterization of Rare Earth Doped Waveguides and Lasers Introduction Active micro and nano-photonic devices are considered

  2. Rare earth-doped integrated glass components: modeling and optimization

    Microsoft Academic Search

    Ole Lumholt; Anders Bjarklev; Thomas Rasmussen; G. Lester

    1995-01-01

    For the integrated optic erbium-doped phosphate silica-amplifier, a comprehensive model is presented which includes high-concentration dissipative ion-ion interactions. Based on actual waveguide parameters, the model is seen to reproduce measured gains closely. A rigorous design optimization is performed, and the influence of variations in the launched pump power, the core cross section, the waveguide length, the erbium concentration, and the

  3. Three-color integration on rare-earth-doped GaN electroluminescent Y. Q. Wang and A. J. Steckla)

    E-print Network

    Steckl, Andrew J.

    Three-color integration on rare-earth-doped GaN electroluminescent thin films Y. Q. Wang and A. J June 2002; accepted 25 November 2002 We have realized full color integration on rare-earth-doped thin . This phenomenon has been em- ployed to fabricate flat panel display3,4 emitting a variety of visible colors

  4. Modeling and fabrication of rare-earth-doped integrated optical waveguide amplifiers

    NASA Astrophysics Data System (ADS)

    Krishnaswamy, Madhu

    This thesis addresses modeling and fabrication issues related to erbium/ytterbium-doped glass waveguide amplifiers. Compact optical waveguides which amplify light in the 1.55 ?m wavelength window will play an important role in complementing other integrated optic devices such as modulators and switches. In designing waveguide amplifiers, two features are of utmost importance: (1) high signal gain over short distances. (2) compatibility for integration with other devices. The requirement for gain over a short distance necessitates the use of rare-earth dopant levels two orders of magnitude higher than currently employed in fiber amplifiers. A numerical model to simulate the gain and noise characteristics of waveguide amplifiers doped heavily with rare-earth ions is described. Deleterious effects associated with high doping, such as ion-ion interaction, are included in the model. The model is validated by comparing simulation results with experimental and numerical results found in the literature. Based on modeling results, an attempt was made to fabricate compact ridge waveguides from thin films of sputter- deposited erbium-doped glass. In response to various spectroscopic and micromachining impediments encountered with this process, alternative waveguide configurations were explored. The design and fabrication of strip-loaded waveguides using two dielectric glass films in conjunction is discussed. In this configuration, micromachining impediments inherent to the active glass film can be circumvented. Experimental and simulation results for this device are shown to be in close agreement. Improvements are forecast by the model. Optical waveguides were also formed directly on rare- earth-doped bulk glasses. In one approach, a passive polymer waveguide was dispensed on top of a bulk glass. The evanescent field of light propagating in the polymer layer was seen to penetrate the bulk substrate and interact with rare-earth ions. Experimental and simulation results associated with this novel approach are discussed. Finally, an Er/Yb-doped optical waveguide amplifier yielding 3.5 dB of net signal gain over 4.2 cm with 120 mW of pump power is demonstrated. This singlemode device was formed on a bulk glass using a field-assisted, silver-sodium ion-exchange process.

  5. Emission and Absorption Cross-Section Calculation of Rare Earth Doped Materials for Applications to Integrated Optic Devices

    Microsoft Academic Search

    P. L. Pernas; E. Cantelar

    2005-01-01

    With the increasing sophistication required in integrated-optical devices it has become necessary to develop accurate methods that allow for an optimization of component design. In this paper we present an overview of the theory and the experimental conditions needed to obtain optical cross sections applicable to rare-earth doped materials. The values generated by the method provide the accuracy needed in

  6. Emission and Absorption Cross-Section Calculation of Rare Earth Doped Materials for Applications to Integrated Optic Devices

    NASA Astrophysics Data System (ADS)

    Pernas, P. L.; Cantelar, E.

    2005-01-01

    With the increasing sophistication required in integrated-optical devices it has become necessary to develop accurate methods that allow for an optimization of component design. In this paper we present an overview of the theory and the experimental conditions needed to obtain optical cross sections applicable to rare-earth doped materials. The values generated by the method provide the accuracy needed in the modelling of rare earth-doped integrated devices. As a test case, we have applied the method to the 4I13/2 ? 4I15/2 transition of Er3+-doped LiNbO3 crystals and Zn diffused Er:LiNbO3 channel waveguides developed in our laboratory. Adverse effects of concentration determination and ion-clustering are investigated.

  7. Masters Project Integrated Optical Microsystems Group (IOMS) Design and Optical Characterization of Rare Earth Doped On-chip Waveguide

    E-print Network

    Al Hanbali, Ahmad

    of Rare Earth Doped On-chip Waveguide Laser Components Introduction Active micro and nano-photonic devices materials doped with rare earth elements, in particular Er:Al2O3, are potentially very useful

  8. Integrated optical amplifiers based on rare-earth doped (red) oxide glasses

    Microsoft Academic Search

    Giancarlo C. Righini; Massimo Brenci; Guaktiero N. Conti; Stefano Pelli; Maurizio Ferrari; Marco Bettinelli; Adolfo Speghini; Baojiu Chen

    2003-01-01

    Oxide glasses have been used since long time to host a number of active compounds, first of all rare-earth (RE) ions, for lasing. Recently, the advantages offered by guided-wave format, namely the small size, the high pump power density, and the larger flexibility in design and fabrication, led to the development of fiber lasers and amplifiers based on Er3+-doped glasses.

  9. Rare-earth-ion-doped double tungstates: A promising gain material for integrated optics

    Microsoft Academic Search

    Sonia M. Garcia-Blanco; Dimitri Geskus; Dalfsen van Koop; Shanmugam Aravazhi; Markus Pollnau

    2011-01-01

    In this paper, an overview of the technology as well as the latest developments on RE-doped double tungstate waveguide amplifiers and micro-lasers will be given, including high-gain on-chip waveguide amplifiers inKGdxLu1 x(WO4)2:Yb3+, high-power (>400 mW), broadly tunable (~65 nm), low-quantum-defect (0.7 %) channel waveguide lasers inKGdxLu1-x(WO4)2:Yb3+ as well as on-chip microlasers at ~2 um wavelength inKY1-x-yGdxLuy(WO4)2:Tm3+ for trace-gas detection for

  10. SYNTHESIS & INTEGRATION Earth Stewardship

    E-print Network

    Jackson, Robert B.

    SYNTHESIS & INTEGRATION Earth Stewardship: science for action to sustain the human-earth system F, A. G. Power, and A. Bartuska. 2011. Earth Stewardship: science for action to sustain the human. This paper describes Earth Stewardship, an initiative of the Ecological Society of America to provide

  11. Photosensitivity of rare-earth-doped glasses

    NASA Astrophysics Data System (ADS)

    Williams, Glen M.; Dutt, David A.; Ruller, Jacqueline A.; Griscom, David L.; Jewell, John M.; Crahan, Kathleen K.; Friebele, E. J.

    1993-12-01

    Rare earth-doped glasses exhibit high initial photosensitivity but their response saturates at relatively modest values of (Delta) n (approximately 5 X 10-7), which greatly limits their usefulness for device applications. In the context of our model, saturation results from either exhaustion of photosensitive rare earth sites, trap sites, or through competition between two photon creation and one photon bleaching processes. In this paper we report the results of new experiments designed to further elucidate the photosensitivity process with specific emphasis on the saturation mechanisms(s). Based on these new experimental results we present a refinement of our earlier model.

  12. Overview of Nd and Er-Doped glass integrated optics amplifiers and lasers

    Microsoft Academic Search

    S. Iraj Najafi

    1997-01-01

    There has been significant progress since 1990 on development of rare-earth-doped glass integrated optics amplifiers and lasers. Several fabrication processes were utilized to make rare-earth-doped waveguides. Neodymium and erbium doped waveguides were successfully produced, and amplifiers and lasers were demonstrated. Recently, high performance erbium-doped amplifiers in phosphate glasses were achieved. In this paper, we review the progress in development of

  13. 40 CFR 721.10423 - Complex strontium aluminate, rare earth doped (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...false Complex strontium aluminate, rare earth doped (generic). 721.10423 Section...10423 Complex strontium aluminate, rare earth doped (generic). (a) Chemical substances...generically as complex strontium aluminate, rare earth doped (PMNs P-12-22,...

  14. Rare earth-doped glass microbarcodes

    PubMed Central

    Dejneka, Matthew J.; Streltsov, Alexander; Pal, Santona; Frutos, Anthony G.; Powell, Christy L.; Yost, Kevin; Yuen, Po Ki; Müller, Uwe; Lahiri, Joydeep

    2003-01-01

    The development of ultraminiaturized identification tags has applications in fields ranging from advanced biotechnology to security. This paper describes micrometer-sized glass barcodes containing a pattern of different fluorescent materials that are easily identified by using a UV lamp and an optical microscope. A model DNA hybridization assay using these “microbarcodes” is described. Rare earth-doped glasses were chosen because of their narrow emission bands, high quantum efficiencies, noninterference with common fluorescent labels, and inertness to most organic and aqueous solvents. These properties and the large number (>1 million) of possible combinations of these microbarcodes make them attractive for use in multiplexed bioassays and general encoding. PMID:12515864

  15. Scintillation of rare earth doped fluoride nanoparticles

    SciTech Connect

    Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Ballato, J. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Yukihara, E. G. [Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States); DeVol, T. A. [Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634-0905 (United States)

    2011-09-12

    The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

  16. ac impedance studies of rare earth oxide doped ceria

    Microsoft Academic Search

    G. Bryan Balazs; Robert S. Glass

    1995-01-01

    The ionic conductivities of cerium oxide doped with oxides of the entire rare earth series (except Pm) were measured using ac impedance in air at temperatures ranging from 400 °C to 900 °C. All of these samples showed an increase in the conductivity over undoped ceria, with ceria doped with Gd, Sm and Y exhibiting the highest values. The maximum

  17. Radiation effects on rare-earth doped optical fibers

    NASA Astrophysics Data System (ADS)

    Girard, Sylvain; Ouerdane, Youcef; Vivona, Marilena; Tortech, Blandine; Robin, Thierry; Boukenter, Aziz; Marcandella, C.; Cadier, Benoît; Meunier, Jean-Pierre

    2010-09-01

    In this paper, we reviewed our previous work concerning the responses of rare-earth (RE) doped fibers (Yb, Er and Er/Yb) to various types of radiations like ?-rays, X-rays and protons. For all these harsh environments, the main measured macroscopic radiation-induced effect is an increase of the linear attenuation of these waveguides due to the generation of point defects in the RE-doped core and silica-based cladding. To evaluate the vulnerability of this class of optical fibers for space missions, we characterize the growth and decay kinetics of their radiation-induced attenuation (RIA) during and after irradiation for various compositions. Laboratory testing reveals that this class of optical fibers is very sensitive to radiations compared to passive (RE-free) samples. As a consequence, despite the small length used for space applications, the understanding of the radiation-induced effects in this class of optical fibers becomes necessary before their integration as part of fiber-based systems like gyroscopes or communication systems. In this paper, we more particularly discussed about the relative influence of the rare-earth ions (Er3+ and/or Yb3+) and of the glass matrix dopants (Al, P, ...) on the optical degradation due to radiations. This has been done by using a set of five prototype optical fibers designed by the fiber manufacturer iXFiber SAS to enlighten the role of these parameters. Additional spectroscopic tools like confocal microscopy of luminescence are also used to detect possible changes in the spectroscopy of the rare-earth ions and their consequences on the functionality of the active optical fibers.

  18. Laser development of rare-earth doped crystals

    Microsoft Academic Search

    N. D Vieira; I. M Ranieri; L. V. G Tarelho; N. U Wetter; S. L Baldochi; L Gomes; P. S. F de Matos; W de Rossi; G. E. C Nogueira; L. C Courrol; E. A Barbosa; E. P Maldonado; S. P Morato

    2002-01-01

    Rare earth doped laser crystals present good optical properties providing most of the solid state lasers available today. In particular, some fluoride crystals are capable of forming solid solution with several rare earth fluorides, allowing one to take full advantage of the energy transfer mechanisms that might occur among them. LiREF4 (RE=rare earth) crystals, for example, are so flexible that

  19. Optical properties of rare-earth-doped silicon nanocomposites

    NASA Astrophysics Data System (ADS)

    Hryciw, Aaron Christopher

    Silicon-based light-emitting materials show much promise for integrated photonics applications. In particular, nanocrystalline silicon can exhibit efficient visible emission, though the mechanism of luminescence is still the subject of some controversy. This thesis reports on the optical properties and device applications of silicon nanocomposite thin films with varying characteristics: amorphous and crystalline nanoclusters (NCs), both undoped and doped with rare-earth (RE) elements. Silicon nanocomposite thin films can be prepared by co-evaporation of Si, SiO, and/or SiO2 followed by annealing to induce phase separation. Such films typically exhibit a broad photoluminescence (PL) band centred between ˜600-800 nm. RE-doped a-Si-NC films can exhibit relatively sharp emission in the near infrared, with excitation cross-sections on the order of 10 -16 cm2 due to the sensitisation effect of the Si NCs---an increase in excitation efficiency by over five orders of magnitude compared with typical values for RE-doped SiO2. Er3+ in particular is important due to its emission at 1.5 mum, corresponding to the wavelength of minimum attenuation in conventional silica optical fibres. To demonstrate control over the spectral width and centre wavelength of emission for photonic applications, undoped and RE-doped a-Si-NC films have been incorporated into optical resonator structures (microcavities) with Ag mirrors. For a-Si films, the emission is tunable from 475 to 875 nm, extendable to 1630 nm upon the addition of Er. It is well known that Si NCs are capable of efficient energy transfer to many of the RE3+ ions; the specific nature of the non-radiative transfer process, however, has not been established with certainty. Efficient nanocluster-mediated excitation has been demonstrated for Nd-, Tb-, Dy-, Er-, Tm-, and Yb-doped a-Si-NC films. From luminescence modelling of ensembles of a-Si NCs, the observed quenching with increased annealing temperature can be accounted for by assuming a non-radiative defect density of ˜1020 cm-3. The population dynamics of the coupled NC-Er3+ system were investigated via a phenomenological rate-equation model for weak optical pumping. A phonon-assisted energy-transfer process is suggested by comparison with experimental time-resolved PL measurements; future work in this area is required to confirm this interpretation.

  20. On the upconversion emission of rare earth doped zirconia fiber

    Microsoft Academic Search

    F. S. Vicente; A. C. Hernandes; M. F. De Souza; M. R. B. Andreeta; M. Siu Li

    1998-01-01

    Optical rare earth doped zirconia fiber were produced using a CO2 laser and upconversion emission from a ZrO2:Er:Y:Pr single crystal fiber sample has been observed. The experiment was done exciting the Er ion through the 647–676.4 nm multilines of a Kr laser resulting in a broad and structured emission around 550 nm. From well known Er doped LiNbO3 emission it

  1. On the upconversion emission of rare earth doped zirconia fiber

    Microsoft Academic Search

    F. S. Vicente; A. C. Hernandes; M. F. de Souza; M. R. B. Andreeta; M. Siu Li

    1998-01-01

    Optical rare earth doped zirconia fiber were produced using a CO2 laser and upconversion emission from a ZrO2:Er3+:Y3+:Pr3+ single crystal fiber sample has been observed. The experiment was done exciting the Er3+ ion through the 647-676.4 nm multilines of a Kr+ laser resulting in a broad and structured emission around 550 nm. From well known Er3+ doped LiNbO3 emission it

  2. Scintillation of Sol-Gel derived Lutetium orthophosphate doped with rare earth ions.

    E-print Network

    Paris-Sud XI, Université de

    1 Scintillation of Sol-Gel derived Lutetium orthophosphate doped with rare earth ions. C. Mansuy1. In order to exhibit luminescence properties, these materials are generally doped with rare earth ions. Lu

  3. Highly doped alkaline earth nanofluorides synthesized from ionic liquids

    NASA Astrophysics Data System (ADS)

    Lorbeer, C.; Cybinska, J.; Zych, E.; Mudring, A.-V.

    2011-12-01

    Bulk alkaline earth fluorides co-doped with optically active ions are prominent materials for luminescent applications. However, for phosphor materials the changeover to the nanoscale is a tightrope walk between achieving desirable features of small particles such as reduced light scattering and unwanted drawbacks such as a high surface defect concentration which is likely to result in quenching of luminescence. A new preparation route via ionic liquids allows obtaining pure and oxygen-free alkaline earth fluorides co-doped with Eu 3+ and Gd 3+ on the nanoscale with excellent quantum cutting abilities.

  4. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    E-print Network

    Paris-Sud XI, Université de

    Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor * Corresponding author: wilfried.blanc@unice.fr Rare earth (RE) doped silica-based optical fibers with transparent and amplifiers. 1 #12;I. Introduction Developing of new rare-earth (RE)-doped optical fibers for power amplifiers

  5. Growth of rare-earth doped oxyde nanoparticles in silica fibers Valrie Mauroy*

    E-print Network

    Paris-Sud XI, Université de

    Growth of rare-earth doped oxyde nanoparticles in silica fibers Valérie Mauroy* , Wilfried Blanc7336 Parc Valrose, 06180 Nice Cedex 2 ABSTRACT Rare earth (RE) doped silica-based optical fibers Developing of new rare-earth (RE)-doped optical fibers for power amplifiers and lasers requires continuous

  6. Rare-earth doped polymer waveguides and light emitting diodes

    Microsoft Academic Search

    L. H. Slooff

    2000-01-01

    Polymer-based optical waveguide amplifiers offer a low-cost alternative for inorganic waveguide amplifiers. Due\\u000a to the fact that their refractive index is almost similar to that of standard optical fibers, they can be easily coupled\\u000a with existing fibers at low coupling losses. Doping the polymer with rare-earth ions that can yield optical gain is\\u000a not straightforward, as the rare-earth salts are

  7. Magnetocrystalline Anisotropy of Rare Earth Impurities Doped in Gadolinium. I. Heavy Rare Earth

    Microsoft Academic Search

    Keisuke Tajima

    1971-01-01

    The magnetocrystalline anisotropy of the heavy rare earth impurities doped in gadolinium metal was measured by a torque method in a temperature range from 4.2°K to about 200°K. The large contribution from the heavy rare earth impurities to the anisotropy is well explained by the crystal field theory. The temperature dependence of the anisotropy constant can be explained fairly well

  8. Probing single ion luminescence in rare-earth doped nanocrystals

    Microsoft Academic Search

    Michael D. Barnes; Adosh Mehta; Thomas Thundat; Ramesh Bhargava

    2001-01-01

    Recently there has been a great deal of attention focused on rare-earth doped nanocrystals (DNCs) as a new class of luminescent nanomaterials with novel and tunable optical properties. Such species have properties that make them attractive candidates for biological tags such as narrow spectral width and very high photochemical stability. However, the transitions that give rise to visible luminescence of

  9. Rare earth-doped confined structures for amplifiers and lasers

    Microsoft Academic Search

    B Jacquier; E Lebrasseur; S Guy; A Belarouci; F Menchini

    2000-01-01

    Here, we present an overview of the specific spectroscopic properties of fluoride planar waveguides which emphasize the difference between rare earth-doped waveguide and bulk and demonstrate their potentiality to be used as lasers and amplifiers. We illustrate this with recent results obtained at strategic wavelengths for telecommunications. Furthermore, we are dealing with even more confined structures such as optical microcavities

  10. Molecular dynamics simulations of rare-earth-doped glasses

    Microsoft Academic Search

    S. Chaussedent; V. Teboul; A. Monteil

    2003-01-01

    In the recent years the use of the molecular dynamics technique has become very common in the study of glass. The purpose of the present paper is to focus on recent advancements on the use of this method to investigate rare-earth-doped glasses. We report an overview of the use of simulations to study their specific structural features and luminescence properties.

  11. Crystallization behavior of rare-earth doped fluorochlorozirconate glasses.

    PubMed

    Paßlick, C; Ahrens, B; Henke, B; Johnson, J A; Schweizer, S

    2011-06-01

    A series of fluorochlorozirconate (FCZ) glasses, each doped with a different rare-earth, was prepared and examined to determine thermal stability and activation energy, Ea , of the dopant dependent BaCl2 crystallization. Non-isothermal differential scanning calorimetry (DSC) measurements were done to investigate the endothermic and exothermic reactions upon heat treatment of the glass samples. In comparison to the rare-earth free FCZ glass, significant changes in the Hruby constant, Hr , and Ea were found due to the addition of a rare-earth and also between the individual dopants. PMID:23493406

  12. Crystallization behavior of rare-earth doped fluorochlorozirconate glasses

    PubMed Central

    Paßlick, C.; Ahrens, B.; Henke, B.; Johnson, J.A.; Schweizer, S.

    2012-01-01

    A series of fluorochlorozirconate (FCZ) glasses, each doped with a different rare-earth, was prepared and examined to determine thermal stability and activation energy, Ea, of the dopant dependent BaCl2 crystallization. Non-isothermal differential scanning calorimetry (DSC) measurements were done to investigate the endothermic and exothermic reactions upon heat treatment of the glass samples. In comparison to the rare-earth free FCZ glass, significant changes in the Hruby constant, Hr, and Ea were found due to the addition of a rare-earth and also between the individual dopants. PMID:23493406

  13. Silica-optical-fiber-based rare-earth-doped sensors

    NASA Astrophysics Data System (ADS)

    Sun, Tong; Grattan, Kenneth T. V.; Wade, Scott A.; Forsyth, David

    2001-10-01

    This paper reports on work done with a range of silica fibres, doped with several important rare earth ions such as Er, Nd, Yb and Tm, to create a range of novel optical sensors. The approach reported herein is based on monitoring and analysis of the fluorescence decay from such fibres in the time domain as well as in the frequency domain. With these fibres, temperature sensors operating in the range from as low as -200 degree(s)C to beyond 1000 degree(s)C have been constructed. A temperature resolution of the order of a few degrees Celsius has been typically reported from these types of sensors. Fibre of this type has been used in a simple yet effective structural integrity monitoring system (being incorporated successfully into concrete samples) and an optical fire alarm system with potential applications for engine monitoring has been developed. A further recent discovery is a small level of strain sensitivity in such fibres - this has been explored over the region from 0 to 2000(mu) e, showing a level of resolution better than a few tens of microstrain, and sensors based on this effect are discussed and reported on in this work.

  14. Nanocrystalline Rare Earth-doped Gallium Nitride Phosphor Powders

    Microsoft Academic Search

    G. A. Hirata; J. Tao; P. Chen; K. C. Mishra; J. McKittrick

    We report on the fabrication and luminescent properties of rare earth-doped gallium nitride (GaN) phosphor powders. Single phase GaN and GaN:RE3+ powders were prepared by using a novel chemical route. In this work a new method for the synthesis of high purity, single phase doped GaN powders is reported. (Ga1-xREx)N powders are obtained by dissolving metal nitrates (Ga(NO3)3, (RE(NO3)3) in

  15. Production and Rare Earth Doping of Aerogels

    NASA Astrophysics Data System (ADS)

    Montejo, Genderzon; Sanchez, Freddy; Wenzlau, Dylan; Hoffman, Kurt

    2010-10-01

    We present recent studies into several methods for making Aerogels. We used both critical point drying methods and chemical dehydroxylation to achieve low density glasses. We used an SEM to characterize the increased pore sizes in these glass materials. In addition, we will present preliminary results of our efforts to add rare earth ions to the glass structure. We are attempting to add the rare earth ions to the glass while avoiding the clustering problems normally encountered in the sol-gel synthesis technique.

  16. Magnetic property improvement of niobium doped with rare earth elements

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; He, Fei-Si; Jiao, Fei; He, Fa; Lu, Xiang-Yang; Zhao, Kui; Zhao, Hong-Yun; You, Yu-Song; Chen, Lin

    2014-05-01

    A new idea is proposed by the PKU group to improve the magnetic properties of the Type-II superconductor niobium. Rare earth elements like scandium and yttrium are doped into ingot niobium during the smelting processes. A series of experiments have been done since 2010. The preliminary testing results show that the magnetic properties of niobium materials have changed with different doping elements and proportions while the superconductive transition temperature does not change very much. This method may increase the superheating magnetic field of niobium so as to improve the performance of the niobium cavity, which is a key component of SRF accelerators. A Tesla-type single-cell cavity made of scandium-doped niobium is being fabricated.

  17. Rare Earth Doped High Temperature Ceramic Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

  18. Structural studies of rare-earth doped phosphate glasses

    SciTech Connect

    Matic, A.; Boerjesson, L. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Applied Physics; Wannberg, A.; McGreevy, R.L. [Studsvik Neutron Research Lab., Nykoeping (Sweden)

    1997-12-31

    The authors have performed neutron scattering experiments on rare-earth (La, Pr, Ho) doped phosphate glasses around the metaphosphate composition R(PO{sub 3}){sub 3}. Combining the diffraction experiment with Reverse Monte Carlo simulations they obtain a 3-D model of the structure. The models propose a rare-earth ion environment primarily consisting of oxygens with the average rare earth-oxygen distances; 2.56, 2.51 and 2.40 for the La, Pr and Ho samples respectively. They also observe that the rare earth ions are not uniformly distributed. The first R-R shell is on average about 3.3 {angstrom} to be compared with a value of 7 {angstrom} for a uniform distribution of R ions in the structure. From the models the authors also conclude that a chain like structure of the phosphate network is in agreement with the experiment.

  19. Recent developments on rare-earth-doped glasses

    Microsoft Academic Search

    Jean-Luc Adam; Jacques Lucas; Shibin Jiang

    1997-01-01

    Recent developments in rare-earth (RE)-doped glasses are presented. The paper includes an overview of UV, blue, green and IR fluoride glass fiber lasers, together with the performances of RE optical amplifiers of the first, second, and third telecommunication windows. Spectroscopic results concerning low-photon-energy sulfide and chloro-fluoride glasses for 1.3 micrometers amplification are discussed. A special section is devoted to phosphate

  20. Rare earth doped zinc oxide varistors

    DOEpatents

    McMillan, A.D.; Modine, F.A.; Lauf, R.J.; Alim, M.A.; Mahan, G.D.; Bartkowiak, M.

    1998-12-29

    A varistor includes a Bi-free, essentially homogeneous sintered body of a ceramic composition including, expressed as nominal weight %, 0.2--4.0% oxide of at least one rare earth element, 0.5--4.0% Co{sub 3}O{sub 4}, 0.05--0.4% K{sub 2}O, 0.05--0.2% Cr{sub 2}O{sub 3}, 0--0.2% CaO, 0.00005--0.01% Al{sub 2}O{sub 3}, 0--2% MnO, 0--0.05% MgO, 0--0.5% TiO{sub 3}, 0--0.2% SnO{sub 2}, 0--0.02% B{sub 2}O{sub 3}, balance ZnO. 4 figs.

  1. Rare earth doped zinc oxide varistors

    DOEpatents

    McMillan, April D. (Knoxville, TN); Modine, Frank A. (Oak Ridge, TN); Lauf, Robert J. (Oak Ridge, TN); Alim, Mohammad A. (Medina, OH); Mahan, Gerald D. (Oak Ridge, TN); Bartkowiak, Miroslaw (Oak Ridge, TN)

    1998-01-01

    A varistor includes a Bi-free, essentially homogeneous sintered body of a ceramic composition including, expressed as nominal weight %, 0.2-4.0% oxide of at least one rare earth element, 0.5-4.0% Co.sub.3 O.sub.4, 0.05-0.4% K.sub.2 O, 0.05-0.2% Cr.sub.2 O.sub.3, 0-0.2% CaO, 0.00005-0.01% Al.sub.2 O.sub.3, 0-2% MnO, 0-0.05% MgO, 0-0.5% TiO.sub.3, 0-0.2% SnO.sub.2, 0-0.02% B.sub.2 O.sub.3, balance ZnO.

  2. Rare Earth Doped IR Fiber Lasers For Medical Applications

    NASA Astrophysics Data System (ADS)

    Esterowitz, Leon; Allen, Roger

    1989-06-01

    Trivalent rare earth doped lasers in fluorozirconate glasses and fibers that lase between 2 and 3 ?m are reviewed. There have been a large number of laser-fiber optic systems below 2pm developed for clinical microsurgery at a variety of sites. The required flexibility of the fiber optic waveguide varies with the clinical use, such as: intraocular (through a small diameter rigid tube), endoscopically accessible pulmonary and gastric mucosa (through a port of a fiber-optic endoscope of intermediate flexibility), and intra-arterial (as an integral part of a flexible catheter, which in the case of the coronaries must be very flexible so as to negotiate abrupt bends and bifurcations without damage to the vessels). Laser energy absorbed by tissue is capable of coagulation of tissue (denaturation of structural proteins), melting of fatty deposits or other structures (solid or gel to liquid phase transitions), as well as direct breakage of chemical bonds by high energy photons. It is of general interest to develop a pulsed laser system transmitted through flexible fiber optics that is capable of precise ablation of targeted tissue with minimal damage to the remaining tissue. Ideally, the device should be able to ablate any tissue because of the general absorptive properties of tissue, and not a specific chromophore such as melanin or hemoglobin, the concentration of which varies widely among tissues. Two obvious ubiquitous chromophores have been widely discussed: 1) proteins and nucleic acids whose high concentration and absorption coefficients lead to strong tissue absorption in the ultraviolet and 2) water whose strong infrared absorption bands have been widely utilized in CO2 laser surgery. Non-linear absorption occurring at very high power densities (~1 GW/cm2) has been shown to be very effective for non-invasive ocular (an optically transparent field) microsurgery at the image plane of a slit lamp, but this approach appears impractical in fiber optic systems because of similar non-linear damage mechanisms within the fiber.

  3. Experimental demonstration of efficient and selective population transfer and qubit distillation in a rare-earth-metal-ion-doped crystal

    E-print Network

    Suter, Dieter

    in a rare-earth-metal-ion-doped crystal Lars Rippe, Mattias Nilsson, and Stefan Kröll Department of Physics on optical interactions in rare-earth- metal-ion-doped crystals. The optical transition lines of the rare-earth-metal out in preparation for two-qubit gate operations in the rare-earth-metal-ion-doped crystals

  4. Persistent luminescence phenomena in materials doped with rare earth ions

    NASA Astrophysics Data System (ADS)

    Aitasalo, T.; Dere?, P.; Hölsä, J.; Jungner, H.; Krupa, J.-C.; Lastusaari, M.; Legendziewicz, J.; Niittykoski, J.; Str?k, W.

    2003-02-01

    The luminescent efficiency of rare earth ions is usually drastically lowered when defects are present in the host lattice. Persistent luminescence is the most recent rare earth application based on lattice defects. Typical materials are the Eu 2+-doped alkaline earth aluminates, MAl 2O 4:Eu 2+ ( M=Ca and Sr). The trivalent R 3+ ions as co-dopants enhance greatly the duration and intensity of persistent luminescence. As a result of very slow thermal bleaching of the excitation energy from the lattice defects acting as traps, the new persistent luminescent materials yield luminescence still visible to naked eye for more than 10 h. Despite the seemingly simple stoichiometry and structure of these materials, the determination of persistent luminescence mechanism(s) presents a very complicated problem. This report presents in detail some of the factors affecting the luminescence properties of the Eu 2+-, R 3+-doped MAl 2O 4. The possible mechanisms involved with different defect centers and interactions between them and the emitting Eu 2+ ion are discussed based on the results of systematic investigations carried out on the preparation, composition, structure and different luminescence properties.

  5. Rare Earth Doped Magnetic Clusters of Gold for Medical Application

    NASA Astrophysics Data System (ADS)

    Yadav, Brahm Deo; Kumar, Vijay

    2011-03-01

    In recent years gold clusters have been studied extensively due to their unusual properties and applications in cancer treatment and catalysis. Small gold clusters having up to 15 atoms are planar as shown in figure 1. Thereafter a transition occurs to 3D structures but the atomic structures continue to have high dispersion. Doping of these clusters could transform them in to new structures and affect the properties. Gold clusters with cage structures such as W@Au12 can be prepared with large highest occupied-lowest unoccupied molecular orbital (HOMO-LUMO) gap by doping with a transition metal atom such as W. By changing the transition metal atom, cage structures of different sizes as well as different HOMO-LUMO gaps can be formed which could be useful in different optical applications. In these structures gold clusters are generally non-magnetic. However, it is also possible to form magnetic clusters of gold such as Gold clusters have been found to be good for cancer treatment. We have performed ab initio calculations on doping of rare earths in small gold clusters to obtain magnetic clusters using projector augmented wave pseudopotential method within generalized gradient approximation for the exchange-correlation energy. Elemental gold clusters having up to 15 atoms are planar and thereafter 3D structures become favorable. We have explored the changes in the growth behavior when a rare earth atom is doped and studied the variation in the magnetic behavior as a function of size. Our results suggest that gold clusters may have twin advantage of treating cancer as well as be helful in magnetic imaging such as by MRI.

  6. Rare Earth doped nanoparticles in imaging and PDT

    PubMed Central

    Yust, Brian G.; Sardar, Dhiraj K.; Mimun, Lawrence C.; Gangadharan, Ajith K.; Tsin, Andrew T.

    2014-01-01

    Nanoparticles doped with rare earth ions for biomedical imaging and infrared photodynamic therapy (IRPDT) have been synthesized, characterized, and compared. Specifically, these nanoparticles utilize two primary modalities: near infrared excitation and emission for imaging, and near infrared upconversion for photodynamic therapy. These nanoparticles are optimized for both their infrared emission and upconversion energy transfer to a photoactive agent conjugated to the surface. Finally, these nanoparticles are tested for toxicity, imaged in cells using the near infrared emission pathway, and used for selective killing of cells through the upconversion driven IRPDT. PMID:25429335

  7. Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

  8. Multicomponent, Rare-Earth-Doped Thermal-Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.; Zhu, Dongming

    2005-01-01

    Multicomponent, rare-earth-doped, perovskite-type thermal-barrier coating materials have been developed in an effort to obtain lower thermal conductivity, greater phase stability, and greater high-temperature capability, relative to those of the prior thermal-barrier coating material of choice, which is yttria-partially stabilized zirconia. As used here, "thermal-barrier coatings" (TBCs) denotes thin ceramic layers used to insulate air-cooled metallic components of heat engines (e.g., gas turbines) from hot gases. These layers are generally fabricated by plasma spraying or physical vapor deposition of the TBC materials onto the metal components. A TBC as deposited has some porosity, which is desirable in that it reduces the thermal conductivity below the intrinsic thermal conductivity of the fully dense form of the material. Undesirably, the thermal conductivity gradually increases because the porosity gradually decreases as a consequence of sintering during high-temperature service. Because of these and other considerations such as phase transformations, the maximum allowable service temperature for yttria-partially stabilized zirconia TBCs lies in the range of about 1,200 to 1,300 C. In contrast, the present multicomponent, rare-earth-doped, perovskite-type TBCs can withstand higher temperatures.

  9. White light emission from GaN stack layers doped by different rare-earth metals

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Liu, Chang

    2015-02-01

    Experimental progress of electroluminescence devices (ELDs) employing GaN doped with rare-earth metals had been significantly made targeting RGB displays. However, reports on the theoretical models to design the devices and the applications were limited. Our previous paper proposed a device model using the quantum collision theory and Judd–Ofelt approximation to design the ELDs for white light illumination. In the present study, the model is modified by considering the light extraction efficiency and optical loss during propagating in the films. To improve the luminous efficiency, an ELD with three stack layers of GaN:Tm/GaN:Er/GaN:Eu is proposed and designed. The model predicts that the color of the integrated light can be controlled by applied voltage, thickness of each doping layer and doping concentrations of the rare earth metals. The luminous efficacy of white light emission at a bias of ?100 V is calculated to be 274 lm/W, which is much higher than that of fluorescent lumps. The proposed ELD will open a door to efficient solid-state lighting.

  10. FLUORESCENCE PROPERTIES OF As2S3 GLASS DOPED WITH RARE-EARTH ELEMENTS

    Microsoft Academic Search

    M. Iovu; A. Andriesh; I. Culeac

    Chalcogenide glasses doped with various rare-earth ions are extensively studied as potential materials for fiber optic amplifiers operating at 1.3 and 1.5 ?m telecommunication windows. The experimental results on optical absorption and photoluminescence of arsenic sulfide glasses and optical fibers doped with rare-earth elements (Pr3+, Sm3+, Er3+ and Dy3+) are presented. Near the absorption edge the rare-earth impurities affect strongly

  11. Rare-earth doped polymer waveguides and light emitting diodes

    NASA Astrophysics Data System (ADS)

    Slooff, L. H.

    2000-11-01

    Polymer-based optical waveguide amplifiers offer a low-cost alternative for inorganic waveguide amplifiers. Due to the fact that their refractive index is almost similar to that of standard optical fibers, they can be easily coupled with existing fibers at low coupling losses. Doping the polymer with rare-earth ions that can yield optical gain is not straightforward, as the rare-earth salts are poorly soluble in the polymer matrix. This thesis studies two different approaches to dope a polymer waveguide with rare-earth ions. The first one is based on organic cage-like complexes that encapsulate the rare-earth ion and are designed to provide enough coordination sites to bind the rare-earth ion and to shield it from the surrounding matrix. Chapter 2 describes the optical properties of Er-doped organic polydentate cage complexes. The complexes show clear photoluminescence at 1.54 mm with a bandwidth of 70 nm, the highest reported for an erbium-doped material so far. The luminescence lifetime is very short (~1 ms) due to coupling to vibrational overtones of O-H and C-H bonds. Due to this short luminescence lifetime, high pump powers (~1 W) are needed for optical gain in a waveguide amplifier based on these complexes. The pump power can be reduced if the Er is excited via the aromatic part of the complex, which has a higher absorption cross section. In Chapter 3 a lissamine-functionalised neodymium complex is studied in which the highly absorbing lissamine acts as a sensitiser. The lissamine is first excited into the singlet state from which intersystem crossing to the triplet state can take place. From there it can transfer its energy to the Nd ion by a Dexter transfer mechanism. Room-temperature photoluminescence at 890, 1060, and 1340 nm from Nd is observed, together with luminescence from the lissamine sensitiser at 600 nm. Photodegradation of the lissamine sensitiser is observed, which is studied in more detail in Chapter 4. The observed change in time of the spectral shape of the lissamine luminescence can be explained by assuming that two types of complexes exist. One type in which energy transfer to the Nd3+ ion can take place, and one that is not coupled to Nd. The highly absorbing sensitiser makes the standard butt-end coupling of the pump light into a waveguide amplifier impractical. The pump power can be used more efficiently by using a novel coupled waveguide system as described in Chapter 5. This employs gradual evanescent field coupling between parallel pump and signal waveguides. An alternative approach to make a rare-earth doped polymer waveguide is by combining the excellent properties of SiO2 as a host for the rare-earth with the easy processing of polymers. The optical properties of Er-doped silica films made by an acid-catalysed sol-gel synthesis are reported in Chapter 6. The Er exhibits long luminescence lifetimes of 10-12 ms, which indicates that OH from the wet chemical synthesis is successfully removed during the vacuum anneal treatment. Using a base-catalysed sol-gel synthesis, silica colloidal spheres with diameters of 175 and 340 nm were grown. Chapter 7 describes the luminescence properties of the 340 nm spheres, implanted with Er up to concentrations of 1.0 at.%. The Er shows a very long luminescence lifetime of 17 ms, and the radiative lifetime is estimated to be 20-22 ms, indicating a high quantum efficiency. This long luminescence lifetime is partly due to the low local optical density of states (DOS) in the free standing silica colloids. Optical gain calculations are made for the colloid/polymer waveguide that predicts a net gain of 8.7 dB at a pump power of 30 mW, for a 15 cm long waveguide. Such a length can be rolled up on an area of 16 mm2. In Chapter 8, calculations of the DOS are described for thin films as well as the spherical colloids. By comparing the calculation with experimentally probed decay rates, radiative and non-radiative components in the decay of Er are determined. Besides optical pumping of planar waveguide amplifiers it would be interesting if electrical pumping could b

  12. On the upconversion emission of rare earth doped zirconia fiber

    NASA Astrophysics Data System (ADS)

    Vicente, F. S.; Hernandes, A. C.; de Souza, M. F.; Andreeta, M. R. B.; Li, M. Siu

    Optical rare earth doped zirconia fiber were produced using a CO2 laser and upconversion emission from a ZrO2:Er3+:Y3+:Pr3+ single crystal fiber sample has been observed. The experiment was done exciting the Er3+ ion through the 647-676.4 nm multilines of a Kr+ laser resulting in a broad and structured emission around 550 nm. From well known Er3+ doped LiNbO3 emission it is concluded the upconversion emission results from the 2H11/2 ? 4I15/2 (510-540 nm) and from the 4S3/2 ? 4I15/2 (540-570 nm) Er3+ transitions. Regardles of the Er3+ electron shielding and the broadened emission observed in the zirconia, the shape of the emission spectra is very similar to the one observed in the LiNbO3 sample. Some possibilities arise from these results. The Er3+ ion is sitting in many multiequivalent and different sites in the zirconia (cubic symmetry) rather than in the LiNbO3 (hexagonal symmetry).

  13. Computer modelling of doped mixed metal fluorides and oxides for device applications: Rare earth, sodium and barium doped KYF 4

    NASA Astrophysics Data System (ADS)

    Jackson, Robert A.; Maddock, Elizabeth M.; Valerio, Mario E. G.

    2008-06-01

    The mixed metal fluorides and oxides have a range of important applications in optical and electronic devices. For example, rare earth doped LiCaAlF 6 is used in solid state lasers; and pure and doped LiNbO 3 is used in a wide range of optical and electronic applications. In attempting to develop new materials, two questions which arise include: which host lattices are most suitable, and which dopants will produce the required optical behaviour? This paper continues recent work designed to provide straightforward computational approaches to predict and assess properties of such materials, presenting the results of recent calculations on rare earth doping in KYF 4, as well as sodium and barium doping, which has been prompted by experimental work in this area.

  14. Pressure studies of alkali, alkaline earth and rare earth doped C{sub 60} superconductors

    SciTech Connect

    Schirber, J.E.; Bayless, W.R. [Sandia National Labs., Albuquerque, NM (United States); Kortan, A.R.; Ozdas, E.; Zhou, O.; Murphy, D. [AT and T Bell Labs., Murray Hill, NJ (United States); Fischer, J.E. [Pennsylvania Univ., Philadelphia, PA (United States)

    1994-06-01

    Pressure studies of the superconducting transition temperature T{sub c} of the alkali metal doped C{sub 60} compounds helped to establish a universal curve of T{sub c} versus lattice constant upon which nearly all of these materials lie. Various theoretical schemes incorporate this finding and suggest that only the lattice parameter and not the details of the dopant determine T{sub c}. Ca{sub 5}C{sub 60}, the highest T{sub c} member of the alkaline earth doped C{sub 60} superconductor has a T{sub c} which lies on this universal curve so this material, from these considerations, should have the same large negative pressure derivative as the alkali doped superconductors. We have measured dT{sub c}/dP for Ca{sub 5}C{sub 60} and for Yb{sub x}C{sub 60} (x near 3) and find small and positive values indicating that the theoretical models must be expanded to include band structure effects.

  15. Rare-earth-doped waveguide lasers in glass and LiNbO3: a review

    Microsoft Academic Search

    Kim A. Winick

    1998-01-01

    This paper presents an overview of rare earth-doped waveguide lasers in both glass and lithium niobate (LiNbO3). The historical development of these devices together with the most recent advances in the field are described.

  16. Engineering broadband and anisotropic photoluminescence emission from rare earth doped tellurite thin film photonic crystals

    E-print Network

    Vanhoutte, Michiel

    Broadband and anisotropic light emission from rare-earth doped tellurite thin films is demonstrated using Er[superscript 3+]-TeO[subscript 2] photonic crystals (PhCs). By adjusting the PhC parameters, photoluminescent light ...

  17. Faraday Rotation in Rare-Earth Doped Glasses and Nanocrystalline II-VI Semiconductor Composites

    Microsoft Academic Search

    Joseph H. Kratzer; John Schroeder; Kristin A. Vogel; David B. Hall

    2001-01-01

    We have measured Faraday rotation in glasses doped with rare earth oxides. The base glass before doping consisted of 25Na2O.75SiO2. Faraday rotation studies were also done on Selected II-VI semiconductor nanocrystals contained in a glass composite. The quantum dots in these samples had average diameters from about 2 nm to 7 nm. The glass doped with Terbium oxide showed the

  18. Synthesized rare-earth doped oxide glasses for nonlinear optics

    NASA Astrophysics Data System (ADS)

    Kityk, I. V.; Wasylak, J.; Benet, S.; Dorosz, D.; Kucharski, J.; Krasowski, J.; Sahraoui, B.

    2002-09-01

    Photostimulated nonlinear optical effects in synthesized PbO-Ga2O3-Bi2O3-CdO (PGBC) glasses doped by Yb3+, Er3+, and Dy3+ rare-earth (RE3+) ions were discovered. Temperature-dependent measurements of optical photoinduced second-harmonic generation (PISHG) and two-photon absorption were performed in the infrared (IR) range. CO pulse laser (lambda=5.5 mum, energy power density up to 3.8 GW/cm2 per pulse) was applied as a source of IR-photoinducing and probing (fundamental) light. Absolute values of the PISHG were more than 22% higher than corresponding values obtained for other glasses: As2Te3-CaCl2-PbCl2 1 or Sb2Se3-BaCl2-PbCl2 2 type. The investigated PGBC system possesses a shorter time response (about 18 ps), compared with other IR nonlinear optical glasses. We have also established that all nonlinear optical susceptibilities are dependent on the type of RE3+ ion. A maximal value of the PISHG is achieved for the glasses doped by Yb3+. The PISHG values increase significantly below 25 K. We have carried out ab initio molecular dynamics and quantum chemical simulations in order to evaluate the possible contribution of electron-phonon anharmonic interactions in the observed phenomena. We have modeled the influence of the external CO photoinduced beam through the photoinduced anharmonic electron-phonon interactions. A decrease of the delaying time response is achieved. To obtain independent confirmation of the observed dependencies, we have carried out measurements of the epsilon2)(E during the external IR pumping. We have also compared the measured and theoretically calculated dependencies of the IR-induced effects.

  19. Physical and electrochemical properties of alkaline earth doped, rare earth vanadates

    SciTech Connect

    Adijanto, Lawrence, E-mail: adijanto@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States); Balaji Padmanabhan, Venu, E-mail: venub@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States); Holmes, Kevin J., E-mail: kholmes@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States); Gorte, Raymond J., E-mail: gorte@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States); Vohs, John M., E-mail: vohs@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, 220 South 33rd Street 311A Towne Building, University of Pennsylvania Philadelphia, PA 19104-6315 (United States)

    2012-06-15

    The effect of partial substitution of alkaline earth (AE) ions, Sr{sup 2+} and Ca{sup 2+}, for the rare earth (RE) ions, La{sup 3+}, Ce{sup 3+}, Pr{sup 3+}, and Sm{sup 3+}, on the physical properties of REVO{sub 4} compounds were investigated. The use of the Pechini method to synthesize the vanadates allowed for high levels of AE substitution to be obtained. Coulometric titration was used to measure redox isotherms for these materials and showed that the addition of the AE ions increased both reducibility and electronic conductivity under typical solid oxide fuel cell (SOFC) anode conditions, through the formation of compounds with mixed vanadium valence. In spite of their high electronic conductivity, REVO{sub 4}-yttira stabilized zirconia (YSZ) composite anodes exhibited only modest performance when used in SOFCs operating with H{sub 2} fuel at 973 K due to their low catalytic activity. High performance was obtained, however, after the addition of a small amount of catalytically active Pd to the anode. - Graphical abstract: Coulometric titration isotherms for ({open_square}) LaVO{sub 4}, ( White-Circle ) PrVO{sub 4}, ( Lozenge ) CeVO{sub 4}, ( Black-Up-Pointing-Triangle ) Ce{sub 0.7}Sr{sub 0.3}VO{sub 3.85}, and ( Black-Square ) Ce{sub 0.7}Ca{sub 0.3}VO{sub 3.85}, at 973 K. Highlights: Black-Right-Pointing-Pointer Infiltration procedures were used to prepare SOFC anodes from various vanadates. Black-Right-Pointing-Pointer Doping of Alkaline Earth to Rare Earth Vanadates showed to improve conductivity and chemical stability. Black-Right-Pointing-Pointer Alkaline Earth Doped Rare Earth Vanadates-YSZ composites showed conductivities as high as 5 S cm{sup -1} at 973 K. Black-Right-Pointing-Pointer As with other ceramic anodes, the addition of a catalyst was required to achieve low anode impedance.

  20. VISIBLE AND INFRARED RARE-EARTH ACTIVATED ELECTROLUMINESCENCE FROM ERBIUM DOPED GaN

    E-print Network

    Steckl, Andrew J.

    temperature visible and IR light electroluminescence (EL) has been obtained from Er-doped GaN Schottky barrierVISIBLE AND INFRARED RARE-EARTH ACTIVATED ELECTROLUMINESCENCE FROM ERBIUM DOPED GaN M. Garter*, R-unity power law dependence on bias current. An external quantum efficiency of 0.1% has also been demonstrated

  1. Mixedness determination of rare earth-doped ceramics

    NASA Astrophysics Data System (ADS)

    Czerepinski, Jennifer H.

    The lack of chemical uniformity in a powder mixture, such as clustering of a minor component, can lead to deterioration of materials properties. A method to determine powder mixture quality is to correlate the chemical homogeneity of a multi-component mixture with its particle size distribution and mixing method. This is applicable to rare earth-doped ceramics, which require at least 1-2 nm dopant ion spacing to optimize optical properties. Mixedness simulations were conducted for random heterogeneous mixtures of Nd-doped LaF3 mixtures using the Concentric Shell Model of Mixedness (CSMM). Results indicate that when the host to dopant particle size ratio is 100, multi-scale concentration variance is optimized. In order to verify results from the model, experimental methods that probe a mixture at the micro, meso, and macro scales are needed. To directly compare CSMM results experimentally, an image processing method was developed to calculate variance profiles from electron images. An in-lens (IL) secondary electron image is subtracted from the corresponding Everhart-Thornley (ET) secondary electron image in a Field-Emission Scanning Electron Microscope (FESEM) to produce two phases and pores that can be quantified with 50 nm spatial resolution. A macro was developed to quickly analyze multi-scale compositional variance from these images. Results for a 50:50 mixture of NdF3 and LaF3 agree with the computational model. The method has proven to be applicable only for mixtures with major components and specific particle morphologies, but the macro is useful for any type of imaging that produces excellent phase contrast, such as confocal microscopy. Fluorescence spectroscopy was used as an indirect method to confirm computational results for Nd-doped LaF3 mixtures. Fluorescence lifetime can be used as a quantitative method to indirectly measure chemical homogeneity when the limits of electron microscopy have been reached. Fluorescence lifetime represents the compositional fluctuations of a dopant on the nanoscale while accounting for billions of particles in a fast, non-destructive manner. The significance of this study will show how small-scale fluctuations in homogeneity limit the optimization of optical properties, which can be improved by the proper selection of particle size and mixing method.

  2. Rare-earth-doped materials for applications in quantum information storage and signal processing

    Microsoft Academic Search

    C. W. Thiel; Thomas Böttger; R. L. Cone

    2011-01-01

    Realization of practical quantum memory and optical signal processing systems critically depends on suitable materials that offer specific combinations of properties. Solid-state materials such as rare-earth ions doped into dielectric crystals are one of the most promising candidates for several quantum information storage protocols, including quantum storage of single photons. This article provides an overview of rare-earth-doped material properties and

  3. Roadmap: Integrated Science -Earth Science Bachelor of Science in Education

    E-print Network

    Sheridan, Scott

    11040 Earth Dynamics 3 C Fulfills Kent Core Basic Sciences GEOL 11041 Earth Dynamics Laboratory 1 C Society 3 C GEOL 11042 Earth History 3 C Fulfills Kent Core Basic Sciences GEOL 11043 Earth HistoryRoadmap: Integrated Science - Earth Science ­ Bachelor of Science in Education [EH

  4. Earth System Science at Cornell Earth system sciences looks at the integrated whole of the planet,

    E-print Network

    Angenent, Lars T.

    Earth System Science at Cornell Earth system sciences looks at the integrated whole of the planet for earth system science range from nm to 1000's of kilometers. Advancing earth system science requires whose work contributes to an understanding of earth system science. We think that organizing ourselves

  5. Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

    PubMed Central

    Hao, Shuwei; Chen, Guanying; Yang, Chunhui

    2013-01-01

    Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit. PMID:23650480

  6. DIPOLE ORIENTATION EFFECTS IN RARE-EARTH DOPED CdF, R. CAPELLETTI, F. FERMI and E. OKUNO (*)

    E-print Network

    Boyer, Edmond

    DIPOLE ORIENTATION EFFECTS IN RARE-EARTH DOPED CdF, R. CAPELLETTI, F. FERMI and E. OKUNO (*) Gruppo in the tempera- ture range 80-200 K shows ~~nequivocallythat n. 11. Rare Earth-Fluorine Interstitial (RE known that rare earth doped CaF, shows two well delined 1TC peaks [8], [9] due to orientation of RE

  7. Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions.

    E-print Network

    Boyer, Edmond

    Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions. C. Mansuy-669" DOI : 10.1016/j.tsf.2005.12.235 #12;Abstract Rare earth doped LuBO3 thin films have been prepared, 81.20. Fw, Keywords : Sol-Gel, Scintillators, XPS, RBS, Rare earth ions, Luminescence hal-00154764

  8. Towards atomic scale engineering of rare-earth-doped SiAlON ceramics through aberration-corrected scanning transmission

    E-print Network

    Pennycook, Steve

    Towards atomic scale engineering of rare-earth-doped SiAlON ceramics through aberration visualization of rare earths in a- and b-SiAlON unit-cells is performed through Z-contrast imaging technique kinds of rare-earth-doped materials. Ó 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights

  9. Enhanced blue and green emission in rare-earth-doped GaN electroluminescent devices by optical photopumping

    E-print Network

    Steckl, Andrew J.

    to the infrared IR . Applications for rare-earth RE ELDs range from visible flat panel displays FPD to sourcesEnhanced blue and green emission in rare-earth-doped GaN electroluminescent devices by optical from rare-earth-doped GaN GaN:RE EL devices ELD emission has been observed to be greatly enhanced

  10. In vivo demonstration of enhanced radiotherapy using rare earth doped titania nanoparticles

    NASA Astrophysics Data System (ADS)

    Townley, Helen E.; Kim, Jeewon; Dobson, Peter J.

    2012-07-01

    Radiation therapy is often limited by damage to healthy tissue and associated side-effects; restricting radiation to ineffective doses. Preferential incorporation of materials into tumour tissue can enhance the effect of radiation. Titania has precedent for use in photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon photoexcitation, but is limited by the penetration depth of UV light. Optimization of a nanomaterial for interaction with X-rays could be used for deep tumour treatment. As such, titania nanoparticles were doped with gadolinium to optimize the localized energy absorption from a conventional medical X-ray, and further optimized by the addition of other rare earth (RE) elements. These elements were selected due to their large X-ray photon interaction cross-section, and potential for integration into the titania crystal structure. Specific activation of the nanoparticles by X-ray can result in generation of ROS leading to cell death in a tumour-localized manner. We show here that intratumoural injection of RE doped titania nanoparticles can enhance the efficacy of radiotherapy in vivo.Radiation therapy is often limited by damage to healthy tissue and associated side-effects; restricting radiation to ineffective doses. Preferential incorporation of materials into tumour tissue can enhance the effect of radiation. Titania has precedent for use in photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon photoexcitation, but is limited by the penetration depth of UV light. Optimization of a nanomaterial for interaction with X-rays could be used for deep tumour treatment. As such, titania nanoparticles were doped with gadolinium to optimize the localized energy absorption from a conventional medical X-ray, and further optimized by the addition of other rare earth (RE) elements. These elements were selected due to their large X-ray photon interaction cross-section, and potential for integration into the titania crystal structure. Specific activation of the nanoparticles by X-ray can result in generation of ROS leading to cell death in a tumour-localized manner. We show here that intratumoural injection of RE doped titania nanoparticles can enhance the efficacy of radiotherapy in vivo. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30769c

  11. Rare-earth-ion-doped waveguide lasers on a silicon chip

    NASA Astrophysics Data System (ADS)

    Pollnau, Markus

    2015-03-01

    Rare-earth-ion-doped materials are of high interest as amplifiers and lasers in integrated optics. Their longer excited-state lifetimes and the weaker refractive-index change accompanied with rare-earth-ion excitation compared to electron-hole pairs in III-V semiconductors provide spatially and temporally stable optical gain, allowing for high-speed amplification and narrow-linewidth lasers. Amorphous Al2O3 deposited onto thermally oxidized silicon wafers offers the advantage of integration with silicon photonics and electronics. Layer deposition by RF reactive co-sputtering and micro-structuring by chlorine-based reactive-ion etching provide low-loss channel waveguides. With erbium doping, we improved the gain to 2 dB/cm at 1533 nm and a gain bandwidth of 80 nm. The gain is limited by migration-accelerated energy-transfer upconversion and a fast quenching process. Since stimulated emission is even faster than this quenching process, lasers are only affected in terms of their threshold, allowing us to demonstrate diode-pumped micro-ring, distributed-feedback (DFB), and distributed-Bragg-reflector (DBR) lasers in Al2O3:Er3+ and Al2O3:Yb3+ on a silicon chip. Surface-relief Bragg gratings were patterned by laser-interference lithography. Monolithic DFB and DBR cavities with Q-factors of 1.35×106 were realized. In an Er-doped DFB laser, single-longitudinal-mode operation at 1545 nm was achieved with a linewidth of 1.7 kHz, corresponding to a laser Q-factor of 1.14×1011. Yb-doped DFB and DBR lasers were demonstrated at 1020 nm with output powers of 55 mW and a slope efficiency of 67% versus launched pump power. A dual-phaseshift, dual-wavelength laser was achieved and a stable microwave signal at ~15 GHz was created via the heterodyne photo-detection of the two laser wavelengths.

  12. Influence of Rare Earth Doping on the Structural and Catalytic Properties of Nanostructured Tin Oxide

    NASA Astrophysics Data System (ADS)

    Fajardo, Humberto V.; Longo, Elson; Probst, Luiz F. D.; Valentini, Antoninho; Carreño, Neftalí L. V.; Nunes, Michael R.; Maciel, Adeilton P.; Leite, Edson R.

    2008-05-01

    Nanoparticles of tin oxide, doped with Ce and Y, were prepared using the polymeric precursor method. The structural variations of the tin oxide nanoparticles were characterized by means of nitrogen physisorption, carbon dioxide chemisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The synthesized samples, undoped and doped with the rare earths, were used to promote the ethanol steam reforming reaction. The SnO2-based nanoparticles were shown to be active catalysts for the ethanol steam reforming. The surface properties, such as surface area, basicity/base strength distribution, and catalytic activity/selectivity, were influenced by the rare earth doping of SnO2 and also by the annealing temperatures. Doping led to chemical and micro-structural variations at the surface of the SnO2 particles. Changes in the catalytic properties of the samples, such as selectivity toward ethylene, may be ascribed to different dopings and annealing temperatures.

  13. Influence of Rare Earth Doping on the Structural and Catalytic Properties of Nanostructured Tin Oxide

    PubMed Central

    2008-01-01

    Nanoparticles of tin oxide, doped with Ce and Y, were prepared using the polymeric precursor method. The structural variations of the tin oxide nanoparticles were characterized by means of nitrogen physisorption, carbon dioxide chemisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The synthesized samples, undoped and doped with the rare earths, were used to promote the ethanol steam reforming reaction. The SnO2-based nanoparticles were shown to be active catalysts for the ethanol steam reforming. The surface properties, such as surface area, basicity/base strength distribution, and catalytic activity/selectivity, were influenced by the rare earth doping of SnO2and also by the annealing temperatures. Doping led to chemical and micro-structural variations at the surface of the SnO2particles. Changes in the catalytic properties of the samples, such as selectivity toward ethylene, may be ascribed to different dopings and annealing temperatures.

  14. DFT Calculations using WIEN2K to determine oxygen defect structure of rare earth doped ceria

    E-print Network

    Khalife, Ali Rida

    2014-01-01

    We perform density functional calculations using the program WIEN2K in order to study oxygen vacancies in rare earth doped ceria. The calculation for all rare earth elements were prepared, however only those foe Cadmium and Europium were performed due to lack of time. Also a short description of my stay at CERN was presented

  15. Special glassy materials doped with rare-earth elements for fiber optics

    Microsoft Academic Search

    Jan Wasylak; Dominik Dorosz; Jan Kucharski; Jan Kityk

    2003-01-01

    Lead-bismuth-gallium-cadmium glasses doped with rare earths elements have been investigated. Certain optical properties of the glasses have been determined. The results of luminescence investiations in the form of absorption and luminescence spectra are presented, and the quantum yields as well as the calculated and measured luminescence lifetimes of the particular rare earths elements in the matrix of the examined glasses

  16. Thermoluminescent spectra of rare earth doped MgB4O7 dosemeters.

    PubMed

    Karali, T; Rowlands, A P; Prokic, M; Townsend, P D; Halmagean, E

    2002-01-01

    This paper presents X ray excited TL spectra of magnesium borate doped with either single rare earth ions Dy or Tm, or co-doped with Dy/Tm, Tm/Mn or Dy/Tb. Intrinsic emission from the host material is in the UV/blue region at approximately 375 nm, with a tail extending to 200 nm. The main dosimetric peak is detected at approximately 180 degrees C but slight differences are noted between the glow peak maxima from the different rare earth ions and there were changes following thermal treatments. The results are discussed according to the interaction between trapping and rare earth sites. PMID:12382891

  17. Origin of enhanced magnetization in rare earth doped multiferroic bismuth ferrite

    SciTech Connect

    Nayek, C.; Thirmal, Ch.; Murugavel, P., E-mail: muruga@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 36 (India); Tamilselvan, A.; Balakumar, S. [National Centre for Nanoscience and Nanotechnology, University of Madras, Chennai 25 (India)

    2014-02-21

    We report structural and magnetic properties of rare earth doped Bi{sub 0.95}R{sub 0.05} FeO{sub 3} (R?=?Y, Ho, and Er) submicron particles. Rare earth doping enhances the magnetization and the magnetization shows an increasing trend with decreasing dopant ionic radii. In contrast to the x-ray diffraction pattern, we have seen a strong evidence for the presence of rare earth iron garnets R{sub 3}Fe{sub 5}O{sub 12} in magnetization measured as a function of temperature, in selected area electron diffraction, and in Raman measurements. Our results emphasised the role of secondary phases in the magnetic property of rare earth doped BiFeO{sub 3} compounds along with the structural distortion favoring spin canting by increase in Dzyaloshinskii-Moriya exchange energy.

  18. Integrated Instrument Simulator Suites for Earth Science

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Tao, Wei-Kuo; Matsui, Toshihisa; Hostetler, Chris; Hair, Johnathan; Butler, Carolyn; Kuo, Kwo-Sen; Niamsuwan, Noppasin; Johnson, Michael P.; Jacob, Joseph C.; Tsang, Leung; Shams, Khawaja; Jaruwatanadilok, Sermsak; Oveisgharan, Shadi; Simard, Marc; Turk, Francis J.

    2012-01-01

    The NASA Earth Observing System Simulators Suite (NEOS3) is a modular framework of forward simulations tools for remote sensing of Earth's Atmosphere from space. It was initiated as the Instrument Simulator Suite for Atmospheric Remote Sensing (ISSARS) under the NASA Advanced Information Systems Technology (AIST) program of the Earth Science Technology Office (ESTO) to enable science users to perform simulations based on advanced atmospheric and simple land surface models, and to rapidly integrate in a broad framework any experimental or innovative tools that they may have developed in this context. The name was changed to NEOS3 when the project was expanded to include more advanced modeling tools for the surface contributions, accounting for scattering and emission properties of layered surface (e.g., soil moisture, vegetation, snow and ice, subsurface layers). NEOS3 relies on a web-based graphic user interface, and a three-stage processing strategy to generate simulated measurements. The user has full control over a wide range of customizations both in terms of a priori assumptions and in terms of specific solvers or models used to calculate the measured signals.This presentation will demonstrate the general architecture, the configuration procedures and illustrate some sample products and the fundamental interface requirements for modules candidate for integration.

  19. Upconversion-pumped luminescence efficiency of rare-earth-doped hosts sensitized with trivalent ytterbium

    SciTech Connect

    Page, R.H.; Schaffers, K.I.; Waide, P.A.; Tassano, J.B.; Payne, S.A.; Kruplce, W.F.; Bischel, W.K. [Gemfire Corporation, Palo Alto, CA (United States)

    1997-07-26

    We discuss the upconversion luminescence efficiencies of phosphors that generate red, green, and blue light. The phosphors studied are single crystals and powders co-doped with Er{sup 3+} and Yb{sup 3+}, and with Tm{sup 3+} and Yb{sup 3+}. The Yb ions are pumped near 980 nm; transfers of two or three quanta to the co-doped rare earth ion generate visible luminescence. The main contribution embodied in this work is the quantitative measurement of this upconversion efficiency, based on the use of a calibrated integrating sphere, determination of the fraction of pump light absorbed, and careful control of the pump laser beam profile. The green phosphors are the most efficient, yielding efficiency values as high as 4 %, with the red and blue materials giving 1 - 2 %. Saturation was observed in all cases, suggesting that populations of upconversion steps of the ions are maximized at higher power. Quasi-CW modeling of the intensity- dependent upconversion efficiency was attempted; input data included level lifetimes, transition cross sections, and cross-relaxation rate coefficients. The saturation of the Yb,Er:fluoride media is explained as the pumping of Er{sup 3+} ions into a bottleneck (long-lived state)- the {sup 4}I{sub 13/2} metastable level, making them unavailable for further excitation transfer. 32 refs., 5 figs., 3 tabs.

  20. In vivo demonstration of enhanced radiotherapy using rare earth doped titania nanoparticles.

    PubMed

    Townley, Helen E; Kim, Jeewon; Dobson, Peter J

    2012-08-21

    Radiation therapy is often limited by damage to healthy tissue and associated side-effects; restricting radiation to ineffective doses. Preferential incorporation of materials into tumour tissue can enhance the effect of radiation. Titania has precedent for use in photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon photoexcitation, but is limited by the penetration depth of UV light. Optimization of a nanomaterial for interaction with X-rays could be used for deep tumour treatment. As such, titania nanoparticles were doped with gadolinium to optimize the localized energy absorption from a conventional medical X-ray, and further optimized by the addition of other rare earth (RE) elements. These elements were selected due to their large X-ray photon interaction cross-section, and potential for integration into the titania crystal structure. Specific activation of the nanoparticles by X-ray can result in generation of ROS leading to cell death in a tumour-localized manner. We show here that intratumoural injection of RE doped titania nanoparticles can enhance the efficacy of radiotherapy in vivo. PMID:22767269

  1. Synthesis and optical properties of sub-micron sized rare earth-doped zirconia particles

    Microsoft Academic Search

    I. Freris; P. Riello; F. Enrichi; D. Cristofori; A. Benedetti

    2011-01-01

    Sub-micron sized crystalline particles of Eu3+ and Er3+-doped zirconia (ZrO2) were prepared via a wet chemical sol–gel route and post synthesis annealing. The doping was achieved by introduction of the respective rare earth salts into the zirconia precursor solution, with insitu generation of sodium chloride for stabilization of the particle surface during growth. A series of materials with differing europium

  2. TOPICAL REVIEW: Ferromagnetic nitride-based semiconductors doped with transition metals and rare earths

    Microsoft Academic Search

    A. Bonanni

    2007-01-01

    This review summarizes the state-of-the-art in the search for room temperature ferromagnetic semiconductors based on transition-metal- and rare-earth-doped nitrides. The major methods of synthesis are reported, together with an overview of the magnetic, structural, electrical and optical characterization of the materials systems, where available. The controversial experimental results concerning the actual value of the apparent Curie temperature in magnetically doped

  3. Synthesis and Photoresponse of Rare-Earth-Doped Phosphosilicates

    SciTech Connect

    Cao, Z.; Lee, Burtrand I.; Samuels, William D.; Exarhos, Gregory J.

    1998-12-14

    Phosphate ceramics doped with Tb3+ ions were synthesized through Sol-Gel process (SGP). the emission intensity as a function of various factors such as matrix composition, crystal structure, particle size, dopant concentration, and synthesis conditions was investigated.

  4. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles

    E-print Network

    Derom, S; Pillonnet, A; Benamara, O; Jurdyc, A M; Girard, C; Francs, G Colas des

    2013-01-01

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) are achieved by tuning either the dipolar or quadrupolar particle resonance to the rare earth ions excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved.

  5. Interfacing superconducting qubits and telecom photons via a rare-earth-doped crystal.

    PubMed

    O'Brien, Christopher; Lauk, Nikolai; Blum, Susanne; Morigi, Giovanna; Fleischhauer, Michael

    2014-08-01

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of ? pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare-earth doped crystals, we make use of a special transfer protocol using staggered ? pulses. We predict total transfer efficiencies on the order of 90%. PMID:25148328

  6. Interfacing Superconducting Qubits and Telecom Photons via a Rare-Earth-Doped Crystal

    NASA Astrophysics Data System (ADS)

    O'Brien, Christopher; Lauk, Nikolai; Blum, Susanne; Morigi, Giovanna; Fleischhauer, Michael

    2014-08-01

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of ? pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare-earth doped crystals, we make use of a special transfer protocol using staggered ? pulses. We predict total transfer efficiencies on the order of 90%.

  7. Interfacing Superconducting Qubits and Telecom Photons via a Rare-Earth Doped Crystal

    E-print Network

    Christopher O'Brien; Nikolai Lauk; Susanne Blum; Giovanna Morigi; Michael Fleischhauer

    2014-07-25

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of $\\pi$-pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare earth doped crystals, we make use of a special transfer protocol using staggered $\\pi$-pulses. We predict total transfer efficiencies on the order of 90%.

  8. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles.

    PubMed

    Derom, S; Berthelot, A; Pillonnet, A; Benamara, O; Jurdyc, A M; Girard, C; Colas des Francs, G

    2013-12-13

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare earth ion's excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved. PMID:24231223

  9. Laser induced breakdown spectroscopy diagnosis of rare earth doped optical glasses

    SciTech Connect

    Dwivedi, Y.; Thakur, S. N.; Rai, S. B.

    2010-05-01

    In the present work, rare earth (Nd, Eu, Er, Ho) doped oxyfluoroborate glasses were studied using laser induced breakdown spectroscopy (LIBS) technique. It has been observed that rare earth elements other than the doped one also reveal their presence in the spectrum. In addition the spectral lines of elements constituting the glass matrix have also been observed. Different plasma parameters such as plasma temperature and electron density have been estimated. It is concluded that the LIBS is a potential technique to identify simultaneously the light elements (B, O, F) as well as the heavy elements (Fe, Ba, Ca, Eu, Nd, Ho, Er) present in optical glasses.

  10. Magnetic-field effect on the phonon echoes in a rare-earth-doped glass F. Lerbet and G. Bellessa

    E-print Network

    Boyer, Edmond

    observed phonon echoes in a holmium-doped aluminosilica glass, down to 10 mK, up to 60 kOe, in the acoustic.50K Photon echoes in a rare-earth-doped glass have shown that the optical dephasing rates are enhanced1251 Magnetic-field effect on the phonon echoes in a rare-earth-doped glass F. Lerbet and G

  11. Rare-earth doping of the Mo 3Se 4 superconductor

    Microsoft Academic Search

    F. Le Berre; D. Tshimanga; A.-L. Guilloux; J. Leclercq; M. Sergent; O. Peña; R. Horyn; A. Wojakowski

    1996-01-01

    Superconducting properties of the binary Chevrel phase Mo3Se4 have been modified by rare-earth doping. Very small quantities of lanthanides make the Tc of this compound to increase by almost 1 K (from 6.45 to 7.2 K) for the bigger ions, while no effects are seen for heavy rare earths (smaller ions). A clear correlation has been established between Tc and

  12. UV and gamma-ray excited luminescence of cerium-doped rare-earth oxyorthosilicates

    Microsoft Academic Search

    H. Suzuki; T. A. Tombrello; C. L. Melcher; J. S. Schweitzer

    1992-01-01

    Gamma-ray and UV-excitation of cerium-doped rare-earth oxyorthosilicates (RE = Y, Gd, and Lu) has been used to investigate the emission mechanism for this family of scintillators. The data clearly indicate the presence of two different luminescence centers, which are attributed to cerium substitution in the two different rare-earth crystallographic sites. While this model explains much of the present and previous

  13. Sol-Gel synthesis of an optical silica glass doped with rare-earth elements

    Microsoft Academic Search

    N. N. Khimich; G. M. Berdichevskii; E. N. Poddenezhnyi; V. V. Golubkov; A. A. Boiko; V. M. Ken’ko; O. B. Evreinov; L. A. Koptelova

    2007-01-01

    An optical quality silica glass doped with Er3+, Yb3+ and Lu3+ ions is synthesized by the sol-gel method. Virtually unavoidable clusterization of rare-earth elements that occurs upon introduction\\u000a of lanthanide salts into a sol-gel system and leads to concentration quenching of luminescence of the glass is eliminated\\u000a through the use of rare-earth phosphate complexes that are chemically bound to the

  14. Rare-earth-doped GaN: growth, properties, and fabrication of electroluminescent devices

    Microsoft Academic Search

    Andrew J. Steckl; Jason C. Heikenfeld; Dong-Seon Lee; Michael J. Garter; Christopher C. Baker; Yongqiang Wang; Robert Jones

    2002-01-01

    A review is presented of the fabrication, operation, and applications of rare-earth-doped GaN electroluminescent devices (ELDs). GaN:RE ELDs emit light due to impact excitation of the rare earth (RE) ions by hot carriers followed by radiative RE relaxation. By appropriately choosing the RE dopant, narrow linewidth emission can be obtained at selected wavelengths from the ultraviolet to the infrared. The

  15. Earth’s Nearest Neighbors: Dynamical integrations of NEO-Earth approaches in support of MANOS

    NASA Astrophysics Data System (ADS)

    Endicott, Thomas; Moskovitz, Nicholas; Binzel, Richard; Polishook, David; Burt, Brian

    2014-11-01

    The Mission Accessible Near-Earth Object Survey (MANOS) began in August 2013 as a multi-year physical characterization survey that was awarded large survey status by NOAO. MANOS will target several hundred mission-accessible NEOs across visible and near-infrared wavelengths, ultimately providing a comprehensive catalog of physical properties (astrometry, light curves, spectra). In support of this telescopic survey, we are performing a suite of orbital integrations to investigate the dynamical evolution of the near-Earth asteroid population.Using orbital information from the Lowell Observatory AstOrb database and the swift orbital integration package, we compute the orbital history of every known NEO from present day to five hundred thousand years in the past. This orbital history is used to identify the temporal evolution of each NEO's minimum orbital intersection distance (MOID) value, quantifying the physical distance between the orbits of a given NEO and that of a terrestrial planet. Due to the non-deterministic behavior of many NEO orbits beyond a few hundred years, these integrated MOIDs do not uniquely determine whether an NEO and a planet will actually encounter one another, bur rather provide a probabilistic metric for the proximity in which two objects can encounter one another. Integrated MOIDs can be a useful tool for correlating measured physical properties with high probabilities of planetary encounters (e.g. Binzel et al. 2010, Nature 463, 331).We will present the status of these orbital integrations. These integrations show a variety of dynamical histories, from objects that are stable over the integration limits to those that show chaotic behavior after approximately fifty to one hundred thousand years. These orbital integrations are being used to track the potentially hazardous object (PHA) population over time, to evaluate dynamical history for both specific objects and NEO sub-populations, and to estimate the evolution of NEO surface temperatures due to changing perihelion distances.

  16. Modeling rare-earth doped microfiber ring lasers.

    PubMed

    Li, Yuhang; Vienne, Guillaume; Jiang, Xiaoshun; Pan, Xinyun; Liu, Xu; Gu, Peifu; Tong, Limin

    2006-08-01

    We propose a compact laser configuration based on resonating both the pump and signal light along a microfiber ring doped with active ions. We estimate the minimum Q-factor to obtain lasing and find that values already demonstrated in passive microfiber rings will be sufficient. We model the performance of this device in steady state using rate equations and show that pump resonance can significantly reduce the threshold and increase the quantum efficiency, especially for rings made of materials with weak active ion absorption. Numerical examples for erbium and ytterbium doped devices are presented. Taking into account scattering and coupling losses the optimum pump coupling factor is calculated. The dependences of the quantum efficiency and threshold power on the coupling losses are also investigated. We predict that efficient ytterbium-doped lasers can be obtained with a ring diameter down to a few tens of micrometers. PMID:19529078

  17. Fluorescence in rare earth-doped fluorozirconate fibers

    SciTech Connect

    Saissy, A.; Ostrowsky, D.B. (University of Nice, Laboratory for the Physics of Condensed Matter, U.A. 190, Parc Valrose, F-06034 Nice Cedex, France (FR)); Maze, G. (Le Verre Fluore S. A., ZI due Champ Martin, Vernsur-Seiche, F-35230 Saint Erblon, France (FR))

    1991-05-20

    Spontaneous fluorescence band of erbium-, holmium-, and thulium-doped fluorozirconate fibers are studied experimentally and theoretically. From experimental data and for each trivalent ion we identify the set of optical transitions that gives rise to the observed linear fluorescence and unconversion process. Fiber perturbation theory and density matrix formalism are used to model fluorescence spectra with particular attention to modal structure, loss, and mode coupling in the fiber. The relationship between the experimental emission spectrum of thulium-doped fiber and the theoretical model is discussed.

  18. Numerical simulations of the optical gain of crystalline fiber doped by rare earth and transition ion

    NASA Astrophysics Data System (ADS)

    Daoui, A. K.; Boubir, B.; Adouane, A.; Demagh, N.; Ghoumazi, M.

    2015-02-01

    A fiber laser is a laser whose gain medium is a doped fiber, although lasers whose cavity is made wholly of fibers have also been called fiber lasers. The gain media in a fiber laser is usually fiber doped with rare-earth ions, such as erbium (Er), neodymium (Nd), ytterbium (Yb), thulium (Tm), or praseodymium (Pr), which is doped into the core of the optical fiber, similar to those used to transmit telecommunications signals. Fiber lasers find many applications in materials processing, including cutting, welding, drilling, and marking metal. To maximize their market penetration, it is necessary to increase their output power. In this work, we present a detailed study based on the numerical simulation using MATLAB, of one of the principal characteristics of a fiber laser doped with rare earth ions and transition ion. The gain depends on several parameters such as the length of the doped fiber, the density, the pump power, noise, etc.). The used program resolves the state equations in this context together with those governing the light propagation phenomena. The developed code can also be used to study the dynamic operating modes of a doped fiber laser.

  19. Infrared spectroscopy of rare-earth-doped CaFe2As2

    NASA Astrophysics Data System (ADS)

    Xing, Zhen; Huffman, T. J.; Xu, Peng; Qazilbash, M. M.; Saha, S. R.; Drye, Tyler; Paglione, J.

    2014-03-01

    Recently, rare-earth doping in CaFe2As2 has been used to tune its electronic, magnetic, and structural properties. The substitution of rare-earth ions at the alkaline-earth sites leads to the suppression of the spin-density wave (SDW) phase transition in CaFe2As2. For example, Pr substitution results in a paramagnetic metal in the tetragonal phase that is susceptible to a low temperature structural transition to a collapsed tetragonal phase. However, La-doped CaFe2As2 remains in the uncollapsed tetragonal structure down to the lowest measured temperatures. Both the uncollapsed and collapsed tetragonal structures exhibit superconductivity with maximum Tc reaching 47 K, the highest observed in inter-metallics albeit with a small superconducting volume fraction. In this work, we perform ab-plane infrared spectroscopy of rare-earth-doped CaFe2As2 at different cryogenic temperatures. Our aim is to ascertain the contributions of electron doping and chemical pressure to the charge and lattice dynamics of this iron-arsenide system.

  20. Optical and structural properties of rare earth doped GaN quantum dots

    Microsoft Academic Search

    T. Andreev; Y. Hori; X. Biquard; E. Monroy; D. Jalabert; A. Farchi; M. Tanaka; O. Oda; Le Si Dang; B. Daudin

    2004-01-01

    We have studied the structural and optical properties of GaN quantum dots (QDs) doped with Tm and Eu. It has been found that the morphology of the dots was affected by the presence of the rare earth atoms. Differences in incorporation have also been pointed out, Eu being located inside the QDs while Tm is more likely to be found

  1. Resonant photosensitivity in rare-earth-doped glasses and optical fibers

    Microsoft Academic Search

    Matthijs M. Broer

    1993-01-01

    An overview is given of permanent changes in the refractive index and optical transmission which occur in some rare earth-doped inorganic glasses and optical fibers when resonantly excited into specific 4f and 5d manifolds. These phenomena are believed to be electronic in nature involving color centers. They are important for both refractive index grating devices as well as for the

  2. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    E-print Network

    Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

    2011-01-01

    Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

  3. Supplementary Information: The Grid ENabled Integrated Earth system modelling (GENIE)

    E-print Network

    Edwards, Neil

    Supplementary Information: The Grid ENabled Integrated Earth system modelling (GENIE) framework T Integrated Earth system modelling (GENIE) frame- work supports modularity (i.e. interchangeable components) and scala- bility (i.e. variable resolution of the components), which aids traceability, meaning the ability

  4. Holeburning in rare earth doped nanoparticles of MgS

    Microsoft Academic Search

    Sameh Dardona; Aras Konjhodzic; Deepika Chhabria; Omer Salihoglu; Zameer Hasan

    2004-01-01

    In this paper we report the optical holeburning in nanoparticles of Eu-doped in MgS. In the form of microparticles and thin films MgS:Eu is known to have very favorable characteristics for spectral holeburning-based memories. Nanoparticles of MgS:Eu have been produced by quench condensing the laser ablated vapors from a solid target. The pressure of the ambient gas in the chamber

  5. Electrodynamics of rare-earth-doped CaFe2As2

    NASA Astrophysics Data System (ADS)

    Xing, Zhen; Huffman, T. J.; Xu, Peng; Hollingshad, A. J.; Brooker, D. J.; Qazilbash, M. M.; Saha, Shanta; Drye, Tyler; Roncaioli, Connor; Paglione, J.

    2015-03-01

    Rare-earth substitution at alkaline-earth sites leads to the suppression of the spin density wave phase transition in CaFe2As2 without the emergence of bulk superconductivity. In this work, we perform cryogenic infrared reflectance spectroscopy and spectroscopic ellipsometry on Pr-doped and La-doped CaFe2As2 single crystals. In both Ca0.8La0.2Fe2As2 and Ca0.85Pr0.15Fe2As2 samples, the spin density wave transition is completely suppressed. The temperature dependence of the ab-plane optical conductivity of the La-doped CaFe2As2 crystal exhibits conventional metallic behavior consistent with the absence of any structural, magnetic, or superconducting instabilities. On the other hand, the Pr-doped CaFe2As2 crystal undergoes a structural transition about 70 K from a tetragonal lattice to a collapsed tetragonal lattice with the same symmetry but reduced volume. In the Pr-doped CaFe2As2 crystal, the ab-plane optical conductivity reveals subtle but distinct spectral changes upon cooling through the structural transition. We provide results on the influence of the structural collapse on the charge dynamics, correlation effects and the electronic configuration. This work was supported by NASA / Virginia Space Grant Consortium.

  6. Ferromagnetism and Photoluminescence in Rare-Earth doped GaN via Diffusion

    NASA Astrophysics Data System (ADS)

    Luen, M. Oliver; Nepal, N.; Bedair, S. M.; Zavada, J. M.; Brown, Ei Ei; Hommerich, U.; Frajtag, P.; El-Masry, N. A.

    2009-03-01

    Rare-earth doped GaN is attracting attention both as a diluted magnetic semiconductor (DMS) material and for optical devices useful in communications and multi-color semiconductor display technology. GaN's large band gap (3.4 eV) gives rise to optical transparency over a wide spectral range, from the infrared (IR) to the ultraviolet. These properties make it an optimum host for the various emissions that are possible from rare-earth (RE) ions. Recently, rare-earth doped GaN also has demonstrated above room temperature ferromagnetism. In this study, we report the diffusion of RE (Nd, Sm, Gd and Er) into undoped, Mg-doped and Si-doped GaN templates. Room temperature optical and ferromagnetic properties were studied using photoluminescence (PL) and alternating gradient magnetometer, respectively. Ferromagnetic properties show a preference for undoped and n-type GaN. PL spectra exhibit RE ion inner shell transitions in the visible and infrared regions. The mechanisms for above room temperature ferromagnetism and emission intensity related to the RE concentration, is discussed.

  7. Luminescent dye-doped or rare-earth-doped monodisperse silica nanospheres as efficient labels in DNA microarrays

    NASA Astrophysics Data System (ADS)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Marinello, F.; Schiavuta, P.

    2009-08-01

    Luminescent nanoparticles are gaining more and more interest in bio-labeling and bio-imaging applications, like for example DNA microarray. This is a high-throughput technology used for detection and quantification of nucleic acid molecules and other ones of biological interest. The analysis is resulting by specific hybridization between probe sequences deposited in array and a target ss-DNA usually expressed by PCR and functionalized by a fluorescent dye. These organic labels have well known disadvantages like photobleaching and limited sensitivity. Quantum dots may be used as alternatives, but they present troubles like blinking, toxicity and excitation wavelengths out of the usual range of commercial instruments, lowering their efficiency. Therefore in this work we investigate a different strategy, based on the use of inorganic silica nanospheres incorporating standard luminescent dyes or rare earth doped nanocrystals. In the first case it is possible to obtain a high luminescence emission signal, due to the high number of dye molecules that can be accommodated into each nanoparticle, reduced photobleaching and environmental protection of the dye molecules thanks to the encapsulation in the silica matrix. In the second case, rare earths exhibit narrow emission bands (easy identification), large Stokes shifts (efficient discrimination of excitation and emission) and long luminescence lifetimes (possibility to perform time-delayed analysis) which can be efficiently used for the improvement of signal to noise ratio. The synthesis and characterization of good luminescent silica spheres either by organic dye-doping or by rare-earth-doping are investigated and reported. Moreover, their application in the DNA microarray technology in comparison to the use of standard molecular fluorophores or commercial quantum dots is discussed. The cheap and easy synthesis of these luminescent particles, the stability in water, the surface functionalization and bio-compatibility makes them very promising for present and future applications in bio-labeling and bio-imaging.

  8. A combined DFT + U and Monte Carlo study on rare earth doped ceria.

    PubMed

    Grieshammer, Steffen; Grope, Benjamin O H; Koettgen, Julius; Martin, Manfred

    2014-06-01

    We investigate the dopant distribution and its influence on the oxygen ion conductivity of ceria doped with rare earth oxides by combining density functional theory and Monte Carlo simulations. We calculate the association energies of dopant pairs, oxygen vacancy pairs and between dopant ions and oxygen vacancies by means of DFT + U including finite size corrections. The cation coordination numbers from ensuing Metropolis Monte Carlo simulations show remarkable agreement with experimental data. Combining Metropolis and Kinetic Monte Carlo simulations we find a distinct dependence of the ionic conductivity on the dopant distribution and predict long term degradation of electrolytes based on doped ceria. PMID:24477833

  9. Luminescence properties of rare earth ions doped glasses excited by broadband lights

    NASA Astrophysics Data System (ADS)

    Ren, Linjiao; Lei, Xiaohua; Chen, Weimin; Du, Xiaoqing; Jin, Lei

    2013-09-01

    The experimental excitations for luminescent glasses are usually monochromatic, but LED chips in applications have an emission bandwidth. In order to investigate the luminescence properties of rare earth ions doped glasses excited by broadband lights, a computational model was presented based on the dependences of excitation wavelengths on emission spectra, chromaticity coordinates and correlated color temperatures (CCTs). The simulations were carried out applying Ce/Tb/Eu co-doped calcium borosilicate glasses as examples. The results show that for the same CCTs, the center wavelengths of chips are different with the excitation wavelengths of fluorescence spectrophotometers.

  10. Radioluminescence and thermoluminescence of rare earth element and phosphorus-doped zircon

    SciTech Connect

    Karali, T.; Can, N.; Townsend, P.D.; Rowlands, A.P.; Hanchar, J.M.

    2000-06-01

    The radioluminescence and thermoluminescence spectra of synthetic zircon crystals doped with individual trivalent rare earth element (REE) ions (Pr, Sm, Eu, Gd, Dy, Ho, Er, and Yb) and P are reported in the temperature range 25 to 673 K. Although there is some intrinsic UV/blue emission from the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the REE{sup 3+} states. The shapes of the glow curves are different for each dopant, and there are distinct differences between glow peak temperatures for different rare-earth lines of the same element. Within the overall set of signals there are indications of linear trends in which some glow peak temperatures vary as a function of the ionic size of the rare earth ions. The temperature shifts of the peaks are considerable, up to 200{degree}, and much larger than those cited in other rare-earth-doped crystals of LaF{sub 3} and Bi{sub 4}Ge{sub 3}O{sub 12}. The data clearly suggest that the rare-earth ions are active both in the trapping and luminescence steps, and hence the TL occurs within localized defect complexes that include REE{sup 3+} ions.

  11. Radiation Induced Absorption in Rare Earth Doped Optical Fibers

    Microsoft Academic Search

    M. Lezius; K. Predehl; W. Stower; A. Turler; M. Greiter; Ch. Hoeschen; P. Thirolf; W. Assmann; D. Habs; A. Prokofiev; C. Ekstrom; T. W. Hansch; R. Holzwarth

    2012-01-01

    We have investigated the radiation induced absorption (RIA) of optical fibers with high active ion concentration. Comparing our results to the literature leads us to the conclusion that RIA appears to be only weakly dependent on the rare earth dopant concentration. Instead, co-dopants like Al, Ge, or P and manufacturing processes seem to play the major role for the radiation

  12. Enhanced Thermopower in Nano-SrTiO3 Via Rare Earth Doping

    NASA Astrophysics Data System (ADS)

    Kinemuchi, Yoshiaki; Mimura, Ken-ichi; Kato, Kazumi

    2015-06-01

    Doped perovskite titanates are known to exhibit non-linear electrical conductivity when they are in polycrystalline form. This non-linear behavior is attributed to the barrier potential at the grain boundary (GB). In this paper, we focus on the influence of the barrier potential on the thermopower (S) of rare earth (RE)-doped SrTiO3 with a grain size of 20 nm. |S| was found to increase linearly for smaller RE dopants despite the use of identical carrier concentrations. Capacitance-voltage measurements showed that the barrier potential increased linearly for the smaller RE dopants. Energy-selective scattering by the GB potential was evaluated theoretically, and allowed us to qualitatively explain the enhanced S in this system. The results indicate that the GB nature, which is a crucial factor for nanostructured thermoelectric materials, can be tuned by RE doping in this system.

  13. Modification of phonon processes in nano-structured rare-earth-ion-doped crystals

    E-print Network

    Thomas Lutz; Lucile Veissier; Charles W. Thiel; Rufus L. Cone; Paul E. Barclay; Wolfgang Tittel

    2015-04-09

    Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals to enable, or improve, persistent spectral hole-burning and optical coherence for inhomogeneously broadened absorption lines in rare-earth-ion-doped crystals. This is crucial for applications such as ultra-precise radio-frequency spectrum analyzers and certain approaches to optical quantum memories. We specifically discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the telecommunication band, and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y$_2$SiO$_5$, a widely-used material in current quantum memory research.

  14. Modification of phonon processes in nano-structured rare-earth-ion-doped crystals

    E-print Network

    Lutz, Thomas; Thiel, Charles W; Cone, Rufus L; Barclay, Paul E; Tittel, Wolfgang

    2015-01-01

    Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals to enable, or improve, persistent spectral hole-burning and optical coherence for inhomogeneously broadened absorption lines in rare-earth-ion-doped crystals. This is crucial for applications such as ultra-precise radio-frequency spectrum analyzers and certain approaches to optical quantum memories. We specifically discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the telecommunication band, and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y$_2$SiO$_5$, a widely-used material in current quantum memory research.

  15. Growth and properties of pure and rare earth-doped Ca 3 (BO 3) 2 single crystal

    Microsoft Academic Search

    Xiuai Lu; Zhenyu You; Jianfu Li; Zhaojie Zhu; Guohua Jia; Yan Wang; Baichang Wu; Chaoyang Tu

    2005-01-01

    Large novel birefringent pure and rare earth-doped calcium borate crystals (Ca3(BO3)2) have been grown successfully by Czochralski technique. Thermal expansion coefficients of pure Ca3(BO3)2 have been obtained for the first time. Trivalent rare earth ions (RE3+), such as Dy3+- and Nd3+-doped calcium borate crystal, have been grown for optic application. Absorption and fluorescence spectra as well as fluorescence decay curves

  16. Ab initio Disordered Local Moment Approach for a Doped Rare-Earth Magnet

    NASA Astrophysics Data System (ADS)

    Matsumoto, Munehisa; Banerjee, Rudra; Staunton, Julie B.

    Following the finite-temperature ab initio calculation framework based on the relativistic disordered local moments [J. B. Staunton et al., Phys. Rev. Lett. 93, 257204 (2004); Phys. Rev. B 74, 144411 (2006)], we computationally demonstrate the possibility of doping-enhanced coercivity at high-temperatures, taking YCo5 as a working material in order to extract the 3d-electron part of the electronic structure of the rare-earth permanent magnets. Alkaline-earth dopants are shown to be the candidates to realize the proposed phenomenon.

  17. A Systematic investigation of the dc electrical conductivity of rare-earth doped ceria

    Microsoft Academic Search

    J. Faber; C. Geoffroy; A. Roux; A. Sylvestre; P. Abélard

    1989-01-01

    The dc electrical conductivity of rare-earth doped ceria has been measured as a function of temperature (300–600 K) and composition (0.05–15 mol% M2O3) on using the complex impedance technique. Five dopants have been selected, yttrium and the lanthanides Yb, Gd, Nd, and La. For all of them, the variations of the activation energy versus dopant concentration are similar and characterized

  18. Ultrashort-pulse sources based on single-mode rare-earth-doped fibers

    Microsoft Academic Search

    M. E. Fermann

    1994-01-01

    An overview of ultrashort-pulse sources based on single-mode rare-earth-doped fibers is given. A wide range of pulse-generation schemes comprising mode-locked fiber lasers, parametric pulse sources and hybrid diode-fiber amplifier sources are discussed. Both actively and passively mode-locked fiber lasers are described and their specific merits and operation regimes are elucidated. Techniques for improving the spectral quality and the output powers

  19. Gamma-Radiation-Induced Photodarkening in Unpumped Optical Fibers Doped With Rare-Earth Constituents

    Microsoft Academic Search

    Brian P. Fox; Kelly Simmons-Potter; William J. Thomes Jr.; Dahv A. V. Kliner

    2010-01-01

    Fibers doped with rare-earth constituents such as Er3+ and Yb3+ are exceedingly important to designers of fiber-optical systems due to their ability to amplify signals in the near infra-red, low-absorption regions of conventional silicate fibers. Extending the range of operating conditions for these systems to include adverse radiation environments requires a detailed study of the behavior of the fiber when

  20. EC-EARTH: an Earth System Model based on the ECWMF Integrated Forecasting System

    Microsoft Academic Search

    F. Selten; R. Bintanja; S. Yang; C. Severijns; T. Semmler; K. Wyser; X. Wang; W. Hazeleger

    2009-01-01

    EC-EARTH is the name of an Earth system model that is being developed by a number of institutes in Europe. It is based on the Integrated Forecast System of the European Centre for Medium Range Weather Forecasts (ECWMF). The ECMWF model delivers the best weather forecasts in the world by an objective measure. However, when applied to climate time scales,

  1. Growth and properties of pure and rare earth-doped Ca 3 (BO 3) 2 single crystal

    NASA Astrophysics Data System (ADS)

    Lu, Xiuai; You, Zhenyu; Li, Jianfu; Zhu, Zhaojie; Jia, Guohua; Wang, Yan; Wu, Baichang; Tu, Chaoyang

    2005-08-01

    Large novel birefringent pure and rare earth-doped calcium borate crystals (Ca 3(BO 3) 2) have been grown successfully by Czochralski technique. Thermal expansion coefficients of pure Ca 3(BO 3) 2 have been obtained for the first time. Trivalent rare earth ions (RE 3+), such as Dy 3+- and Nd 3+-doped calcium borate crystal, have been grown for optic application. Absorption and fluorescence spectra as well as fluorescence decay curves of Dy 3+-, Nd 3+-doped Ca 3(BO 3) 2 crystals are measured at room temperature. Optical spectra show that there are obvious absorptions at ultraviolet to IR region. The strong emissions in visible and infrared region show that calcium borate is a suitable for rare earth-doped laser crystal.

  2. Design of a novel optically stimulated luminescent dosimeter using alkaline earth sulfides doped with SrS:Eu,Sm materials

    Microsoft Academic Search

    Yanping Liu; Zhaoyang Chen; Yanwei Fan; Weizhen Ba; Wu Lu; Qi Guo; Shilie Pan; Aimin Chang; Xinqiang Tang

    2008-01-01

    Optically stimulated luminescence (OSL) is the luminescence emitted from an irradiated insulator or semiconductor during exposure to light. The OSL intensity is a function of the dose of radiation absorbed by the sample and thus can be used as the basis of a radiation dosimetry method. Alkaline earth sulfides doped with rare-earth elements such as Ce, Sm and Eu are

  3. Integrating Customized Geographical Data Into Google Earth 

    E-print Network

    Hu, Chenwei

    2011-11-24

    to download these files and then visualize their data in Google Earth. Various languages and programmes were used in this project, including Oracle RDBMS, SQL, Perl, HTML and KML. The Web-based tool provides users with limited GIS knowledge the ability to use...

  4. 28th European Photovoltaic Solar Energy Conference and Exhibition 1.BO11.2 DOWN CONVERTER DEVICE COMBINING RARE-EARTH DOPED THIN LAYER AND PHOTONIC

    E-print Network

    Paris-Sud XI, Université de

    COMBINING RARE-EARTH DOPED THIN LAYER AND PHOTONIC CRYSTAL FOR C-SI BASED SOLAR CELL Thierry Deschamps1 structure combines rare-earths doped thin layer allowing the down-conversion process with a photonic crystal of the rare-earths doped layer, a silicon nitride (SiN) 2D planar PhC is synthesized. For that, SiN is first

  5. Nano and metastable processing of rare earth doped silicate glasses for photonic applications

    NASA Astrophysics Data System (ADS)

    Finley, Matthew Franklin

    2002-01-01

    Nanotechnology and photonic technology have seen rapid and astounding growth in the last 10 years. Many new properties and applications have been developed in the respective fields. In recent years some nanotechnology has been integrated into the field of photonics. In this study nano and metastable processing of silicate glasses for pholonic applications are examined. Nanopowders of SiO2 were fabricated. These powders were characterized by BET gas adsorption, thermogravimetric analysis, X-Ray Diffraction, and Scanning Electron Microscopy. Optimization of SiO2 nanopowder fabrication parameters proved invaluable since the same parameters were used for multicomponent compositions of Al2O3/SiO2/Er2O 3. Optimization of parameters included O2 flow rate, H 2 flow rates, burner distance, and precursor flow rate. Precursor flow rate, was found to be critical to the fabrication of high quality nanopowders. Multicomponent compositions were investigated for 1.55 mum emission from Er3+. Powders with average particle sizes of 9 nm were synthesized. In a complementary study, compositions of Al2O3/SiO 2/Er2O3 powders were hatched and spray dried for plasma melt quenching. These powders with very high concentrations of Er 2O3 were superheated in a plasma then quickly quenched into a water bath. Various compositions were prepared with different codoping ratios of Al2O3/Er2O3. Lifetime and fluorescence data are reported for emission at 1.55 um. Furthermore, green upconversion was observed with Yb/Er codoping. All compositions of plasma spray powders exhibited low multiexponential decay rates for the 4 I13/2 metastable state. Beat treatments of the powders up to 1400°C crystallized a Er2Si2O7 monoclinic pyrochlore structure. Upon crystallization the crystalline phase exhibited increased lifetimes of 7 ms up from <1 ms. Ordering of Er 3+ atoms is seen as the mechanism for increase in lifetime. This investigation has provided insight into the potential of metastable processing of heavily doped rare earth oxide nanopowders for photonic applications. Rare earth concentrations have been achieved which are 1 to 2 orders of magnitude higher then possible by more conventional synthesis methods. These findings should provide the incentive for follow-up research to further advance and exploit nanotechnology for next generation optical materials and devices.

  6. A comparison of the effect of rare earth vs Si site doping on the conductivities of apatite-type rare earth silicates

    Microsoft Academic Search

    J. E. H. Sansom; E. Kendrick; J. R. Tolchard; M. S. Islam; P. R. Slater

    2006-01-01

    Apatite-type lanthanum silicate (La9.33Si6O26) has been attracting significant recent interest due to its high oxide ion conductivity. In this paper, synthesis and conductivity\\u000a data for a range of doped samples (Mg, Ca, Sr, Ba, B, Ga and Zn) are reported, in particular, to compare the effect of rare\\u000a earth vs Si site doping. The results show that Ga, B and

  7. Multi-color fluorescence in rare earth acetylacetonate hydrate doped poly methyl methacrylate

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Y.; Shen, L. F.; Pun, E. Y. B.; Chen, B. J.; Lin, H.

    2013-01-01

    Europium and terbium acetylacetonate hydrates were doped into poly methyl methacrylate (PMMA). Efficient purplish-red and green fluorescence was obtained from europium acetylacetonate hydrates (EAH) and terbium acetylacetonate hydrates (TAH) doped PMMA respectively. Judd-Ofelt parameters ?2 (19.73×10-20 cm2) and ?4 (2.19×10-20 cm2) indicate a high inversion asymmetric and strong covalent environment in PMMA. The maximum stimulated emission cross-sections for the 5D0?7FJ (J=1, 2 and 4) transitions in EAH doped PMMA were calculated to be 0.38×10-21, 4.90×10-21 and 0.36×10-21 cm2, respectively. Variable fluorescence color can be efficiently achieved from the cooperation of three fluorescence colors offered by red (Eu3+), green (Tb3+) and blue (ligand) in EAH/TAH codoped PMMA by adjusting the excitation wavelength. These results indicate that PMMA is an effective photoluminescence co-sensitizer and PMMA doped with rare earth acetylacetonate hydrates is a promising candidate for a series of optoelectronic functional devices.

  8. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO2 fiber

    NASA Astrophysics Data System (ADS)

    Katsumata, Toru; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki

    2014-08-01

    Visible light thermal radiation from SiO2 glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO2 fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO2 fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO2 fibers are smaller than those from SiO2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO2 are potentially applicable for the fiber-optic thermometry above 900 K.

  9. Design of rare-earth-ion doped chalcogenide photonic crystals for enhancing the fluorescence emission

    NASA Astrophysics Data System (ADS)

    Zhang, Peiqing; Dai, Shixun; Niu, Xueke; Xu, Yinsheng; Zhang, Wei; Wu, Yuehao; Xu, Tiefeng; Nie, Qiuhua

    2014-07-01

    Rare-earth-ion doped chalcogenide glass is a promising material for developing mid-infrared light sources. In this work, Tm3+-doped chalcogenide glass was prepared and photonic crystal structures were designed to enhance its fluorescence emission at approximately 3.8 ?m. By employing the finite-difference time-domain (FDTD) simulation, the emission characteristics of the luminescent centers in the bulk material and in the photonic crystals were worked out. Utilizing analysis of the photon excitation inside the sample and the photon extraction on the sample surface, it was found that fluorescence emission can be significantly enhanced 260-fold with the designed photonic crystal structure. The results of this work can be used to realize high-efficiency mid-infrared light sources.

  10. Emission properties of heavy metal oxide glasses doped with rare-earths

    NASA Astrophysics Data System (ADS)

    Heo, Jong

    2003-07-01

    Emissions at 1.3?m and mid-infrared region from several rare-earths ions doped into PbO-Bi2O3-Ga2O3 glasses were investigated. Lifetime of the Pr3+:1G4 level was 53´s with a quantum efficiency of 9%. Emission at 2.73?m from Er3+, which is normally quenched in oxide glass, was evident and the lifetime of the upper emission level was approximately 900´s. Thermal stability of PbO-Bi2O3-Ga2O3 glass was considerably improved by adding 10 mole % of GeO2. Doping of Tm3+ and Ho3+ showed potentials for S-band fiber-optic amplification.

  11. Electrostatic tuning of Kondo effect in a rare-earth-doped wide-band-gap oxide

    NASA Astrophysics Data System (ADS)

    Li, Yongfeng; Deng, Rui; Lin, Weinan; Tian, Yufeng; Peng, Haiyang; Yi, Jiabao; Yao, Bin; Wu, Tom

    2013-04-01

    As a long-lived theme in solid-state physics, the Kondo effect reflects the many-body physics involving the short-range Coulomb interactions between itinerant electrons and localized spins in metallic materials. Here we show that the Kondo effect is present in ZnO, a prototypical wide-band-gap oxide, doped with a rare-earth element (Gd). The localized 4f electrons of Gd ions do not produce remanent magnetism, but interact strongly with the host electrons, giving rise to a saturating resistance upturn and negative magnetoresistance at low temperatures. Furthermore, the Kondo temperature and resistance can be electrostatically modulated using electric-double-layer gating with liquid ionic electrolyte. Our experiments provide the experimental evidence of tunable Kondo effect in ZnO, underscoring the magnetic interactions between localized and itinerant electrons and the emergent transport behaviors in such doped wide-band-gap oxides.

  12. Optical properties of rare earth doped strontium aluminate (SAO) phosphors: A review

    NASA Astrophysics Data System (ADS)

    Kshatri, D. S.; Khare, A.

    2014-11-01

    After the first news on rare earth (RE) doped strontium aluminate (SAO) phosphors in late 1990s, researchers all over the world geared up to develop stable and efficient persistent phosphors. Scientists studied various features of long lasting phosphors (LLP) and tried to earmark appropriate mechanism. However, about two decades after the discovery of SrAl2O4: Eu2+, Dy3+, the number of persistent luminescent materials is not significant. In this review, we present an overview of the optical characteristics of RE doped SAO phosphors in terms of photoluminescence (PL), thermoluminescence (TL) and afterglow spectra. Also, we refresh the work undertaken to study diverse factors like dopant concentration, temperature, surface energy, role of activator, etc. Simultaneously, some of our important findings on SAO are reported and discussed in the end.

  13. Crystallization studies on rare-earth co-doped fluorozirconate-based glasses

    PubMed Central

    Paßlick, C.; Johnson, J.A.; Schweizer, S.

    2013-01-01

    This work focuses on the structural changes of barium chloride (BaCl2) nanoparticles in fluorochlorozirconate-based glass ceramics when doped with two different luminescent activators, in this case rare-earth (RE) ions, and thermally processed using a differential scanning calorimeter. In a first step, only europium in its divalent and trivalent oxidation states, Eu2+ and Eu3+, is investigated, which shows no significant influence on the crystallization of hexagonal phase BaCl2. However, higher amounts of Eu2+ increase the activation energy of the phase transition to an orthorhombic crystal structure. In a second step, nucleation and nanocrystal growth are influenced by changing the structural environment of the glasses by co-doping with Eu2+ and trivalent Gd3+, Nd3+, Yb3+, or Tb3+, due to the different atomic radii and electro-negativity of the co-dopants. PMID:23745010

  14. Influence of doping with alkaline earth metals on the optical properties of thermochromic VO2

    NASA Astrophysics Data System (ADS)

    Dietrich, Marc K.; Kramm, Benedikt G.; Becker, Martin; Meyer, Bruno K.; Polity, Angelika; Klar, Peter J.

    2015-05-01

    Thin films of doped VO2 were deposited, analyzed, and optimized with regard to their solar energy transmittance (Tsol) and visible/luminous light transmittance (Tlum) which are important parameters in the context of smart window applications in buildings. The doping with alkaline earth metals (AEM) like Mg, Ca, Sr, or Ba increased both Tsol and Tlum due to a bandgap widening and an associated absorption edge blue-shift. Thereby, the brown-yellowish color impression of pure VO2 thin films, which is one major hindrance limiting the usage of VO2 as thermochromic window coating, was overcome. Transparent thin films with excellent switching behavior were prepared by sputtering. Highly doped V1-xMexO2 (Me = Ca, Sr, Ba) kept its excellent thermochromic switching behavior up to x(Me) = Me/(Me + V) = 10 at. % doping level, while the optical bandgap energy was increased from 1.64 eV for undoped VO2 to 2.38 eV for x(Mg) = 7.7 at. %, 1.85 eV for x(Ca) = 7.4 at. %, 1.84 eV for x(Sr) = 6.4 at. % and 1.70 eV for x(Ba) = 6.8 at. %, as well as the absorption edge is blue shifted by increasing AEM contents. Also, the critical temperature ?c, at which the semiconductor-to-metal transition (SMT) occurs, was decreased by AEM doping, which amounted to about -0.5 K/at. % for all AEM on average. The critical temperature was determined by transmittance-temperature hysteresis measurements. Furthermore, Tsol and Tlum were calculated and were found to be significantly enhanced by AEM doping. Tlum increased from 32.0% in undoped VO2 to 43.4% in VO2 doped with 6.4 at. % Sr. Similar improvements were found for other AEM. The modulation of the solar energy transmittance ?Tsol, which is the difference of the Tsol values in the low and high temperature phase, was almost constant or even slightly increased when the doping level was increased up to about 10 at. % Ca, Sr, or Ba.

  15. Epithermal and thermal neutron response to rare earth doped fricke dosimeters 

    E-print Network

    Groves, Kenneth Lee

    1970-01-01

    ) December 1970 ABSTRACT Epithezmal and Thermal Neutron Response to Rare Earth Doped Fricke Dosimeters. (Dec~ l970) Kenneth Lee Groves, B. A. , University of New Mexico; M. S. , Texas ASM University; Dir ected by: Dr. J. B. Smath~s The neutron... and 0 neutron fluence used to determine average neutron energy of reactor spec%urn neutrons. 11 vrr LIST OF FIGURES Fig. 1. +3 G Fe of monoenergetic charged panticles versus (&s) ILET: after Allen P~ae I'ig. 2. Absorbance versus dose of undoped...

  16. Fibre tip sensors for localised temperature sensing based on rare earth-doped glass coatings.

    PubMed

    Schartner, Erik P; Monro, Tanya M

    2014-01-01

    We report the development of a point temperature sensor, based on monitoring upconversion emission from erbium:ytterbium-doped tellurite coatings on the tips of optical fibres. The dip coating technique allows multiple sensors to be fabricated simultaneously, while confining the temperature-sensitive region to a localised region on the end-face of the fibre. The strong response of the rare earth ions to changing temperature allows a resolution of 0.1-0.3 °C to be recorded over the biologically relevant range of temperatures from 23-39 °C. PMID:25407907

  17. Coherent spectroscopy of rare-earth-ion doped whispering-gallery mode resonators

    E-print Network

    D. L. McAuslan; D. Korystov; J. J. Longdell

    2011-04-21

    We perform an investigation into the properties of Pr3+:Y2SiO5 whispering gallery mode resonators as a first step towards achieving the strong coupling regime of cavity QED with rare-earth-ion doped crystals. Direct measurement of cavity QED parameters are made using photon echoes, giving good agreement with theoretical predictions. By comparing the ions at the surface of the resonator to those in the center it is determined that the physical process of making the resonator does not negatively affect the properties of the ions. Coupling between the ions and resonator is analyzed through the observation of optical bistability and normal-mode splitting.

  18. Fibre Tip Sensors for Localised Temperature Sensing Based on Rare Earth-Doped Glass Coatings

    PubMed Central

    Schartner, Erik P.; Monro, Tanya M.

    2014-01-01

    We report the development of a point temperature sensor, based on monitoring upconversion emission from erbium:ytterbium-doped tellurite coatings on the tips of optical fibres. The dip coating technique allows multiple sensors to be fabricated simultaneously, while confining the temperature-sensitive region to a localised region on the end-face of the fibre. The strong response of the rare earth ions to changing temperature allows a resolution of 0.1–0.3 °C to be recorded over the biologically relevant range of temperatures from 23–39 °C. PMID:25407907

  19. Comparative study of magnetic properties of dilute Fe doped with transition magnetic ions and GaN, InN doped with rare-earth magnetic ions

    NASA Astrophysics Data System (ADS)

    Alsaad, A.; Qattan, I. A.

    2014-01-01

    We report on ab initio computational results for the density of state (DOS) and local magnetic moment of Fe alloys lightly doped with 3d Cr and Mn transition metals impurities. The DOS and local magnetic moment of both doped systems were calculated using spin local-density approximation within the framework of density functional theory by employing the Korringa-Kohn-Rostoker Green's-function and LIyod's methods. Our results show drastic variations of DOS and local magnetic moments of both doped systems as compared to that of pure Fe. Our results agree fairly well with the available experimental results on Fe doped with 3d and 4d transition impurities. In addition, the effective magnetic moments of GaN and InN doped with rare-earth magnetic ions have been calculated using Vienna ab initio simulation package (VASP) and Cowan's atomic Hartree-Fock (HF) code with relativistic correction. Our results indicate that doping a non-magnetic compounds with a magnetic impurity leads to an effective magnetic dipole moment that are quite larger than the magnetic moment obtained by doping a magnetic material with a magnetic impurity.

  20. Progress in rare-earth-doped mid-infrared fiber lasers.

    PubMed

    Seddon, Angela B; Tang, Zhuoqi; Furniss, David; Sujecki, Slawomir; Benson, Trevor M

    2010-12-01

    The progress, and current challenges, in fabricating rare-earth-doped chalcogenide-glass fibers for developing mid-infrared (IR) fiber lasers are reviewed. For the first time a coherent explanation is forwarded for the failure to date to develop a gallium-lanthanum-sulfide glass mid-IR fiber laser. For the more covalent chalcogenide glasses, the importance of optimizing the glass host and glass processing routes in order to minimize non-radiative decay and to avoid rare earth ion clustering and glass devitrification is discussed. For the first time a new idea is explored to explain an additional method of non-radiative depopulation of the excited state in the mid-IR that has not been properly recognized before: that of impurity multiphonon relaxation. Practical characterization of candidate selenide glasses is presented. Potential applications of mid-infrared fiber lasers are suggested. PMID:21165021

  1. Rare-earth ion doped lead- and cadmium-free bismuthate glasses

    NASA Astrophysics Data System (ADS)

    Lin, H.; Pun, E. Y. B.; Chen, B. J.; Zhang, Y. Y.

    2008-03-01

    Rare-earth ion doped bismuthate (LZBB) glasses without traditional glass formers, lead and cadmium, have been attempted to prepare. In Er3+ doped LKBB glass system, Judd-Ofelt parameters ?2, ?4, and ?6 have been derived to be 3.48×10-20, 9.47×10-21, and 1.01×10-20cm2, respectively, which shows a medium symmetry of the ligand field in the site occupied by Er3+ and a less covalent environment of Er3+. Effective 1.53?m fluorescence was recorded and the peak emission cross section is proved to be more than 9.0×10-21cm2, which is much higher than those in phosphate, silicate, germanate, and tellurite glasses and beneficial to achieving powerful stimulated emission of Er3+ in LZBB glass system. Pr3+, Tm3+, and Ho3+ doped LZBB glasses with the maximum phonon energy of only ˜600 cm-1 are potential candidates for developing O-, S-, and U-band amplifiers and medical lasers.

  2. TOPICAL REVIEW: Ferromagnetic nitride-based semiconductors doped with transition metals and rare earths

    NASA Astrophysics Data System (ADS)

    Bonanni, A.

    2007-09-01

    This review summarizes the state-of-the-art in the search for room temperature ferromagnetic semiconductors based on transition-metal- and rare-earth-doped nitrides. The major methods of synthesis are reported, together with an overview of the magnetic, structural, electrical and optical characterization of the materials systems, where available. The controversial experimental results concerning the actual value of the apparent Curie temperature in magnetically doped nitrides are highlighted, the inadequacy of standard characterization methods alone and the necessity of a possibly exhaustive structural investigation of the systems are proven and underlined. Furthermore, the dependence on the fabrication parameters of the magnetic ions incorporation into the semiconductor matrix is discussed, with special attention to the fundamental concepts of solubility limit and spinodal decomposition. It is argued that high-temperature ferromagnetic features in magnetically doped nitrides result from the presence of nanoscale regions containing a high concentration of the magnetic constituents. Various functionalities of these multicomponent systems are listed. Moreover, we give an extensive overview on the properties of single magnetic-impurity states in the nitride host. The understanding of this limit is crucial when considering the most recent suggestions for the control of the magnetic ion distribution—and consequently of the magnetic response—through the Fermi level engineering as well as to indicate roads for achieving high-temperature ferromagnetism in the systems containing a uniform distribution of magnetic ions.

  3. Postgraduate Education in Earth and Environmental Sciences: an Integrated Concept

    Microsoft Academic Search

    K. Grosfeld; G. Lohmann; A. Ladstätter-Weißenmayer; J. Burrows; C. Sprengel; J. Bijma

    2009-01-01

    Today's graduate and postgraduate education in the field of Earth System and Environmental Science is a highly interdisciplinary and inter-institutional challenge. The integration of observations, palaeoclimate data, and climate modelling requires networks and collaborations of experts and specialists in order to better understand natural climate variations over a broad range of timescales and disciplines, and to cope with the challenges

  4. An Integrated Concept on Earth and Environmental Sciences Postgraduate Education

    Microsoft Academic Search

    Klaus Grosfeld; Gerrit Lohmann; Annette Ladstätter-Weißenmayer; John Burrows; Claudia Sprengel; Jelle Bijma

    2010-01-01

    Today's graduate and postgraduate education in the field of Earth System and Environmental Science is a highly interdisciplinary and inter-institutional challenge. The integration of observations, palaeoclimate data, and climate modelling requires networks and collaborations of experts and specialists in order to better understand natural climate variations over a broad range of timescales and disciplines, and to cope with the challenges

  5. IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 49, NO. 9, SEPTEMBER 2002 1545 Rare-Earth-Doped GaN Switchable Color

    E-print Network

    Steckl, Andrew J.

    IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 49, NO. 9, SEPTEMBER 2002 1545 Rare-Earth-Doped Ga change emission color by varying the electrical bias is of impor- tance for multicolor flat panel here are based on the rare earth-doped GaN phosphor system [12]. GaN has emerged as an excellent host

  6. Microwave study of photoconductivity induced by laser pulses in rare-earth-doped dielectric crystals

    NASA Astrophysics Data System (ADS)

    Joubert, M.-F.; Kazanskii, S. A.; Guyot, Y.; Gâcon, J.-C.; Pédrini, C.

    2004-04-01

    Transient responses of the dielectric permittivity ?=?1-i?2 of rare-earth-doped dielectric crystals under pulsed laser excitation were studied by the 8-mm microwave resonator technique at room temperature. The fluorite-type crystals (CaF2, SrF2, and BaF2) which contained divalent ions of Sm, Eu, and Tm, as well as Lu2(SiO4)O and Y3Al5O12 doped with trivalent Ce ions were investigated. The dielectric response to a laser pulse contains two different types of signals: electronic and heating ones. The electronic peak, which is quite fast (from 40 to 100 ns or more), is the signature of electrons released into the conduction band following an impurity photoionization. The prolonged heating signal has a sawtooth form on which oscillations are imposed. It is due to modulation of the dielectric constant by a sudden temperature rise and subsequent elastic vibrations of the sample caused by the energy absorbed from the laser pulse. In different crystals the electronic peak was caused by the transient response of either ?1, ?2, or a mixture of the two. The modulation of the dielectric loss factor ?2 corresponds to conventional photoconductivity, i.e., the photoexcitation of mobile electrons. The modulation of the dielectric constant ?1 corresponds to the photoexcitation of “bound” electrons, probably captured by traps. The threshold energies of photons at which the photoionization of rare-earth ions may occur, were determined for CaF2:Sm2+ (3.3 eV) and Lu2(SiO4)O:Ce3+ (3.1 eV). In fluorite-type crystals doped with Sm2+ or Tm2+ ions, the significant reduction of a lifetime of electrons in a conduction band was revealed with an increase in energy of laser pulses. In SrF2:Eu crystal the record-high signals of “photoconductivity” were observed upon excitation by VIS light in the optical region of “transparency” of this crystal. The microwave resonant technique may be used for detail studying the photoionization dynamics of rare-earth ions and finding the location of their energy levels with respect to the host conduction band in doped insulators.

  7. Catholuminescence properties of rare earth doped CaSnO3 phosphor.

    PubMed

    Canimoglu, A; Garcia-Guinea, J; Karabulut, Y; Ayvacikli, M; Jorge, A; Can, N

    2015-05-01

    The present study describes cathodoluminescence (CL) properties of CaSnO3 phosphors doped with Eu(3+), Tb(3+) and Dy(3+) synthesized by a solid-state method. X-ray diffraction (XRD) patterns confirm that CaSnO3 sintered at 1200°C exhibits orthorhombic structure. The evidence and rationale for two strong broad emission bands appeared at 360 and 780nm for undoped CaSnO3 are presented. The CL measurements exhibit that the 4f-4f emissions from (5)D4?(7)F6 (490nm), (5)D4 ?(7)F5 (544nm), (5)D4 ?(7)F4 (586nm) and (5)D4 ?(7)F3 (622nm), assigned to possible transitions of Tb(3+) ions are seen. The strongest one, observed at 544nm, due to its probability of both magnetic and electric transitions make the sample emission green. Emissions at 480, 574, 662 and 755nm were detected for the CaSnO3:Dy(3+) and attributed to the transitions from the (4)F9/2 to various energy levels (6)H15/2, (6)H13/2, (6)H11/2 and (6)H9/2+(6)F11/2 of Dy(3+), respectively. CL spectra of Eu doped CaSnO3 reveal that there is a strong emission peak appeared at 615nm due to the electric dipole transition (5)D0?(7)F2 (red). Finally, our results show that the rare earth doped CaSnO3 have remarkable potential for applications as optical materials since it exhibits efficient and sharp emission due to rare earth ions. PMID:25766113

  8. Investigating material trends and lattice relaxation effects for understanding electron transfer phenomena in rare-earth-doped optical materials

    Microsoft Academic Search

    C. W. Thiel; R. L. Cone

    2011-01-01

    Rare-earth-doped insulators and semiconductors play an important role in a wide range of modern optical technologies. Knowledge of the relative energies of rare-earth ions’ localized electronic states and the band states of the host crystal is important for understanding the properties of these materials and for determining the potential material performance in specific applications such as lasers, phosphors, and optical

  9. Systematics of 4f electron energies relative to host bands by resonant photoemission of rare earth doped optical materials

    Microsoft Academic Search

    C. W. Thiel; H. Cruguel; Y. Sun; G. J. Lapeyre; R. M. Macfarlane; R. W. Equall; R. L. Cone

    2001-01-01

    Relative energies of 4fn electronic states and crystal band states are important for a fundamental understanding of rare-earth-doped optical materials and a practical understanding of each material's potential performance in specific applications. With this motivation, the 4fn ground state binding energies of rare earth ions have been studied in the gallium garnets using resonant photoemission spectroscopy and compared with the

  10. Laser-induced generation of micrometer-sized luminescent patterns on rare-earth-doped amorphous films

    Microsoft Academic Search

    A. R. Zanatta; C. T. M. Ribeiro

    2004-01-01

    Room-temperature photoluminescence has been achieved from rare-earth-doped amorphous (a-) GeN films. The samples were prepared by the radio-frequency-sputtering method, and light emission from the rare-earth (RE) centers was obtained after irradiating the films with a highly focused laser beam. As a result of this laser annealing procedure, almost circular holes with approximately 1-?m diameter were produced on the surface of

  11. Laser-induced generation of micrometer-sized luminescent patterns on rare-earth-doped amorphous films

    Microsoft Academic Search

    A. R. Zanatta; C. T. M. Ribeiro

    2004-01-01

    Room-temperature photoluminescence has been achieved from rare-earth-doped amorphous (a-) GeN films. The samples were prepared by the radio-frequency-sputtering method, and light emission from the rare-earth (RE) centers was obtained after irradiating the films with a highly focused laser beam. As a result of this laser annealing procedure, almost circular holes with approximately 1-mum diameter were produced on the surface of

  12. Motivational and social cognitive predictors of doping intentions in elite sports: an integrated approach.

    PubMed

    Barkoukis, V; Lazuras, L; Tsorbatzoudis, H; Rodafinos, A

    2013-10-01

    Doping use is an important issue in both competitive and non-competitive sports, and poses potentially irreversible health consequences to users. Scholars increasingly call for theory-driven studies on the psychosocial processes underlying doping use that will inform subsequent policy-making and prevention interventions. The aim of the study was to implement an integrative theoretical model to assess the direct and indirect effects of motivational variables, moral orientations, and social cognitions on doping intentions. A randomly selected and representative sample of 750 elite athletes anonymously completed a battery of questionnaires on motivational and moral constructs, and social cognitions related to doping. Hierarchical linear regression analysis and multiple mediation modeling were used. The effects of achievement goals and moral orientations were significantly mediated by attitudinal, normative, and self-efficacy beliefs, in both lifetime ever and never doping users. Moral orientations indirectly predicted the doping intentions of never users, but did not predict ever users' doping intentions. Achievement goals and sportspersonship orientations influence doping intentions indirectly, through the effects of attitudes and self-efficacy beliefs. Sportspersonship (moral) orientations were relevant to doping intentions among athletes with no prior experiences with doping, while achievement goals and situational temptation were relevant to both lifetime never and ever dopers. PMID:23574429

  13. Integrating the Earth, Atmospheric, and Ocean Sciences at Millersville University

    NASA Astrophysics Data System (ADS)

    Clark, R. D.

    2005-12-01

    For nearly 40 years, the Department of Earth Sciences at Millersville University (MU-DES) of Pennsylvania has been preparing students for careers in the earth, atmospheric, and ocean sciences by providing a rigorous and comprehensive curricula leading to B.S. degrees in geology, meteorology, and oceanography. Undergraduate research is a hallmark of these earth sciences programs with over 30 students participating in some form of meritorious research each year. These programs are rich in applied physics, couched in mathematics, and steeped in technical computing and computer languages. Our success is measured by the number of students that find meaningful careers or go on to earn graduate degrees in their respective fields, as well as the high quality of faculty that the department has retained over the years. Student retention rates in the major have steadily increased with the introduction of a formal learning community and peer mentoring initiatives, and the number of new incoming freshmen and transfer students stands at an all-time high. Yet until recently, the disciplines have remained largely disparate with only minor inroads made into integrating courses that seek to address the Earth as a system. This is soon to change as the MU-DES unveils a new program leading to a B.S. in Integrated Earth Systems. The B.S. in Integrated Earth Systems (ISS) is not a reorganization of existing courses to form a marketable program. Instead, it is a fully integrated program two years in development that borrows from the multi-disciplinary backgrounds and experiences of faculty, while bringing in resources that are tailored to visualizing and modeling the Earth system. The result is the creation of a cross-cutting curriculum designed to prepare the 21st century student for the challenges and opportunities attending the holistic study of the Earth as a system. MU-DES will continue to offer programs leading to degrees in geology, meteorology, and ocean science, but in addition, the B.S. in Integrated Earth Systems will serve those students who find excitement at the boundaries of these disciplines, and prepare them for careers in this emerging field. The ISS program will target high school students of the highest caliber who demonstrate strong aptitude in mathematics and the physical sciences, who will need a minimum amount of remedial work. These select students will be exposed to courses in Earth Systems: Cycles and Interactions, Geophysical Fluid Dynamics, Air-Sea Interaction, Boundary Layers and Turbulence, Climate Variability and Global Change, Atmosphere-Ocean Modeling, Solar-Terrestrial Interactions, Weather Systems Science, Earth Observing Systems, Remote Sensing and more, as part of the ISS curriculum. This paper will highlight the MU-DES programs and learning initiatives and expand and elaborate on the new program in ISS.

  14. Photon-pair source with controllable delay based on shaped inhomogeneous broadening of rare-earth-metal-doped solids

    SciTech Connect

    Sekatski, Pavel; Sangouard, Nicolas; Gisin, Nicolas; Afzelius, Mikael [Group of Applied Physics, University of Geneva, CH-1211 Geneva 4 (Switzerland); Riedmatten, Hugues de [Group of Applied Physics, University of Geneva, CH-1211 Geneva 4 (Switzerland); ICFO-Institute of Photonic Sciences, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, E-08015 Barcelona (Spain)

    2011-05-15

    Spontaneous Raman emission in atomic gases provides an attractive source of photon pairs with a controllable delay. We show how this technique can be implemented in solid state systems by appropriately shaping the inhomogeneous broadening. Our proposal is eminently feasible with current technology and provides a realistic solution to entangle remote rare-earth-metal-doped solids in a heralded way.

  15. Preparation and Luminescence Properties of Rare Earth Doped Nanostructured Zinc Oxide Thin Films by Sol Gel Technique

    Microsoft Academic Search

    Madzlan Aziz; Sunati Otoi

    2009-01-01

    Zinc oxide is a semiconductor cosidered promising for optoelectronic and solar cell applications. The wide bandgap nature of the zinc oxide has been a limitation in producing devices. Doping has been considered as one of the ways to reduce the band gap. In the present studies rare earth ions in the form of terbium and erbium nitatres have been introduced

  16. Optical spectroscopy of rare earth ion-doped TiO2 nanophosphors.

    PubMed

    Chen, Xueyuan; Luo, Wenqin

    2010-03-01

    Trivalent rare-earth (RE3+) ion-doped TiO2 nanophosphors belong to one kind of novel optical materials and have attracted increasing attention. The luminescence properties of different RE3+ ions in various TiO2 nanomaterials have been reviewed. Much attention is paid to our recent progresses on the luminescence properties of RE3+ (RE = Eu, Er, Sm, Nd) ions in anatase TiO2 nanoparticles prepared by a sol-gel-solvothermal method. Using Eu3+ as a sensitive optical probe, three significantly different luminescence centers of Eu3+ in TiO2 nanoparticles were detected by means of site-selective spectroscopy at 10 K. Based on the crystal-field (CF) splitting of Eu3+ at each site, C2v and D2 symmetries were proposed for Eu3+ incorporated at two lattice sites. A structural model for the formation of multiple sites was proposed based on the optical behaviors of Eu3+ at different sites. Similar multi-site luminescence was observed in Sm(3+)- or Nd(3+)-doped TiO2 nanoparticles. In Eu(3+)-doped TiO2 nanoparticles, only weak energy transfer from the TiO2 host to the Eu3+ ions was observed at 10 K due to the mismatch of energy between the TiO2 band-gap and the Eu3+ excited states. On the contrary, efficient host-sensitized luminescences were realized in Sm(3+)- or Nd(3+)-doped anatase TiO2 nanoparticles due to the match of energy between TiO2 band-gap and the Sm3+ and Nd3+ excited states. The excitation spectra of both Sm(3+)- and Nd(3+)-doped samples exhibit a dominant broad peak centered at approximately 340 nm, which is associated with the band-gap of TiO2, indicating that sensitized emission is much more efficient than direct excitation of the Sm3+ and Nd3+ ions. Single lattice site emission of Er3+ in TiO2 nanocrystals can be achieved by modifying the experimental conditions. Upon excitation by a Ti: sapphire laser at 978 nm, intense green upconverted luminescence was observed. The characteristic emission of Er3+ ions was obtained both in the ultraviolet-visible (UV-vis) and near-infrared regions through the high-resolution experiments at 10 K. The CF experienced by Er3+ in TiO2 nanocrystal was systematically studied by means of the energy level fitting. PMID:20355538

  17. Coherency strain enhanced dielectric-temperature property of rare-earth doped BaTiO{sub 3}

    SciTech Connect

    Jeon, Sang-Chae; Kang, Suk-Joong L. [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)] [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2013-03-18

    Core/shell-grained BaTiO{sub 3} samples were prepared with addition of rare earth elements. The core/shell interface was semi-coherent, and many misfit dislocations formed in Dy-doped samples. In contrast, a coherent interface and few dislocations were observed in Ho- and Er-doped samples. Dy-doped samples exhibited poor temperature stability, showing a peak with no frequency dispersion. Ho- and Er-doped samples exhibited a broad curve with frequency dispersion. This improved temperature stability is attributed to the coherency strain, which leads to the formation of polar nano-regions in the shell. Coherency at the core/shell interface is critical to improve the temperature stability of core/shell-structured BaTiO{sub 3}.

  18. Optical spectra of un-doped and rare-earth-(=Pr, Nd, Eu, and Er) doped transparent ceramic Y3Al5O12

    Microsoft Academic Search

    H. Haneda M. Sekita; S. Shirasaki

    1991-01-01

    Undoped and rare-earth- (Pr, Nd, Eu, and Er) doped transparent Y3Al5O12 ceramics have been prepared, and their optical spectra have been measured. It is found that absorption coefficient of the undoped ceramic Y3Al5O12 is almost independent of wavelength with 0.258 cm?1, which gives transmittance of the undoped ceramic Y3Al5O12 to be, for example, 95% for a 2-mm height. Peaks in

  19. Coherent spectroscopy of rare-earth-metal-ion-doped whispering-gallery-mode resonators

    SciTech Connect

    McAuslan, D. L.; Korystov, D.; Longdell, J. J. [Jack Dodd Centre for Photonics and Ultra-Cold Atoms, Department of Physics, University of Otago, Dunedin, New Zealand. (New Zealand)

    2011-06-15

    We perform an investigation into the properties of Pr{sup 3+}:Y{sub 2}SiO{sub 5} whispering-gallery-mode resonators as a first step toward achieving the strong coupling regime of cavity QED with rare-earth-metal-ion-doped crystals. Direct measurement of cavity QED parameters are made using photon echoes, giving good agreement with theoretical predictions. By comparing the ions at the surface of the resonator to those in the center, it is determined that the physical process of making the resonator does not negatively affect the properties of the ions. Coupling between the ions and resonator is analyzed through the observation of optical bistability and normal-mode splitting.

  20. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1989-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  1. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1990-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  2. Reducing decoherence in optical and spin transitions in rare-earth-ion doped materials

    E-print Network

    D. L. McAuslan; J. G. Bartholomew; M. J. Sellars; J. J. Longdell

    2012-03-22

    In many important situations the dominant dephasing mechanism in cryogenic rare-earth-ion doped systems is due to magnetic field fluctuations from spins in the host crystal. Operating at a magnetic field where a transition has a zero first-order-Zeeman (ZEFOZ) shift can greatly reduce this dephasing. Here we identify the location of transitions with zero first-order Zeeman shift for optical transitions in Pr3+:YAG and for spin transitions in Er3+:Y2SiO5. The long coherence times that ZEFOZ would enable would make Pr3+:YAG a strong candidate for achieving the strong coupling regime of cavity QED, and would be an important step forward in creating long-lived telecommunications wavelength quantum memories in Er3+:Y2SiO5. This work relies mostly on published spin Hamiltonian parameters but Raman heterodyne spectroscopy was performed on Pr3+:YAG to measure the parameters for the excited state.

  3. Nanophotonic coherent light-matter interfaces based on rare-earth-doped crystals

    E-print Network

    Zhong, Tian; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Quantum light-matter interfaces (QLMIs) connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching, and studies of fundamental physics. Rare-earth-ion (REI) doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium REIs to photonic nano-cavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2-4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled REIs is performed via photon echoes. Long optical coherence times (T2~100 microseconds) and small inhomogeneous...

  4. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    NASA Astrophysics Data System (ADS)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  5. New generation high-power rare-earth-doped phosphate glass fiber and fiber laser

    NASA Astrophysics Data System (ADS)

    Wu, Ruikun; Myers, John D.; Myers, Michael J.

    2001-04-01

    High power, high brightness fiber lasers have numerous potential commercial and military applications. Fiber lasers with cladding pump designs represent a new generation of diode pumped configurations that are extremely efficient, have single mode output and may be operated with or without active cooling. Kigre has invented a new family of Er/Yb/Nd phosphate laser glass materials (designated QX) that promise to facilitate a quantum leap in fiber laser technology of this field. The new phosphate glass Rare-Earth doped fiber exhibit many advantages than Silica or Fluoride base fiber, see table.1. Instead of 30 to 50 meters of fused silica with a 50 mm bend radii; Kigre's phosphate glass fiber amplifiers may be designed to be less than 4 meters long .Laser performance and various design parameters, such as the fiber core diameter, NA, inner cladding shape and doping concentration are evaluated. Laser performances was demonstrated for an experimental QX/Er doubled clading fiber commissioned by MIT having 8 micron core, a 240 X 300 micron rectangle shaped inner cladding with 0.4 NA and 500 micron outer clading.. Kigre obtained approximately 2 dB/cm gain from 15cm long fiber under 940nm pumping The same fiber was evaluated by researcher at MIT. They used 975nm pump source. Maximum 270mW output was demonstrated by 30 cm long fiber with Fresnel reflection resonator mirrors. The slope efficiency of absorbed pump power s 47%.

  6. An OpenEarth Framework (OEF) for Integrating and Visualizing Earth Science Data

    NASA Astrophysics Data System (ADS)

    Moreland, J. L.; Nadeau, D. R.; Baru, C.; Crosby, C. J.

    2009-12-01

    The integration of data is essential to make transformative progress in understanding the complex processes operating at the Earth’s surface and within its interior. While our current ability to collect massive amounts of data, develop structural models, and generate high-resolution dynamics models is well developed, our ability to quantitatively integrate these data and models into holistic interpretations of Earth systems is poorly developed. We lack the basic tools to realize a first-order goal in Earth science of developing integrated 4D models of Earth structure and processes using a complete range of available constraints, at a time when the research agenda of major efforts such as EarthScope demand such a capability. Among the challenges to 3D data integration are data that may be in different coordinate spaces, units, value ranges, file formats, and data structures. While several file format standards exist, they are infrequently or incorrectly used. Metadata is often missing, misleading, or relegated to README text files along side the data. This leaves much of the work to integrate data bogged down by simple data management tasks. The OpenEarth Framework (OEF) being developed by GEON addresses these data management difficulties. The software incorporates file format parsers, data interpretation heuristics, user interfaces to prompt for missing information, and visualization techniques to merge data into a common visual model. The OEF’s data access libraries parse formal and de facto standard file formats and map their data into a common data model. The software handles file format quirks, storage details, caching, local and remote file access, and web service protocol handling. Heuristics are used to determine coordinate spaces, units, and other key data features. Where multiple data structure, naming, and file organization conventions exist, those heuristics check for each convention’s use to find a high confidence interpretation of the data. When no convention or embedded data yields a suitable answer, the user is prompted to fill in the blanks. The OEF’s interaction libraries assist in the construction of user interfaces for data management. These libraries support data import, data prompting, data introspection, the management of the contents of a common data model, and the creation of derived data to support visualization. Finally, visualization libraries provide interactive visualization using an extended version of NASA WorldWind. The OEF viewer supports visualization of terrains, point clouds, 3D volumes, imagery, cutting planes, isosurfaces, and more. Data may be color coded, shaded, and displayed above, or below the terrain, and always registered into a common coordinate space. The OEF architecture is open and cross-platform software libraries are available separately for use with other software projects, while modules from other projects may be integrated into the OEF to extend its features. The OEF is currently being used to visualize data from EarthScope-related research in the Western US.

  7. Faraday Rotation Spectrum of Bismuth-Doped Rare-Earth Iron Garnets for Magneto-Optic Sensor Applications

    NASA Astrophysics Data System (ADS)

    Shinn, Mannix; Wu, Dong Ho; Garzarella, Anthony; Tao, Rongjia

    2014-03-01

    Iron garnet Faraday rotators are a promising sensor material for measuring magnetic fields. The rotator's field sensitivity increases inversely with wavelength and beam path, but so does the insertion loss. We wish to optimize sensor sensitivity by studying the transmission coefficient and Verdet constant over a spectrum from 0.4 to 2 um in samples of bismuth-doped rare-earth iron garnet. Data for two different gallium doped samples will be presented, including data of other magnetic field dependent effects that were observed.

  8. Doping Effect of Rare-Earth Ions on Electrical Properties of BiFeO3 Thin Films Fabricated by Chemical Solution Deposition

    Microsoft Academic Search

    Sushil K. Singh; Hiroshi Ishiwara

    2006-01-01

    Rare-earth-ion (La and Nd)-doped BiFeO3 (BFO) thin films were fabricated by depositing sol-gel solutions on Pt\\/Ti\\/SiO2\\/Si(100) structures. It was found from X-ray diffraction analysis that BFO thin films were polycrystalline and 5 at. % La and Nd ion dopings did not cause structural changes in the BFO thin films. By 5 at. % La doping in BFO thin films, breakdown

  9. Room-temperature-grown rare-earth-doped GaN luminescent thin films D. S. Lee and A. J. Steckla)

    E-print Network

    Steckl, Andrew J.

    for publication 24 July 2001 Visible emission has been observed from rare-earth RE -doped GaN electroluminescent that the films had a rough surface and a compact structure consisting of small grains. Electroluminescence for in situ RE doping of GaN has resulted2 in the successful fabrication of electroluminescent devices ELDs

  10. Visible and near-IR luminescence via energy transfer in rare earth doped mesoporous titania thin films with nanocrystalline walls

    NASA Astrophysics Data System (ADS)

    Frindell, Karen L.; Bartl, Michael H.; Robinson, Matthew R.; Bazan, Guillermo C.; Popitsch, Alois; Stucky, Galen D.

    2003-04-01

    Selected photoluminescence in the wavelength range of 600-1540 nm is generated by energy transfer from a light-gathering mesostructured host lattice to an appropriate rare earth ion. The mesoporous titania thin films, which have a well-ordered pore structure and two-phase walls made of amorphous titania and TiO 2 nanocrystallites, were doped with up to 8 mol% lanthanide ions, and the ordered structure of the material was preserved. Exciting the titania in its band gap results in energy transfer and it is possible to observe photoluminescence from the crystal field states of the rare earth ions. This process is successful for certain rare earth ions (Sm 3+, Eu 3+, Yb 3+, Nd 3+, Er 3+) and not for others (Tb 3+, Tm 3+). A mechanism has been proposed to explain this phenomenon, which involves energy transfer through surface states on titania nanocrystals to matching electronic states on the rare earth ions.

  11. Preparation and Photocatalysis Properties of Bacterial Cellulose\\/TiO2 Composite Membrane Doped with Rare Earth Elements

    Microsoft Academic Search

    Xiuju Zhang; Wenbin Chen; Zhidan Lin; Jia Yao; Shaozao Tan

    2011-01-01

    Bacterial cellulose (BC) was chosen as a support for nanometer titanium dioxide (TiO2) particles due to its superfine network structure. The composite membrane of TiO2\\/BC doped with rare earth elements was prepared by a sol-gel method using tetraisopropyl titanate as starting material. Photocatalysis properties of this composite membrane were estimated by using methyl orange as a degradation agent. X-ray fluorescence

  12. Recent developments in the growth, processing, and testing of rare-earth-doped YVO4 single crystals

    Microsoft Academic Search

    Gregory J. Mizell; William R. Fay; Theodore Alekel; Daniel Rytz

    1994-01-01

    The production of the laser host material YVO4 via high temperature solution growth (HTSG) is described as a facile alternative for producing optical quality crystals for research. The effects of dopant concentration on optical absorption properties in 0.7% and 3% Nd:YVO4 crystals are discussed. The rare earth ions Ho3+ and Er3+ have been doped into YVO4 with the HTSG method,

  13. The effect of rare earth doping on the glow peak positions of LiNaSO 4

    Microsoft Academic Search

    M. Maghrabi; D.-E. Arafah; L. Barham; M. Olaimi

    2007-01-01

    Thermoluminescence of the rare earths (Ho, Tb, Gd, Sm, Ce or La) doped LiNaSO4 and irradiated at room temperature was studied in the temperature range 300–673K. The glow curves of this material consistently illustrate the presence of two groups of glow peaks that behave differently. The first group occurs in the temperature range 350–450K, and the individual peaks occur at

  14. Features of an intermetallic n-ZrNiSn semiconductor heavily doped with atoms of rare-earth metals

    SciTech Connect

    Romaka, V. A., E-mail: vromaka@polynet.lviv.ua [National Academy of Sciences of Ukraine, Ya. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics (Ukraine); Fruchart, D.; Hlil, E. K. [CNRS, Institute Neel (France); Gladyshevskii, R. E. [Ivan Franko Lviv National University (Ukraine); Gignoux, D. [CNRS, Institute Neel (France); Romaka, V. V.; Kuzhel, B. S. [Ivan Franko Lviv National University (Ukraine); Krayjvskii, R. V. [Lvivska Politechnika National University (Ukraine)

    2010-03-15

    The crystal structure, density of electron states, electron transport, and magnetic characteristics of an intermetallic n-ZrNiSn semiconductor heavily doped with atoms of rare-earth metals (R) have been studied in the ranges of temperatures 1.5-400 K, concentrations of rare-earth metal 9.5 x 10{sup 19}-9.5 x 10{sup 21} cm{sup -3}, and magnetic fields H {<=} 15 T. The regions of existence of Zr{sub 1-x}R{sub x}NiSn solid solutions are determined, criteria for solubility of atoms of rare-earth metals in ZrNiSn and for the insulator-metal transition are formulated, and the nature of 'a priori doping' of ZrNiSn is determined as a result of redistribution of Zr and Ni atoms at the crystallographic sites of Zr. Correlation between the concentration of the R impurity, the amplitude of modulation of the bands of continuous energies, and the degree of occupation of potential wells of small-scale fluctuations with charge carriers is established. The results are discussed in the context of the Shklovskii-Efros model of a heavily doped and compensated semiconductor.

  15. Roadmap: Integrated Science Earth Science Bachelor of Science in Education

    E-print Network

    Sheridan, Scott

    11040 Earth Dynamics 3 C Fulfills Kent Core Basic Sciences GEOL 11041 Earth Dynamics Laboratory 1 C Society 3 C GEOL 11042 Earth History 3 C Fulfills Kent Core Basic Sciences GEOL 11043 Earth History 23063 Earth Materials I 4 C PHY 13001 General College Physics I 4 C Fulfills Kent Core Basic Sciences

  16. Structure-property-composition relationships in doped zinc oxides: enhanced photocatalytic activity with rare Earth dopants.

    PubMed

    Goodall, Josephine B M; Illsley, Derek; Lines, Robert; Makwana, Neel M; Darr, Jawwad A

    2015-02-01

    In this paper, we demonstrate the use of continuous hydrothermal flow synthesis (CHFS) technology to rapidly produce a library of 56 crystalline (doped) zinc oxide nanopowders and two undoped samples, each with different particle properties. Each sample was produced in series from the mixing of an aqueous stream of basic zinc nitrate (and dopant ion or modifier) solution with a flow of superheated water (at 450 °C and 24.1 MPa), whereupon a crystalline nanoparticle slurry was rapidly formed. Each composition was collected in series, cleaned, freeze-dried, and then characterized using analytical methods, including powder X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area measurement, X-ray photoelectron spectroscopy, and UV-vis spectrophotometry. Photocatalytic activity of the samples toward the decolorization of methylene blue dye was assessed, and the results revealed that transition metal dopants tended to reduce the photoactivity while rare earth ions, in general, increased the photocatalytic activity. In general, low dopant concentrations were more beneficial to having greater photodecolorization in all cases. PMID:25602735

  17. Sol-gel derived hybrid materials doped with rare earth metal ions

    NASA Astrophysics Data System (ADS)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2011-10-01

    Sol-gel derived organic-inorganic hybrid materials doped with rare earth metal ions (Pr 3+) and small amounts of lithium ions (˜0.1-0.2 wt.%) were produced from the tetraethyl orthosilicate (TEOS), AlCl 3·6H 2O (about 10 mol%), ethyl methacrylate, butyl methacrylate and some other organic additions (ca. 35-40 wt.% of organics in the fresh gels) to obtain hybrid organic-inorganic hosts. The gel and hybrid materials obtained were aged at room temperature for three weeks, then heated in an electric drier for 3 h at temperature of 125 °C and investigated for morphology, structure and luminescence properties by X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), 29Si and 27Al MAS nuclear magnetic resonance and fluorescence spectroscopy. An influence of the organic additions and inorganic dopants on microstructure of the materials obtained and their luminescence properties has been examined. Under excitation with UV radiation in a range of ˜210-350 nm, the sharp and relatively intense luminescence emission lines due to 3P 0 ? 3H 4 (blue) and 3P 0 ? 3F 3 (red) transitions of Pr 3+ ions were observed in the luminescence spectra of gel and hybrid materials of SA-series.

  18. Rare earth doped LiCaAlF 6 as a new potential dosimetric material

    NASA Astrophysics Data System (ADS)

    Di Martino, Daniela; Vedda, Anna; Montanari, Cinzia; Rosetta, Emanuela; Mihokova, Eva; Nikl, Martin; Sato, Hiroki; Yoshikawa, Akira; Fukuda, Tsuguo

    2007-09-01

    LiCaAlF 6 (LiCAF) crystals doped with two different rare earth (RE) ions (europium and cerium) have been investigated as potential new dosimetric materials. Thermally stimulated luminescence (TSL) measurements have been carried out and a quantitative comparison has been performed with a standard LiF dosimetric material. Wavelength-resolved TSL measurements have revealed that the TSL spectrum is dominated by RE-related emissions with no significant contributions from defect centers. The glow curve of LiCAF:Eu displays a dosimetric peak at about 240 °C with a good linearity versus imparted dose. Specifically, the material appears more sensitive than LiF at doses lower than 100 mGy (with a sensitivity limit of 10 -5 Gy). Concerning LiCAF:Ce, the glow curve is more complicated, dose memory effects appear and no peaks with good dosimetric properties are found. Therefore, LiCAF:Eu seems to be more promising in the search for a new dosimetric material.

  19. Rare-earth doped colour tuneable up-conversion ZBLAN phosphor for enhancing photocatalysis

    NASA Astrophysics Data System (ADS)

    Méndez-Ramos, J.; Acosta-Mora, P.; Ruiz-Morales, J. C.; Sierra, M.; Redondas, A.; Ruggiero, E.; Salassa, L.; Borges, M. E.; Esparza, P.

    2015-03-01

    Rare-earth doped ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fluoride glasses have been successfully synthesized showing outstanding UV-VIS up-conversion luminescence of Er3+ and Tm3+, sensitized by Yb3+ ions, under near-infrared excitation at 980 nm. The ratio between blue, green and red up-conversion emission bands can be adjusted by varying the pump power density of the incident infrared radiation, resulting in a controlled tuneability of the overall emitting colour from greenish to yellowish. Additionally, the observed high energy UV intense up-conversion emissions are suitable to enhance photocatalytic activity of main water-splitting semiconductor electrodes (such as TiO2) used in sustainable production of hydrogen. Photocatalysis and photolysis degradation of methylene blue in water under sun-like irradiation using benchmark photocatalyst (TiO2 Degussa P25) have been boosted by 20% and by a factor of 2.5 respectively, due to the enhancement of UV radiation that reaches the TiO2 particles by the addition of ZBLAN powder into a slurry-type photo-reactor. Hence, up-conversion ZBLAN phosphors contribute to demonstrate the possibility of transforming the incoming infrared radiation into the UV region needed to bridge the gap of photocatalytic semiconductors.

  20. Nanophotonic coherent light-matter interfaces based on rare-earth-doped crystals

    E-print Network

    Tian Zhong; Jonathan M. Kindem; Evan Miyazono; Andrei Faraon

    2015-07-03

    Quantum light-matter interfaces (QLMIs) connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching, and studies of fundamental physics. Rare-earth-ion (REI) doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium REIs to photonic nano-cavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2-4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled REIs is performed via photon echoes. Long optical coherence times (T2~100 microseconds) and small inhomogeneous broadening are measured for the cavity-coupled REIs, thus demonstrating their potential for on-chip scalable QLMIs.

  1. Rare-earth-doped nanophosphors for multicolor cathodoluminescence nanobioimaging using scanning transmission electron microscopy.

    PubMed

    Furukawa, Taichi; Fukushima, Shoichiro; Niioka, Hirohiko; Yamamoto, Naoki; Miyake, Jun; Araki, Tsutomu; Hashimoto, Mamoru

    2015-05-01

    We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence(CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3?Eu, Y2O3?Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light.Y2O3?Tb and Y2O3?Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared,and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since theRE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL. PMID:26000793

  2. The Characterization of Eu2+-Doped Mixed Alkaline-Earth Iodide Scintillator Crystals

    SciTech Connect

    Neal, John S [ORNL; Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL; Wisniewski, D. [Institute of Physics, Nicolaus Copernicus University, Toru?, Poland; Kolopus, James A [ORNL; Cherepy, Nerine [Lawrence Livermore National Laboratory (LLNL); Payne, Stephen A. [Lawrence Livermore National Laboratory (LLNL)

    2011-01-01

    The high-performance inorganic scintillator, SrI2:Eu2+, when activated with divalent europium in the concentration range of 3 to 6%, has shown great promise for use in applications that require high-energy-resolution gamma-ray detection. We have recently grown and tested crystals in which other alkaline-earth ions have been partially substituted for Sr ions. Specifically, europium-doped single crystals have been grown in which up to 30 at % of the strontium ions have been substituted for either by barium, magnesium, or calcium ions. In the case of the strontium iodide scintillator host, a material that is characterized by an orthorhombic crystal structure, there are three other column IIA elements that are obvious choices for investigations whose purpose is to realize potential improvements in the performance of SrI2:Eu2+-based scintillators via the replacement of strontium ions with either Mg2+, Ca2+, or Ba2+. Light yields of up to 81,400 photons/MeV with an associated energy resolution of 3.7% (fwhm for 662 keV gamma-rays) have been observed in the case of a partial substitution of Ba2+ for Sr2+. The measured decay times ranged from 1.1 to 2.0 s, while the peak emission wavelengths ranged from 432 to 438 nm.

  3. Synthesis and characterization of rare earth doped novel optical materials and their potential applications

    NASA Astrophysics Data System (ADS)

    Pokhrel, Madhab

    There are many application of photonic materials but selection of photonic materials are always constrained by number of factors such as cost, availability of materials, thermal and chemical stability, toxicity, size and more importantly ease of synthesis and processing along with the efficient emission. For example, quantum dots are efficient emitter but they are significantly toxic, whereas dyes are also efficient emitters but they are chemically unstable. On the other hand, display and LED requires the micron size particles but bio application requires the nano-sized particles. On the other hand, laser gain media requires the ceramics glass or single crystal not the nanoparticles. So, realization of practical optical systems critically depends on suitable materials that offer specific combinations of properties. Solid-state powders such as rare-earth ions doped nano and micron size phosphors are one of the most promising candidates for several photonic applications discussed above. In this dissertation, we investigate the upconversion (UC) fluorescence characteristics of rare earth (RE) doped M2O2S (M = Y, Gd, La) oxysulphide phosphors, for near-infrared to visible UC. Both nano and micron size phosphors were investigated depending on their applications of interest. This oxysulphide phosphor possesses several excellent properties such as chemical stability, low toxicity and can be easily mass produced at low cost. Mainly, Yb3+, Er3+, and Ho3+ were doped in the host lattice, resulting in bright red, green, blue and NIR emissions under 980 nm and 1550 nm excitation at various excitation power densities. Maximum UC quantum yields (QY) up to 6.2 %, 5.8%, and 4.6% were respectively achieved in Yb3+/Er3+ :La2O2S, Y2O2S, and Gd2O 2S. Comparisons have been made with respect to reported most efficient upconverting phosphors beta-NaYF4:20 % Yb/ 2% Er. We believe that present phosphors are the most efficient and lower excitation threshold upconverting phosphors at 980 and 1550 nm excitation reported to date for UV, green, red and NIR emissions, which makes them potential candidates for many photonic applications. In addition, UC mechanisms were proposed in these phosphors based on the time resolved spectroscopic measurements, including concentration, and power dependence studies. Potential applications of these phosphors in different areas such as solar cells, displays, etc. have been explored depending on the measured absolute quantum yield as well as color coordinate measurements. In addition, the application of nanophosphors for bioimaging application has been explored. Results from imaging of the nanoparticles together with aggregates of cultured cells have been studied. In vitro toxicity tests were conducted too. Nanoparticles internalization into the nucleus and cytoplasm were conformed using 3D reconstruction of the Z-stack images collected using the confocal mode of the two photon microscope. Measurement of the magnetization of the phosphor was conducted to study the paramagnetic strength of these Gd based nanoparticles. Magnetic resonance imaging with better contrast was also collected using these particles. Finally, the application of these UC phosphors for solar cell and display has been discussed briefly.

  4. EC-EARTH: an Earth System Model based on the ECWMF Integrated Forecasting System

    NASA Astrophysics Data System (ADS)

    Selten, F.; Bintanja, R.; Yang, S.; Severijns, C.; Semmler, T.; Wyser, K.; Wang, X.; Hazeleger, W.

    2009-04-01

    EC-EARTH is the name of an Earth system model that is being developed by a number of institutes in Europe. It is based on the Integrated Forecast System of the European Centre for Medium Range Weather Forecasts (ECWMF). The ECMWF model delivers the best weather forecasts in the world by an objective measure. However, when applied to climate time scales, the performance is not better than the state-of-art climate models by an objective metrics. In the Numerical Weather Prediction version, the top of the atmosphere fluxes (TOA) are not balanced with observed sea surface temperatures as a lower boundary condition. After consultation of experts at ECMWF, a set of parameters was identified that could be used to reduce the model biases and close the TOA heat budget. We describe a set of tuning experiments and show the subsequent improvements in the simulated climate by an objective metrics. The adjusted model at T159L62 resolution coupled to the NEMO2/ORCA1 ocean model outperforms the mean CMIP3 model using this metrics. Additional transient integrations show the extent to which 'fast processes' contribute to the errors in the mean state and variance.

  5. Postgraduate Education in Earth and Environmental Sciences: an Integrated Concept

    NASA Astrophysics Data System (ADS)

    Grosfeld, K.; Lohmann, G.; Ladstätter-Weißenmayer, A.; Burrows, J.; Sprengel, C.; Bijma, J.

    2009-04-01

    Today's graduate and postgraduate education in the field of Earth System and Environmental Science is a highly interdisciplinary and inter-institutional challenge. The integration of observations, palaeoclimate data, and climate modelling requires networks and collaborations of experts and specialists in order to better understand natural climate variations over a broad range of timescales and disciplines, and to cope with the challenges of recent climate change. The existing research infrastructure at the Alfred-Wegener-Institut Bremerhaven (AWI), University of Bremen (Uni-HB), and Jacobs University Bremen offers a unique research environment in north-western Germany to study past, present and future changes of the climate system, with special focus on high latitudinal processes. It covers all kind of disciplines, climate science, geosciences and biosciences, and provides a consistent framework for education and qualification of a new generation of expertly trained, internationally competitive master and PhD students. On postgraduate level, the Postgraduate Programme Environmental Physics (PEP) at University of Bremen (www.pep.uni-bremen.de) educates the participants on the complex relationship between atmosphere, hydrosphere (ocean), cryosphere (ice region) and solid earth (land). Here, the learning of experimental methods in environmental physics at the most advanced level, numerical data analysis using supercomputers, and data interpretation via sophisticated methods prepare students for a scientific career. The foundation of an Earth System Research School (ESSReS) (www.earth-system-science.org) at the AWI enables PhD students from a variety of disciplines to cooperate and exchange views on the common theme of ‘linking data and modelling', leading to a better understanding of local processes within a global context. Computational and conceptual models of the Earth system provide the ability to investigate different scenarios in biogeochemistry, such as the carbon cycle, the structure of marine sediments, and isotope distribution in climate components. Training and education, especially in time-series and data analysis, is a common key component for all participants. The Helmholtz graduate school for Polar and Marine Research (POLMAR) (polmar.awi.de), beyond the aforementioned programmes in further cooperation with the Max Planck Institute for Microbiology, Bremen, the University Potsdam, Bremerhaven University of Applied Science and the Institute for Marine Resources (IMARE), provides a consistent framework for education and qualification for PhD students in general. Developing all categories of skills needed for analysing complex climate and environmental systems and the development of integrated solutions in a supportive network of collaborating research institutions fosters outstanding career options. Structured training and supervision supported by a broad range of transferrable skill development courses is indicative for the entire concept. This structured and integrated educational concept provides a strong basis for qualifying the next generation of excellent scientists for the challenging questions in Earth System Science and Polar and Marine Research.

  6. An Integrated Concept on Earth and Environmental Sciences Postgraduate Education

    NASA Astrophysics Data System (ADS)

    Grosfeld, Klaus; Lohmann, Gerrit; Ladstätter-Weißenmayer, Annette; Burrows, John; Sprengel, Claudia; Bijma, Jelle

    2010-05-01

    Today's graduate and postgraduate education in the field of Earth System and Environmental Science is a highly interdisciplinary and inter-institutional challenge. The integration of observations, palaeoclimate data, and climate modelling requires networks and collaborations of experts and specialists in order to better understand natural climate variations over a broad range of timescales and disciplines, and to cope with the challenges of recent climate change. The existing research infrastructure at the Alfred-Wegener-Institut Bremerhaven (AWI), University of Bremen, and Jacobs University Bremen offers a unique research environment in north-western Germany to study past, present and future changes of the climate system, with special focus on high latitudinal processes. It covers all kind of disciplines, climate science, geosciences and biosciences, and provides a consistent framework for education and qualification of a new generation of expertly trained, internationally competitive master and PhD students. On postgraduate level, the Postgraduate Programme Environmental Physics (PEP) at the University of Bremen (www.pep.uni-bremen.de) educates the participants on the complex relationship between atmosphere, hydrosphere (ocean), cryosphere (ice region) and solid earth (land). Here, the learning of experimental methods in environmental physics at the most advanced level, numerical data analysis using supercomputers, and data interpretation via sophisticated methods prepare students for a scientific career. Within cooperation with the Ocean University of China (OUC) students are participating one year in the PEP programme during their master studies since 2006, to get finally a double degree of both universities. Based on this successful cooperation a similar programme is in preparation with the Lulea University of Technology, Sweden. The Earth System Science Research School (ESSReS) (www.earth-system-science.org) at the AWI enables PhD students from a variety of disciplines to cooperate and exchange views on the common theme of ‘linking data and modelling', leading to a better understanding of local processes within a global context. Computational and conceptual models of the Earth system provide the ability to investigate different scenarios in biogeochemistry, such as the carbon cycle, the structure of marine sediments, and isotope distribution in climate components. Training and education, especially in time-series and data analysis, is a common key component for all participants. The Helmholtz Graduate School for Polar and Marine Research (POLMAR) (polmar.awi.de), beyond the aforementioned programmes in further cooperation with the Max Planck Institute for Marine Microbiology, Bremen, the University of Potsdam, Bremerhaven University of Applied Science and the Institute for Marine Resources (IMARE), provides a consistent framework for education and qualification for PhD students in general. Developing all categories of skills needed for analysing complex climate and environmental systems and the development of integrated solutions in a supportive network of collaborating research institutions fosters outstanding career options. Structured scientific training and supervision supported by a broad range of transferable skills development courses is indicative for the entire concept. This structured and integrated educational concept provides a strong basis for qualifying the next generation of excellent scientists for the challenging questions in Earth System Science and Polar and Marine Research.

  7. Evidence for interface superconductivity in rare-earth doped CaFe2As2 single crystals

    NASA Astrophysics Data System (ADS)

    Lv, Bing; Deng, L. Z.; Wei, F. Y.; Xue, Y. Y.; Chu, C. W.

    2014-03-01

    To unravel to the mysterious non-bulk superconductivity up to 49K observed in rare-earth (R =La, Ce, Pr and Nd) doped CaFe2As2 single-crystals whose Tc is higher than that of any known compounds consisting of one or more of its constituent elements of R, Ca, Fe, and As at ambient or under pressures, systematic magnetic, compositional and structural have carried out on different rare-earth-doped (Ca1-xRx) Fe2As2 samples. We have detected extremely large magnetic anisotropy, doping-level independent Tc, unexpected superparamagnetic clusters associated with As vacancies and their close correlation with the superconducting volume fraction, the existence of mesoscopic-2D structures and Josephson-junction arrays in this system. These observations lead us to conjecture that the Tc enhancement may be associated with naturally occurring chemical interfaces and thus provided evidence for the possible interface-enhanced Tc in naturally-grown single crystals of Fe-based superconductors.

  8. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources

    PubMed Central

    2013-01-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence. PMID:24180684

  9. Microstructure and properties of in-flight rare-earth doped thermal barrier coatings prepared by suspension plasma spray

    NASA Astrophysics Data System (ADS)

    Gong, Stephanie

    Thermal barrier coatings with lower thermal conductivity improve the efficiency of gas turbine engines by allowing higher operating temperatures. Recent studies were shown that coatings containing a pair of rare-earth oxides with equal molar ratio have lower thermal conductivity and improved sintering resistance compared to the undoped 4-4.5 mol.% yttria-stabilized zirconia (YSZ). In the present work, rare-earth doped coatings were fabricated via suspension plasma spray by spraying YSZ powder-ethanol suspensions that contained dissolved rare-earth nitrates. The compositions of the coatings determined by inductively coupled plasma mass spectroscopy verified that 68 +/- 8% of the rare-earth nitrates added into the suspension was incorporated into the coatings. Two coatings containing different concentrations of the same dopant pair (Nd2O3/Yb2O3), and three coatings having similar concentrations of different dopant pairs (Nd 2O3/Yb2O3, Nd2O3/Gd 2O3, and Gd2O3/Yb2O 3) were produced and compared. The effect of dopant concentration and dopant pair type on the microstructure and properties of the coatings in the as-sprayed and heat treated conditions were investigated using XRD, SEM, TEM, STEM-EDX, and the laser flash method. The cross-sectional morphology of all coatings displayed columnar structure. The porosity content of the coating was found to increase with increasing dopant concentration, but did not significantly change with dopant pairs. Similarly, increasing the Nd2O3/Yb2O 3 concentration lowered the thermal conductivity of the as-sprayed coatings. Although the effect of changing dopant pair type is not as significant as increasing the dopant concentration, the coating that contained Gd2O 3/Yb2O3 exhibited the lowest conductivity compared to coatings that had other dopant pairs. Thermal conductivity measurement performed on the heat treated coatings indicated a larger conductivity increase for the rare-earth doped coatings. A detailed study on the microstructural change of the coatings after various heat treatments at 1200°C and 1300°C showed evidence of crack healing and grain growth. Comparison between the rare-earth dopant distribution of a selected coating before and after a 1300°C/50 hr heat treatment suggests the possibility of dopant rearrangement, which can further increase the thermal conductivity. An explanation on the difference in the properties of the rare-earth doped coatings produced by SPS and conventional processes was discussed.

  10. Polarization dependence of two-photon transition intensities in rare-earth doped crystals

    SciTech Connect

    Le Nguyen, An-Dien

    1996-05-01

    A polarization dependence technique has been developed as a tool to investigate phonon scattering (PS), electronic Raman scattering (ERS), and two-photon absorption (TPA) transition intensities in vanadate and phosphate crystals. A general theory for the polarization dependence (PD) of two-photon transition intensities has been given. Expressions for the polarization dependent behavior of two-photon transition intensities have been tabulated for the 32 crystallographic point groups. When the wavefunctions for the initial and final states of a rare-earth doped in crystals are known, explicit PD expressions with no unknown parameters can be obtained. A spectroscopic method for measuring and interpreting phonon and ERS intensities has been developed to study PrVO{sub 4}, NdVO{sub 4}, ErVO{sub 4}, and TmVO{sub 4} crystals. Relative phonon intensities with the polarization of the incident and scattered light arbitrarily varied were accurately predicted and subsequently used for alignment and calibration in ERS measurements in these systems for the first time. Since ERS and PS intensities generally follow different polarization curves as a function of polar angles, the two can be uniquely identified by comparing their respective polarization behavior. The most crucial application of the technique in ERS spectroscopy is the establishment of a stringent test for the Axe theory. For the first time, the F{sub 1}/F{sub 2} ratio extracted from the experimental fits of the ERS intensities were compared with those predicted by theories which include both the second- and third-order contributions. Relatively good agreement between the fitted values of F{sub 1}/F{sub 2} and the predicted values using the second-order theory has been found.

  11. Visualization of melanoma tumor with lectin-conjugated rare-earth doped fluoride nanocrystals

    PubMed Central

    Dumych, Tetiana; Lutsyk, Maxym; Banski, Mateusz; Yashchenko, Antonina; Sojka, Bartlomiej; Horbay, Rostyslav; Lutsyk, Alexander; Stoika, Rostyslav; Misiewicz, Jan; Podhorodecki, Artur; Bilyy, Rostyslav

    2014-01-01

    Aim To develop specific fluorescent markers for melanoma tumor visualization, which would provide high selectivity and reversible binding pattern, by the use of carbohydrate-recognizing proteins, lectins, combined with the physical ability for imaging deep in the living tissues by utilizing red and near infrared fluorescent properties of specific rare-earth doped nanocrystals (NC). Methods B10F16 melanoma cells were inoculated to C57BL/6 mice for inducing experimental melanoma tumor. Tumors were removed and analyzed by lectin-histochemistry using LABA, PFA, PNA, HPA, SNA, GNA, and NPL lectins and stained with hematoxylin and eosin. NPL lectin was conjugated to fluorescent NaGdF4:Eu3+-COOH nanoparticles (5 nm) via zero length cross-linking reaction, and the conjugates were purified from unbound substances and then used for further visualization of histological samples. Fluorescent microscopy was used to visualize NPL-NaGdF4:Eu3+ with the fluorescent emission at 600-720 nm range. Results NPL lectin selectively recognized regions of undifferentiated melanoblasts surrounding neoangiogenic foci inside melanoma tumor, PNA lectin recognized differentiated melanoblasts, and LCA and WGA were bound to tumor stroma regions. NPL-NaGdF4:Eu3+ conjugated NC were efficiently detecting newly formed regions of melanoma tumor, confirmed by fluorescent microscopy in visible and near infrared mode. These conjugates possessed high photostability and were compatible with convenient xylene-based mounting systems and preserved intensive fluorescent signal at samples storage for at least 6 months. Conclusion NPL lectin-NaGdF4:Eu3+ conjugated NC permitted distinct identification of contours of the melanoma tissue on histological sections using red excitation at 590-610 nm and near infrared emission of 700-720 nm. These data are of potential practical significance for development of glycans-conjugated nanoparticles to be used for in vivo visualization of melanoma tumor. PMID:24891277

  12. An integrated view of data quality in Earth observation.

    PubMed

    Yang, X; Blower, J D; Bastin, L; Lush, V; Zabala, A; Masó, J; Cornford, D; Díaz, P; Lumsden, J

    2013-01-28

    Data quality is a difficult notion to define precisely, and different communities have different views and understandings of the subject. This causes confusion, a lack of harmonization of data across communities and omission of vital quality information. For some existing data infrastructures, data quality standards cannot address the problem adequately and cannot fulfil all user needs or cover all concepts of data quality. In this study, we discuss some philosophical issues on data quality. We identify actual user needs on data quality, review existing standards and specifications on data quality, and propose an integrated model for data quality in the field of Earth observation (EO). We also propose a practical mechanism for applying the integrated quality information model to a large number of datasets through metadata inheritance. While our data quality management approach is in the domain of EO, we believe that the ideas and methodologies for data quality management can be applied to wider domains and disciplines to facilitate quality-enabled scientific research. PMID:23230156

  13. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    SciTech Connect

    Katsumata, Toru, E-mail: katsumat@toyo.jp; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki [Faculty of Science and Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.

  14. Novel kinds of down/up-conversion luminescent rare earth doped fluoride BaMgF{sub 4}: RE{sup 3+} microcrystals

    SciTech Connect

    Yan, Zhi-Yuan; Yan, Bing, E-mail: byan@tongji.edu.cn; Jia, Li-Ping

    2013-10-15

    Graphical abstract: We achieve the liquid phase chemical synthesis of rare earth fluoride system BaMgF4: RE{sup 3+} microphosphors, which realize down/up-conversion luminescence. - Highlights: • Doped BaMgF{sub 4} microphosphors are firstly prepared by hydrothermal process. • Doped BaMgF{sub 4} nanosheets are firstly prepared by high temperature solution reaction. • The down-conversion luminescence is realized in the rare earth doped BaMgF{sub 4}. • The upconversion luminescence is realized in the rare earth doped BaMgF{sub 4}. - Abstract: In this paper, we realize the liquid-phase chemical synthesis of high-quality orthorhombic polycrystalline BaMgF{sub 4}: RE{sup 3+} (RE = Eu, Tb, Sm, Dy, Yb–Er/Tm) compounds with hydrothermal and high-temperature solution methods, respectively. The products from hydrothermal technology show the micrometer size while the products from hydrothermal technology present nanosheet morphology. The rare earth ions doped BaMgF{sub 4} from hydrothermal synthesis are discussed in details, which can realize the downconversion luminescence for doped Eu{sup 3+} or Tb{sup 3+} and upconversion luminescence for Yb{sup 3+}/Er{sup 3+} (Tm{sup 3+}), respectively. To our knowledge, the hydrothermal or high temperature solution synthesis and photoluminescence (Eu{sup 3+}, Tb{sup 3+} or Yb{sup 3+}/Er{sup 3+}(Tm{sup 3+})) of these fluoride systems are firstly reported.

  15. Dosimetric studies of YAlO3: Mn co-doped with transition (Co, Cu, Fe) and rare earth (Yb, Ce) metal ions

    NASA Astrophysics Data System (ADS)

    Premkumar, H. B.; Nagabhushana, H.; Sharma, S. C.; Prashantha, S. C.; Nagabhushana, B. M.; Nagaswarupa, H. P.; Zhao, Guangjun; Chen, Jianyu

    2014-04-01

    Dosimetric studies on single crystals of YAlO3:Mn co-doped with transition (Co, Cu, Fe) and rare earth (Yb, Ce) metal ions using UV radiation exposure for the duration 5-30 min have been studied. A single well resolved thermoluminescence glow peak was observed at 183 °C in Co and Cu co-doped single crystals. In Fe co-doped single crystals, two well resolved glow peaks at 196 °C and 238 °C were observed. A well resolved glow peak at 215 °C in Yb and 176 °C in Ce co-doped single crystals was observed. Variations of thermoluminescent (TL) glow peaks intensity in all the co-doped crystals with different UV-exposures were studied. TL glow peak intensity increases sublinearly in Co, Cu co-doped crystals, whereas in Fe co-doped crystals glow peaks at 196 °C and 238 °C increase linearly. Fading effect was studied at different intervals up to 30 d for all co-doped crystals exposed to UV source for 10 min. Strong fading was observed initially and stabilized after 15 d. Fe co-doped YAlO3:Mn2+ records 40% fading, whereas other samples of YAlO3:Mn2+ co-doped with Cu, Co, Yb and Ce show 60% fading. The kinetic parameters (E, b, s) were estimated using glow peak shape method for UV irradiated samples and results are discussed in detail.

  16. Structural changes and the nature of superconductivity in rare-earth doped CaFe2As2

    NASA Astrophysics Data System (ADS)

    Drye, Tyler

    Chemical substitution into iron-pnictide parent compounds (e.g. AFe2As2 where A=Ba, Sr, or Ca) has proven to be an effective means to induce bulk high-temperature superconductivity in these systems. By doping CaFe2As2 with rare-earth lanthanides (La, Ce, Pr, and Nd), we have observed a 47 K superconducting phase coexisting with a lattice distorting "collapse" transition. Both of these effects have important ramifications: the collapse transition occurs when interlayer As atoms form a bond, shrinking the c-axis lattice constant and simultaneously quenching the iron magnetic moment. This transition is further explored in context of a similar system, Sr-doped BaNi2As2. The superconducting phase, given the right combination of conditions, appears with a critical temperature as high as 49 K, but always in a very small volume of the sample (as determined by shielding effects). This has led to interesting theories about the nature of this superconductivity. A recently posited idea of "interfacial superconductivity" has been ruled out by our tests. Additionally, increasing the concentration of rare-earth atoms does not increase the superconducting volume fraction, but, in fact lowers the transition temperature, excluding the hypothesis that rare-earth defects are responsible for the minority superconducting phase. New pressure measurements have shown that the superconducting phase is stabilized when antiferromagnetic order is fully suppressed.

  17. Piezoelectric/photoluminescence effects in rare-earth doped lead-free ceramics

    NASA Astrophysics Data System (ADS)

    Yao, Qirong; Wang, Feifei; Jin, Chengchao; Tang, Yanxue; Wang, Tao; Shi, Wangzhou

    2013-10-01

    In the present work, we report the environmentally-friendly multifunctional effects—piezoelectric/photoluminescence effects, which originated from the combination of the electromechanical properties and the photoluminescence effect through introducing the rare-earth elements (Pr and Eu) into the (Bi0.5Na0.5)TiO3-BaTiO3 ceramics with the composition around the morphotropic phase boundary. Compared to the pure piezoelectric ceramic, the proposed system simultaneously exhibited enhanced ferroelectric, piezoelectric, dielectric properties along with strong photoluminescence effects, which exhibited potential applications in sensor, and electro-mechano-optical integration. In addition, the present work also provides a promising path for us to fabricate multifunctional composites.

  18. Overview of the MERRA Aerosol Reanalysis: Toward and Integrated Earth System Analysis

    E-print Network

    Overview of the MERRA Aerosol Reanalysis: Toward and Integrated Earth System Analysis Arlindo da Radiative Forcing #12;Integrated Earth System Analysis Preliminary IESA (PIESA): MERRA driven component) Constrained by MERRA Meteorology (Replay) Land sees obs. precipitation (like MERRALand) Driven by QFED daily

  19. Spectroscopic evaluation of rare earth doped GaN for full-color display applications

    Microsoft Academic Search

    E. E. Nyein; U. Hommerich; J. Heikenfeld; D. S. Lee; A. J. Steckl; J. M. Zavada

    2002-01-01

    Summary form only given. We are currently engaged in a spectroscopic evaluation of Er doped GaN and Eu doped GaN as phosphor materials. The investigated samples were grown by solid-source molecular beam epitaxy on Si [111] substrates. An overview of the room-temperature emission spectra from both samples is shown.

  20. Integrating the Earth, Atmospheric, and Ocean Sciences at Millersville University

    Microsoft Academic Search

    R. D. Clark

    2005-01-01

    For nearly 40 years, the Department of Earth Sciences at Millersville University (MU-DES) of Pennsylvania has been preparing students for careers in the earth, atmospheric, and ocean sciences by providing a rigorous and comprehensive curricula leading to B.S. degrees in geology, meteorology, and oceanography. Undergraduate research is a hallmark of these earth sciences programs with over 30 students participating in

  1. Rare-earth-doped LiNbO3 and KTiOPO4 (KTP) for waveguide quantum memories

    Microsoft Academic Search

    C W Thiel; Y Sun; R M Macfarlane; Thomas Böttger; R L Cone

    2012-01-01

    Optical waveguides in rare-earth-doped crystals are one of the most promising systems for practical implementations of quantum memory. To further develop these systems, detailed understanding of these materials is required. We report experimental studies of the optical properties and decoherence for Tm3+:LiNbO3, Pr3+:LiNbO3, Er3+:LiNbO3 and Er3+:KTiOPO4 (KTP) bulk crystals for quantum memory applications and discuss potential differences between the properties

  2. Growth of metallic Ag nanoparticles in fluoroborate glasses doped with rare-earth ions and their optical characterization

    NASA Astrophysics Data System (ADS)

    Riano, L. P.; de Araujo, Cid B.; Malta, O. L.; Santa Cruz, P.; Couto dos Santos, Marcos A.

    2004-10-01

    Fluoroborate glasses have been prepared containing silver nanoparticles (NP) and rare-earth (RE) ions. Optical techniques were used for analysis of the surface plasmon (SP) band formation and to determine the influence of the NP on the RE ions luminescence. Electron microscopy was applied to measure the particles concentration and their size distributions. The techniques used allowed to identify the presence of Ag particles with diameters in the range of 5 - 200 nm. The absorption band of SP is centered at 425 nm for samples doped with Eu3+ and centered at 416 nm for samples with Pr3+. The ions luminescence shows enhancement or quenching for metallic particles of different sizes.

  3. Epithermal and thermal neutron response to rare earth doped fricke dosimeters

    E-print Network

    Groves, Kenneth Lee

    1970-01-01

    spectrum neutrons. 28 1 5 1 ~ 0 0 ~ 9 0 ~ 8 0 ~ 7 0 ~ 6 0 ~ 5 8 0 ~ 0 0 ~ 2 2nd Run Dy 0 1st Run Dy Norma1z. zed 2nd B1n 0. 1 0 0 1 ~ 0 2 ~ 0 3'0 0'0 5 ' 0 6 ' 0 Dose (Rads x 10') Fig. 14. "Log" absorbance versus dose for Dy doped... Fnicke dosimeters exposed to "Co gamma rays. . 14 Fig. 3. Absczbance versus dose from Eu doped Fricke dosimeters exposed to "Co gamma rays, . 15 Fig. 4. Absonbance versus dose for Dy doped Fricke dosimeters exposed to "Co gamma rays. . Fig. 5...

  4. Luminescence and scintillation properties of rare-earth-doped LuF3 scintillation crystals

    NASA Astrophysics Data System (ADS)

    Pejchal, Jan; Fukuda, Kentaro; Kurosawa, Shunsuke; Yokota, Yuui; Yoshikawa, Akira

    2015-03-01

    The Nd-doped and Er-doped LuF3 single crystals were grown by the micro-pulling-down method to study their scintillation properties in the vacuum-ultraviolet (VUV) region. The doubly Nd-Er codoped single crystal was grown to study possibility of scintillation performance improvement by energy transfer from Er3+ to Nd3+ ions. The LiF flux was to avoid phase transition below melting temperature. The 1%Nd-doped sample showed the highest overall scintillation efficiency under X-ray excitation which was 7 times as high as that of the LaF3:Nd 8% standard. The leading Nd3+ 5d-4f emission was situated at 176 nm, while the Er3+ 5d-4f emission for Er-doped samples was observed at 163 nm, which better matches the sensitivity of some VUV-sensitive photodetectors. The optimum Er concentration was determined to be around 1-3 mol%. No Er3+ 5d-4f emission was observed for the doubly Er,Nd-codoped sample due to energy transfer from the Er3+ to Nd3+ ions. Slight improvement of the light yield was observed in the doubly-doped sample with respect to the Nd-only doped one.

  5. Frequency dependence of Verdet constant of Bismuth-Doped Rare-Earth Iron Garnets for Magneto-Optic Sensor Applications

    NASA Astrophysics Data System (ADS)

    Shinn, Mannix; Tao, Rongjia; Wu, Dong Ho; Garzarella, Anthony

    2013-03-01

    There is growing interest in applying magneto-optic materials toward sensor applications. One of these applications is to exploit the Faraday Effect to measure magnetic fields. Bismuth-doped rare-earth iron garnets have proven to be highly sensitive Faraday rotators, but their frequency response and dynamic range to magnetic fields require further study. The Faraday Effect was studied in two samples of bismuth-doped rare-earth iron garnets grown in different conditions, and experiments were performed in a static field as well as in a RF field. Static magnetic fields up to 3 kG were used, and we found that the Faraday rotation became saturated at high fields, indicating that the field dependence follows the hyperbolic tangent function. We extracted each sample's Verdet constant from the Faraday rotation at low magnetic fields of < 0.1 kG. These experiments were repeated using different laser probe beam wavelengths, ranging from 405 nm to 2000 nm. We measured the transmission coefficient and the Verdet constant for each sample for different probe beam wavelengths and for an external magnetic field at various frequencies. We will discuss the implication of our experimental results.

  6. Generation of wide color gamut visible light in rare-earth triply doped tantalum oxide crystalline ceramic powders

    NASA Astrophysics Data System (ADS)

    Gouveia-Neto, A. S.; Bueno, L. A.; da Costa, E. B.; Silva, E. A.; Ferrari, J. L.; Lima, K. O.; Gonçalves, R. R.

    2010-05-01

    Multicolor visible light emitting near-infrared (NIR)-excited Tm/Ho/Yb-codoped tantalum oxide nanopowders were produced using the sol-gel method. The generation of wide color gamut fluorescence in glass-ceramic with orthorhombic Ta2O5 nanocrystals dispersed into amorphous silica-based matrix is observed. The light emission spectroscopic properties of the rare-earth doped SiO2:Ta2O5 nanocomposites as a function of the tantalum content and temperature of annealing is examined. Simultaneously emitted multicolor fluorescence consisting of blue (480 nm), green (540 nm), and red (650 nm) upconversion signals in the SiO2:Ta2O5 system doped with holmium and thulium and sensitized with ytterbium, is demonstrated. It is also demonstrated that the proper choice of the rare-earth content and the NIR excitation power yielded the generation and control of the three primary colors and allows the emission of a balanced white overall luminescence from the glass-ceramic nanopowder samples.

  7. Integration of a modulated barrier photodiode with a doped-channel quasi-MISFET

    NASA Astrophysics Data System (ADS)

    Li, W. Q.; Bhattacharya, Pallab K.

    1989-09-01

    An integration scheme for a front-end photoreceiver is demonstrated, wherein an identical GaAs/InGaAs/AlGaAs heterostructure is used for realizing a modulated barrier photodiode (MBP) and a doped-channel quasi-MISFET. The detectors exhibit optical gains of 200. The FETs have an extrinsic transconductance of 250 mS/mm, with f(T) = 12 GHz and f(max) = GHz.

  8. Photoluminescence of the Eu-doped thin film heterojunction GaAs/SnO2 and rare-earth doping distribution

    NASA Astrophysics Data System (ADS)

    Bueno, C. F.; Scalvi, L. V. A.; Saeki, M. J.; Li, M. S.

    2015-03-01

    Tin dioxide (SnO2) thin films doped with Eu3+ are deposited by the sol-gel-dipcoating process on top of GaAs films, which is deposited by resistive evaporation on glass substrate. This heterojunction assembly presents luminescence from the rare-earth ion, unlike the SnO2 deposition directly on a glass substrate, where emissions from the Eu3+ transitions are absent. The Eu3+ transitions are clearly identified and are similar to the observation on SnO2 pressed powder (pellets), thermally treated at much higher temperatures. However, in the form of heterojunction films, the Eu emission comes along a broad band, located at higher energy compared to Eu3+ transitions, which is blue-shifted as the thermal annealing temperature increases. The size of nanocrystallites points toward quantum confinement or electron transfer between oxygen vacancies, originated from the disorder in the material, and trivalent rare-earth ions, which present acceptor-like character in this matrix. This electron transfer may relax for higher temperatures in the case of pellets, and the broad band is eliminated.

  9. Investigation of thermal diffusivity dependence on temperature in a group of optical single crystals doped with rare earth ions

    NASA Astrophysics Data System (ADS)

    Trefon-Radziejewska, D.; Bodzenta, J.

    2015-07-01

    The group of YAG, YVO4 and GdCOB single crystals was examined to determine the thermal diffusivity as a function of temperature in range from 30 °C to 300 °C. Further investigations concerned on analysis of the influence of dopants on these dependencies. The experimental setup based on thermal wave method with mirage detection was used. The samples represented different crystallographic systems such as cubic (YAG) tetragonal (YVO4) and monoclinic (GdCOB). The anisotropy of thermal conductivity of investigated samples was taken into account in the investigations. The crystals were doped with calcium ions, rare earth ions such as ytterbium, neodymium, and thulium, and also with transition metal vanadium. The results confirmed that influence of doping on the thermal diffusivity of investigated materials strongly depends on temperature. In general the thermal diffusivity decreases with increasing of sample temperature from 30 °C to 300 °C, however the drop in thermal diffusivity is the highest for pure single crystals. Doping is another factor reducing the heat transport in single crystals. Introduction of dopant ions into a crystal lattice leads to a significant decrease in the thermal diffusivity at lower temperatures in comparison with pure crystals. However, the influence of dopants becomes less pronounced with increasing temperature, and in case of weakly doped crystals it becomes negligible at higher temperatures. The interpretation of thermal diffusivity dependence on temperature for single crystals was based on the Debye model of lattice thermal conductivity of solids. The results allowed to conclude that the decrease of thermal diffusivity with temperature and increasing concentration of impurities is caused by shortening of the phonons mean free path due to phonon-phonon and phonon-point defect scatterings.

  10. Enhancement of thermopower of TAGS-85 high-performance thermoelectric materials by doping with the rare earth Dy

    SciTech Connect

    Levin, Evgenii; Budko, Serfuei; Schmidt-Rohr, Klaus

    2012-04-10

    Enhancement of thermopower is achieved by doping the narrow-band semiconductor Ag{sub 6.52}Sb{sub 6.52}Ge{sub 36.96}Te{sub 50} (acronym TAGS-85), one of the best p-type thermoelectric materials, with 1 or 2% of the rare earth dysprosium (Dy). Evidence for the incorporation of Dy into the lattice is provided by X-ray diffraction and increased orientation-dependent local fields detected by {sup 125}Te NMR spectroscopy. Since Dy has a stable electronic configuration, the enhancement cannot be attributed to 4f-electron states formed near the Fermi level. It is likely that the enhancement is due to a small reduction in the carrier concentration, detected by {sup 125}Te NMR spectroscopy, but mostly due to energy filtering of the carriers by potential barriers formed in the lattice by Dy, which has large both atomic size and localized magnetic moment. The interplay between the thermopower, the electrical resistivity, and the thermal conductivity of TAGS-85 doped with Dy results in an enhancement of the power factor (PF) and the thermoelectric figure of merit (ZT) at 730 K, from PF = 28 ?W cm{sup ?1} K{sup ?2} and ZT ? 1.3 in TAGS-85 to PF = 35 ?W cm{sup ?1} K{sup ?2} and ZT ? 1.5 in TAGS-85 doped with 1 or 2% Dy for Ge. This makes TAGS-85 doped with Dy a promising material for thermoelectric power generation.

  11. Spectroscopic Studies of Rare Earth Doped Fibers and Their Applications in Optical Amplifiers, Fiber Lasers, and Gas Sensors.

    NASA Astrophysics Data System (ADS)

    Oh, Kyunghwan

    1994-01-01

    Rare earth doped silica fibers were fabricated using Modified Chemical Vapor Deposition with an aerosol delivery technique. Active fiber devices were fabricated and their spectroscopic properties were characterized. In an Er^{+3} doped rm Ta_2O_5-rm Al_2O_3-SiO_2 fiber, addition of rm Ta_2O_5 was found to show more spectroscopic structures of Er ions than rm Al_2O_3 -SiO_2 glass. When pumped at 975 nm this fiber showed a gain of 26 +/- 1 dB over 35 nm. In a Eu doped aluminosilicate fiber a permanent index change of 2.3times 10^{-5} was observed when irradiated by 249 nm excimer laser. From UV-visible absorption spectra of the preform, it is suggested that UV photosensitivity of the fiber may be related to Eu^{+2 } ions. A permanent index change of 5.1 times 10^{-5} was induced in a Sm^{+2}/Sm ^{+3} doped aluminosilicate fiber by irradiating 2W of multi-line output from an Ar ion laser. The origin of the photosensitivity in the Sm doped fiber may be the bleaching of Sm^{2+} ion absorption bands enhanced by multiphoton processes. Tm doped rm Ta_2O_5- rm Al_2O_3-SiO_2 glass fiber lasers were fabricated using a Fabry -Perot type fiber laser cavity. Multi-line lasing was observed and the emission wavelength was found to depend on the cavity length and the output coupling ratio. Amplified spontaneous emission from the ^3 H_4to ^3 H_6 transition of Tm^{+3} in the fiber has been observed at 1.91 ?m with a FWHM of 77 nm, an output power of 1.2 mW. Continuous wave laser oscillations in a Tm^{3+ } and Ho^{3+} codoped silica fiber have been observed from the ^5 I_7to^5 I_8 transition of Ho^{3+} in the 2 ?m region, by pumping into a Tm^{3+} absorption between 800 and 830 nm. By changing the cavity length, the laser was tunable between 2.037 and 2.096 mum. Pumped with a Ti:Sapphire laser at 820 nm, an absorbed threshold power of 214 mW, a slope efficiency of 4.2% and maximum extracted power of 12.5 mW were measured. Using fluorescence of this fiber CO_2 gas was detected down to 1% in a simple white cell spectroscopy setup.

  12. INTEGRATED EARTH OBSERVATIONS: APPLICATION TO AIR QUALITY AND HUMAN HEALTH

    EPA Science Inventory

    In February 2005, ministers from 60 countries and the European Commission met in Brussels, Belgium to endorse the 10-year plan for a Global Earth Observation System of Systems(GEOSS) prepared by the Group on Earth Observations (GEO), a partnership of nations and international org...

  13. INTEGRATED FRAMEWORKS FOR EARTH AND SPACE WEATHER SIMULATION

    Microsoft Academic Search

    Timothy Killeen; Cecelia DeLuca; Tamas Gombosi; Gabor Toth; Quentin Stout; Charles Goodrich; Alan Sussman; Michael Hesse

    Simulations of Earth and space weather require the representation and coupling of distinct physical domains in a flexible, computationally efficient manner. There is increasing call to interface Earth and space models, as the interplay of phenomena between these domains is an active topic of basic research, and a key factor in operational prediction systems. Software frameworks have been developed in

  14. [Effect of bivalent alkaline earth fluorides introduction on thermal stability and spectroscopic properties of Er3+/Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses].

    PubMed

    Hu, Yue-bo; Zhang, Xin-na; Zhou, Da-li; Jiao, Qing; Wang, Rong-fei; Huang, Jin-feng; Long, Xiao-bo; Qiu, Jian-bei

    2012-01-01

    Transparent Er3+/Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses alone containing MgF2, CaF2, SrF2 or BaF2 and nano-glass-ceramics only containing BaF2 were prepared. The thermal stabilities and the up-conversion emission properties of the samples were investigated. Analyses of absorbance spectra reveal that the UV cutoff band moves slightly to shortwave band with the doping bivalent cation mass increasing. The results show that the emission color can be adjusted by changing the alkaline earth cation species in the glass matrixes, especially as Mg2+ is concerned, and the emission intensity can increase notably by heating the glass containing alkaline-earth fluoride into glass ceramic containing alkaline-earth fluoride nanocrystals or increasing the content of bivalent alkaline earth fluorides. PMID:22497127

  15. Computer modelling of defect structure and rare earth doping in LiCaAlF6 and LiSrAlF6

    NASA Astrophysics Data System (ADS)

    Amaral, J. B.; Plant, D. F.; Valerio, M. E. G.; Jackson, R. A.

    2003-05-01

    This paper describes a computational study of the mixed metal fluorides LiCaAlF6 and LiSrAlF6, which have potential technological applications when doped with a range of elements, especially those from the rare earth series. Potentials are derived to represent the structure and properties of the undoped materials, then defect properties are calculated, and finally solution energies for rare earth elements are calculated, enabling preferred dopant sites and charge compensation mechanisms to be predicted.

  16. Electroluminescence and Photoluminescence of Thin Films of ZnS Doped with Rare-Earth Metals

    Microsoft Academic Search

    D. C. Krupka; D. M. Mahoney

    1972-01-01

    It has been shown recently that efficient electroluminescence may be obtained from thin films formed by the coevaporation of ZnS and rare-earth fluorides. In order to assess the importance of the fluorine ions in such systems, films have been produced by coevaporating ZnS and rare-earth metals (Tb, Sm, Nd). It is shown that large concentrations of well-dispersed rare-earth ions may

  17. Electromagnetic wave propagation over an inhomogeneous flat earth - Two-dimensional integral equation formulation

    Microsoft Academic Search

    G. de Jong

    1975-01-01

    With the aid of a two-dimensional integral equation formulation, the ground wave propagation of electromagnetic waves transmitted by a vertical electric dipole over an inhomogeneous flat earth is investigated. For the configuration in which a ground wave is propagating across an 'island' on a flat earth, the modulus and argument of the attenuation function have been computed. The results for

  18. The SISMA prototype system: integrating Geophysical Modeling and Earth Observation for time dependent seismic hazard assessment

    Microsoft Academic Search

    A. Peresan; G. F. Panza; R. Sabadini; R. Barzaghi; A. Amodio; G. Bianco

    2009-01-01

    A new approach to seismic hazard assessment is illustrated that, based on the available knowledge of the physical properties of the Earth structure and of seismic sources, as well as on the geophysical forward modeling, allows for a time dependent definition of the seismic input. According to the proposed approach, a fully formalized system integrating Earth Observation data and new

  19. A spray drying system for synthesis of rare-earth doped cerium oxide nanoparticles

    Microsoft Academic Search

    Vaneet Sharma; Kathryn M. Eberhardt; Renu Sharma; James B. Adams; Peter A. Crozier

    2010-01-01

    We have constructed a spray dryer to synthesize doped ceria nanoparticles. The system was employed to synthesize mixed oxide nanoparticles of praseodymium doped CeO2 (Ce0.97Pr0.03O2, Ce0.90Pr0.10O2, and Ce0.80Pr0.20O2). X-ray diffraction confirmed the fluorite-like cubic crystal structure of the synthesized materials after heat treatment at 700°C for 2h. As-dried CeO2 samples were found to have an average particle size of (6.0±0.2)nm

  20. The integration of the motion equations of low-orbiting earth satellites using Taylor's method

    NASA Astrophysics Data System (ADS)

    Krivov, A. V.; Chernysheva, N. A.

    1990-04-01

    A method for the numerical integration of the equations of motion for a satellite is proposed, taking the earth's oblateness and atmospheric drag into account. The method is based on Taylor's representation of the solution to the corresponding polynomial system. The algorithm for choosing the integration step and error estimation is constructed. The method is realized as a subrouting package. The method is applied to a low-orbiting earth satellite and the results are compared with those obtained using Everhart's method.

  1. Preparation and Properties of Pressing Powders for Bioactivity Pottery Doped with Rare Earth

    Microsoft Academic Search

    Meng Junping; Liang Jinsheng; Wang Lijuan; Li Yangxian; Ding Yan; Nie Lei

    2007-01-01

    Pressing powders for bioactivity pottery (PPBP) were prepared using rare earth (RE), magnetic materials (MM) and other mineral materials, according to structural characteristics of water clusters, the oscillation law of molecule and bioactivity mechanism. The microstructures and bioactivity of the powders were characterized by SEM, IR, etc. The results showed that tourmaline, rare earth and magnetic materials could cooperate together

  2. Exchange integrals in Mn- and Co-doped II-VI semiconductors

    NASA Astrophysics Data System (ADS)

    Savoyant, A.; D'Ambrosio, S.; Kuzian, R. O.; Daré, A. M.; Stepanov, A.

    2014-08-01

    Exchange integrals between nearest-neighbor (NN) transition metal ions in II-VI diluted magnetic semiconductors (DMSs) are calculated within a local superexchange model, which includes orbital-dependent transfer, on-site Coulomb repulsion and Hund's exchange between 3d electrons, and ligand field effects. This extended model gives a quantitative account for the available experimental data on the NN exchange constants in all II-VI DMS family (wurtzite and zinc-blende) doped by cobalt or manganese. As expected, all obtained exchange integrals are antiferromagnetic. Remarkably, the model input parameters are taken directly from the photoemission spectroscopy. We show that in the case of Co-doped compounds, as compared to Mn-doped ones, the exchange process has at least two salient features. The first one is that the electron transfer between NN Co2+3d orbitals strongly depends on their symmetry positions in the crystal lattice. The second one is related to a peculiar virtual process, involving empty and occupied Co2+3d orbitals, which leads to an additional ferromagnetic contribution to the exchange constant. We argue that our systematic study of the superexchange opens a pathway toward an understanding of other exchange mechanisms occurring in DMSs.

  3. Energy Transfer in Rare Earth Ion Clusters and Fluorescence from Rare Earth Doped LANTHANUM(1.85)STRONTIUM(0.15)COPPER -OXYGEN(4) Superconductors.

    NASA Astrophysics Data System (ADS)

    Tissue, Brian Max

    1988-12-01

    Laser spectroscopy of rare earth ions in solids was used to study mechanisms of non-resonant energy transfer within rare earth clusters, and to detect insulating, impurity phases in rare earth doped La_{1.85 }Sr_{0.15}CuO _4 superconductors. The mechanisms of phonon-assisted, non-resonant energy transfer were studied in well-defined dimer sites in Er^{3+ }:SrF_2 and Pr ^{3+}:CaF_2. Application of a magnetic field to Er^{3+} :SrF_2 greatly increased the energy transfer rate. The magnetic field dependence in Er^{3+}:SrF _2 indicates that the mechanism of non-resonant energy transfer is a two-phonon, resonant process (Orbach process). Application of a magnetic field to Pr ^{3+}:CaF_2 had no effect on the energy transfer rate because no significant Zeeman splittings occurred. The temperature dependence of the energy transfer rate in Pr^{3+ }:CaF_2 showed the mechanism to be a one-phonon-assisted process at low temperatures and predominantly an Orbach process above 10 K. In the second part of this thesis, laser spectroscopy of a Eu ^{3+} probe ion is developed to detect impurity phases in La_{1.85 }Sr_{0.15}CuO _4 superconductors. Two impurity phases were found in polycrystalline La_ {1.85}Sr_{0.15} CuO_4: unreacted La _2O_3 starting material, and a La-silicate phase, which formed from contamination during sintering. The spectroscopic technique was found to be more than 100 times more sensitive than powder x -ray diffraction to detect minor impurity phases. In preparing the superconductors, several studies were made on the effect of Pr^{3+}, Eu ^{3+}, Bi^{3+ }, and fluorine dopants on the superconducting properties of La_{1.85}Sr _{0.15}CuO_4 and La_2Cuo_4 . Pr^{3+}, Eu ^{3+}, Bi^ {3+}, and F_2 doping all decreased the superconductivity in La_ {1.85}Sr^{0.15} CuO_4. Treating semi-conducting La_2CuO_4 in F_2 gas converted it to a superconductor with an onset T_{rm c} of 30-35 K.

  4. Rare-Earth Doped LaF? Nanocrystals for Upconversion Fluorescence

    E-print Network

    Yi, Guang-Shun

    Upconversion fluorescent nanocrystals, Yb-Er, Yb-Ho and Yb-Tm co-doped LaF? were chemically synthesized. The average particle size was 4.4 nm with a narrow size distribution of ± 0.3 nm. Under the 980 nm NIR excitation, ...

  5. Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO? thin films.

    PubMed

    Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

    2013-05-22

    Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different. PMID:23615045

  6. Integrated visualization of remote sensing data using Google Earth

    NASA Astrophysics Data System (ADS)

    Castella, M.; Rigo, T.; Argemi, O.; Bech, J.; Pineda, N.; Vilaclara, E.

    2009-09-01

    The need for advanced visualization tools for meteorological data has lead in the last years to the development of sophisticated software packages either by observing systems manufacturers or by third-party solution providers. For example, manufacturers of remote sensing systems such as weather radars or lightning detection systems include zoom, product selection, archive access capabilities, as well as quantitative tools for data analysis, as standard features which are highly appreciated in weather surveillance or post-event case study analysis. However, the fact that each manufacturer has its own visualization system and data formats hampers the usability and integration of different data sources. In this context, Google Earth (GE) offers the possibility of combining several graphical information types in a unique visualization system which can be easily accessed by users. The Meteorological Service of Catalonia (SMC) has been evaluating the use of GE as a visualization platform for surveillance tasks in adverse weather events. First experiences are related to the integration in real-time of remote sensing data: radar, lightning, and satellite. The tool shows the animation of the combined products in the last hour, giving a good picture of the meteorological situation. One of the main advantages of this product is that is easy to be installed in many computers and does not need high computational requirements. Besides this, the capability of GE provides information about the most affected areas by heavy rain or other weather phenomena. On the opposite, the main disadvantage is that the product offers only qualitative information, and quantitative data is only available though the graphical display (i.e. trough color scales but not associated to physical values that can be accessed by users easily). The procedure developed to run in real time is divided in three parts. First of all, a crontab file launches different applications, depending on the data type (satellite, radar, or lightning) to be treated. For each type of data, the time of launching is different, and goes from 5 (satellite and lightning) to 6 minutes (radar). The second part is the use of IDL and ENVI programs, which search in each archive file the last images in one hour. In the case of lightning data, the files are generated for the procedure, while for the others the procedure searches for existing imagery. Finally, the procedure generates metadata information required by GE, kml files, and sends them to the internal server. At the same time, in the local computer where GE is running, there exists kml files which update the information referring to the server ones. Another application that has been evaluated is the analysis of past events. In this sense, further work is devoted to develop access procedures to archived data via cgi scripts in order to retrieve and convert the information in a format suitable for GE. The presentation includes examples of the evaluation of the use of GE, and a brief comparison with other existing visualization systems available within the SMC.

  7. Optical properties and size distribution of the nanocolloids made of rare-earth ion-doped NaYF4

    NASA Astrophysics Data System (ADS)

    Patel, Darayas N.; Lewis, Ashley; Wright, Donald M.; Lewis, Danielle; Valentine, Rueben; Valentine, Maucus; Wessley, Dennis; Sarkisov, Sergey; Darwish, Abdalla M.

    2015-03-01

    In this paper we investigate optical properties and size distribution of the nano-colloids made of trivalent rare-earth ion doped fluorides: holmium and ytterbium, thulium and ytterbium, and erbium and ytterbium co-doped NaYF4. These materials were synthesized by using simple co-precipitation synthetic method. The initially prepared micro-crystals had very weak or no visible upconversion fluorescence signals when being pumped with a 980-nm laser. The fluorescence intensity significantly increased after the crystals were annealed at a temperature of 400°C - 600°C undergoing the transition from cubic alpha to hexagonal beta phase of the fluoride host. Nano-colloids of the crystals were made in polar solvents using the laser ablation and ball milling methods. Size analyses of the prepared nano-colloids were conducted using a dynamic light scatterometer and atomic force microscope. The nano-colloids were filled in holey PCFs and their fluorescent properties were studied and the feasibility of new a type of fiber amplifier/laser was evaluated.

  8. Resonantly enhanced nonlinearaties in rare-earth-doped fibers and waveguides

    Microsoft Academic Search

    John W. Arkwright; Graham R. Atkins; John Canning; Pak L. Chu; Mark Janos; Mark G. Sceats; Bin Wu

    1996-01-01

    The use of rare-earth dopants for all-optical switching is of interest because of the very low pump powers required to achieve full switching. In addition, the ease with which rare-earth ions can be incorporated into silica based fibers and waveguides makes them ideally suited for the fabrication of fiber compatible components. The principal disadvantages of this type of nonlinearity are

  9. Spectral emission of rare-earth doped Lu 2SiO 5 single crystals

    NASA Astrophysics Data System (ADS)

    Cooke, D. W.; Muenchausen, R. E.; McClellan, K. J.; Bennett, B. L.

    2005-12-01

    Radioluminescence of float-zone grown single-crystal Lu 2SiO 5:RE (RE = Tb, Sm, Tm, Eu, Pr, Yb) has been measured and prominent electronic transitions have been identified. Tb, Sm and Tm are excellent host-lattice activators that yield strong emission relative to the luminescence from well-known Lu 2SiO 5:Ce. Eu- and Pr-doped Lu 2SiO 5 exhibit weak luminescence whereas the Yb-doped sample is non-luminescent in the UV-vis portion of the spectrum. With the possible exception of Lu 2SiO 5:Pr, Tb 3+ is found to be an unintentional impurity in all samples investigated. Lu 2SiO 5:Sm is a candidate phosphor for radiation detection because it is dense and bright with orange-red emission that matches the spectral response of high-efficiency photodiodes.

  10. Laser cooling with rare-earth doped direct band gap semiconductors

    NASA Astrophysics Data System (ADS)

    Nemova, Galina; Kashyap, Raman

    2013-02-01

    We present a theoretical scheme for laser cooling with ytterbium doped indium phosphide (Yb3+:InP). Yb3+:InP is a rareearth doped direct band-gap semiconductor. The cooling process in our system is based on thermal quenching of excited ytterbium ions. The mechanism of cooling in our system consists of laser excitation of ytterbium ions in the long wavelength tail of the Yb3+absorption spectrum followed by thermal quenching of excited ions accompanied by phonon absorption providing cooling. The band-to-band radiative recombination completing the cooling cycle removes energy from the system. This new approach to laser cooling of solids permits an increase in the efficiency of the cooling cycle approximately by the order, to accelerate the cooling process considerably, and allows cooling with pump wavelengths shorter than the mean fluorescence wavelength.

  11. Anomalous transport property at surface and interface of metal\\/rare earth doped ceria

    Microsoft Academic Search

    Haruo Kishimoto; Natsuko Sakai; Katsuhiko Yamaji; Teruhisa Horita; Manuel E. Brito; Harumi Yokokawa; Koji Amezawa; Yoshiharu Uchimoto

    2008-01-01

    The oxygen transport around gold\\/oxide ion conducting oxides such as gadolinium doped ceria (GDC) and yttria stabilized zirconia (YSZ) was investigated by using oxygen isotope exchange and secondary ion mass spectrometry (SIMS). The active area of oxygen exchange was clearly observed in the vicinity of Au\\/YSZ\\/O2 triple phase boundary at T=973 K in dry O2 condition. On the other hand, the

  12. Mechanisms of persistent luminescence in Eu 2+, RE 3+ doped alkaline earth aluminates

    Microsoft Academic Search

    Tuomas Aitasalo; Jorma Hölsä; Högne Jungner; Mika Lastusaari; Janne Niittykoski

    2001-01-01

    Persistent luminescence of Eu2+ doped calcium aluminate, CaAl2O4:Eu2+, was studied under UV- and visible illumination. Broad band luminescence was observed in the blue region (?max=440nm) due to the 4f65d1?4f7 transition of Eu2+. The threshold for the visible excitation was found at about 530nm, which is not high enough in energy to create a monovalent Eu+ ion required by the mechanisms

  13. Synthesis and characterization of rare earth doped barium fluoride nanoparticles and derivatized copper phthalocyanine nanoparticles

    Microsoft Academic Search

    Christopher Mark Bender

    1998-01-01

    Nanoparticles of neodymium doped barium fluoride (Nd:BaFsb2) were synthesized for use as the inorganic component of an optical amplifier composite. Microemulsions were used to maintain domain size in the nano-regime (˜100 nm), and decreasing the volume fraction of the aqueous content, while simultaneously increasing the volume fraction of the cosurfactant (methanol), gave a linear relationship between decreasing domain size and

  14. Multiple Energy Transfers in Rare Earth Complex-Doped SiO 2 Spheres

    Microsoft Academic Search

    Changqing Huang; Ting Sun; Weijian Tian; Baoping Zhao

    2006-01-01

    Silica spheres doped with Eu(TTFA)3 and\\/or Sm(TTFA)3 were synthesized by using the modified Stober method. The transmission electron microscope image reveals that the hybrid spheres have smooth surfaces and an average diameter of about 210 nm. Fluorescence spectrometer was used to analyze the fluorescence properties of hybrid spheres. The results show that multiple energy transfer processes are simultaneously achieved in

  15. NIR to visible upconversion in rare-earth Ion-doped NaYF4 crystals

    Microsoft Academic Search

    Darayas Patel; Calvin Vance; Newton King; Malcolm Jessup; Lekara Green; Sergey Sarkisov

    2010-01-01

    In this paper we investigate the infrared-to-visible upconversion luminescence in bulk crystals and nanocolloid filled photonic crystal fiber with ytterbium and erbium co-doped NaYF4 upconversion phosphor. The phosphor was prepared by using simple co-precipitation synthetic method. The initially prepared phosphor has very weak upconversion fluorescence. The fluorescence significantly increased after the phosphor was annealed at a temperature of 400°C. Nanocolloids

  16. Development of a new doping principle for manufacturing of rare earth ion activated silica preforms for optical fibers and study of their spectroscopic properties

    NASA Astrophysics Data System (ADS)

    Shubochkin, Roman Leonidovich

    A new doping principle for the fabrication of optical waveguides has been proposed and developed. The principle involves the use of a "building block" approach, when a doping precursor, which includes some or all chemical elements necessary for the formation of an optical waveguide, also contains optically active rare earth ions that are spatially organized in a desired manner on a molecular level. This research has been concerned with the use of precursors that potentially have large minimum distances between rare earth ions in order to increase resulting minimum distances in the final glass made from such precursors and therefore decrease the rate of cooperative energy transfers between rare earth ions leading to quenching of luminescence. Aluminosilicate molecular sieves, zeolites X and Y, with rare earth loading levels not exceeding 16 ions per unit cell in the network of small cages have been proposed and investigated as "building block", large minimum distance precursors for the fabrication of silica optical fibers. Zeolite derived optical preforms and fibers with ultra-high rare earth concentrations up to 1.2 · 1021 ion/cm 3 have been fabricated for the first time using methods developed in this work. A new acid-free low-water neutral pH sol-gel process has been developed for the deposition of sol-gel films containing zeolite powders. Luminescent properties of neodymium doped zeolite derived preforms have been studied as a function of the total rare earth concentration and levels of rare earth loading of zeolites. Luminescent properties of zeolite-doped sol-gel films at various stages of vitrification have also been studied to evaluate rare earth ion quantum yield and the ion arrangement at different fabrication stages. It has been demonstrated that the lifetime of the Nd3+ metastable level in dehydrated unsintered zeolite-doped sol-gel films strongly increases when zeolite loading becomes less than 16 neodymium ions per unit cell in the network of small pores in both zeolite X and Y. It has also been determined that zeolites with rare earth loading levels between 12 and 25 ions per unit cell allow fabrication of optical preforms with luminescent properties comparable to those obtained by other known approaches.

  17. Low-power continuous-wave nonlinear optics in doped silica glass integrated waveguide structures

    NASA Astrophysics Data System (ADS)

    Ferrera, M.; Razzari, L.; Duchesne, D.; Morandotti, R.; Yang, Z.; Liscidini, M.; Sipe, J. E.; Chu, S.; Little, B. E.; Moss, D. J.

    2008-12-01

    Photonic integrated circuits are a key component of future telecommunication networks, where demands for greater bandwidth, network flexibility, and low energy consumption and cost must all be met. The quest for all-optical components has naturally targeted materials with extremely large nonlinearity, including chalcogenide glasses and semiconductors, such as silicon and AlGaAs (ref. 4). However, issues such as immature fabrication technology for chalcogenide glass and high linear and nonlinear losses for semiconductors motivate the search for other materials. Here we present the first demonstration of nonlinear optics in integrated silica-based glass waveguides using continuous-wave light. We demonstrate four-wave mixing, with low (5 mW) continuous-wave pump power at ? = 1,550 nm, in high-index, doped silica glass ring resonators. The low loss, design flexibility and manufacturability of our device are important attributes for low-cost, high-performance, nonlinear all-optical photonic integrated circuits.

  18. Rare-Earth Doped Particles as Dual-Modality Contrast Agent for Minimally-Invasive Luminescence and Dual-Wavelength Photoacoustic Imaging

    PubMed Central

    Sheng, Yang; Liao, Lun-De; Thakor, Nitish; Tan, Mei Chee

    2014-01-01

    Multi-modal imaging is an emerging area that integrates multiple imaging modalities to simultaneously capture visual information over many spatial scales. Complementary contrast agents need to be co-developed in order to achieve high resolution and contrast. In this work, we demonstrated that rare-earth doped particles (REDPs) can be employed as dual-modal imaging agents for both luminescence and photoacoustic (PA) imaging to achieve intrinsic high contrast, temporal and spatial resolution, reaching deeper depth. REDPs synthesized with different surfactants (citric acid, polyacrylic acid, ethylenediaminetetraacetic acid and sodium citrate) exhibit tunable emission properties and PA signal amplitudes. Amongst these samples, sodium citrate-modified REDPs showed the strongest PA signals. Furthermore, since REDPs have multiple absorption peaks, they offer a unique opportunity for multi-wavelength PA imaging (e.g. PA signals were measured using 520 and 975?nm excitations). The in vivo PA images around the cortical superior sagittal sinus (SSS) blood vessel captured with enhanced signal arising from REDPs demonstrated that in addition to be excellent luminescent probes, REDPs can also be used as successful PA contrast agents. Anisotropic polyacrylic acid-modified REDPs were found to be the best candidates for dual-modal luminescence and PA imaging due to their strong luminescence and PA signal intensities. PMID:25297843

  19. Rare-Earth Doped Particles as Dual-Modality Contrast Agent for Minimally-Invasive Luminescence and Dual-Wavelength Photoacoustic Imaging

    NASA Astrophysics Data System (ADS)

    Sheng, Yang; Liao, Lun-De; Thakor, Nitish; Tan, Mei Chee

    2014-10-01

    Multi-modal imaging is an emerging area that integrates multiple imaging modalities to simultaneously capture visual information over many spatial scales. Complementary contrast agents need to be co-developed in order to achieve high resolution and contrast. In this work, we demonstrated that rare-earth doped particles (REDPs) can be employed as dual-modal imaging agents for both luminescence and photoacoustic (PA) imaging to achieve intrinsic high contrast, temporal and spatial resolution, reaching deeper depth. REDPs synthesized with different surfactants (citric acid, polyacrylic acid, ethylenediaminetetraacetic acid and sodium citrate) exhibit tunable emission properties and PA signal amplitudes. Amongst these samples, sodium citrate-modified REDPs showed the strongest PA signals. Furthermore, since REDPs have multiple absorption peaks, they offer a unique opportunity for multi-wavelength PA imaging (e.g. PA signals were measured using 520 and 975 nm excitations). The in vivo PA images around the cortical superior sagittal sinus (SSS) blood vessel captured with enhanced signal arising from REDPs demonstrated that in addition to be excellent luminescent probes, REDPs can also be used as successful PA contrast agents. Anisotropic polyacrylic acid-modified REDPs were found to be the best candidates for dual-modal luminescence and PA imaging due to their strong luminescence and PA signal intensities.

  20. Characterizing the Purple Earth: Modeling the globally integrated spectral variability of the Archean Earth

    SciTech Connect

    Sanromá, E.; Pallé, E.; López, R.; Montañés-Rodríguez, P. [Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n E-38200, La Laguna (Spain); Parenteau, M. N. [NASA Ames Research Center, Exobiology Branch, Mountain View, CA 94035 (United States); Kiang, N. Y. [NASA Goddard Institute for Space Studies, New York, NY 10025 (United States); Gutiérrez-Navarro, A. M., E-mail: mesr@iac.es [Department of Microbiology, Faculty of Biology, University of La Laguna, ES-38206 La Laguna (Spain)

    2014-01-01

    Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. However, the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Gyr ago. At that time, one of the more widespread life forms on the planet was purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and purple bacteria concentration/distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

  1. Bridging the Gap between Earth Science and Students: An Integrated Approach using NASA Earth Science Climate Data

    NASA Technical Reports Server (NTRS)

    Alston, Erica J.; Chambers, Lin H.; Phelps, Carrie S.; Oots, Penny C.; Moore, Susan W.; Diones, Dennis D.

    2007-01-01

    Under the auspices of the Department of Education's No Child Left Behind (NCLB) Act, beginning in 2007 students will be tested in the science area. There are many techniques that educators can employ to teach students science. The use of authentic materials or in this case authentic data can be an engaging alternative to more traditional methods. An Earth science classroom is a great place for the integration of authentic data and science concepts. The National Aeronautics and Space Administration (NASA) has a wealth of high quality Earth science data available to the general public. For instance, the Atmospheric Science Data Center (ASDC) at NASA s Langley Research Center houses over 800 Earth science data sets related to Earth's radiation budget, clouds, aerosols and tropospheric chemistry. These data sets were produced to increase academic understanding of the natural and anthropogenic factors that influence global climate; however, a major hurdle in using authentic data is the size of the data and data documentation. To facilitate the use of these data sets for educational purposes, the Mentoring and inquirY using NASA Data on Atmospheric and Earth science for Teachers and Amateurs (MY NASA DATA) project has been established to systematically support educational activities at all levels of formal and informal education. The MY NASA DATA project accomplishes this by reducing these large data holdings to microsets that are easily accessible and explored by K-12 educators and students though the project's Web page. MY NASA DATA seeks to ease the difficulty in understanding the jargon-heavy language of Earth science. This manuscript will show how MY NASA DATA provides resources for NCLB implementation in the science area through an overview of the Web site, the different microsets available, the lesson plans and computer tools, and an overview of educational support mechanisms.

  2. Synthesis of rare earth doped yttrium-vanadate nanoparticles encapsulated within apoferritin.

    PubMed

    Harada, Tomoaki; Yoshimura, Hideyuki

    2014-07-28

    Luminescent europium (Eu) and dysprosium (Dy) doped yttrium-vanadate (Y-V) nanoparticles (NPs) were synthesized in the cavity of the protein, apoferritin. Y-V NPs were synthesized by incubating a solution of apoferritin with Y(3+) and VO3(-) ions in the presence of ethylene diamine-N-N'-diacetic acid (EDDA). EDDA plays an important role in preventing Y-vanadate precipitation in bulk solution by chelating the Y(3+) ions. Using high resolution electron microscopy, the obtained NPs in the apoferritin cavities were confirmed to be amorphous, and to consist of Y and V. Eu-doped Y-V (Y-V:Eu) NPs were synthesized by the same procedure as Y-V NPs, except that Eu(NO3)3 was added. Y-V:Eu NPs exhibited a strong absorption peak due to the O-V charge transfer transition and remarkable luminescence at 618 nm due to the (5)D0 ? (7)F2 transition. The luminescence lifetime of Y:Eu and Y-V:Eu NPs measured in H2O and D2O solution showed reduction of non-radiative transition to the O-H vibration in Y-V:Eu NPs. Accordingly, Y-V NPs showed strong luminescence compared to Y:Eu NPs. Dy-doped Y-V NPs were also synthesized in apoferritin cavities and showed luminescence peaks at 482 nm and 572 nm, corresponding to (4)F9/2 ? (6)H15/2 and (4)F9/2 ? (6)H13/2 transitions. These NPs stably dispersed in water solution since their aggregation was prevented by the protein shell. NPs encapsulated in the protein are likely to be biocompatible and would have significant potential for biological imaging applications. PMID:24930497

  3. Cerium-doped mixed-alkali rare-earth double-phosphate scintillators for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Neal, John S.; Boatner, Lynn A.; Spurrier, Merry; Szupryczynski, Piotr; Melcher, Charles L.

    2007-08-01

    Previous measurements of the scintillation properties of members of the single-alkali, rare-earth double-phosphate family have demonstrated high light output and fast decay times when exposed to ionizing radiation. Because of the ease with which the alkali constituents (Li, Na, K, Rb, Cs) of the crystal matrix may be interchanged (e.g. K 2CsLu(PO 4) 2 and CsLi 2Lu(PO 4) 2), the rare-earth double-phosphate family of scintillators provides an ideal system for the study of matrix effects on scintillation efficiency and kinetics. New members of the rare-earth double-phosphate family have been synthesized by high-temperature flux growth. These new samples, represented by the general formula (A,B) 3Lu(PO 4) 2:Ce where A and B are alkali elements, incorporate lithium as one of the components and varying levels of Ce doping. Characteristics important to gamma-ray and thermal neutron excitation are calculated for three model systems which incorporate total lithium-ion substitution. Light output, scintillation decay times, and photoluminescence measurements for the most promising of the samples to date are reported. Future work includes (1) synthesis of mixed-alkali scandium and yttrium double-phosphates in which Li ions are substitutional in the structure with varying lithium-ion content up to and including total lithium-ion substitution on the alkali ion site and (2) measurements of light output and pulse shape using thermal neutron excitation.

  4. Crystal chemistry and domain structure of rare-earth doped BiFeO 3 ceramics

    Microsoft Academic Search

    S. Karimi; I. M. Reaney; Y. Han; J. Pokorny; I. Sterianou

    2009-01-01

    Bi(1?x)RE\\u000a x\\u000a FeO3 (BREF100x, RE = La, Nd, Sm, Gd) has been investigated with a view to establish a broad overview of their crystal chemistry\\u000a and domain structure. For x ? 0.1, the perovskite phase in all compositions could be indexed according to the rhombohedral, R3c cell of BiFeO3. For Nd and Sm doped compositions with 0.1 x ? 0.2 and x = 0.15, respectively, a new antipolar phase

  5. Rare-earth Doped Amorphous Silicon Microdisk and Microstadium Resonators with Emission at 1550nm

    E-print Network

    Figueira, D S L

    2007-01-01

    Microdisks and microstadium resonators were fabricated on erbium doped amorphous hydrogenated silicon (a-Si:H) layers sandwiched in air and native SiO2 on Si substrates. Annealing condition is optimized to allow large emission at 1550 nm for samples with erbium concentrations as high as 1.02x10^20 atoms/cm3. Near field scanning optical microscopy shows evidences of the simultaneous presence of bow-tie and diamond scars. These modes indicate the high quality of the resonators and the potentiality for achieving amorphous silicon microcavity lasers.

  6. Effects of rare-earth doping on femtosecond laser waveguide writing in zinc polyphosphate glass

    SciTech Connect

    Fletcher, Luke B.; Witcher, Jon J.; Troy, Neil; Krol, Denise M. [Department of Applied Science, University of California Davis, Davis, California 95616 (United States); Reis, Signo T.; Brow, Richard K. [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, Missouri 65409 (United States)

    2012-07-15

    We have investigated waveguide writing in Er-Yb doped zinc polyphosphate glass using a femtosecond laser with a repetition rate of 1 KHz. We find that fabrication of good waveguides requires a glass composition with an O/P ratio of 3.25. The dependence on laser writing parameters including laser fluence, focusing conditions, and scan speed is reported. Waveguide properties together with absorption and emission data indicate that these glasses can be used for the fabrication of compact, high gain amplifying devices.

  7. Measuring and analyzing excitation-induced decoherence in rare-earth-doped optical materials

    NASA Astrophysics Data System (ADS)

    Thiel, C. W.; Macfarlane, R. M.; Sun, Y.; Böttger, T.; Sinclair, N.; Tittel, W.; Cone, R. L.

    2014-10-01

    A method is introduced for quantitatively analyzing photon echo decay measurements to characterize excitation-induced decoherence resulting from the phenomenon of instantaneous spectral diffusion. Detailed analysis is presented that allows fundamental material properties to be extracted that predict and describe excitation-induced decoherence for a broad range of measurements, applications and experimental conditions. Motivated by the need for a method that enables systematic studies of ultra-low decoherence systems and direct comparison of properties between optical materials, this approach employs simple techniques and analytical expressions that avoid the need for difficult to measure and often unknown material parameters or numerical simulations. This measurement and analysis approach is demonstrated for the 3H6 to 3H4 optical transition of three thulium-doped crystals, Tm3+:YAG, Tm3+:LiNbO3 and Tm3+:YGG, that are currently employed in quantum information and classical signal processing demonstrations where minimizing decoherence is essential to achieve high efficiencies and large signal bandwidths. These new results reveal more than two orders of magnitude variation in sensitivity to excitation-induced decoherence among the materials studied and establish that the Tm3+:YGG system offers the longest optical coherence lifetimes and the lowest levels of excitation-induced decoherence yet observed for any known thulium-doped material.

  8. The Digital Library for Earth System Education: A Community Integrator

    NASA Astrophysics Data System (ADS)

    Marlino, M. R.; Pandya, R. E.

    2003-12-01

    The rapid changes in the geoscience research environment have prompted educators to request support for their efforts to reform geoscience educational practices. DLESE, the Digital Library for Earth System Education, responds to this request by providing a single point of access to high-quality educational resources for teaching about the Earth as a system. DLESE is supported by the National Science Foundation and is an operational library used by tens of thousands of educators every month. DLESE resources include a variety of media formats, from text-based lesson plans to highly-sophisticated tools for interactive three-dimensional visualization of authentic scientific data. The DLESE community is particularly interested in partnering with scientific researchers to ensure that the tools of practicing scientists become widely available to geoscience educators. Two emerging large-scale scientific efforts, the GEON project and EarthScope, provide compelling illustrations of the potential of these partnerships. Both are cutting-edge, cross-disciplinary projects that use digital tools in a distributed environment to support scientific investigation. Both have also made a deep commitment to use these same tools to support geoscience education, and both are including DLESE as part of that commitment. Our interactive presentation will allow users to discover a variety of educational resources and communication services within the library. We will highlight those library resources and services that take particular advantage of the digital media to support new modes of learning and teaching. For example, annotation tools allow educators to add tips on the most effective way to use a specific resource. Data services will help educators find and use real-time data to illustrate geoscience phenomena. Multi-dimensional visualization tools allow students to interact with authentic student data in inquiry-based learning environment. DLESE will continue to actively collaborate with scientific research efforts to ensure that the practices and tools of the research community also support the needs of geoscience learners and educators.

  9. Integrating Research Infrastructures for solid Earth Science: the EPOS preparatory phase roadmap and achievements

    NASA Astrophysics Data System (ADS)

    Cocco, M.; EPOS Consortium

    2012-04-01

    The European Plate Observing System (EPOS) is a long-term integrated research infrastructure plan to promote innovative approaches for a better understanding of the physical processes controlling earthquakes, volcanic eruptions, unrest episodes and tsunamis as well as those driving tectonics and Earth surface dynamics. The EPOS plan aims at integrating the currently scattered, but highly advanced European facilities into one, distributed, but coherent multidisciplinary Research Infrastructure (RI) allowing sustainable long-term Earth science research strategies and an effective coordinated European-scale monitoring facility for solid Earth dynamics taking full advantage of new e-science opportunities. The EPOS preparatory phase (EPOS PP), funded by the European Commission within the Capacities program, started on November 1st 2010 and it has completed its first year of activity. The EPOS mission is to integrate the existing research infrastructures (RIs) in solid Earth science in order to increase the accessibility and usability of multidisciplinary data from monitoring networks, laboratory experiments and computational simulations enhancing worldwide interoperability in Earth Science by establishing a leading integrated European infrastructure and services. We will present the EPOS PP roadmap for the long-term solid Earth observation strategies as well as the e-science implementation plan envisioned to establish an innovative integrated e-infrastructure component necessary to create an effective service to users. Moreover, we will show the preliminary outcomes from the first inventory of the RIs we are going to integrate in EPOS. We also plan to discuss the outreach and dissemination actions and the strategy designed to meet the specific user needs. More recently the EPOS and the satellite Earth Observation communities are collaborating in order to promote the integration of data from in-situ monitoring networks and satellite observing systems. The goal is to coordinate the access to data relevant for geohazard research for selected "Supersites" locations in Europe as well as to contribute to the global supersite initiative in the framework of the GEO work program. Making observations of solid Earth dynamic processes controlling natural phenomena immediately available and promoting their comparison with numerical simulations and their interpretation through theoretical analyses will represent a multidisciplinary platform for discoveries which will foster scientific excellence in solid Earth research. Finally, we will also discuss the priorities for the second year of activity and the key actions planned to better involve users in EPOS. In particular, we will discuss the work done to finalize the identification of the mission needs as well as the activities to start the design phase of the EPOS infrastructure.

  10. Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

    PubMed

    Pisarski, W A; Pisarska, J; M?czka, M; Lisiecki, R; Grobelny, ?; Goryczka, T; Dominiak-Dzik, G; Ryba-Romanowski, W

    2011-08-15

    Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)?BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis. PMID:21093353

  11. Fluorescence spectra of Sm 3+-doped rare earth oxybromide powder phosphors

    Microsoft Academic Search

    U. Rambabu; P. K. Khanna; S. Buddhudu

    1999-01-01

    The fluorescence properties of a new family of Sm3+-doped powder phosphors of GdOBr, (Gd0.9Y0.1)OBr, (Gd0.6Y0.4)OBr, (Gd0.3Y0.7)OBr, and YOBr are reported. The measured fluorescence spectra have been analysed by computing the colour coordinates (X?,?) and stimulated emission cross-sections (?pE, cm2). These Sm3+-phosphors display bright reddish-orange colour due to transitions 4G5\\/2?6H9\\/2 (red) and 4G5\\/2?6H7\\/2 (orange) under a UV source. The relative fluorescence

  12. The optical properties of trivalent rare earth ions (Er3+) doped borotellurite glass

    NASA Astrophysics Data System (ADS)

    Nurbaisyatul, E. S.; Azman, K.; Azhan, H.; Razali, W. A. W.; Noranizah, A.; Hashim, S.; Alajerami, Y. S. M.

    2014-03-01

    Erbium doped borotellurite glass has been fabricated by using conventional melting method. The density and molar volume have been calculated and analyzed while their optical properties were studied by measuring the optical absorption and luminescence spectra at room temperature. From the XRD results, since the patterns do not exhibit any diffraction line thus it confirms their amorphous nature. It is found that the density of the glass samples increased and the molar volume decreased with respect to Er ions content. Meanwhile, the upconversion emissions centered at 487, 523, 558, 642, 695 and 782 nm have been observed under the 650 nm excitation in the 4 F 9/2 level. Some other results will be analysed and discussed in details.

  13. Rare-earth-doped biological composites as in vivo shortwave infrared reporters

    PubMed Central

    Naczynski, D.J.; Tan, M.C.; Zevon, M.; Wall, B.; Kohl, J.; Kulesa, A.; Chen, S.; Roth, C.M.; Riman, R.E.; Moghe, P.V.

    2013-01-01

    The extension of in vivo optical imaging for disease screening and image-guided surgical interventions requires brightly-emitting, tissue-specific materials that optically transmit through living tissue and can be imaged with portable systems that display data in real-time. Recent work suggests that a new window across the short wavelength infrared region can improve in vivo imaging sensitivity over near infrared light. Here we report on the first evidence of multispectral, real-time short wavelength infrared imaging offering anatomical resolution using brightly-emitting rare-earth nanomaterials and demonstrate their applicability toward disease-targeted imaging. Inorganic-protein nanocomposites of rare-earth nanomaterials with human serum albumin facilitated systemic biodistribution of the rare-earth nanomaterials resulting in the increased accumulation and retention in tumor tissue that was visualized by the localized enhancement of infrared signal intensity. Our findings lay the groundwork for a new generation of versatile, biomedical nanomaterials that can advance disease monitoring based on a pioneering infrared imaging technique. PMID:23873342

  14. Fluorescence in nanocomposites based on polyethylene oxides and block copolymers of polyethylene oxide-polypropylene oxide loaded with rare earth doped fluorides

    NASA Astrophysics Data System (ADS)

    Yust, Brian; Pedraza, Francisco; Sardar, Dhiraj; Saenz, Aaron; Chipara, Mircea

    2015-03-01

    Rare earth doped fluoride nanoparticles with a size of about 25 nm have been synthesized by a solvothermal process. Polymer-based nanocomposites, containing various weight fraction of nanofillers, have been obtained by dissolving the polymeric matrix (polyethylene oxide) within a solvent (deionized water), adding the nanoparticles, sonicating the mixture, and finally removing the solvent. The complete removal of the solvent has been confirmed by Thermogravimetric Analysis. Additional information about the thermal features have been obtained by Differential Scanning Calorimetry, Wide Angle X-Ray Scattering, FTIR, UV-Visible, and Raman. The effect of the loading with nanoparticles on the glass, crystallization, and melting transition temperatures of the polymeric matrix are reported. Fluorescence of rare earth doped nanoparticles dispersed within the polymeric matrix has been tested by laser spectroscopy. The dependence of fluorescence intensity on the concentration of nanofillers and on temperature in the range 300 to 400 K is analyzed.

  15. Multiple doping structures of the rare-earth atoms in ?-SiAlON:Ce phosphors and their effects on luminescence properties.

    PubMed

    Gan, Lin; Xu, Fang-Fang; Zeng, Xiong-Hui; Li, Zuo-Sheng; Mao, Zhi-Yong; Lu, Ping; Zhu, Ying-Chun; Liu, Xue-Jian; Zhang, Lin-Lin

    2015-06-25

    The critical doping structures of rare-earth atoms in the promising ?-SiAlON phosphors have long been argued owing to the lack of direct evidence. Here, the exact locations and coordination of the Ce rare-earth atoms in the ?-SiAlON structure have been examined using an atom-resolved Cs-corrected scanning transmission electron microscope. Three different occupation sites for the Ce atoms have been directly observed: two of them are in the structural channel coordinated with six and nine N(O) atoms, respectively; the other one is the unexpected substitution site for Si(Al). The chemical valences and stabilities of the doping Ce ions at the different occupation sites have been evaluated using density functional calculations. Correlation of the different doping structures with the luminescence properties has been investigated by the aid of cathodoluminescence (CL) microanalysis, which verifies the different contribution of the interstitial trivalent Ce ions to the light emission while no luminescence is observed for the substitutional doping of quadrivalent Ce. PMID:26073879

  16. Microstructural relationship with fracture toughness of undoped and rare earths (Y, La) doped Al 2O 3–ZrO 2 ceramic composites

    Microsoft Academic Search

    Kuntal Maiti; Anjan Sil

    2011-01-01

    Ceramic composites in undoped Al2O3–5wt% ZrO2 (AZ) and doped with rare earth elements Y, La separately and simultaneously were prepared by solid state sintering process. These composites were characterized for microstructural investigation and determination of phase formation to draw a possible relationship between these characterization results with the fracture toughness measured by single-edge precracked beam (SEPB) test method using three-point

  17. VUV spectroscopic properties of rare-earth (RE3+ = Eu, Tb, Tm)-doped AZr2(PO4)3 (A+ = Li, Na, K) type phosphate

    Microsoft Academic Search

    Zhi-Jun Zhang; Hao-Hong Chen; Xin-Xin Yang; Jing-Tai Zhao; Guo-Bin Zhang; Chao-Shu Shi

    2008-01-01

    The excitation spectra of pure and rare-earth (RE3+ = Eu, Tb, Tm)-doped AZr2(PO4)3 (A+ = Li, Na, K) in the vacuum ultraviolet (VUV) regions are investigated. The results indicate that these samples show strong absorption in the VUV range. The band ranging from 130 to 160 nm is due to the absorption band of host lattice or PO4 groups; the

  18. A review of visible, near-IR, and mid-IR transitions in rare-earth doped glass waveguides for remote sensing and LIDAR

    NASA Astrophysics Data System (ADS)

    Jha, Animesh

    2006-12-01

    In the review article we explain the recent investigations on rare-earth doped glass and optical fibres for designing lasers which may be suitable for remote sensing and LIDAR applications. The paper explains the importance of engineering efficient lasing transitions in visible (480-650 nm) for generating UV lasers via one-stage harmonic generation. Besides visible transitions, we also demonstrate the transitions in near- and mid-IR via near-IR pumping scheme.

  19. Optical spectra of undoped and rare-earth-(=Pr, Nd, Eu, and Er) doped transparent ceramic Y sub 3 Al sub 5 O sub 12

    Microsoft Academic Search

    M. Sekita; H. Haneda; S. Shirasaki; T. Yanagitani

    1991-01-01

    Undoped and rare-earth- (Pr, Nd, Eu, and Er) doped transparent YâAlâOââ ceramics have been prepared, and their optical spectra have been measured. It is found that absorption coefficient of the undoped ceramic YâAlâOââ is almost independent of wavelength with 0.258 cm⁻¹, which gives transmittance of the undoped ceramic YâAlâOââ to be, for example, 95% for a 2-mm height. Peaks in

  20. Micro Infrared Earth Sensor project: an integrated IR camera for Earth remote sensing

    NASA Astrophysics Data System (ADS)

    Soto-Romero, Georges; Bony, Francis; Simonne, Jean-Jacques; Fourniols, Jean-Yves

    2001-12-01

    MEMS technology now makes possible to produce active microdevices combining detection, signal processing, and data storage with accuracy and compactness. In view of their characteristics, it can be expected that such microsensors will be used extensively in space applications dedicated to micro and nano satellites. The advanced architecture of a MicroInfraRedEarthSensor generic system based on a Vox microbolometer array associated with optics and electronics 'on the shelves' for signal processing and depointing computation, used to control the attitude of satellites in low earth orbits, has been completely developed, through the design of a virtual prototype combined with a breadboard implementation of an IR camera (called MST, and has been developed by EADS-SODERN, in the frame of IASI project). The correlation of the virtual prototyping approach, has allowed to build one complete optical head part of the instrument with efficient and optimized parameters where the performances are consistent with the main mission specifications (pointing accuracy 10 Hz, aperture angle: > 36 degree(s), volume

  1. Alpha-particle-induced luminescence of rare-earth-doped Y{sub 2}O{sub 3} nanophosphors

    SciTech Connect

    Cress, Cory D. [NanoPower Research Laboratories at the Rochester Institute of Technology, 85 Lomb Memorial Road, Rochester, NY 14623 (United States); Microsystems Engineering Program at the Rochester Institute of Technology, Rochester, NY 14623 (United States)], E-mail: cory_cress@hotmail.com; Redino, Christopher S. [NanoPower Research Laboratories at the Rochester Institute of Technology, 85 Lomb Memorial Road, Rochester, NY 14623 (United States)], E-mail: csr8932@rit.edu; Landi, Brian J. [NanoPower Research Laboratories at the Rochester Institute of Technology, 85 Lomb Memorial Road, Rochester, NY 14623 (United States)], E-mail: bjlsps@rit.edu; Raffaelle, Ryne P. [NanoPower Research Laboratories at the Rochester Institute of Technology, 85 Lomb Memorial Road, Rochester, NY 14623 (United States); Microsystems Engineering Program at the Rochester Institute of Technology, Rochester, NY 14623 (United States)], E-mail: rprsps@rit.edu

    2008-08-15

    The feasibility of utilizing Y{sub 2}O{sub 3}:Tb{sup 3+} and Y{sub 2}O{sub 3}:Eu{sup 3+} as radioluminescent nanophosphors under alpha-particle excitation is investigated. Materials synthesized by the urea homogeneous precipitation method were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The XRD analysis of as-produced precipitates and nanophosphors fired at temperatures ranging from 950 to 1100 deg. C indicated the presence of highly crystalline cubic Y{sub 2}O{sub 3} with crystallite sizes of {approx}40 nm. SEM and TEM analysis revealed that particles with average diameters of {approx}200 nm and comprised of {approx}40 nm grains were obtained. High-resolution radioluminescence and photoluminescence spectra were used to investigate the unwanted radioluminescence saturation effects associated with the high ionization rate of alpha-particles. Additionally, the radioluminescence intensity as a function of rare-earth ion dopant concentration is investigated for these materials under alpha-particle excitation. The prospect for utilizing these materials as intermediate absorbers in indirect-conversion radioisotope batteries is discussed. - Graphical abstract: The photoluminescence and radioluminesce emission from rare-earth doped Y{sub 2}O{sub 3} nanophosphors are being investigated. Below is a representative image of the photoluminescence from Y{sub 2}O{sub 3}:Eu{sup 3+} (left) and Y{sub 2}O{sub 3}:Tb{sup 3+} (right) under UV-light excitation.

  2. Multiferroic Properties of Rare-Earth Eu and Nd Doped BiFeO3 Thin Films

    Microsoft Academic Search

    Meiya Li; Zhongqiang Hu; Ling Pei; Jun Liu; Jing Wang; Benfang Yu; Xingzhong Zhao

    2010-01-01

    Pure BiFeO3 (BFO), Eu doped BFO (BEF), and Nd doped BFO (BNF) multiferroic films were prepared by pulsed laser deposition on Pt\\/Ti\\/SiO2\\/Si substrates. XRD analysis revealed that the films had the rhombohedral structure with doping-induced lattice distortion. The Eu and Nd doping significantly improved the dielectric, ferroelectric, and ferromagnetic properties of the BFO films. Saturated hysteresis loops were observed in

  3. Absorption and photoluminescence of Ga-La-S:O and Ga-Ge-As-S glasses doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Iovu, M. S.; Andries, A. M.; Syrbu, N. N.; Seddon, A. B.; Furniss, D.; Adriaenssens, G. J.; Tver'yanovich, Yu. S.

    2007-05-01

    The visible luminescence from Pr 3+, Dy 3+, Nd 3+, Sm 3+ and co-doped with Ho 3+ and Dy 3+ ions embedded in Ga 0.017Ge 0.25As 0.083S 0.65 glass hosts at room temperature and at T10 K is reported, when pumping with an Ar +-ion laser at lambda=488 nm. Fluorescence emissions at 1 .3 ? was observed for Dy 3+ and both at 1.3 and at 1.5 ? for Pr 3+ doped glasses with wavelength pumping at 950 nm. The emission bands correlate with the absorption bands characteristic for the electronic transitions of the rare-earth ions. Energy transfer from Ho 3+: 5F 3 level to Dy 3+: 4F 9/2 level increase the visible emission efficiency at 650 nm in the co-doped glasses. The emission spectra correlate with the absorption spectra of the investigated glasses. The investigated Ga 0.017Ge 0.25As 0.083S 0.65 glasses doped with Pr 3+ are promising materials for optical fibers amplifiers operating at 1300 and 1500 nm telecommunication windows. The effect of oxygen on the absorption and luminescence spectra of Pr 3+-doped Ga-La-S-O (GLS) glasses with a constant cationic ratio Ga/La=O.7/O.3 and varying both oxygen (0.65 and 2.95 wt %) and praseodymium (0. 1 and 1 .0 wt %) content also are presented.

  4. Earth

    NSDL National Science Digital Library

    This lithograph depicts a view of Earth taken from Apollo 10 during its journey to the Moon in May 1969. False-color satellite images showing chlorophyll concentration, sea surface temperature, topography, and ozone concentration are also featured. The images are accompanied by a brief description, some statistical facts, and a list of important dates in the history of Earth exploration.

  5. The EPOS Implementation Phase: building thematic and integrated services for solid Earth sciences

    NASA Astrophysics Data System (ADS)

    Cocco, Massimo; Epos Consortium, the

    2015-04-01

    The European Plate Observing System (EPOS) has a scientific vision and approach aimed at creating a pan-European infrastructure for Earth sciences to support a safe and sustainable society. To follow this vision, the EPOS mission is integrating a suite of diverse and advanced Research Infrastructures (RIs) in Europe relying on new e-science opportunities to monitor and understand the dynamic and complex Earth system. To this goal, the EPOS Preparatory Phase has designed a long-term plan to facilitate integrated use of data and products as well as access to facilities from mainly distributed existing and new research infrastructures for solid Earth Science. EPOS will enable innovative multidisciplinary research for a better understanding of the Earth's physical processes that control earthquakes, volcanic eruptions, ground instability and tsunami as well as the processes driving tectonics and Earth surface dynamics. Through integration of data, models and facilities EPOS will allow the Earth Science community to make a step change in developing new concepts and tools for key answers to scientific and socio-economic questions concerning geo-hazards and geo-resources as well as Earth sciences applications to the environment and to human welfare. Since its conception EPOS has been built as "a single, Pan-European, sustainable and distributed infrastructure". EPOS is, indeed, the sole infrastructure for solid Earth Science in ESFRI and its pan-European dimension is demonstrated by the participation of 23 countries in its preparatory phase. EPOS is presently moving into its implementation phase further extending its pan-European dimension. The EPOS Implementation Phase project (EPOS IP) builds on the achievements of the successful EPOS preparatory phase project. The EPOS IP objectives are synergetic and coherent with the establishment of the new legal subject (the EPOS-ERIC in Italy). EPOS coordinates the existing and new solid Earth RIs within Europe and builds the integrating RI elements. This integration requires a significant coordination between, among others, disciplinary (thematic) communities, national RIs policies and initiatives, as well as geo- and IT-scientists. The RIs that EPOS is coordinating include: i) regionally-distributed geophysical observing systems (seismological and geodetic networks); ii) local observatories (including geomagnetic, near-fault and volcano observatories); iii) analytical and experimental laboratories; iv) integrated satellite data and geological information services v) new services for natural and anthropogenic hazards. Here we present the successful story of the EPOS Preparatory Phase and the progress towards the implementation of both integrated core services (ICS) and thematic core services (TCS) for the different communities participating to the integration plan. We aim to discuss the achieved results and the approach followed to design the implementation phase. The goal is to present and discuss the strategies adopted to foster the implementation of TCS, clarifying their crucial role as domain-specific service hubs for coordinating and harmonizing national resources/plans with the European dimension of EPOS, and their integration to develop the new ICS. We will present the prototype of the ICS central hub as a key contribution for providing multidisciplinary services for solid Earth sciences as well as the glue to keep ICT aspects integrated and rationalized across EPOS. Finally, we will discuss the well-defined role of the EPOS-ERIC Headquarter to coordinate and harmonize national RIs and EPOS services (through ICS and TCS) looking for an effective commitment by national governments. It will be an important and timely opportunity to discuss the EPOS roadmap toward the operation of the novel multidisciplinary platform for discoveries to foster scientific excellence in solid Earth sciences.

  6. DECADE Web Portal: Integrating MaGa, EarthChem and GVP Will Further Our Knowledge on Earth Degassing

    NASA Astrophysics Data System (ADS)

    Cardellini, C.; Frigeri, A.; Lehnert, K. A.; Ash, J.; McCormick, B.; Chiodini, G.; Fischer, T. P.; Cottrell, E.

    2014-12-01

    The release of gases from the Earth's interior to the exosphere takes place in both volcanic and non-volcanic areas of the planet. Fully understanding this complex process requires the integration of geochemical, petrological and volcanological data. At present, major online data repositories relevant to studies of degassing are not linked and interoperable. We are developing interoperability between three of those, which will support more powerful synoptic studies of degassing. The three data systems that will make their data accessible via the DECADE portal are: (1) the Smithsonian Institution's Global Volcanism Program database (GVP) of volcanic activity data, (2) EarthChem databases for geochemical and geochronological data of rocks and melt inclusions, and (3) the MaGa database (Mapping Gas emissions) which contains compositional and flux data of gases released at volcanic and non-volcanic degassing sites. These databases are developed and maintained by institutions or groups of experts in a specific field, and data are archived in formats specific to these databases. In the framework of the Deep Earth Carbon Degassing (DECADE) initiative of the Deep Carbon Observatory (DCO), we are developing a web portal that will create a powerful search engine of these databases from a single entry point. The portal will return comprehensive multi-component datasets, based on the search criteria selected by the user. For example, a single geographic or temporal search will return data relating to compositions of emitted gases and erupted products, the age of the erupted products, and coincident activity at the volcano. The development of this level of capability for the DECADE Portal requires complete synergy between these databases, including availability of standard-based web services (WMS, WFS) at all data systems. Data and metadata can thus be extracted from each system without interfering with each database's local schema or being replicated to achieve integration at the DECADE web portal. The DECADE portal will enable new synoptic perspectives on the Earth degassing process. Other data systems can be easily plugged in using the existing framework. Our vision is to explore Earth degassing related datasets over previously unexplored spatial or temporal ranges.

  7. Integrated microfluidic flowmeter based on a micro-FBG inscribed in Co²?-doped optical fiber.

    PubMed

    Liu, Zhengyong; Tse, Ming-Leung Vincent; Zhang, A Ping; Tam, Hwa-Yaw

    2014-10-15

    A novel microfluidic flowmeter integrated with microfiber Bragg grating (µFBG) is presented. Two glass capillaries and a short length of high-light-absorption Co²?-doped optical fiber were stacked inside a larger outer capillary tube. The stack was then drawn into a tapered device. Two microchannels with the diameter of ~50???m were formed inside the capillaries for flowing of microfluidics. An FBG was inscribed in the tapered Co²?-doped fiber with waist diameter of ~70???m, and acts as a flow-rate sensor. A pump laser with wavelength of 1480 nm was utilized to locally heat the µFBG, rendering the µFBG as miniature "hot-wire" flowmeter. The flow rate of the liquid in the microchannels is determined by the induced wavelength shift of the µFBG. The experimental results achieve a minimum detectable change of ~16??nL/s in flow rate, which is very promising in the use as part of biochips. PMID:25361108

  8. Adjustable up-conversion luminescence color in rare earth co-doped transparent oxyfluoride nano-glass-ceramics.

    PubMed

    Song, Zhiguo; Zhou, Dacheng; Qiu, Jianbei

    2010-03-01

    Transparent oxyfluoride nano-glass-ceramics with highly efficient up-conversion and adjustable color luminescence were developed in the 28SiO2 x 17Al2O3 28PbF2 x 22CdF2 x 0.1NdF3 x xYbF3 x yHoF3 zTmF3 x (4.9 - x - y - z)GdF3 composition, in mol%. X-ray diffraction and transmission electron microscopy measurements revealed that heat treatments of the oxyfluoride glasses cause the homogeneous precipitation of rare-earth ions co-doped fluorite-type Pb(x)Cd1-xF2 nanocrystals of about 10 nm in diameter in the glass matrix. Under single 808 nm laser excitation, intense red, green and blue up-conversion luminescences were simultaneously observed in these transparent nano-glass-ceramics owing to the successive energy transfer from Nd3+ ions to Ho3+ and Tm3+ via Yb3+ ions. Various colors of luminescence, including bright perfect white light, can be tuned by adjusting the concentrations of the Tm3+ ions in the material. A possible energy transfer process and up-conversion luminescence mechanism in the nano-glass-ceramics are proposed and discussed. PMID:20355610

  9. Calcination-free micropatterning of rare-earth-ion-doped nanoparticle films on wettability-patterned surfaces of plastic sheets.

    PubMed

    Watanabe, Satoshi; Hamada, Yudai; Hyodo, Hiroshi; Soga, Kohei; Matsumoto, Mutsuyoshi

    2014-05-15

    We demonstrate a patterning technique of rare-earth-ion-doped (RE) nanoparticle films directly on wettability-patterned surfaces fabricated on plastic sheets in one step. Self-assembled monolayers consisting of silane-coupling agent with hydrophobic groups were fabricated on plastic sheets. UV-ozone treatments were performed through a metal mask to selectively remove the self-assembled monolayers in a patterned manner, resulting in the formation of wettability-patterned surfaces on plastic sheets. Using a water dispersion of Er(3+) and Yb(3+)-codoped Y2O3 nanoparticles at a diameter of 100 nm, RE-nanoparticle films were fabricated on the wettability-patterned surfaces by a dip-coating technique. By adjusting the concentration of RE-nanoparticle dispersion, withdrawal speed, and withdrawal angle, amount of RE-nanoparticles, we were able to control the structures of the RE-nanoparticle films. Fluorescence microscope observations demonstrate that visible upconversion luminescence and near-infrared fluorescence were emitted from the RE-nanoparticle films on the wettability-patterned surfaces. This technique allows for the fabrication of flexible emitting devices with long-operating life time with minimized material consumption and few fabrication steps, and for the application to sensors, emitting devices, and displays in electronics, photonics, and bionics in the future. PMID:24655829

  10. Enhancement of single particle rare earth doped NaYF4: Yb, Er emission with a gold shell.

    PubMed

    Li, Ling; Green, Kory; Hallen, Hans; Lim, Shuang Fang

    2015-01-16

    Upconversion of infrared light to visible light has important implications for bioimaging. However, the small absorption cross-section of rare earth dopants has limited the efficiency of these anti-Stokes nanomaterials. We present enhanced excitation absorption and single particle fluorescent emission of sodium yttrium fluoride, NaYF4: Yb, Er based upconverting nanoparticles coated with a gold nanoshell through surface plasmon resonance. The single gold-shell coated nanoparticles show enhanced absorption in the near infrared, enhanced total emission intensity, and increased green relative to red emission. We also show differences in enhancement between single and aggregated gold shell nanoparticles. The surface plasmon resonance of the gold-shell coated nanoparticle is shown to be dependent on the shell thickness. In contrast to other reported results, our single particle experimental observations are corroborated by finite element calculations that show where the green/red emission enhancement occurs, and what portion of the enhancement is due to electromagnetic effects. We find that the excitation enhancement and green/red emission ratio enhancement occurs at the corners and edges of the doped emissive core. PMID:25517688

  11. Enhancement of single particle rare earth doped NaYF4: Yb, Er emission with a gold shell

    NASA Astrophysics Data System (ADS)

    Li, Ling; Green, Kory; Hallen, Hans; Lim, Shuang Fang

    2015-01-01

    Upconversion of infrared light to visible light has important implications for bioimaging. However, the small absorption cross-section of rare earth dopants has limited the efficiency of these anti-Stokes nanomaterials. We present enhanced excitation absorption and single particle fluorescent emission of sodium yttrium fluoride, NaYF4: Yb, Er based upconverting nanoparticles coated with a gold nanoshell through surface plasmon resonance. The single gold-shell coated nanoparticles show enhanced absorption in the near infrared, enhanced total emission intensity, and increased green relative to red emission. We also show differences in enhancement between single and aggregated gold shell nanoparticles. The surface plasmon resonance of the gold-shell coated nanoparticle is shown to be dependent on the shell thickness. In contrast to other reported results, our single particle experimental observations are corroborated by finite element calculations that show where the green/red emission enhancement occurs, and what portion of the enhancement is due to electromagnetic effects. We find that the excitation enhancement and green/red emission ratio enhancement occurs at the corners and edges of the doped emissive core.

  12. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    SciTech Connect

    Li, Jiawei; Huo, Juntao; Chang, Chuntao, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Du, Juan, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Man, Qikui; Wang, Xinmin; Li, Run-Wei [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Law, Jiayan [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

    2014-08-14

    The effects of heavy rare earth (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE?=?Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune T{sub C} in a large temperature range of 120?K without significantly decreasing the magnetic entropy change (?S{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ?S{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{sub C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  13. Optical clock transition in a rare-earth-ion-doped crystal: coherence lifetime extension for quantum storage applications

    NASA Astrophysics Data System (ADS)

    Tongning, Robert-Christopher; Chanelière, Thierry; Le Gouët, Jean-Louis; Florencia Pascual-Winter, María

    2015-04-01

    Atomic clock transitions are desirable for quantum information storage and processing thanks to the protection from decoherence they provide. In the context of rare- earth-ion-doped crystals for quantum information storage, clock Zeeman or hyperfine transitions have been identified and exploited for long-lived storage in spin degrees of freedom. We present a theoretical and experimental analysis on the existence of an optical clock transition in Tm3+:YAG, in view of storage in optical coherences. The combination of a Zeeman-like term and a quadratic electronic Zeeman term in the Hamiltonian, lead to the existence of a magnetic field amplitude (12 mT) for which the derivative of the optical transition energy with respect to the field amplitude vanishes, regardless of the magnetic field orientation. We have verified this prediction through hole-burning spectroscopy experiments. In addition to that, a study of the behavior of the Hamiltonian as a function of the magnetic field orientation yields the direction for which both derivatives with respect to the magnetic field angular coordinates also vanish. The condition for an optical clock transition with three vanishing partial derivatives is met.

  14. Structural, morphological and spectroscopic properties of Eu{sup 3+}-doped rare earth fluorides synthesized by the hydrothermalmethod

    SciTech Connect

    Grzyb, Tomasz, E-mail: tgrzyb@amu.edu.pl [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland); Runowski, Marcin [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland); Szczeszak, Agata [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, Pozna? 60-179 (Poland); Lis, Stefan [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland)

    2013-04-15

    Rare earth fluorides (REF{sub 3}, RE=Y, La, Gd or Yb) doped with 5% of Eu{sup 3+} ions were synthesized via the hydrothermal method and their physicochemical properties were compared. The synthesis was carried out in an aqueous medium at elevated pressure and temperature. The reaction was performed in situ, with use of NaBF{sub 4} as a source of fluoride ions. Structural and morphological properties of obtained nanophosphors were characterized with the use of powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. Synthesized products were nanocrystalline with hexagonal or orthorhombic crystal structures. They showed different morphology, from nanoplates to nanorings, depending on the used REF{sub 3} fluoride as the host for the Eu{sup 3+} ions. The elemental composition was confirmed by the energy-dispersive X-ray spectroscopy (EDX) results. Spectroscopic properties were investigated by measuring the excitation and emission spectra. Also luminescence lifetimes were determined. The synthesized materials showed bright red luminescence, due to the presence of Eu{sup 3+} ions in their structure. - Graphical abstract: Luminescence spectra of the REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd and Yb) fluorides and their TEM images as background. Highlights: ? Nanocrystalline fluorides were synthesized using modified hydrothermal method. ? Structural and morphological properties of in situ prepared nanomaterials were studied. ? Luminescence properties of REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd, Yb) were compared and investigated.

  15. Energy transfer kinetics in oxy-fluoride glass and glass-ceramics doped with rare-earth ions

    SciTech Connect

    Sontakke, Atul D.; Annapurna, K. [Glass Science and Technology Section, CSIR-Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Road, Kolkata - 700 032 (India)

    2012-07-01

    An investigation of donor-acceptor energy transfer kinetics in dual rare earths doped precursor oxy-fluoride glass and its glass-ceramics containing NaYF{sub 4} nano-crystals is reported here, using three different donor-acceptor ion combinations such as Nd-Yb, Yb-Dy, and Nd-Dy. The precipitation of NaYF{sub 4} nano-crystals in host glass matrix under controlled post heat treatment of precursor oxy-fluoride glasses has been confirmed from XRD, FESEM, and transmission electron microscope (TEM) analysis. Further, the incorporation of dopant ions inside fluoride nano-crystals has been established through optical absorption and TEM-EDX analysis. The noticed decreasing trend in donor to acceptor energy transfer efficiency from precursor glass to glass-ceramics in all three combinations have been explained based on the structural rearrangements that occurred during the heat treatment process. The reduced coupling phonon energy for the dopant ions due to fluoride environment and its influence on the overall phonon assisted contribution in energy transfer process has been illustrated. Additionally, realization of a correlated distribution of dopant ions causing clustering inside nano-crystals has also been reported.

  16. Up-conversion in rare-earth doped micro-particles applied to new emissive two-dimensional displays

    NASA Astrophysics Data System (ADS)

    Milliez, Anne Janet

    Up-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two photon absorption in which a strong absorbing constituent absorbs two low energy photons and transfers this energy to another constituent which emits visible light. Some of the UC emitters' most appealing characteristics for displays are: a wide color gamut with very saturated colors, very high brightness operation without damage to the emitters, long lifetimes and efficiencies comparable to those of existing technologies. Other advantages include simplicity of fabrication, versatility of operating modes, and the potential for greatly reduced display weight and depth. Thanks to recent advances in material science and diode laser technology at the excitation wavelength, UC selected materials can be very efficient visible emitters. However, optimal UC efficiencies strongly depend on chosing proper operating conditions. In this thesis, we studied the conditions required for optimization. We demonstrated that high efficiency UC depends on high pump irradiance, low temperature and low scattering. With this understanding we can predict how to optimally use UC emitters in a wide range of applications. In particular, we showed how our very efficient UC emitters can be applied to make full color displays and very efficient white light sources.

  17. Time-frequency-domain dispersion measurement in rare earth doped large effective mode area multicore fibers

    NASA Astrophysics Data System (ADS)

    Baselt, T.; Taudt, Ch.; Hartmann, P.

    2014-03-01

    Ytterbium doped multicore fibers have been recently employed in the field of high power and Quasi-Gaussian beam lasers to design truly single-mode multicore fiber lasers. The special design of these fibers offers low bending loss even for compact high power lasers and amplifiers. Moreover, the Multi-core fiber amplifier possesses a large effective mode area which results in a significant decrease of the related nonlinear effects. In the paper, modal resolved group-velocity dispersion measurements in active multicore fibers are performed using time-frequency-domain white-light interferometry. A Mach-Zehnder-type interferometer with dual-channel detection in the spectral range from 0.4 ?m up to 1.7 ?m and a home-made supercontinuum source are used. Temporally resolved spectrograms recorded at distinct delay positions enable the detection of interference fringes for the equalizationwavelength. The group-velocity dispersion can be derived by applying a Sellmeier polynomial fit to the wavelength dependent differential group delay function. The dispersion parameters for several LMA fibers are investigated over a broad spectral range of about 1.3 ?m.

  18. Rare earth doped silicon nanocrystals derived from an erbium amidinate precursor

    NASA Astrophysics Data System (ADS)

    Ji, Jumin; Senter, Robert A.; Tessler, Leandro R.; Back, Dwayne; Winter, Charles H.; Coffer, Jeffery L.

    2004-05-01

    We describe the use of Er(tBuNC(CH3)NtBu)3 as a dopant source in the preparation of silicon nanocrystals, particularly as regards their observed structure, composition, and photophysical properties. These nanocrystals were prepared by the co-pyrolysis of Er(tBuNC(CH3)NtBu)3 and disilane in a dilute helium stream at 1000 °C. Characterization methods include high resolution electron microscopy, selected area electron diffraction, energy dispersive x-ray measurements, extended x-ray absorption spectroscopy, and photoluminescence spectroscopy. In conditions identical to those used previously for bgr-diketonate precursors, nanocrystals doped using this amidinate source are larger in size, of a narrower size distribution, and contain more erbium in the nanocrystal on average. Steady state photoluminescence measurements as a function of excitation wavelength confirm that the characteristic 1540 nm emission detected in these nanocrystals emit by a silicon exciton-mediated pathway. These results are a clear example of precursor dopant chemistry exerting a significant effect on resultant nanoparticle properties.

  19. Incorporating Stakeholder Decision Support Needs into an Integrated Regional Earth System Model

    Microsoft Academic Search

    Jennie S. Rice; Richard H. Moss; Paul J. Runci; K. L. Anderson; Elizabeth L. Malone

    2012-01-01

    A new modeling effort exploring the opportunities, constraints, and interactions between mitigation and adaptation at regional scale is utilizing stakeholder engagement in an innovative approach to guide model development and demonstration, including uncertainty characterization, to effectively inform regional decision making. This project, the integrated Regional Earth System Model (iRESM), employs structured stakeholder interactions and literature reviews to identify the most

  20. Evaluating and improving CLM hydrologic processes for integrated earth system modeling at regional scales

    Microsoft Academic Search

    M. Huang; L. Leung; M. S. Wigmosta; A. M. Coleman; Y. Ke; T. K. Tesfa; H. Li

    2010-01-01

    The community land model (CLM) was designed for coupling with atmospheric models to simulate water, energy, and carbon fluxes between the land surface and atmosphere. These fluxes are regulated in various degrees by its hydrologic processes, which have not been vigorously evaluated for applications at watershed or regional scales. In the framework of an integrated regional earth system model being

  1. Electromagnetic wave propagation over an inhomogeneous flat earth (two-dimensional integral equation formulation)

    Microsoft Academic Search

    G. de Jong

    1975-01-01

    With the aid of a two-dimensional integral equation formulation, the ground wave propagation of electromagnetic waves transmitted by a vertical electric dipole over an inhomogeneous flat earth is investigated. For the configuration in which a ground wave is propagating across an \\

  2. Research priorities in land use and land-cover change for the Earth system and integrated assessment modelling

    E-print Network

    Hibbard, Kathy; Janetos, Anthony; van Vuuren, Detlef P.; Pongtatz, Julia; Rose, Steven K.; Betts, Richard; Herold, Martin; Feddema, Johannes J.

    2010-01-01

    ). Copyright ? 2010 Royal Meteorological Society and Crown Copyright. KEY WORDS land use; land cover; Earth system models; integrated assessment models; research priorities Received 12 January 2009; Revised 9 March 2010; Accepted 14 March 2010 1. Introduction 1... biogeophysical, socio- economic and human decision-making perspectives. The Earth System Modeling (ESM) and the Integrated Assessment Modeling (IAM) communities play an impor- tant role in understanding and quantifying Earth system analysis and, specifically...

  3. Ultraviolet direct printing of rare-earth-doped polymer waveguide amplifiers

    SciTech Connect

    Wong, W.H.; Chan, K.S.; Pun, E.Y.B. [Department of Electronic Engineering and Department of Physics and Material Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Department of Physics and Material Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

    2005-07-04

    Polymer channel waveguide amplifier arrays were fabricated using ultraviolet direct printing methodology. The effects of different weight percentage (wt. %) combinations of rare-earth ions erbium (Er{sup 3+}) and ytterbium (Yb{sup 3+}) on the absorption spectrum, as well as the internal gain, were investigated. With an input signal power of {approx}-18 dBm, the highest internal gain obtained is {approx}16.5 dB at a wavelength of 1533 nm for a 20 mm long multimode channel waveguide codoped with {approx}1 wt. % of Er{sup 3+} and {approx}10 wt. % of Yb{sup 3+} derivatives. The UV direct printing methodology opens a simple platform for the fabrication of dense and compact polymer waveguide laser arrays.

  4. Promoting effect of alkaline earth metal doping on catalytic activity of HC and NOx conversion over Pd-only three-way catalyst.

    PubMed

    Yang, Linyan; Lin, Siyu; Yang, Xue; Fang, Weimin; Zhou, Renxian

    2014-08-30

    The influence of alkaline earth metal (M=Mg, Ca, Sr and Ba) promoter on the structural/textural properties of Ce0.67Zr0.33O2 (designated as CZ) and the catalytic behavior of its supported Pd-only three-way catalyst (Pd/CZM) have been investigated. The results show that the modification with alkaline earth metal obviously improves the catalytic activity for hydrocarbon (HC) and nitrogen oxides (NOx) conversion, especially the introduction of Ba. Furthermore, the operation window of the promoted catalysts has also been widened. The doping of alkaline earth metal leads to the formation of more homogeneous Ce-Zr-M ternary solid solution with higher surface area and smaller crystallite size, and the corresponding Pd/CZM catalysts present improved reducibility of PdO species. The modification with Ca, Sr and Ba improves the thermal aging resistance, especially Ba. DRIFTS results reveal that the doping of alkaline earth metal enhances the oxygen and electron transfer ability and favors the dissociation of NO, which promotes the activation and storage capacity of the acidic atoms like NOx, and leads to enhanced catalytic activity performance. PMID:25064260

  5. Earth

    NSDL National Science Digital Library

    2008-10-03

    With three levels to choose from on each page - beginner, intermediate or advanced - this site provides information on our plant Earth. There is a section about water on earth and its many different varities, like freshwater, groundwater, and frozen water. There is information about the chemical make-up of water and many images showing the different water anvironments. There is a section about life in water, such as animals, plants, and plankton.

  6. Development of Uncooled Micro-bolometer Arrays Based on Hole-doped Rare-Earth Manganites

    NASA Astrophysics Data System (ADS)

    Tanyi, E.; Yong, Grace; Keshavarz, Camron; Sharma, Prakash; Rubin, Christopher; Kolagani, Rajeswari; Gross, Steven

    2013-03-01

    Material properties indicate that rare earth manganites have a competitive advantage over VOx which is a material commonly employed as bolometric sensors in state of the art uncooled imaging arrays. We will present the results of our work on developing manganite thin films for uncooled micro-bolometer arrays. By fine tuning the cation composition and stoichiometry, we have identified material compositions suitable for uncooled bolometer operation and developed thin films of these materials by Pulsed Laser Deposition (PLD) on Si. For hetero-epitaxy on Si, we employ lattice engineering schemes to circumvent problems such as chemical incompatibility and amorphization of the substrate surface due to the native oxide. We are in the process of fabricating single test bolometers and micro-bolometer arrays. We will discuss the results of materials development and device fabrication efforts and will present performance parameters and estimated figures of merit for test bolometers. We will also discuss efforts towards understanding and alleviating material problems such as the residual stresses in the thin film heterostructures which are of critical importance for the fabrication of suspended microstructures. Material properties indicate that rare earth manganites have a competitive advantage over VOx which is a material commonly employed as bolometric sensors in state of the art uncooled imaging arrays. We will present the results of our work on developing manganite thin films for uncooled micro-bolometer arrays. By fine tuning the cation composition and stoichiometry, we have identified material compositions suitable for uncooled bolometer operation and developed thin films of these materials by Pulsed Laser Deposition (PLD) on Si. For hetero-epitaxy on Si, we employ lattice engineering schemes to circumvent problems such as chemical incompatibility and amorphization of the substrate surface due to the native oxide. We are in the process of fabricating single test bolometers and micro-bolometer arrays. We will discuss the results of materials development and device fabrication efforts and will present performance parameters and estimated figures of merit for test bolometers. We will also discuss efforts towards understanding and alleviating material problems such as the residual stresses in the thin film heterostructures which are of critical importance for the fabrication of suspended microstructures. We acknowledge support from the NSF grant ECCS 1128586 at Towson University.

  7. Hole and Electron Doping of R2BaNiO 5 ( R = Rare Earths)

    NASA Astrophysics Data System (ADS)

    Alonso, J. A.; Rasines, I.; Rodriguez-Carvajal, J.; Torrance, J. B.

    1994-04-01

    Black polycrystalline samples of the composition R2- x Ca x BANiO 5 (Ni-oxidized samples), with R = Y, Nd, Er, Lu, and 0.2 ? x ? 0.5, have been prepared in air by solid state reaction of R 2O 3, CaCO 3, BaO 2, and NiO. They crystallized in the orthorhombic Nd 2BaNiO 5 structure type, space group Immm, that contains chains of flattened NiO 6 octahedra sharing corners along the [100] direction. X-ray and neutron powder diffraction data show that Ca 2+ replaces R3+ at random, whereas the oxygen positions remain fully occupied, which induces a proportional increase in the formal oxidation state of Ni with Ca content. The unit-cell volume decreases as a result of the shrinkage of the NiO 6 octahedra. The electrical conductivity rises with Ca doping, showing a semiconductor behavior. The linearity of the log ? vs T-1/4 plot suggests a thermally activated electron hopping conduction mechanism, by intervalence transitions between adjacent Ni 2+-Ni 3+ cations. The samples can be reduced in two steps, giving oxygen-deficient compounds in which the structure is basically unchanged. After the first step all the Ni 3+ is reduced to Ni 2+. The second reduction process leads to phases, greenish in color, that are thought to contain Ni in both monovalent and divalent oxidation states. The presence of Ca 2+ in the structure seems to be essential in the stabilization of Ni +. A neutron diffraction study of the compounds Er 2- xCa xBaNiO 5-?, prepared in a H 2/N 2 flow at 500°C, shows that the O2 axial oxygens are lost during the reduction process. This breaks the continuity of the chains of octahedra, thus hindering the intervalence transitions along the chains. The electrical conductivity is, in fact, several orders of magnitude lower than that of the corresponding Ni-oxidized samples.

  8. MT+, integrating magnetotellurics to determine earth structure, physical state, and processes

    USGS Publications Warehouse

    Bedrosian, P.A.

    2007-01-01

    As one of the few deep-earth imaging techniques, magnetotellurics provides information on both the structure and physical state of the crust and upper mantle. Magnetotellurics is sensitive to electrical conductivity, which varies within the earth by many orders of magnitude and is modified by a range of earth processes. As with all geophysical techniques, magnetotellurics has a non-unique inverse problem and has limitations in resolution and sensitivity. As such, an integrated approach, either via the joint interpretation of independent geophysical models, or through the simultaneous inversion of independent data sets is valuable, and at times essential to an accurate interpretation. Magnetotelluric data and models are increasingly integrated with geological, geophysical and geochemical information. This review considers recent studies that illustrate the ways in which such information is combined, from qualitative comparisons to statistical correlation studies to multi-property inversions. Also emphasized are the range of problems addressed by these integrated approaches, and their value in elucidating earth structure, physical state, and processes. ?? Springer Science+Business Media B.V. 2007.

  9. Alpha-particle-induced luminescence of rare-earth-doped Y 2O 3 nanophosphors

    NASA Astrophysics Data System (ADS)

    Cress, Cory D.; Redino, Christopher S.; Landi, Brian J.; Raffaelle, Ryne P.

    2008-08-01

    The feasibility of utilizing Y 2O 3:Tb 3+ and Y 2O 3:Eu 3+ as radioluminescent nanophosphors under alpha-particle excitation is investigated. Materials synthesized by the urea homogeneous precipitation method were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The XRD analysis of as-produced precipitates and nanophosphors fired at temperatures ranging from 950 to 1100 °C indicated the presence of highly crystalline cubic Y 2O 3 with crystallite sizes of ˜40 nm. SEM and TEM analysis revealed that particles with average diameters of ˜200 nm and comprised of ˜40 nm grains were obtained. High-resolution radioluminescence and photoluminescence spectra were used to investigate the unwanted radioluminescence saturation effects associated with the high ionization rate of alpha-particles. Additionally, the radioluminescence intensity as a function of rare-earth ion dopant concentration is investigated for these materials under alpha-particle excitation. The prospect for utilizing these materials as intermediate absorbers in indirect-conversion radioisotope batteries is discussed.

  10. Theoretical Study on Interactions between Oxygen Vacancy and Doped Rare-Earth Elements in Barium Titanate

    NASA Astrophysics Data System (ADS)

    Honda, Atsushi; Higai, Shin'ichi; Motoyoshi, Yasuhiro; Wada, Nobuyuki; Takagi, Hiroshi

    2011-09-01

    We performed first-principles theoretical calculations to examine the interactions between oxygen vacancy (VO) and rare-earth (RE) elements in barium titanate (BaTiO3), in order to clarify the mechanism of VO trapping by RE dopants, which affects the insulating reliability of BaTiO3-based multilayer ceramic capacitors (MLCC). It was found that VO is stabilized at the first and second nearest O sites of RE at Ba site (REBa), and at the second nearest O site of RE at Ti site (RETi). The structural relaxations on bond lengths of REBa-O and RETi-O in BaTiO3, which are brought about by the existence of VO at the above sites, decrease the total energy, and thus VO is stabilized. Furthermore, we revealed that the stability of VO increases with decreasing solution stability of RE dopants in BaTiO3. Accordingly, we concluded that RE dopants with higher solution energy in BaTiO3 efficiently trap VO, and thus the insulation reliability of MLCC is improved.

  11. Earth

    NSDL National Science Digital Library

    This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Earth. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions show Earth features such as the Ross Ice Shelf in Antarctica, Simpson Desert in Australia, Mt. Etna in Sicily, the Cassiar Mountains in Canada, the Strait of Gibraltar, Mississippi River, Grand Canyon, Wadi Kufra Oasis in Libya, and Moon images such as Hadley Rille, Plum Crater, massifs and Moon rocks. These images were taken with the Galileo Spacecraft and by the Apollo missions.

  12. 56.6 DB High Gain L-Band Edfa Utilizing Short-Length Highly-Doped Erbium Rare-Earth Material

    NASA Astrophysics Data System (ADS)

    Al-Mansoori, M. H.; Al-Ghaithi, W. S.

    2014-07-01

    In this paper, we experimentally investigate the performance of an efficient high gain L-band erbium-doped fiber (EDF) amplifier structure utilizing short-length highly-doped erbium rare-earth material with a single pump source. The amplifier gain and noise figure variation for different amplifier structures have been investigated. A filter is used to reduce the self-saturation effect and suppress the C-band amplified spontaneous emission (ASE) noise. The amplifier achieves a signal gain of 56.6 dB with a low noise figure of 4.8 dB at -50 dBm input signal power using only 8 m of EDF length. The amplifier gain shows significant improvement of 6 dB with C/L band coupler and 13 dB with tunable-band pass filter compared to amplifier structure without ASE suppression.

  13. Theoretical model and experimental demonstration of frequency control in rare-earth-doped fiber lasers with a 3{times}3 nonplanar fused-fiber coupler

    SciTech Connect

    Gloag, A.; Forster, R.J.; Langford, N. [Department of Physics and Applied Physics, University of Strathclyde, 107 Rottenrow East, Glasgow G4 ONG (United Kingdom)

    1997-04-01

    We present a numerical analysis that illustrates the potential of 3{times}3 nonplanar fused-fiber couplers for inhibiting longitudinal mode hops in rare-earth-doped-fiber lasers. A unidirectional erbium-doped ring-fiber laser is configured that contains a single 3{times}3 fused-fiber coupler. Narrow linewidth operation without any evidence of longitudinal mode hops is observed. The oscillating linewidth is 14 kHz with a rms frequency jitter {approximately}2 kHz. The relative intensity noise is measured in both the frequency stabilized and the frequency unstabilized cases. An average 15-dB reduction in the relative intensity noise over the 0{endash}200 Hz frequency range is observed when the laser is stabilized. {copyright} 1997 Optical Society of America

  14. Continuous monitoring of a large active earth flow using an integrated GPS - automatic total station approach

    Microsoft Academic Search

    A. Corsini

    2009-01-01

    Landslide monitoring has evolved as a crucial tool in civil protection to mitigate and prevent disasters. The research presents an approach to continuous monitoring of a large-scale active earth flow using a system that integrates surface measurements obtained by a GPS and an automatic total station. With the data obtained from the system the landslide can be monitored in near-real-time

  15. A model of integrated information-analytic system for basic research support in earth sciences

    Microsoft Academic Search

    Yu. M. Arskii; A. V. Veselovskii; A. N. Shogin

    2007-01-01

    The paper considers the design of integrated information-analytic systems by using a mathematical model of grouping of the\\u000a related scientific-research institutes and choosing a group center, i.e., an Internet portal. The modeling accounts for thematic\\u000a similarity of targeted tasks and cost issues. The Electronic Earth project launched by the Presidium of the Russian Academy\\u000a of Sciences (RAS) is aimed at

  16. Using the Collaborative Sun-Earth Connector for integrating data systems

    Microsoft Academic Search

    N. Hurlburt; S. Freeland; G. Slater; R. Bentley; F. Hill; P. Bose

    2005-01-01

    We demonstrate the coupling of disjoint data systems into virtual collaborative operations using the Collaborative Sun-Earth Connector (CoSEC). In addition to demonstrating possible interactions between Virtual observatories, we will present how individual missions and researchers can integrate their systems with space science services already incorporated into CoSEC. We present more advanced concepts of how to create collaborative data environments using

  17. A Hamiltonian theory for an elastic earth: First order analytical integration

    Microsoft Academic Search

    Juan Getino; José M. Ferrándiz

    1991-01-01

    In this article an approximate analytical integration is performed of the Hamiltonian corresponding to the rotational motion\\u000a of an Earth whose elastic mantle is deformed by rotation and lunisolar attraction, using Deprit's perturbation method for\\u000a the first order. Besides the usual terms, this Hamiltonian includes the perturbation of the kinetic energy and the elastic\\u000a energy produced with the deformation, as

  18. Eigensensitivity in integrated design. [of earth-pointing satellite's control system

    NASA Technical Reports Server (NTRS)

    Kenny, Sean P.; Hou, Gene J.; Belvin, W. K.

    1990-01-01

    An application of eigensensitivity analysis to the control-structure integrated design process is presented with an emphasis placed on computational efficiency improvement of the overall design optimization process. The computational efficiency of eigenvalue/vector sensitivity analysis is demonstrated using the Earth Pointing Satellite in the context of a control-structure integrated design program. Results for a 2 percent design variable perturbation with and without the effects of the actuator mass show a 42 and 52 percent reduction in CPU time, respectively.

  19. Observation of coherent population transfer in a four-level tripod system with a rare-earth-metal-ion-doped crystal

    SciTech Connect

    Goto, Hayato; Ichimura, Kouichi [Frontier Research Laboratory, Corporate Research and Development Center, Toshiba Corporation, 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, 212-8582 (Japan)

    2007-03-15

    Coherent population transfer in a laser-driven four-level system in a tripod configuration is experimentally investigated with a rare-earth-metal-ion-doped crystal (Pr{sup 3+}:Y{sub 2}SiO{sub 5}). The population transfers observed here indicate that a main process inducing them is not optical pumping, which is an incoherent process inducing population transfer. Moreover, numerical simulation, which well reproduces the experimental results, also shows that the process inducing the observed population transfers is similar to stimulated Raman adiabatic passage (STIRAP) in the sense that this process possesses characteristic features of STIRAP.

  20. Information Requirements for Integrating Spatially Discrete, Feature-Based Earth Observations

    NASA Astrophysics Data System (ADS)

    Horsburgh, J. S.; Aufdenkampe, A. K.; Lehnert, K. A.; Mayorga, E.; Hsu, L.; Song, L.; Zaslavsky, I.; Valentine, D. L.

    2014-12-01

    Several cyberinfrastructures have emerged for sharing observational data collected at densely sampled and/or highly instrumented field sites. These include the CUAHSI Hydrologic Information System (HIS), the Critical Zone Observatory Integrated Data Management System (CZOData), the Integrated Earth Data Applications (IEDA) and EarthChem system, and the Integrated Ocean Observing System (IOOS). These systems rely on standard data encodings and, in some cases, standard semantics for classes of geoscience data. Their focus is on sharing data on the Internet via web services in domain specific encodings or markup languages. While they have made progress in making data available, it still takes investigators significant effort to discover and access datasets from multiple repositories because of inconsistencies in the way domain systems describe, encode, and share data. Yet, there are many scenarios that require efficient integration of these data types across different domains. For example, understanding a soil profile's geochemical response to extreme weather events requires integration of hydrologic and atmospheric time series with geochemical data from soil samples collected over various depth intervals from soil cores or pits at different positions on a landscape. Integrated access to and analysis of data for such studies are hindered because common characteristics of data, including time, location, provenance, methods, and units are described differently within different systems. Integration requires syntactic and semantic translations that can be manual, error-prone, and lossy. We report information requirements identified as part of our work to define an information model for a broad class of earth science data - i.e., spatially-discrete, feature-based earth observations resulting from in-situ sensors and environmental samples. We sought to answer the question: "What information must accompany observational data for them to be archivable and discoverable within a publication system as well as interpretable once retrieved from such a system for analysis and (re)use?" We also describe development of multiple functional schemas (i.e., physical implementations for data storage, transfer, and archival) for the information model that capture the requirements reported here.

  1. VARIABILITY OF WATER AND OXYGEN ABSORPTION BANDS IN THE DISK-INTEGRATED SPECTRA OF EARTH

    SciTech Connect

    Fujii, Yuka; Suto, Yasushi [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Turner, Edwin L., E-mail: yuka.fujii@utap.phys.s.u-tokyo.ac.jp [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2013-03-10

    We study the variability of major atmospheric absorption features in the disk-integrated spectra of Earth with future application to Earth-analogs in mind, concentrating on the diurnal timescale. We first analyze observations of Earth provided by the EPOXI mission, and find 5%-20% fractional variation of the absorption depths of H{sub 2}O and O{sub 2} bands, two molecules that have major signatures in the observed range. From a correlation analysis with the cloud map data from the Earth Observing Satellite (EOS), we find that their variation pattern is primarily due to the uneven cloud cover distribution. In order to account for the observed variation quantitatively, we consider a simple opaque cloud model, which assumes that the clouds totally block the spectral influence of the atmosphere below the cloud layer, equivalent to assuming that the incident light is completely scattered at the cloud top level. The model is reasonably successful, and reproduces the EPOXI data from the pixel-level EOS cloud/water vapor data. A difference in the diurnal variability patterns of H{sub 2}O and O{sub 2} bands is ascribed to the differing vertical and horizontal distribution of those molecular species in the atmosphere. On Earth, the inhomogeneous distribution of atmospheric water vapor is due to the existence of its exchange with liquid and solid phases of H{sub 2}O on the planet's surface on a timescale short compared with atmospheric mixing times. If such differences in variability patterns were detected in spectra of Earth-analogs, it would provide the information on the inhomogeneous composition of their atmospheres.

  2. PHOTOMETRIC VARIABILITY OF THE DISK-INTEGRATED THERMAL EMISSION OF THE EARTH

    SciTech Connect

    Gomez-Leal, I.; Selsis, F. [Univ. Bordeaux, LAB, UMR 5804, F-33270 Floirac (France); Palle, E., E-mail: gomezleal@obs.u-bordeaux1.fr, E-mail: selsis@obs.u-bordeaux1.fr, E-mail: epalle@iac.es [Instituto de Astrofisica de Canarias, Via Lactea s/n, La Laguna E-38205, Tenerife (Spain)

    2012-06-10

    Here we present an analysis of the global-integrated mid-infrared emission flux of the Earth based on data derived from satellite measurements. We have studied the photometric annual, seasonal, and rotational variability of the thermal emission of the Earth to determine which properties can be inferred from the point-like signal. We find that the analysis of the time series allows us to determine the 24 hr rotational period of the planet for most observing geometries, due to large warm and cold areas, identified with geographic features, which appear consecutively in the observer's planetary view. However, the effects of global-scale meteorology can effectively mask the rotation for several days at a time. We also find that orbital time series exhibit a seasonal modulation, whose amplitude depends strongly on the latitude of the observer but weakly on its ecliptic longitude. As no systematic difference of brightness temperature is found between the dayside and the nightside, the phase variations of the Earth in the infrared range are negligible. Finally, we also conclude that the phase variation of a spatially unresolved Earth-Moon system is dominated by the lunar signal.

  3. Visible light responsive sulfated rare earth doped TiO(2)@fumed SiO(2) composites with mesoporosity: enhanced photocatalytic activity for methyl orange degradation.

    PubMed

    Zhan, Changchao; Chen, Feng; Yang, Jintao; Dai, Daoxing; Cao, Xiaohua; Zhong, Mingqiang

    2014-02-28

    Visible light (VL) responsive mesoporous sulfated rare earth ions (Nd(3+), La(3+), Y(3+)) incorporated TiO2@fumed SiO2 photocatalysts were prepared by sol-gel method with P123 (EO20PO70EO20) as a template. The resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption measurements (BET), UV-vis diffuse reflectance spectroscopy, photoluminescence (PL) spectra, Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA). In comparison with nondoped sample, RE-doped samples showed not only an increase in the surface areas and pore volumes, but also an inhibition of titania phase transition from anatase to rutile. Photo-degradation results revealed that RE-doped samples could greatly improve the photocatalytic activity, and the experimental degradation rates of methyl orange (MO) were higher than that catalyzed by undoped samples and Degussa P-25, obeyed the order of Nd(3+)>La(3+)>Y(3+). Nd-doped sample expressed the highest photoactivity and the optimal dosage was 0.25mol%, which resulted in MO degradation rates of 99.8% and 90.05% irradiation under UV for 60min and VL (?>400nm) for 40h, respectively. The enhanced photocatalytic activity could be attributed to the higher specific area, good crystallinity, strong VL absorption and effective separation of photogenerated electron-hole pairs in the catalyst. PMID:24418494

  4. Rare-earth doped gadolinia based phosphors for potential multicolor and white light emitting deep UV LEDs

    Microsoft Academic Search

    Vinila Bedekar; Dimple P. Dutta; M. Mohapatra; S. V. Godbole; R. Ghildiyal; A. K. Tyagi

    2009-01-01

    Gadolinium oxide host and europium\\/dysprosium\\/terbium doped gadolinium oxide nanoparticles were synthesized using the sonochemical technique. Gadolinium oxide nanocrystals were also co-doped with total 2 mol% of Eu3+\\/Dy3+,Eu3+\\/Tb3+,Dy3+\\/Tb3+, and also Eu3+\\/Dy3+\\/Tb3+ ions, by the same method. The nanoparticles obtained were characterized using powder x-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) techniques. The size of the

  5. LaAlO3/SrTiO3 interfaces doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Sanders, T. D.; Gray, M. T.; Wong, F. J.; Suzuki, Y.

    2015-05-01

    Doping the LaAlO3 (LAO) side of the LaAlO3/SrTiO3 interface with 2% Tm or Lu does not significantly affect its electron transport. Also, at low temperatures, carrier mobility is steeply anticorrelated with carrier concentration for both doped and undoped interfaces. This relationship cannot be explained by ionized impurities alone but may be driven by positive charge in or on the LAO film.

  6. Crystal growth, characterization and theoretical studies of alkaline earth metal-doped tetrakis(thiourea)nickel(II) chloride.

    PubMed

    Agilandeshwari, R; Muthu, K; Meenatchi, V; Meena, K; Rajasekar, M; Aditya Prasad, A; Meenakshisundaram, S P

    2015-02-25

    The influence of Sr(II)-doping on the properties of tetrakis(thiourea)nickel(II) chloride (TTNC) has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies of doped specimens confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the Sr(II) are observed by scanning electron microscopy. The incorporation of metal into the host crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The nonlinear optical properties of the doped and undoped specimens were studied. Theoretical calculations were performed using the Density functional theory (DFT) method with B3LYP/LANL2DZ as the basis set. The molecular geometry and vibrational frequencies of TTNC in the ground state were calculated and the observed structural parameters of TTNC are compared with parameters obtained from single crystal X-ray studies. The atomic charge distributions are obtained by Mulliken charge population analysis. The first-order molecular hyperpolarizability, polarizability and dipole moment were derived. PMID:25233030

  7. Crystal growth, characterization and theoretical studies of alkaline earth metal-doped tetrakis(thiourea)nickel(II) chloride

    NASA Astrophysics Data System (ADS)

    Agilandeshwari, R.; Muthu, K.; Meenatchi, V.; Meena, K.; Rajasekar, M.; Aditya Prasad, A.; Meenakshisundaram, SP.

    2015-02-01

    The influence of Sr(II)-doping on the properties of tetrakis(thiourea)nickel(II) chloride (TTNC) has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies of doped specimens confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the Sr(II) are observed by scanning electron microscopy. The incorporation of metal into the host crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The nonlinear optical properties of the doped and undoped specimens were studied. Theoretical calculations were performed using the Density functional theory (DFT) method with B3LYP/LANL2DZ as the basis set. The molecular geometry and vibrational frequencies of TTNC in the ground state were calculated and the observed structural parameters of TTNC are compared with parameters obtained from single crystal X-ray studies. The atomic charge distributions are obtained by Mulliken charge population analysis. The first-order molecular hyperpolarizability, polarizability and dipole moment were derived.

  8. Semi-analytical integration of the Earth's precession-nutation based on the GCRS coordinates of the CIP unit vector

    NASA Astrophysics Data System (ADS)

    Capitaine, N.; Folgueira, M.

    2012-12-01

    In a previous paper (Capitaine et al. 2006), referred here as Paper I, we demonstrated the possibility of integrating the Earth's rotational motion in terms of the coordinates (X, Y ) of the celestial intermediate pole (CIP) unit vector in the Geocentric celestial reference system (GCRS). Here, we report on the approach that has been followed for solving the equations in the case of an axially symmetric rigid Earth and the semi-analytical (X, Y ) solution obtained from the expression of the external torque acting on the Earth derived from the most complete semi-analytical solutions for the Earth, Moon and planets.

  9. From the Earth Summit to Rio+20: integration of health and sustainable development.

    PubMed

    Haines, Andy; Alleyne, George; Kickbusch, Ilona; Dora, Carlos

    2012-06-01

    In 2012, world leaders will meet at the Rio+20 conference to advance sustainable development--20 years after the Earth Summit that resulted in agreement on important principles but insufficient action. Many of the development goals have not been achieved partly because social (including health), economic, and environmental priorities have not been addressed in an integrated manner. Adverse trends have been reported in many key environmental indicators that have worsened since the Earth Summit. Substantial economic growth has occurred in many regions but nevertheless has not benefited many populations of low income and those that have been marginalised, and has resulted in growing inequities. Variable progress in health has been made, and inequities are persistent. Improved health contributes to development and is underpinned by ecosystem stability and equitable economic progress. Implementation of policies that both improve health and promote sustainable development is urgently needed. PMID:22682465

  10. A Terrestrial Integrated Modeling System (TIMS) at a catchment scale - implications for Earth System Modeling

    NASA Astrophysics Data System (ADS)

    Niu, G. Y.; Fang, Y.; Wu, R.; Mathias, A.; Paniconi, C.; Troch, P. A. A.; Zeng, X.; Chorover, J.; Monson, R. K.

    2014-12-01

    To enhance our predictive understandings of the interactions between the soil, plants, and air and their integrated behavior at hillslope and catchment scales, we have been developing a Terrestrial Integrated Modeling System (TIMS). TIMS aims to numerically simulate various physical and chemical processes that occur over the Earth's terrestrial surface, e.g., exchanges and flows of energy, water, carbon and other chemicals between and within the soil, plants, and air. TIMS is being compiled from existing models that have arisen from individual scientific communities, including 1) a surface energy, water, and carbon exchange scheme (NoahMP), 2) a 3-dimensional physically-based hydrological model (CATHY), 3) a reactive transport model (CrunchFlow), and 4) an individual-based vegetation dynamics model (ECOTONE). TIMS also integrates newly developed components, e.g., a microbial enzyme based soil organic carbon decomposition model and a solar radiation correction scheme accounting for the effects of terrain shading and slope angle and aspect. We will present the current state of TIMS development and some validations against measurements at various scales, the challenges for developing and evaluating such a complex modeling system, and implications for scaling-up plot-scale processes (e.g., AmeriFlux) to global-scale land surface models for use in Earth System Models (ESMs).

  11. Time-integrated photoluminescence and pump-probe reflection spectroscopy of Si doped InN thin films

    SciTech Connect

    Mohanta, Antaryami; Jang, Der-Jun, E-mail: djjang@mail.nsysu.edu.tw; Wang, Ming-Sung; Tu, L. W. [Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China)

    2014-01-28

    Temperature and excitation power dependent time-integrated photoluminescence of Si doped InN thin films are investigated. Photoluminescence (PL) spectra at low temperatures are described by single emission peak ensued due to “free-to-bound” recombination; whereas PL spectra at higher temperatures above 150?K are characterized by both “band-to-band” and “free-to-bound” transition. Carrier dynamics of Si doped InN thin films is studied using pump-probe reflection spectroscopy at room temperature. The hot electron cooling process is well described by electron-electron scattering. The dependence of the hot electron cooling rate on total electron density shows sublinear to linear behavior with increase of background electron density. The variation of the carrier recombination lifetime with total electron density implicates the dominance of the defect-related nonradiative recombination channel over other recombination processes.

  12. Earth Systems Science in an Integrated Science Content and Methods Course for Elementary Education Majors

    NASA Astrophysics Data System (ADS)

    Madsen, J. A.; Allen, D. E.; Donham, R. S.; Fifield, S. J.; Shipman, H. L.; Ford, D. J.; Dagher, Z. R.

    2004-12-01

    With funding from the National Science Foundation, we have designed an integrated science content and methods course for sophomore-level elementary teacher education (ETE) majors. This course, the Science Semester, is a 15-credit sequence that consists of three science content courses (Earth, Life, and Physical Science) and a science teaching methods course. The goal of this integrated science and education methods curriculum is to foster holistic understandings of science and pedagogy that future elementary teachers need to effectively use inquiry-based approaches in teaching science in their classrooms. During the Science Semester, traditional subject matter boundaries are crossed to stress shared themes that teachers must understand to teach standards-based elementary science. Exemplary approaches that support both learning science and learning how to teach science are used. In the science courses, students work collaboratively on multidisciplinary problem-based learning (PBL) activities that place science concepts in authentic contexts and build learning skills. In the methods course, students critically explore the theory and practice of elementary science teaching, drawing on their shared experiences of inquiry learning in the science courses. An earth system science approach is ideally adapted for the integrated, inquiry-based learning that takes place during the Science Semester. The PBL investigations that are the hallmark of the Science Semester provide the backdrop through which fundamental earth system interactions can be studied. For example in the PBL investigation that focuses on energy, the carbon cycle is examined as it relates to fossil fuels. In another PBL investigation centered on kids, cancer, and the environment, the hydrologic cycle with emphasis on surface runoff and ground water contamination is studied. In a PBL investigation that has students learning about the Delaware Bay ecosystem through the story of the horseshoe crab and the biome that swirls around this remarkable arthropod, students are exposed to interactions between the hydrosphere, atmosphere, and geosphere and they examine ways in which climate change can affect this ecosystem.

  13. Diamond-modified AFM probes: from diamond nanowires to atomic force microscopy-integrated boron-doped diamond electrodes.

    PubMed

    Smirnov, Waldemar; Kriele, Armin; Hoffmann, René; Sillero, Eugenio; Hees, Jakob; Williams, Oliver A; Yang, Nianjun; Kranz, Christine; Nebel, Christoph E

    2011-06-15

    In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are suitable for probing, manipulating, sculpting, and sensing at single digit nanoscale. PMID:21534601

  14. Integrating EarthScope seismic, GPS, and other active Earth observations into informal education programs in parks and museums

    Microsoft Academic Search

    R. J. Lillie; C. Goddard; J. Braunmiller; A. M. Trehu

    2008-01-01

    EarthScope is a National Science Foundation program that uses seismic, GPS, and other geophysical devices to explore the structure and evolution of the North American continent and to understand the physical processes that cause earthquakes and volcanic eruptions. Two challenges facing the EarthScope community include providing the public with access to timely science results and presenting complex data and related

  15. Hydrogels dispersed by doped rare earth fluoride nanocrystals: ionic liquid dispersion and down/up-conversion luminescence.

    PubMed

    Yan, Zhi-Yuan; Jia, Li-Ping; Yan, Bing

    2014-01-01

    Two typical kinds of rare earth fluoride nanocrystals codoped with rare earth ions (Eu(3+) and Tm(3+)/Er(3+),Yb(3+)) are synthesized and dispersed in ionic liquid compound (1-chlorohexane-3-methylimidazolium chloride, abbreviated as [C6mim][Cl]). Assisted by agarose, the luminescent hydrogels are prepared homogeneously. The down/up-conversion luminescence of these hydrogels can be realized for the dispersed rare earth fluoride nanocrystals. The results provide a strategy to prepare luminescent (especially up-conversion luminescent) hydrogels with ionic liquid to disperse rare earth fluoride nanocrystals. PMID:24388702

  16. Integrating emerging earth science technologies into disaster risk management: an enterprise architecture approach

    NASA Astrophysics Data System (ADS)

    Evans, J. D.; Hao, W.; Chettri, S. R.

    2014-12-01

    Disaster risk management has grown to rely on earth observations, multi-source data analysis, numerical modeling, and interagency information sharing. The practice and outcomes of disaster risk management will likely undergo further change as several emerging earth science technologies come of age: mobile devices; location-based services; ubiquitous sensors; drones; small satellites; satellite direct readout; Big Data analytics; cloud computing; Web services for predictive modeling, semantic reconciliation, and collaboration; and many others. Integrating these new technologies well requires developing and adapting them to meet current needs; but also rethinking current practice to draw on new capabilities to reach additional objectives. This requires a holistic view of the disaster risk management enterprise and of the analytical or operational capabilities afforded by these technologies. One helpful tool for this assessment, the GEOSS Architecture for the Use of Remote Sensing Products in Disaster Management and Risk Assessment (Evans & Moe, 2013), considers all phases of the disaster risk management lifecycle for a comprehensive set of natural hazard types, and outlines common clusters of activities and their use of information and computation resources. We are using these architectural views, together with insights from current practice, to highlight effective, interrelated roles for emerging earth science technologies in disaster risk management. These roles may be helpful in creating roadmaps for research and development investment at national and international levels.

  17. Luminescence properties of SrSi 2O 2N 2 doped with divalent rare earth ions

    Microsoft Academic Search

    Volker Bachmann; Thomas Jüstel; Andries Meijerink; Cees Ronda; Peter J. Schmidt

    2006-01-01

    The optical properties of SrSi2O2N2 doped with divalent Eu2+ and Yb2+ are investigated. The Eu2+ doped material shows efficient green emission peaking at around 540nm that is consistent with 4f7?4f65d transitions of Eu2+. Due to the high quantum yield (90%) and high quenching temperature (>500K) of luminescence, SrSi2O2N2:Eu2+ is a promising material for application in phosphor conversion LEDs. The Yb2+

  18. Earth science information: Planning for the integration and use of global change information

    NASA Technical Reports Server (NTRS)

    Lousma, Jack R.

    1992-01-01

    Activities and accomplishments of the first six months of the Consortium for International Earth Science Information Network (CIESIN's) 1992 technical program have focused on four main missions: (1) the development and implementation of plans for initiation of the Socioeconomic Data and Applications Center (SEDAC) as part of the EOSDIS Program; (2) the pursuit and development of a broad-based global change information cooperative by providing systems analysis and integration between natural science and social science data bases held by numerous federal agencies and other sources; (3) the fostering of scientific research into the human dimensions of global change and providing integration between natural science and social science data and information; and (4) the serving of CIESIN as a gateway for global change data and information distribution through development of the Global Change Research Information Office and other comprehensive knowledge sharing systems.

  19. Improving reservoir operations modeling for integration in a regional Earth system model

    NASA Astrophysics Data System (ADS)

    Voisin, N.; Li, H.; Ward, D. L.; Huang, M.; Leung, L.; Wigmosta, M. S.

    2012-12-01

    In integrated Earth system models (EaSMs), accurate hydrologic information in all of its components including socio-economy, atmosphere, land, and energy infrastructure is needed to represent the interactions between human and Earth system processes. The hydrology processes regulate the water, energy and carbon fluxes in this integrated framework. Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of EaSMs in hydrologic and climate predictions, as well as impact studies such as integrated assessment activities at regional to global scales. Dynamic programming approaches to optimize operations of reservoir systems have been widely used for water resources management planning at local and regional scales and recently have emerged in global-scale applications; albeit they are performed offline from the EaSMs , and require accurate knowledge of future flow for the upcoming water year. Other emerging large-scale research reservoir models use generic operating rules that are more flexible for coupling with EaSMs. Those generic operating rules have been successful in reproducing overall regulated flow at large basin scales. Improved generic operating rules are presented and evaluated across multiple spatial scales and objectives (flow but also storage and supply) over the complex multi-objective Columbia River Regulation System, which is representative of large river systems with increasing competitive reservoir purposes in the future. Challenges due to the difference in time and spatial scales between the physical processes versus reservoir operations and targets (irrigation, flood control, hydropower, environmental flow, navigation) are then discussed in the context of improving hydrology and evapotranspiration fluxes within an integrated EaSM.

  20. Earth Science Research Discovery, Integration, 3D Visualization and Analysis using NASA World Wind

    NASA Astrophysics Data System (ADS)

    Alameh, N.; Hogan, P.

    2008-12-01

    NASA plays a leadership role in the world of Advanced Information Technologies. Part of our mission is to leverage those technologies to increase the usability of the growing amount of earth observation produced by the science community. NASA World Wind open source technology provides a complete 3D visualization platform that is being continually advanced by NASA, its partners and the open source community. The technology makes scientific data and observations more accessible to Earth scientists and offers them a standards-based extensible platform to manipulate and analyze that data. The API-centric architecture of World Wind's SDK allows others to readily extend or embed this technology (including in web pages). Such multiple approaches to using the technology accelerate opportunities for the research community to provide "advances in fundamental understanding of the Earth system and increased application of this understanding to serve the nation and the people of the world" (NRC Decadal Survey). The opportunities to advance this NASA Open Source Agreement (NOSA) technology by leveraging advances in web services, interoperability, data discovery mechanisms, and Sensor Web are unencumbered by proprietary constraints and therefore provide the basis for an evolving platform that can reliably service the needs of the Earth Science, Sensor Web and GEOSS communities. The ability for these communities to not only use this technology in an unrestricted manner but to also participate in advancing it leads to accelerated innovation and maximum exchange of information. 3 characteristics enable World Wind to push the frontier in Advanced Information Systems: 1- World Wind provides a unifying information browser to enable a variety of 3D geospatial applications. World Wind consists of a coherent suite of modular components to be used selectively or in concert with any number of programs. 2- World Wind technology can be embedded as part of any application and hence makes it more possible to include virtual globe capability in support of any Earth science objective. 3- With the source code being fully accessible, anyone can advance this technology (including in a commercial or other proprietary manner). Such features enable World Wind to provide easy discovery, access and 3D integration/visualization/analysis of Earth observation data in a flexible, customizable open source tool. This positions World Wind to become a key part of an Advanced Information Systems infrastructure supporting a collaborative decision-making environment for a variety of applications.

  1. Towards a comprehensive model of Earth's disk-integrated Stokes vector

    NASA Astrophysics Data System (ADS)

    García Muñoz, A.

    2015-07-01

    A significant body of work on simulating the remote appearance of Earth-like exoplanets has been done over the last decade. The research is driven by the prospect of characterizing habitable planets beyond the Solar System in the near future. In this work, I present a method to produce the disk-integrated signature of planets that are described in their three-dimensional complexity, i.e. with both horizontal and vertical variations in the optical properties of their envelopes. The approach is based on Pre-conditioned Backward Monte Carlo integration of the vector Radiative Transport Equation and yields the full Stokes vector for outgoing reflected radiation. The method is demonstrated through selected examples inspired by published work at wavelengths from the visible to the near infrared and terrestrial prescriptions of both cloud and surface albedo maps. I explore the performance of the method in terms of computational time and accuracy. A clear strength of this approach is that its computational cost does not appear to be significantly affected by non-uniformities in the planet optical properties. Earth's simulated appearance is strongly dependent on wavelength; both brightness and polarization undergo diurnal variations arising from changes in the planet cover, but polarization yields a better insight into variations with phase angle. There is partial cancellation of the polarized signal from the northern and southern hemispheres so that the outgoing polarization vector lies preferentially either in the plane parallel or perpendicular to the planet scattering plane, also for non-uniform cloud and albedo properties and various levels of absorption within the atmosphere. The evaluation of circular polarization is challenging; a number of one-photon experiments of 109 or more is needed to resolve hemispherically integrated degrees of circular polarization of a few times 10-5. Last, I introduce brightness curves of Earth obtained with one of the Messenger cameras at three wavelengths (0.48, 0.56 and 0.63 ?m) during a flyby in 2005. The light curves show distinct structure associated with the varying aspect of the Earth's visible disk (phases of 98-107°) as the planet undergoes a full 24 h rotation; the structure is reasonably well reproduced with model simulations.

  2. Dynamics of global vegetation biomass simulated by the integrated Earth System Model

    NASA Astrophysics Data System (ADS)

    Mao, J.; Shi, X.; Di Vittorio, A. V.; Thornton, P. E.; Piao, S.; Yang, X.; Truesdale, J. E.; Bond-Lamberty, B. P.; Chini, L. P.; Thomson, A. M.; Hurtt, G. C.; Collins, W.; Edmonds, J.

    2014-12-01

    The global vegetation biomass stores huge amounts of carbon and is thus important to the global carbon budget (Pan et al., 2010). For the past few decades, different observation-based estimates and modeling of biomass in the above- and below-ground vegetation compartments have been comprehensively conducted (Saatchi et al., 2011; Baccini et al., 2012). However, uncertainties still exist, in particular for the simulation of biomass magnitude, tendency, and the response of biomass to climatic conditions and natural and human disturbances. The recently successful coupling of the integrated Earth System Model (iESM) (Di Vittorio et al., 2014; Bond-Lamberty et al., 2014), which links the Global Change Assessment Model (GCAM), Global Land-use Model (GLM), and Community Earth System Model (CESM), offers a great opportunity to understand the biomass-related dynamics in a fully-coupled natural and human modeling system. In this study, we focus on the systematic analysis and evaluation of the iESM simulated historical (1850-2005) and future (2006-2100) biomass changes and the response of the biomass dynamics to various impact factors, in particular the human-induced Land Use/Land Cover Change (LULCC). By analyzing the iESM simulations with and without the interactive LULCC feedbacks, we further study how and where the climate feedbacks affect socioeconomic decisions and LULCC, such as to alter vegetation carbon storage. References Pan Y et. al: A large and persistent carbon sink in the World's forests. Science 2011, 333:988-993. Saatchi SS et al: Benchmark map of forest carbon stocks in tropical regions across three continents. Proc Natl Acad Sci 2011, 108:9899-9904. Baccini A et al: Estimated carbon dioxide emissions from tropical deforestation improved by carbon-density maps. Nature Clim Change 2012, 2:182-185. Di Vittorio AV et al: From land use to land cover: restoring the afforestation signal in a coupled integrated assessment-earth system model and the implications for CMIP5 RCP simulations. Biogeosciences Discuss 2014, 11:7151-7188. Bond-Lamberty, B et al: Coupling earth system and integrated assessment models: The problem of steady state. Geosci. Model Dev. Discuss 2014, 7: 1499-1524, doi:10.5194/gmdd-7-1499-2014.

  3. Comparing morphologies of drainage basins on Mars and Earth using integral-geometry and neural maps

    NASA Technical Reports Server (NTRS)

    Stepinski, T. F.; Coradetti, S.

    2004-01-01

    We compare morphologies of drainage basins on Mars and Earth in order to confine the formation process of Martian valley networks. Basins on both planets are computationally extracted from digital topography. Integral-geometry methods are used to represent each basin by a circularity function that encapsulates its internal structure. The shape of such a function is an indicator of the style of fluvial erosion. We use the self-organizing map technique to construct a similarity graph for all basins. The graph reveals systematic differences between morphologies of basins on the two planets. This dichotomy indicates that terrestrial and Martian surfaces were eroded differently. We argue that morphologies of Martian basins are incompatible with runoff from sustained, homogeneous rainfall. Fluvial environments compatible with observed morphologies are discussed. We also construct a similarity graph based on the comparison of basins hypsometric curves to demonstrate that hypsometry is incapable of discriminating between terrestrial and Martian basins. INDEX TERMS: 1824 Hydrology: Geomorphology (1625); 1886 Hydrology: Weathering (1625); 5415 Planetology: Solid Surface Planets: Erosion and weathering; 6225 Planetology: Solar System Objects Mars. Citation: Stepinski, T. F., and S. Coradetti (2004), Comparing morphologies of drainage basins on Mars and Earth using integral-ge

  4. Integration of Google Maps/Earth with microscale meteorology models and data visualization

    NASA Astrophysics Data System (ADS)

    Wang, Yansen; Huynh, Giap; Williamson, Chatt

    2013-12-01

    The Google Maps/Earth GIS has been integrated with a microscale meteorological model to improve the system's functionality and ease of use. Almost all the components of the model system, including the terrain data processing, morphological data generation, meteorological data gathering and initialization, and displaying/visualizing the model results, have been improved by using this approach. Different from the traditional stand-along model system, this novel system takes advantages of enormous resources in map and image data retrieving/handling, four-dimensional (space and time) data visualization, overlaying, and many other advanced GIS features that the Google Maps/Earth platform has to offer. We have developed modular components for all of the model system controls and data processing programs which are glued together with the JavaScript language and KML/XML data. We have also developed small modular software using the Google application program interface to convert the model results and intermediate data for visualizations and animations. Capabilities such as high-resolution image, street view, and 3D buildings in the Google Earth/Map are also used to quickly generate small-scale vegetation and building morphology data that are required for the microscale meteorological models. This system has also been applied to visualize the data from other instruments such as Doppler wind lidars. Because of the tight integration of the internet based GIS and a microscale meteorology model, the model system is more versatile, intuitive, and user-friendly than a stand-along system we had developed before. This kind of system will enhance the user experience and also help researchers to explore new phenomena in fine-scale meteorology.

  5. Absolute light yield measurements on SrF$_{2}$ and BaF$_{2}$ doped with rare earth ions

    E-print Network

    Shendrik, Roman

    2013-01-01

    Results of absolute light output measurements on strontium and barium fluoride doped with PrF$_3$ and CeF$_3$ are presented and compared with scintillators having well-known light output (NaI-Tl, CsI-Tl, BGO). For pure SrF$_2$ crystal we obtain a value of about 28600 photons/MeV.

  6. Absolute light yield measurements on SrF$_{2}$ and BaF$_{2}$ doped with rare earth ions

    E-print Network

    Roman Shendrik; Evgeny Radzhabov

    2013-08-19

    Results of absolute light output measurements on strontium and barium fluoride doped with PrF$_3$ and CeF$_3$ are presented and compared with scintillators having well-known light output (NaI-Tl, CsI-Tl, BGO). For pure SrF$_2$ crystal we obtain a value of about 28600 photons/MeV.

  7. Path Integral Hybrid Monte Carlo Study on Structure of Small Helium-4 Clusters Doped with a Linear Molecule

    NASA Astrophysics Data System (ADS)

    Miura, Shinichi

    2007-09-01

    Microscopic structure of small helium-4 clusters doped with a carbonyl sulfide molecule, OCS(4He) N , at 0.37 K is studied by the path integral hybrid Monte Carlo method; the size of the cluster N ranges from N=2 to N=5. In all the cases examined in the present study, the helium atoms are localized around the carbon atom of the OCS molecule, forming a doughnut-type structure around the molecular axis. Bosonic exchange among the helium atoms is found to be promoted in the doughnut region, showing an anisotropic “superfluid” response of the clusters.

  8. Charge Compensation in RE3+ (RE = Eu, Gd) and M+ (M = Li, Na, K) Co-Doped Alkaline Earth Nanofluorides Obtained by Microwave Reaction with Reactive Ionic Liquids Leading to Improved Optical Properties

    SciTech Connect

    Lorbeer, C [Ruhr-Universitat Bochum; Behrends, F [Westfalische Wilhelsm-Universitat Munster; Cybinska, J [Ruhr Universitat Bochum; Eckert, H [Westfalische Wilhelsm-Universitat Munster; Mudring, Anja -V [Ames Laboratory

    2014-01-01

    Alkaline earth fluorides are extraordinarily promising host matrices for phosphor materials with regard to rare earth doping. In particular, quantum cutting materials, which might considerably enhance the efficiency of mercury-free fluorescent lamps or SC solar cells, are often based on rare earth containing crystalline fluorides such as NaGdF4, GdF3 or LaF3. Substituting most of the precious rare earth ions and simultaneously retaining the efficiency of the phosphor is a major goal. Alkaline earth fluoride nanoparticles doped with trivalent lanthanide ions (which are required for the quantum cutting phenomenon) were prepared via a microwave assisted method in ionic liquids. As doping trivalent ions into a host with divalent cations requires charge compensation, this effect was thoroughly studied by powder X-ray and electron diffraction, luminescence spectroscopy and 23Na, 139La and 19F solid state NMR spectroscopy. Monovalent alkali ions were codoped with the trivalent lanthanide ions to relieve stress and achieve a better crystallinity and higher quantum cutting abilities of the prepared material. 19F-magic angle spinning (MAS)-NMR-spectra, assisted by 19F{23Na} rotational echo double resonance (REDOR) studies, reveal distinct local fluoride environments, the populations of which are discussed in relation to spatial distribution and clustering models. In the co-doped samples, fluoride species having both Na+ and La3+ ions within their coordination sphere can be identified and quantified. This interplay of mono- and trivalent ions in the CaF2 lattice appears to be an efficient charge compensation mechanism that allows for improved performance characteristics of such co-doped phosphor materials.

  9. Refluxing synthesis, photoluminescence and binding ability to deoxyribonucleic acid of water-soluble rare earth ion-doped LaF3 nanoparticles.

    PubMed

    Wang, Zhenling; Zhang, Yi; Li, Chunyang; Zhang, Xinlei; Chang, Jiazhong; Xie, Jianping; Li, Chengwei

    2014-06-01

    Water-soluble rare earth ion (Ce3+, Tb3+)-doped LaF3 nanoparticles with the ability to bind to deoxyribonucleic acid (DNA) were prepared by the refluxing method in a glycerol/water mixture and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and so on. The obtained LaF3:Ce3+, LaF3:Tb3+ and LaF3:Ce3+, Tb3+ nanoparticles are well crystallized with a hexagonal structure and composed of spherical particles with an average size from 11 to 19 nm. The as-prepared samples can be dispersed into water to form a colloidal solution. Under ultraviolet (UV) light irradiation, the emission lines of Tb3+ in the co-doped LaF3:Ce3+, Tb3+ are evidently strengthened compared to those in the single-doped LaF3:Tb3+ nanoparticles, which is due to the energy transfer from Ce3+ to Tb3+ ions in the LaF3:Ce3+, Tb3+ samples. The biological experiment confirms that the water-soluble LaF3:Ce3+, Tb3+ nanoparticles can be bonded to the DNA molecules and emit visible light under UV irradiation. These luminescent nanoparticles could be used similarly to ethidium bromide (EtBr), which has been used extensively as a DNA staining reagent. The advantage that LaF3:Ce3+, Tb3+ nanoparticles have lower toxicity than EtBr makes them a potential reagent instead of EtBr in the DNA staining in biological experiments. PMID:24738421

  10. Emission sensitization and mechanisms of electron-excitation migration in structures based on III-nitrides doped with rare-earth elements (Eu, Er, Sm)

    SciTech Connect

    Mezdrogina, M. M., E-mail: margaret.m@mail.ioffe.ru; Danilovsky, E. Yu.; Kuzmin, R. V. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

    2010-03-15

    The effect of doping with Eu, Er, and Sm rare-earth ions on the shape of the luminescence spectrum for heterostructures with GaN/In{sub x}Ga{sub 1-x}N (0.1 < x < 0.4) quantum wells and from p-GaN/n-GaN and p-AlGaN/n-GaN junctions is investigated. The results of measurements of the electroluminescence of these structures correlate with the previous data on photoluminescence and Moessbauer spectroscopy. It is shown that it is the GaN 'yellow' (5000-6000 A) band that plays the important role in the excitation of intracenter states in the structures with several GaN/InGaN quantum wells doped with Eu and Sm. In this case, Eu is most likely the sensitizer for Sm. Additional introduction of 3d metal (Fe{sup 57}) in p-GaN/n-GaN:Eu results in the realization of intracenter transitions in Eu{sup 3+}: {sup 5}D{sub 0} {sup {yields} 7}F{sub 1} (6006 A), {sup 5}D{sub 0} {sup {yields} 7}F{sub 2} (6195 A), {sup 5}D{sub 0} {sup {yields} 7}F{sub 3} (6627 A), and {sup 5}D{sub 1} {sup {yields} 7}F{sub 4} (6327 A) due to the occurrence of new, efficient channels of excitation transfer to intracenter states and in the effect of Fe on the local environment of rare-earth ions including due to the f-d hybridization enhancement.

  11. Self-Guided Field Explorations: Integrating Earth Science into Students' Lives

    NASA Astrophysics Data System (ADS)

    Kirkby, K. C.; Kirkby, S.

    2013-12-01

    Self-guided field explorations are a simple way to transform an earth science class into a more pedagogically effective experience. Previous experience demonstrated that self-guided student explorations of museum and aquarium exhibits were both extremely popular and remarkably effective. That success led our program to test an expansion of the concept to include self-guided student explorations in outdoor field settings. Preliminary assessment indicates these self-guided field explorations are nearly as popular with students as the museum and aquarium explorations and are as pedagogically effective. Student gains on post-instruction assessment match or exceed those seen in instructor-assisted, hands-on, small group laboratory activities and completely eclipse gains achieved by traditional lecture instruction. As importantly, self-guided field explorations provide a way to integrate field experiences into large enrollment courses where the sheer scale of class trips makes them logistically impossible. This expands course breadth, integrating new topics that could not be as effectively covered by the original class structure. Our introductory program assessed two models of self-guided field explorations. A walking/cycling exploration of the Saint Anthony Falls area, a mile from campus, focuses on the intersections of geological processes with human history. Students explore the geology behind the waterfalls' evolution as well as its subsequent social and economic impacts on human history. A second exploration focuses on the campus area geology, including its building stones as well as its landscape evolution. In both explorations, the goal was to integrate geology with the students' broader understanding of the world they live in. Although the explorations' creation requires a significant commitment, once developed, self-guided explorations are surprisingly low maintenance. These explorations provide a model of a simple, highly effective pedagogical tool that is easily adapted to almost any campus setting. A number of factors contribute to self-guided explorations' success. For most students, these are novel, particularly memorable experiences. Interactive in nature, self-guided explorations are also relaxed, self-paced instruction without the pressures that can dominate other educational settings. Well designed explorations build on students' prior knowledge, allowing them to integrate new earth science concepts with familiar ideas and settings. By creating connections between geology and human society, these explorations also make earth science more relevant to students who had not previously considered their world from a geological perspective. By their very nature, explorations are place-centered education which helps ground instruction and makes it more relevant to students without strong science backgrounds. Further these explorations give students control over, and responsibility for, their own learning, which is always a pedagogically sound approach. Finally, self-guided explorations can integrate earth science education into students' social lives as most students choose to complete the explorations in groups, often with friends and family who are not enrolled in the course.

  12. Homogeneous line width of rare-earth-doped glasses for levels in a Stark level ladder: A new simple rule

    Microsoft Academic Search

    F. Auzel; R. Balda; J. Fernandez

    2007-01-01

    Concentrating on higher Stark states in multiplet ladders of lanthanide-doped glasses, we show that at 10K, the homogeneous widths along Stark ladders vary quasi-linearly with the energy position in the ladder.Assuming that the mechanisms creating the homogeneous widths are first-order processes, either direct processes or two-phonon non-radiative transitions, the observed behavior is simply explained by the fact that energy separations

  13. Integration of external metadata into the Earth System Grid Federation (ESGF)

    NASA Astrophysics Data System (ADS)

    Berger, Katharina; Levavasseur, Guillaume; Stockhause, Martina; Lautenschlager, Michael

    2015-04-01

    International projects with high volume data usually disseminate their data in a federated data infrastructure, e.g.~the Earth System Grid Federation (ESGF). The ESGF aims to make the geographically distributed data seamlessly discoverable and accessible. Additional data-related information is currently collected and stored in separate repositories by each data provider. This scattered and useful information is not or only partly available for ESGF users. Examples for such additional information systems are ES-DOC/metafor for model and simulation information, IPSL's versioning information, CHARMe for user annotations, DKRZ's quality information and data citation information. The ESGF Quality Control working team (esgf-qcwt) aims to integrate these valuable pieces of additional information into the ESGF in order to make them available to users and data archive managers by (i) integrating external information into ESGF portal, (ii) integrating links to external information objects into the ESGF metadata index, e.g. by the use of PIDs (Persistent IDentifiers), and (iii) automating the collection of external information during the ESGF data publication process. For the sixth phase of CMIP (Coupled Model Intercomparison Project), the ESGF metadata index is to be enriched by additional information on data citation, file version, etc. This information will support users directly and can be automatically exploited by higher level services (human and machine readability).

  14. Release of AGAP Aerogeophysical Data through the Integrated Earth Data Applications Facility

    NASA Astrophysics Data System (ADS)

    O'hara, S. H.; Abdi, A.; Bonczkowski, J.; Bell, R. E.; Frearson, N.; Ferraccioli, F.; Corr, H.; Jordan, T. A.; Rose, K. C.; Studinger, M.; Gogineni, P. S.; Braaten, D. A.; Damaske, D.

    2011-12-01

    During the International Polar Year 2007 - 2009, scientists from six nations collaborated on a multi-disciplinary investigation of the Gamburtsevs, the least explored mountain range on Earth buried beneath the East Antarctic Ice Sheet, as part of the Antarctic Gamburtsev Province (AGAP) project. The AGAP project collected more than 120,000 line km of new aerogeophysical data using two Twin Otter aircraft. Data included ice penetrating radar, magnetometer, gravimeter and laser altimeter measurements. The main AGAP survey grid included north-south lines spaced 5 km apart, with crossing lines every 33 km and transects over the Vostok Subglacial Highlands, South Pole and southern Recovery lakes region. 150-MHz ice penetrating radars with bandwidths of 15 to 20 MHz measured ice thickness, bedrock topography, sub-ice hydrology, and produced high-resolution images of the internal structure of the East Antarctic Ice Sheet. Magnetic data map geologic structures across the mountain range, while gravity data provide new insights into the tectonic evolution and crustal thickness of the region. A swath-scanning laser altimeter with a spatial resolution of 2 meters measured elevation and details of the ice surface. Complete AGAP datasets are now in the process of becoming publicly available and freely accessible through the Java-based data visualization tool GeoMapApp (http://www.geomapapp.org), and the Antarctic & Southern Ocean Data Portal (http://www.marine-geo.org/tools/search/entry.php?id=AGAP_GAMBIT), both part of the Integrated Earth Data Applications (IEDA) Data Facility (http://www.iedadata.org) based at the Lamont-Doherty Earth Observatory of Columbia University. AGAP data will also be accessible through the Natural Environment Research Council (NERC) Polar Data Center, based at the British Antarctic Survey (http://www.antarctica.ac.uk/bas_research/data/index.php) and at the Center for the Remote Sensing of Ice Sheets (https://www.cresis.ku.edu/research/gambit).

  15. Integrated magnetometer-horizon sensor low-earth orbit determination using UKF

    NASA Astrophysics Data System (ADS)

    Farahanifar, Mohammad; Assadian, Nima

    2015-01-01

    The estimation of the satellite orbital elements using the integrated magnetometer and horizon sensors data has been investigated in this study. These sensors are generally employed for attitude estimation. The magnetometer and the horizon sensor measure the Earth's magnetic field as well as the Earth's center direction in the body frame, respectively. The magnitude of the magnetic field and the angle between two vectors have been used for orbit estimation purpose. This excludes the knowledge of the attitude in the orbit determination. The Gaussian variation of parameters equations is used for the orbital motion dynamical model to have the orbital elements as the states of the system. Since the dynamics of the system and the measurement model are nonlinear, the unscented Kalman filter (UKF) is utilized. Moreover, the magnetometer is subjected to scale factor and bias errors and these parameters are also estimated together with the orbital elements. It has been revealed that the UKF-based orbit determination algorithm can determine the sensor error parameters as well as the Keplerian orbital elements. The sensitivity analysis results show that this approach is insensitive to inclination and eccentricity for most orbits and can be adopted for near equatorial as well as near circular orbits.

  16. Spherical-earth Gravity and Magnetic Anomaly Modeling by Gauss-legendre Quadrature Integration

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J. (principal investigators)

    1981-01-01

    The anomalous potential of gravity and magnetic fields and their spatial derivatives on a spherical Earth for an arbitrary body represented by an equivalent point source distribution of gravity poles or magnetic dipoles were calculated. The distribution of equivalent point sources was determined directly from the coordinate limits of the source volume. Variable integration limits for an arbitrarily shaped body are derived from interpolation of points which approximate the body's surface envelope. The versatility of the method is enhanced by the ability to treat physical property variations within the source volume and to consider variable magnetic fields over the source and observation surface. A number of examples verify and illustrate the capabilities of the technique, including preliminary modeling of potential field signatures for Mississippi embayment crustal structure at satellite elevations.

  17. Magnetoelectric emission in rare-earth doped ferroelectric crystals La2Ti2O7:R3+ ( R=Er , Eu, and Nd)

    NASA Astrophysics Data System (ADS)

    Shimada, Y.; Kiyama, H.; Tokura, Y.

    2007-06-01

    The optical magnetoelectric (OME) effect, i.e., the change of optical response on the reversal of light propagation vector (k) , has been investigated for the emission of rare earth R3+ ion ( R=Nd , Eu, Er) doped in a ferroelectric La2Ti2O7 single crystal under magnetic field (H) . The symmetry condition for the appearance of the OME effect for H?k was confirmed by varying the relative angle between the electric polarization and magnetic field. Another tensor component of the second-order magnetolectric tensor ?ijk for H?k , i.e., the magnetochiral effect, is allowed in the Faraday configuration but found to be small compared with the OME effect in the Voigt configuration. The importance of the spin-orbit coupling, the magnetic dipole transition, and the noncentrosymmetric crystal structure is discussed as the origin of the OME effect on the basis of the observed signal magnitude depending on the species of the rare-earth ion and its optical transition moment.

  18. DECADE web portal: toward the integration of MaGa, EarthChem and VOTW data systems to further the knowledge on Earth degassing

    NASA Astrophysics Data System (ADS)

    Cardellini, Carlo; Frigeri, Alessandro; Lehnert, Kerstin; Ash, Jason; McCormick, Brendan; Chiodini, Giovanni; Fischer, Tobias; Cottrell, Elizabeth

    2015-04-01

    The release of volatiles from the Earth's interior takes place in both volcanic and non-volcanic areas of the planet. The comprehension of such complex process and the improvement of the current estimates of global carbon emissions, will greatly benefit from the integration of geochemical, petrological and volcanological data. At present, major online data repositories relevant to studies of degassing are not linked and interoperable. In the framework of the Deep Earth Carbon Degassing (DECADE) initiative of the Deep Carbon Observatory (DCO), we are developing interoperability between three data systems that will make their data accessible via the DECADE portal: (1) the Smithsonian Institutionian's Global Volcanism Program database (VOTW) of volcanic activity data, (2) EarthChem databases for geochemical and geochronological data of rocks and melt inclusions, and (3) the MaGa database (Mapping Gas emissions) which contains compositional and flux data of gases released at volcanic and non-volcanic degassing sites. The DECADE web portal will create a powerful search engine of these databases from a single entry point and will return comprehensive multi-component datasets. A user will be able, for example, to obtain data relating to compositions of emitted gases, compositions and age of the erupted products and coincident activity, of a specific volcano. This level of capability requires a complete synergy between the databases, including availability of standard-based web services (WMS, WFS) at all data systems. Data and metadata can thus be extracted from each system without interfering with each database's local schema or being replicated to achieve integration at the DECADE web portal. The DECADE portal will enable new synoptic perspectives on the Earth degassing process allowing to explore Earth degassing related datasets over previously unexplored spatial or temporal ranges.

  19. The SISMA prototype system: integrating Geophysical Modeling and Earth Observation for time dependent seismic hazard assessment

    NASA Astrophysics Data System (ADS)

    Peresan, A.; Panza, G. F.; Sabadini, R.; Barzaghi, R.; Amodio, A.; Bianco, G.

    2009-12-01

    A new approach to seismic hazard assessment is illustrated that, based on the available knowledge of the physical properties of the Earth structure and of seismic sources, as well as on the geophysical forward modeling, allows for a time dependent definition of the seismic input. According to the proposed approach, a fully formalized system integrating Earth Observation data and new advanced methods in seismological and geophysical data analysis, is currently under development in the framework of the Pilot Project SISMA, funded by the Italian Space Agency (ASI). The synergic use of geodetic Earth Observation data (EO) and Geophysical Forward Modeling (GFM) deformation maps at the national scale complements the space and time dependent information provided by real-time monitoring of seismic flow (performed by means of the earthquake prediction algorithms CN and M8S), so as to permit the identification and routine updating of alerted areas. At the small spatial scale (tens of km) of the seismogenic nodes identified by pattern recognition analysis, both GNSS (Global Navigation Satellite System) and SAR (Synthetic Aperture Radar) techniques, coupled with expressly developed models for inter-seismic phases, allow us to retrieve the deformation style and stress evolution within the seismogenic areas. The displacements fields obtained from EO data provide the input for the geophysical modeling, which permits to indicate whether a specific fault is in a "critical state". The scenarios of expected ground motion, associated with the alerted areas are then defined by means of full waveforms modeling, based on the possibility to compute synthetic seismograms by the modal summation technique. In this way a set of deterministic scenarios of ground motion, which refers to the time interval when a strong event is likely to occur within the alerted area, can be defined either at national and local scale. The considered integrated approach opens new routes in understanding the dynamics of fault zones as well as in modeling the expected ground motion. The SISMA system, in fact, provides tools for establishing warning criteria based on deterministic and rigorous forward geophysical models and hence allows for a well controlled real-time testing and validation of the proposed methodology over the Italian territory. The proposed approach complements the traditional probabilistic approach to seismic hazard estimates, since it supplies routinely updated information that can be useful in assigning priorities for timely mitigation actions and hence it is particularly relevant for Civil Defence purposes.

  20. Svalbard Integrated Arctic Earth Observing System - A New Coordinated Foundation for Environmental Services in and around Svalbard

    NASA Astrophysics Data System (ADS)

    Lilja Bye, Bente

    2015-04-01

    Svalbard Integrated Earth Observing System (SIOS) is an international infrastructure project. There were 28 partners from Europe and Asia involved in the preparatory phase of this ESFRI project. The essential objectives are to establish a mechanism for integration among the existing research institutions in Svalbard to create a joint state-of-the-art observing system in Earth System Science, and better coordinated services for the International Research community with respect to access, data and knowledge management, logistics and training. In addition to the SIOS members various data services, SIOS itself will provide a few new services such as processed satellite data (from Copernicus' Sentinels as well as others) and combined in-situ and satellite data. All in all SIOS represent a new capacity and foundation for more Earth System Science, including climate and environment, data services in and around Svalbard. A presentation of SIOS including time schedule for implementation of the basic services will be given.

  1. On the hot-electron energy distribution in the electroluminescence of rare-earth-doped zinc chalcogenides

    Microsoft Academic Search

    F. J. Bryant; W. E. Hagston; A. Krier

    1986-01-01

    It is argued that the very large variation in the electroluminescence emission intensities from a given type of rare-earth ion indicates a hot-electron energy distribution in which the probability of finding an electron of energy E has an exponential dependence on E. Means of ascertaining the precise nature of this energy dependence are briefly described.

  2. Lifting from Earth Marshall is NASA's designated developer and integrator of launch systems. The Center has the engineering capabilities

    E-print Network

    Waliser, Duane E.

    Lifting from Earth Marshall is NASA's designated developer and integrator of launch systems and innovative scientific discoveries of our time. The deep space images from the Hubble Space Telescope for testing large telescope mirrors in a space-simulated environment. Teams at Marshall manage NASA's programs

  3. Double Rare-Earth Oxides Co-doped Strontium Zirconate as a New Thermal Barrier Coating Material

    NASA Astrophysics Data System (ADS)

    Ma, Wen; Wang, Dongxing; Dong, Hongying; Lun, Wenshan; He, Weiyan; Zheng, Xuebin

    2013-03-01

    Y2O3 and Yb2O3 co-doped strontium zirconate with chemistry of Sr(Zr0.9Y0.05Yb0.05)O2.95 (SZYY) was synthesized and had a minor second phase of Yb2O3. The SZYY showed good phase stability not only from room temperature to 1400 °C but also at high temperature of 1450 °C for a long period, analyzed by thermogravimetry-differential scanning calorimetry and x-ray diffraction, respectively. The coefficients of thermal expansion (CTEs) of the sintered bulk SZYY were recorded by a high-temperature dilatometer and revealed a positive influence on phase transitions of SrZrO3 by co-doping with Y2O3 and Yb2O3. The thermal conductivities of SZYY were at least ~30% lower in contrast to that of SrZrO3 and 8YSZ in the whole tested temperature range. Good chemical compatibility was observed for SZYY with 8YSZ or Al2O3 powders after a 24 h heat treatment at 1250 °C. The phase stability and the microstructure evolution of the as-sprayed SZYY coating during annealing at 1400 °C were also investigated.

  4. As-grown color centers and radiation damage in Ce3+ -doped dense rare-earth orthoaluminate scintillators

    NASA Astrophysics Data System (ADS)

    Petrosyan, Ashot G.; Shirinyan, Grigoriy O.; Ovanesyan, Karine L.; Butaeva, Tat'yana I.; Pedrini, Christian; Dujardin, Christophe; Belsky, Andrey

    1999-12-01

    Optical transmission and scintillation light yields were measured in Ce3+-doped LuAlO3 and (LuY)AlO3 solid solution single crystals grown by the vertical Bridgman and Czochralski processes. Depending on the growth history, the crystals exhibit dissimilar transmission properties in the UV range. The as-grown color centers possibly responsible for poor transmission properties in the range of Ce3+ emission were characterized by exposing non-activated crystals to 1 Mrad of 60Co gamma-rays. Radiation induced absorption in Ce3+-doped crystals is found to be higher in crystals with good initial transmission properties, while the crystals with high density of as-grown color centers are radiation hard. With time, partial slow-rate natural recovery from the damage was observed at room temperature in all studied crystals. Annealing at higher temperatures or optical bleaching contribute to recombination of gamma-ray induced color centers but affect inconsiderably the as-grown color centers.

  5. Integrating Diverse Geophysical and Geological Data to Construct MultiDimensional Earth Models: The Open Earth Framework

    Microsoft Academic Search

    C. Baru; R. Keller; B. Wallet; C. Crosby; J. Moreland; D. Nadeau

    2008-01-01

    Currently, many large geoscientific efforts (e.g., EarthScope, Continental Dynamics, and GeoSwath) have emphasized that a crucial need in advancing our understanding of the structure and evolution of the continents is high-resolution, 3-D models of lithospheric structure. In addition, the geoscience community recognizes that our ultimate goal is the addition of the dimension of time to make the problem 4-D. Adding

  6. Few-mode erbium-doped fiber amplifier design method based on the signal-pump overlap integral

    NASA Astrophysics Data System (ADS)

    Herbster, Adolfo F.; Romero, Murilo A.

    2014-09-01

    Space-division multiplexing allows an increase of link capacity by using either multicore or single-core few-mode (FM) optical fibers. In the case of FM systems, each mode carries its own data stream and long-haul transmission can be hampered by the use of conventional erbium-doped fiber amplifiers (EDFAs), since because of distinct field profile configurations, each mode experiences a different value of optical gain. The role of the FM-EDFA designer, usually done by solving rate and propagation equations, is to define both the fiber cross-section and the pumping configuration to provide the best possible mode equalization of optical gain and noise figure. An optimization method is proposed here based on the definition of a figure of merit related to the equalization of the pump-mode signal overlap integral, significantly reducing computation time and allowing a multiobjective optimization approach. The results obtained were validated against the solution provided by the full set of rate and propagation equations and we conducted an FM-EDFA optimization case study. Our double-ring Er doping profile design requires a single 180-mW LP11 pump to provide a mean gain of 21.3 dB, within 0.6 dB of equalization for each of the four modes considered.

  7. Integration of a stack of two fluorine doped silicon oxide thin films with interconnect metallization for a sub-0.35 ?m inter-metal dielectric application

    Microsoft Academic Search

    L. Baud; G. Passemard; Y. Gobil; H. M'Saad; A. Corte; F. Pires; P. Fugier; P. Noel; P. Rabinzohn; I. Beinglass

    1997-01-01

    Fluorine doped silicon oxide films were deposited on HDP-CVD system and on PECVD system to realize a stack to be integrated in metal lines' architecture. Resistance to moisture absorption of both films was investigated by film exposure in humid atmosphere for 1 week followed by an annealing. Physical properties of uncapped FSG films were measured before and after test in

  8. Integration of Earth Remote Sensing into the NOAA/NWS Damage Assessment Toolkit

    NASA Astrophysics Data System (ADS)

    Molthan, A.; Burks, J. E.; Camp, P.; McGrath, K.; Bell, J. R.

    2014-12-01

    Following the occurrence of severe weather, NOAA/NWS meteorologists are tasked with performing a storm damage survey to assess the type and severity of the weather event, primarily focused with the confirmation and assessment of tornadoes. This labor-intensive process requires meteorologists to venture into the affected area, acquire damage indicators through photos, eyewitness accounts, and other documentation, then aggregation of data in order to make a final determination of the tornado path length, width, maximum intensity, and other characteristics. Earth remote sensing from operational, polar-orbiting satellites can support the damage assessment process by helping to identify portions of damage tracks that are difficult to access due to road limitations or time constraints by applying change detection techniques. In addition, higher resolution commercial imagery can corroborate ground-based surveys by examining higher-resolution commercial imagery. As part of an ongoing collaboration, NASA and NOAA are working to integrate near real-time Earth remote sensing observations into the NOAA/NWS Damage Assessment Toolkit (DAT), a suite of applications used by meteorologists in the survey process. The DAT includes a handheld application used by meteorologists in the survey process. The team has recently developed a more streamlined approach for delivering data via a web mapping service and menu interface, allowing for caching of imagery before field deployment. Near real-time products have been developed using MODIS and VIIRS imagery and change detection for preliminary track identification, along with conduits for higher-resolution Landsat, ASTER, and commercial imagery as they become available. In addition to tornado damage assessments, the team is also investigating the use of near real-time imagery for identifying hail damage to vegetation, which also results in large swaths of damage, particularly in the central United States during the peak growing season months of June, July, and August. This presentation will present an overview of recent activities, challenges and successes, best practices, and opportunities for future work and collaboration.

  9. An integrative 'omics' solution to the detection of recombinant human erythropoietin and blood doping.

    PubMed

    Pitsiladis, Yannis P; Durussel, Jérôme; Rabin, Olivier

    2014-05-01

    Administration of recombinant human erythropoietin (rHumanEPO) improves sporting performance and hence is frequently subject to abuse by athletes, although rHumanEPO is prohibited by the WADA. Approaches to detect rHumanEPO doping have improved significantly in recent years but remain imperfect. A new transcriptomic-based longitudinal screening approach is being developed that has the potential to improve the analytical performance of current detection methods. In particular, studies are being funded by WADA to identify a 'molecular signature' of rHumanEPO doping and preliminary results are promising. In the first systematic study to be conducted, the expression of hundreds of genes were found to be altered by rHumanEPO with numerous gene transcripts being differentially expressed after the first injection and further transcripts profoundly upregulated during and subsequently downregulated up to 4 weeks postadministration of the drug; with the same transcriptomic pattern observed in all participants. The identification of a blood 'molecular signature' of rHumanEPO administration is the strongest evidence to date that gene biomarkers have the potential to substantially improve the analytical performance of current antidoping methods such as the Athlete Biological Passport for rHumanEPO detection. Given the early promise of transcriptomics, research using an 'omics'-based approach involving genomics, transcriptomics, proteomics and metabolomics should be intensified in order to achieve improved detection of rHumanEPO and other doping substances and methods difficult to detect such a recombinant human growth hormone and blood transfusions. PMID:24627340

  10. The properties of Sn9Zn lead-free solder alloys doped with trace rare earth elements

    Microsoft Academic Search

    C. M. L. Wu; D. Q. Yu; C. M. T. Law; L. Wang

    2002-01-01

    The Sn-Zn alloys have been considered as lead-free solders. It is well known that their poor properties of wetting and oxidation\\u000a resistance are the main problems to prevent them from becoming commercially viable solders. In this paper, trace rare earth\\u000a (RE) elements of mainly Ce and La have been used as alloying elements into the Sn-9Zn alloy. The results indicated

  11. Eu 3+ doped rare earth orthoborates, RBO 3 (R = Y, La and Gd), obtained by combustion synthesis

    Microsoft Academic Search

    Mika Tukia; Jorma Hölsä; Mika Lastusaari; Janne Niittykoski

    2005-01-01

    Vaterite type YBO3 and GdBO3 and aragonite type LaBO3 were prepared by the combustion. Combustion synthesis is a straightforward method to produce nanocrystalline powders requiring only a simple apparatus. The reaction was carried out by heating a mixture of rare earth nitrates, orthoboric acid and an organic fuel. For each RBO3, the ratios of starting materials were varied to obtain

  12. Eu3+ doped rare earth orthoborates, RBO3 (R = Y, La and Gd), obtained by combustion synthesis

    Microsoft Academic Search

    Mika Tukia; Jorma Hölsä; Mika Lastusaari; Janne Niittykoski

    2005-01-01

    Vaterite type YBO3 and GdBO3 and aragonite type LaBO3 were prepared by the combustion. Combustion synthesis is a straightforward method to produce nanocrystalline powders requiring only a simple apparatus. The reaction was carried out by heating a mixture of rare earth nitrates, orthoboric acid and an organic fuel. For each RBO3, the ratios of starting materials were varied to obtain

  13. Preprint of the paper "Analytical Integration Techniques for Earthing Grid Computation by Boundary

    E-print Network

    Colominas, Ignasi

    - lent resistance of grounding systems, but also distribution of potentials on the earth surface due. 08034 Barcelona, SPAIN. SUMMARY Analysis and design of substation earthing involves computing the equiva of the electrokinetic steady-state response, and neglecting the resistivity of the earthing electrode (system

  14. MEOS Microsatellite Earth Observation using Miniature Integrated-Optic IR Spectrometers

    Microsoft Academic Search

    Roman Kruzelecky

    2008-01-01

    Our planetary atmosphere helps to regulate the Earth's thermal budget and the resulting global climate by controlling the energy balance between the incident solar radiation and the thermal emission to space from the Earth's atmosphere and surface. Certain atmospheric gases, most importantly H2 O vapour and CO2 , can absorb some of the Earth's emitted IR radiation and trap it

  15. Effective Integration of the World-Wide Web in Earth Science Education.

    ERIC Educational Resources Information Center

    Herbert, Bruce; Bednarz, Sarah; Boyd, Tom; Blake, Sally; Harder, Vicki; Sutter, Marilyn

    The earth sciences is an evolving set of disciplines encompassing more than 30 specialties; however, earth scientists continue to be trained within the traditional disciplinary structure. Earth science education should focus not only on student acquisition and retention of factual knowledge, but also on the development of higher-order skills…

  16. Integrating Earth System Science Data Into Tribal College and University Curricula

    Microsoft Academic Search

    P. J. Tilgner; D. J. Perkey

    2007-01-01

    Universities Space Research Association and Sinte Gleska University (SGU) have teamed with eight Tribal Colleges and Universities (TCUs) to participate in a NASA Earth Science funded project, TRibal Earth Science and Technology Education (TRESTE) project which focuses on TCU faculty teaching undergraduate Earth science courses to non-science and science students, with particular attention to TCU faculty teaching K-12 pre- and

  17. Alkaline earth zinc borate glasses doped with Cu 2+ ions studied by EPR, optical and IR techniques

    Microsoft Academic Search

    B. Sumalatha; I. Omkaram; T. Rajavardhana Rao; Ch. Linga Raju

    2011-01-01

    Copper ions incorporated into alkaline earth zinc borate glasses 10RO+30ZnO+60B2O3 (R=Mg, Ca and Sr) and 10SrO+(30?x)ZnO+60B2O3+xCuO (x=0, 0.1, 0.3, 0.5, and 0.7wt.%) were characterized by electron paramagnetic resonance (EPR), optical absorption and FTIR techniques. The EPR spectra of all the glass samples exhibit resonance signals characteristic of Cu2+ ions. The values of spin-Hamiltonian parameters indicate that the Cu2+ ions in

  18. Enhanced 1.53-?m and lowered upconversion luminescence in Er3+-doped Ga2O3-GeO2-Bi2O3-Na2O glass by codoping rare earths

    NASA Astrophysics Data System (ADS)

    Shi, D. M.; Zhao, Y. G.; Wang, X. F.

    2011-07-01

    Spectroscopic properties and energy transfer (ET) in Ga2O3-GeO2-Bi2O3-Na2O (GGBN, glass doped with Er3+ and rare earths (RE3+; RE3+=Ce3+, Tb3+) have been investigated. Intense 1.53-?m emission with the peak emission cross-section achieved to 7.58×10-21 cm2 from Er3+-doped GGBN glass has been obtained upon excitation at 980 nm. Effects of RE3+ (RE3+=Ce3+, Tb3+) codoping on the optical properties of Er3+-doped GGBN glass have been investigated and the possible ET mechanisms involved have also been discussed. Significant enhancement of the 1.53 ?m emission intensity and decrease of upconversion (UC) fluorescence with increasing Ce3+ concentration have been observed. The incorporation of Tb3+ into Er3+-doped GGBN glass could significantly decrease the UC emission intensity, but meanwhile decrease the 1.53 ?m emission intensity due to the ET from Er3+:4I13/2 to Tb3+:7F2. The results indicate that the incorporation of Ce3+ into Er3+-doped GGBN glass can effectively improve 1.53-?m and lower UC luminescence, which makes GGBN glass more attractive for use in C-band optical fiber amplifiers.

  19. Furnace Cyclic Behavior of Plasma-Sprayed Zirconia-Yttria and Multi-Component Rare Earth Oxide Doped Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Nesbitt, James A.; McCue, Terry R.; Barrett, Charles A.; Miller, Robert A.

    2002-01-01

    Ceramic thermal barrier coatings will play an increasingly important role in advanced gas turbine engines because of their ability to enable further increases in engine temperatures. However, the coating performance and durability become a major concern under the increasingly harsh thermal cycling conditions. Advanced zirconia- and hafnia-based cluster oxide thermal barrier coatings with lower thermal conductivity and improved thermal stability are being developed using a high-heat-flux laser-rig based test approach. Although the new composition coatings were not yet optimized for cyclic durability, an initial durability screening of numerous candidate coating materials was carried out using conventional furnace cyclic tests. In this paper, furnace thermal cyclic behavior of the advanced plasma-sprayed zirconia-yttria-based thermal barrier coatings that were co-doped with multi-component rare earth oxides was investigated at 1163 C using 45 min hot cycles. The ceramic coating failure mechanisms were studied by using scanning electron microscopy combined with X-ray diffraction phase analysis after the furnace tests. The coating cyclic lifetime will be discussed in relation to coating phase structures, total dopant concentrations, and other properties.

  20. Dielectric and nonlinear current-voltage characteristics of rare-earth doped CaCu3Ti4O12 ceramics

    NASA Astrophysics Data System (ADS)

    Liu, Laijun; Fang, Liang; Huang, Yanmin; Li, Yunhua; Shi, Danping; Zheng, Shaoying; Wu, Shuangshuang; Hu, Changzheng

    2011-11-01

    CaCu3Ti4O12 (CCTO) ceramics doped with rare earth (RE) oxides, including Y2O3, La2O3, Eu2O3, and Gd2O3, were prepared by the traditional solid-state reaction method in order to investigate the effect of RE oxide dopants on the electrical properties as a varistor. The phase identification and morphology of the ceramics were investigated by x-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. A high voltage measuring unit and precision impedance analyzer were used to determine the nonohmic (J-E) behaviors and measure the dielectric properties and impedance spectroscopy of the ceramics, respectively. The results showed that RE oxides enhanced greatly the breakdown electric flied but reduced the nonlinear coefficient and the mean grain size of CCTO ceramics. There was a good linear relationship between ln J and E1/2, which demonstrated that the Schottky barrier should exist at the grain boundary. A double Schottky barrier model composed of a depletion layer and a negative charge sheet was proposed, analogous to the barrier model for ZnO varistors. The depletion layer width determined by diffusion distance of RE ions and the effective surface states played important roles on the electrical properties of the ceramics.

  1. Structural and luminescence investigations on Sm 3+ doped sodium fluoroborate glasses containing alkali/alkaline earth metal oxides

    NASA Astrophysics Data System (ADS)

    Arul Rayappan, I.; Selvaraju, K.; Marimuthu, K.

    2011-02-01

    Structural and luminescence behavior of the Sm 3+ doped 49B 2O 3+25 xCO 3+25NaF+1Sm 2O 3, (where x=Li 2, Na 2, K 2, Ca and Mg) glasses have been studied and reported. Structural analysis of the prepared glasses was made through FTIR spectra and their optical properties were studied using optical absorption, luminescence and lifetime measurements. The bonding parameters and the oscillator strengths were determined from the absorption spectra. These parameters have been used to obtain the Judd-Ofelt parameters. Using the Judd-Ofelt parameters, radiative properties such as transition probability ( A), stimulated emission cross section (?PE) and branching ratio's ( ?R) for the trivalent samarium ions corresponding to their 4G 5/2? 6H J ( J=5/2, 7/2, 9/2 and 11/2) excited state transitions have been calculated and reported. The decay curve of the 4G 5/2? 6H 7/2 transition exhibits non-exponential behavior. The non-exponential behavior has been attributed to the energy transfer through cross-relaxation between adjacent Sm 3+ ions. The lifetime of the 4G 5/2 level is found to be comparatively less than that of the reported Sm 3+ glasses and the same is due to the presence of OH groups, which is confirmed through the FTIR spectral studies.

  2. Integrating EarthScope Research and Education on a National Scale

    NASA Astrophysics Data System (ADS)

    Hall-Wallace, M. K.; Boyd, T.; Richard, G.; Ellins, K.; Meertens, C.; Semken, S.; Taber, J.; Benthien, M.; Wald, L.; Marvinney, R.

    2002-12-01

    EarthScope's education and outreach mission is to ensure the EarthScope experiment creates as its legacy a public more knowledgeable and understanding of the scientific and societal contributions made by the EarthScope experiment and Earth science. It will fulfill this commitment by developing and disseminating products that utilize the data, models, technology and discoveries of EarthScope and that support existing education and outreach programs. EarthScope EON will carry out educational activities ranging from research experiences for students in grades K-16 to professional development for technical professionals and educators in both formal (e.g. K-20 classrooms) and informal (e.g. museums and parks) venues. It will also provide a wide range of outreach activities from organizing town halls or other local meetings in advance of an instrument deployment, to developing radio, print and video materials that inform the public about the EarthScope experiment and discoveries. The EarthScope Education and Outreach Network (EON) will be facilitated and coordinated through a national center; however, the bulk of the effort will be distributed among local EON alliances of various sizes designed to respond quickly and to meet the specific needs in a region. This allows EarthScope EON to provide customized services that engage culturally, economically and geographically diverse audiences at the national and local scales. The network will be built through national and local partnerships with existing science education and outreach programs at colleges, universities, research facilities and professional societies within the EarthScope community as well as relevant programs at museums and parks, state geologic surveys and emergency management agencies, and K-12 schools. These partnerships will allow EON to use existing resources, networks and expertise to gear up quickly and efficiently. As EON develops, it will reciprocate by contributing new resources and expertise to the partnerships that help improve public understanding of Earth systems overall and promote effective application of EarthScope discoveries.

  3. An Integrated Alternative Conceptual Framework to Heat Engine Earth, Plate Tectonics, and Elastic Rebound

    Microsoft Academic Search

    STAVROS T. TASSOS; DAVID J. FORD

    2005-01-01

    Physical evidence indicates that a thermally driven Earth, plate tectonics, and elastic rebound theory violate fundamental physical principles, and that Earth is a quantified solid body, the size of which possibly increases with time. Earth's core is considered as a low-temperature, high-energy\\/high- frequency, high-tension material, wherein new elements form, constituting the Excess Mass (EM), which is then added atom-by-atom to

  4. Ultraviolet upconversion fluorescence in rare-earth-ion-doped Y2O3 induced by infrared diode laser excitation.

    PubMed

    Chen, G Y; Somesfalean, G; Zhang, Z G; Sun, Q; Wang, F P

    2007-01-01

    Room-temperature ultraviolet emission of Tm(3+) ions at 298 ((1)I(6)-->(3)H(6)), 364 ((1)D(2)-->(3)H(6)), and 391 nm ((1)I(6)-->(3)H(5)) was obtained in Y(2)O(3):Yb(3+)-Tm(3+) by continuous-wave diode laser excitation of 980 nm. Power dependence analysis demonstrates that five- and six-photon upconversion processes populate the (1)D(2) and (1)I(6) states, respectively. We believe that the (1)D(2) population originates from the cross relaxation (1)G(4)+(3)F(4)-->(3)H(4)+(1)D(2) of the Tm(3+) ions, while subsequent energy transfer from Yb(3+) to Tm(3+) excites the (1)D(2) state to the upper (1)I(6) state. High multiphoton-induced ultraviolet emission is also expected for other trivalent rare-earth ions similar to Tm(3+). PMID:17167593

  5. Mechanoluminescence Recording Device Integrated with Photosensitive Material and Europium-Doped SrAl2O4

    NASA Astrophysics Data System (ADS)

    Terasaki, Nao; Xu, Chao-Nan

    2009-04-01

    An accumulative and integrative mechanoluminescence recording system consisting of a mechanoluminescent (ML) material and a photosensitive material was successfully demonstrated. The ML material developed in our laboratory is the world's first light-emitting material for practical use with the application of stress in the elastic deformation region, and we can detect an area of concentrated stress on a measurement object using our ML material. For practical use of such a material, there are many information requirements, such as the size of the stress, its location, frequency, especially stress accumulation from the viewpoints of safety maintenance and reliability. In this system, the ML sheet (aluminum foil coated with ML paint including europium-doped strontium aluminate) was used as a stress detector and an emission unit and a commercial picture film was used as the accumulative and integrative photorecording materials, respectively. Using the ML recording system, the applied stress was successfully recorded onto the picture film accumulatively via the mechanoluminescence from the ML sheet, and the recorded intensity increased with increasing time and number of stress applications.

  6. Electrically tunable fiber-integrated Yb-doped laser covering 74 nm based on a fiber Bragg grating array

    NASA Astrophysics Data System (ADS)

    Tiess, T.; Rothhardt, M.; Chojetzki, C.; Jäger, M.; Bartelt, H.

    2015-03-01

    Fiber lasers provide the foundation to combine an excellent beam quality in single mode operation with a robust and highly efficient design. Based on fiber-integrated configurations, they are employed in many different applications ranging from industry over research to medical technology. However, there is lots of potential to approach even new fields of applications e.g. in spectroscopy based on tunable systems with an adjustable emission wavelength. We present a novel tuning concept for pulsed fiber-integrated laser systems using an array of fiber Bragg gratings (FBGs) as discrete spectral filter. Based on stacking many standard FBGs, the bandwidth and filter properties are easy to scale by increasing the number of gratings allowing huge tuning ranges as well as tailored tuning characteristics. In this work, we demonstrate the potential of this electrically controlled tuning concept. Using an Ytterbium (Yb)-doped fiber laser, we investigate the general tuning characteristics. With variable pulse durations in the nanosecond regime, we demonstrate high signal contrast (~45 dB), excellent wavelength stability and narrow linewidth (<15 GHz). In order to highlight the great spectral freedom, a tuning range of 74 nm in the Yb band is realized which, to the best of our knowledge, is the largest bandwidth reported based on a monolithic filter design.

  7. Potential Uses of EarthSLOT (an Earth Science, Logistics, and Outreach Terrainbase) for Education and Integration in the International Polar Year

    NASA Astrophysics Data System (ADS)

    Nolan, M.

    2004-12-01

    EarthSLOT is an internet-based, 3D, interactive terrain and data visualization system that may have many potential uses as an education and integration tool for International Polar Year projects. Recently funded by NSF's Office of Polar Programs for use in the Arctic, the global nature of the application lends itself well for use at both poles and everywhere in between. The application allows one to start with a spinning earth and zoom down to surface level. The highest resolution digital elevation models available provide the necessary 3D topographic perspective and a variety of possible high-resolution satellite and aerial imagery layers add surface realism; resolution can be down to the centimeter level for either type of data, and frequently acquired satellite imagery may be updated automatically as it arrives. Superimposed on this can be nearly any form of vector or annotation layers, such as shapefiles, polygons, point data, and 3D models (still and moving), which can be easily imported from existing GIS applications or spreadsheets. External databases can also be queried and the results served seamlessly. The entire application is served over the internet, and any connection with speeds over 300kps allows one to interactively fly with a minimum of performance lag. EarthSLOT stands for Earth Science, Logistics, and Outreach Terrainbase, targeting the user-groups of scientists, logisticians, and the public. Approved scientific users can add their own vector content to the application on their own, such that they can create their own custom applications featuring their data but using our underlying earth model with a minimum of interaction with us. For example, an oceanographer can add ship tracks or buoy locations to the model with links to data, host the link on his or her own web page, and invite collaborators to view the spatial relationship of their data to underlying bathymetry. Logisticians or program managers interested in understanding the spatial relationships between different projects for the purposes of coordinating or facilitating cost sharing of logistics can add layers that show the locations and timing of their projects. Educators or principle investigators interested in outreach can design and implement custom applications to share the motivation, rationale, and results of their work in a large variety of ways. Each of these applications can be freely-shared or password-protected, depending on their nature, on either project home pages or on a central IPY-EarthSLOT site. Our prototype application can be found on-line at www.earthslot.org. We already have substantial Landsat coverage of the Arctic, and in the near future plan to incorporate high resolution mosaics of Greenland and Antarctica. With modest additional funding, we propose that EarthSLOT could be used a central integration tool for projects related to the International Polar Year.

  8. A coupled and workflow integrated modeling system applications for earth system science

    Microsoft Academic Search

    Ufuk Utku Turuncoglu; Nuzhet Dalfes; Sylvia Murphy; Cecelia Deluca

    2010-01-01

    The complexity of earth system models and their applications are getting increase because of the continued development of computational resources, storage systems and distributed high-resolution observation networks. Therefore, the multi component earth system models that are used to develop these applications need to be designed in a new programming approach to make easy interaction among those model components and in

  9. Earth System Modeling—An Integrated Assessment Tool for Environmental Studies

    Microsoft Academic Search

    R. A. PIELKE

    This paper overviews a wide spectrum of influences on the Earth's climate system. These include external effects, such as variations in the solar energy output, and internal influences. Internal influences include both natural and human-caused effects. The feedbacks associated with the Earth's climate system are nonlinear and occur over a range of time and space scales. As a result, our

  10. Incorporating Stakeholder Decision Support Needs into an Integrated Regional Earth System Model

    SciTech Connect

    Rice, Jennie S.; Moss, Richard H.; Runci, Paul J.; Anderson, K. L.; Malone, Elizabeth L.

    2012-03-21

    A new modeling effort exploring the opportunities, constraints, and interactions between mitigation and adaptation at regional scale is utilizing stakeholder engagement in an innovative approach to guide model development and demonstration, including uncertainty characterization, to effectively inform regional decision making. This project, the integrated Regional Earth System Model (iRESM), employs structured stakeholder interactions and literature reviews to identify the most relevant adaptation and mitigation alternatives and decision criteria for each regional application of the framework. The information is used to identify important model capabilities and to provide a focus for numerical experiments. This paper presents the stakeholder research results from the first iRESM pilot region. The pilot region includes the Great Lakes Basin in the Midwest portion of the United States as well as other contiguous states. This geographic area (14 states in total) permits cohesive modeling of hydrologic systems while also providing gradients in climate, demography, land cover/land use, and energy supply and demand. The results from the stakeholder research indicate that iRESM should prioritize addressing adaptation alternatives in the water resources, urban infrastructure, and agriculture sectors, such as water conservation, expanded water quality monitoring, altered reservoir releases, lowered water intakes, urban infrastructure upgrades, increased electric power reserves in urban areas, and land use management/crop selection changes. Regarding mitigation alternatives, the stakeholder research shows a need for iRESM to focus on policies affecting the penetration of renewable energy technologies, and the costs and effectiveness of energy efficiency, bioenergy production, wind energy, and carbon capture and sequestration.

  11. Mitochondrial potential (??m) changes in single rat hepatocytes: the effect of orthovanadate nanoparticles doped with rare-earth elements.

    PubMed

    Kavok, Nataliya S; Averchenko, Katherine A; Klochkov, Vladimir K; Yefimova, Svetlana L; Malyukin, Yuri V

    2014-12-01

    Rare-earth-based nanoparticles (NPs) are widely used as fluorescent probes for imaging in vitro and in vivo. One of the challenges that restrain NPs applications in biomedical research is their effect on subcellular structures. In this paper, the ability of lanthanide NPs to affect the cellular oxidative balance and alter the mitochondrial function was analyzed. Since size and shape mutually affect the cellular internalization and intracellular distribution of NPs, the investigations were performed with NPs of spherical (GdYVO4:Eu(3+), spindle-(GdVO4: Eu(3+) and rod-like (LaVO4: Eu(3+) shapes. Quantitative microfluorimetry with JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide) as a mitochondrial probe was used for monitoring of the mitochondrial transmembrane potential (?? m) in single living cells. Changes in the ratio of the JC-1 probe fluorescence were used to analyze the NPs effect on ??(m). The fastest suppressive effect (within 1 hour) was found for spherical NPs. Gradual lowering of ??(m) was observed at the exposure of cells within 24 hours for all types of NPs. Exogenous thiols were required for ??(m) protection. The protective role of exogenous glutathione (GSH) proves that the increase of reactive oxygen species (ROS) formation with depletion of GSH can mediate NPs toxicity. The dynamics of the shape-dependent effect can be explained by the features of NPs transportation into cells. PMID:25533054

  12. Enhancement of Cerenkov Luminescence Imaging by Dual Excitation of Er3+, Yb3+-Doped Rare-Earth Microparticles

    PubMed Central

    Xu, Feng; Feng, Ailing; Zhao, Ying; Lu, Tianjian; Yang, Weidong; Wang, Zhe; Lin, Min; Wang, Jing

    2013-01-01

    Cerenkov luminescence imaging (CLI) has been successfully utilized in various fields of preclinical studies; however, CLI is challenging due to its weak luminescent intensity and insufficient penetration capability. Here, we report the design and synthesis of a type of rare-earth microparticles (REMPs), which can be dually excited by Cerenkov luminescence (CL) resulting from the decay of radionuclides to enhance CLI in terms of intensity and penetration. Methods: Yb3+- and Er3+- codoped hexagonal NaYF4 hollow microtubes were synthesized via a hydrothermal route. The phase, morphology, and emission spectrum were confirmed for these REMPs by power X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectrophotometry, respectively. A commercial CCD camera equipped with a series of optical filters was employed to quantify the intensity and spectrum of CLI from radionuclides. The enhancement of penetration was investigated by imaging studies of nylon phantoms and nude mouse pseudotumor models. Results: the REMPs could be dually excited by CL at the wavelengths of 520 and 980 nm, and the emission peaks overlaid at 660 nm. This strategy approximately doubled the overall detectable intensity of CLI and extended its maximum penetration in nylon phantoms from 5 to 15 mm. The penetration study in living animals yielded similar results. Conclusions: this study demonstrated that CL can dually excite REMPs and that the overlaid emissions in the range of 660 nm could significantly enhance the penetration and intensity of CL. The proposed enhanced CLI strategy may have promising applications in the future. PMID:24205030

  13. Integrating Ecology and Environmental Ethics: Earth Stewardship in the Southern End of the Author(s): Ricardo Rozzi, Juan J. Armesto, Julio R. Gutirrez, Francisca Massardo, Gene E.

    E-print Network

    Berkowitz, Alan R.

    Integrating Ecology and Environmental Ethics: Earth Stewardship in the Southern End of the Americas Stewardship in the Southern End of the Americas RicaRdo Rozzi, Juan J. aRmesto, Julio R. GutiéRRez, FRancisca considered by LTSER programs and helps foster bioculturally diverse forms of Earth stewardship. Keywords

  14. Advancing Access, Attribution, and Integration of Earth & Ocean Science Data: Integrated Services of the Marine Geoscience Data System and the Geoinformatics for Geochemistry Program

    NASA Astrophysics Data System (ADS)

    Lehnert, K. A.; Carbotte, S. M.; Ferrini, V.; Arko, R. A.; Chan, S.; Ryan, W. B.

    2010-12-01

    Development and operation of digital data collections are needed across all areas of the earth and ocean sciences to ensure access and preservation of data sets collected in support of earth and ocean sciences in order to maximize the return on research investments, while enabling verification of research results and contributing to new science initiatives. This is particularly true for data sets that are acquired at high cost, particularly in the marine environment, and that contain irreplaceable observations made of earth’s dynamic properties. The Marine Geoscience Data System (MGDS, www.marine-geo.org) and the Geoinformatics for Geochemistry Program (GfG, www.geoinfogeochem.org) have over the past decade developed, maintained, and operated community-driven data collections that support the preservation, discovery, retrieval, and analysis of a wide range of observational field and analytical data types from the marine and terrestrial environments, among them the PetDB database, the EarthChem data network, the Ridge2000 and MARGINS databases, the Antarctic and Southern Ocean Data System (ASODS), the Global Multi Resolution Topography Synthesis, and the System for Earth Sample Registration (SESAR). MGDS and GfG systems have been developed based on an active understanding of the practices, needs, and concerns of their user communities. They have engaged investigators in the design of the systems, seeking their feedback, and educating the community about responsibilities and benefits of scientific data management and sharing, and worked with funding agencies, editors, publishers, professional societies, and researchers to achieve broad community support, to proactively drive the development of community standards and best practices for data submission, data publication, data documentation, and data archiving, and to advance implementation. In a new formal partnership named IEDA (Integrated Earth Data Applications), the MGDS and GfG will be funded by the US National Science Foundation under a Cooperative Agreement to continue the operation of all MGDS and GfG data systems, while providing new integrated data services that will substantially enhance the utility of all data collection components, and improve data curation, interoperability and efficiency of operations. These will include an on-line service to improve ease of data submission across our user communities, a data publication service for scientists to publish their datasets with citable universal identifiers (DOIs), partnerships with institutions to ensure long-term archiving of data holdings, an authentication service for single sign-on to all systems, and operational services for shared vocabularies and to ease registration of common expeditions and geochemical datasets across our two systems.

  15. Er-doped light emitting slot waveguides monolithically integrated in a silicon photonic chip.

    PubMed

    Ramírez, J M; Ferrarese Lupi, F; Berencén, Y; Anopchenko, A; Colonna, J P; Jambois, O; Fedeli, J M; Pavesi, L; Prtljaga, N; Rivallin, P; Tengattini, A; Navarro-Urrios, D; Garrido, B

    2013-03-22

    An integrated erbium-based light emitting diode has been realized in a waveguide configuration allowing 1.54 ?m light signal routing in silicon photonic circuits. This injection device is based on an asymmetric horizontal slot waveguide where the active slot material is Er(3+) in SiO2 or Er(3+) in Si-rich oxide. The active horizontal slot waveguide allows optical confinement, guiding and lateral extraction of the light for on-chip distribution. Light is then coupled through a taper section to a passive Si waveguide terminated by a grating which extracts (or inserts) the light signal for measuring purposes. We measured an optical power density in the range of tens of ?W/cm(2) which follows a super-linear dependence on injected current density. When the device is biased at high current density, upon a voltage pulse (pump signal), free-carrier and space charge absorption losses become large, attenuating a probe signal by more than 60 dB/cm and thus behaving conceptually as an electro-optical modulator. The integrated device reported here is the first example, still to be optimized, of a fundamental block to realize an integrated silicon photonic circuit with monolithic integration of the light emitter. PMID:23449309

  16. Tunable Second Harmonic Generation in a Nd 3 + -Doped Fiber Laser Using a LiNbO 3Integrated Mach–Zehnder

    Microsoft Academic Search

    Pascal Mollier; Henri Porte; Benoit Grappe; Jérôme Hauden; Jean-Pierre Goedgebuer

    1998-01-01

    We report on a tunable neodymium-doped fiber laser using an intracavity lithium niobate-integrated tuner. The device is a low-voltage asymmetric LiNbO3Mach–Zehnder interferometer working as a tunable spectral filter. Laser emission occurs simultaneously at two wavelengths, ?0=1088 nm and ?2=544 nm, due to the nonlinear properties of the crystal. The lasing wavelengths are tuned over ranges of 12 nm in the

  17. Effects of oxidization and deoxidization on charge-propagation dynamics in rare-earth-doped titanium dioxide with room-temperature luminescence

    NASA Astrophysics Data System (ADS)

    Ishii, Masashi; Towlson, Brian; Poolton, Nigel; Harako, Susumu; Zhao, Xinwei; Komuro, Shuji; Hamilton, Bruce

    2012-03-01

    Anatase titanium dioxide (A-TiO2) with a wide band-gap energy of 3.2 eV can be used as a host semiconductor of rare-earth dopants for optical devices. However, the chemical activity of A-TiO2 strongly affects the luminescence properties of the devices. In this study, we analyzed oxidized and deoxidized samarium (Sm)-doped A-TiO2 (TiO2:Sm) by impedance spectroscopy and microscopic photoluminescence. Charge propagation analyses using dielectric relaxation (DR) revealed that different kinds of charge-trapping centers were formed by the oxidization and deoxidization. For oxidization, Sm-oxygen complexes incorporated in the A-TiO2 formed a trapping level that contributed to Sm excitation, while defective complexes at the A-TiO2 boundary formed other levels that dissipated the charges. For deoxidization using thermal treatment in a hydrogen (H) atmosphere, the number of profitable trapping centers in A-TiO2 was reduced but the remainder maintained the property of Sm excitation. It was also found that H adsorption on the A-TiO2 boundary delocalized the electrons. Photoexcited dielectric relaxation (PEDR) studies confirmed the charge recombination at the profitable traps, and the peak height of the spectra corresponded to the luminescence intensity. Microscopic photoluminescence studies provided results consistent with DR and PEDR measurements and also revealed another quenching factor, i.e., Ti2O3 microcrystal formation on the TiO2:Sm surface.

  18. Quantitative determination of site occupancy of multi-rare-earth elements doped into Ca{sub 2}SnO{sub 4} phosphor by electron channeling microanalysis

    SciTech Connect

    Fujimichi, Y. [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Muto, S., E-mail: s-mutoh@nucl.nagoya-u.ac.j [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Tatsumi, K. [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Kawano, T.; Yamane, H. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2010-09-15

    X-ray fluorescence analysis based on electron channeling effects in transmission electron microscopy (TEM) was performed on Ca{sub 2}SnO{sub 4} phosphor materials doped with Eu{sup 3+}/Y{sup 3+} at various concentrations, which showed red photoluminescence associated with the {sup 5}D{sub 0}-{sup 7}F{sub 2} electric dipole transition of Eu{sup 3+} ions. The method provided direct information on which host element site dopant elements occupy, the results of which were compared with those of X-ray diffraction (XRD)-Rietveld analysis. The obtained results indicated that while it is not favorable for a part of Eu{sup 3+} to occupy the smaller Sn{sup 4+} site, this is still energetically better than creating Ca vacancies or any other of the possible charge balance mechanisms. The local lattice distortions associated with dopant impurities with different ionic radii were also examined by TEM-electron energy-loss spectroscopy (TEM-EELS). The change in PL intensity as a function of dopant concentration is discussed based on the experimental results, although the general concept of concentration quenching applies. - Abstract: The composition of Ca{sub 1.8}Eu{sub 0.2}Y{sub 0.2}Sn{sub 0.8}O{sub 4} determined by electron channeling microanalysis is graphically shown, where the rare-earth dopants, Eu and Y preferentially occupy the Ca and Sn sites, respectively, to maintain the local charge neutrality.

  19. An Integrated Signal Processing System for the Flat River Earth Strain Observatory of St. Louis University

    Microsoft Academic Search

    Robert Slojkowski

    1968-01-01

    An extensive observatory for the measurement of long-period and ultra-long-period earth strains is being operated in a mine of the St. Joseph Lead Company at Flat River, Mo. The principal instruments in the observatory, three 100-foot quartz extensometers, provide electrical outputs proportional to earth strain. Each extensometer output consists of a number of components at various levels and frequencies-ultra-long-period secular

  20. Path Integral Monte Carlo Study Confirms a Highly Ordered Snowball in 4He Nanodroplets Doped with an Ar+ Ion

    NASA Astrophysics Data System (ADS)

    Tramonto, F.; Salvestrini, P.; Nava, M.; Galli, D. E.

    2015-07-01

    By means of the Path Integral Monte Carlo method, we have performed a detailed microscopic study of 4He nanodroplets doped with an argon ion, Ar, at K. We have computed density profiles, energies, dissociation energies, and characterized the local order around the ion for nanodroplets with a number of 4He atoms ranging from 10 to 64 and also 128. We have found the formation of a stable solid structure around the ion, a "snowball", consisting of three concentric shells in which the 4He atoms are placed at the vertices of platonic solids: the first inner shell is an icosahedron (12 atoms); the second one is a dodecahedron with 20 atoms placed on the faces of the icosahedron of the first shell; the third shell is again an icosahedron composed of 12 atoms placed on the faces of the dodecahedron of the second shell. The "magic numbers" implied by this structure, 12, 32, and 44 helium atoms, have been observed in a recent experimental study (Bartl et al., J Phys Chem A 118:8050, 2014) of these complexes; the dissociation energy curve computed in the present work shows jumps in correspondence with those found in the nanodroplets abundance distribution measured in that experiment, strengthening the agreement between theory and experiment. The same structures were predicted in Galli et al. (J Phys Chem A 115:7300, 2011) in a study regarding Na+@4He when ; a comparison between Ar+@4He and Na+@4He complexes is also presented.

  1. Laboratory Earth Under the Lens: Diachronic Evaluation of an Integrated Graduate-Level On-Line Earth System Science Course Series for K-12 Educators

    NASA Astrophysics Data System (ADS)

    Low, R.; Gosselin, D. C.; Haney, C.; Larson-Miller, C.; Bonnstetter, R.; Mandryk, C.

    2012-12-01

    Educational research strives to identify the pedagogies that promote student learning. However, the body of research identifying the characteristics of effective teacher preparation is "least strong for science," and is largely based on studies of the effectiveness of individual courses or workshops (NRC 2010). The National Research Council's "Preparing Teachers: Building Evidence for Strong Policy," (2010) provides a mandate for teacher education providers to conduct research on program-scale effectiveness. The high priority research agenda identified by the NRC is expected to elicit understanding of the aspects of teacher preparation that critically impact classroom student learning outcomes. The Laboratory Lens project is designed to identify effective practices in a teacher education program, with specific reference to the content domain of Earth science. Now in its fifth year, the Masters of Applied Science (MAS) program at UNL offers a variety of science courses, ranging from entomology to food science. The six-course Lab Earth series serves as the backbone of the Specialization for Science Educators within the MAS program, and provides comprehensive content coverage of all Earth science topics identified in the AAAS Benchmarks. "How People Learn," (NRC 2009) emphasizes that expert knowledge includes not only factual knowledge, but also the well-developed conceptual framework critical to the ability to, "remember, reason, and solve problems." A focus of our research is to document the process by which the transition from novice to expert takes place in Lab Earth's on-line teacher participants. A feature of our research design is the standardization of evaluation instruments across the six courses. We have used data derived from implementation of the Community of Inquiry Survey (COI) in pilot offerings to ensure that the course sequence is effective in developing a community of learners, while developing their content knowledge. A pre- and post- course Wilcoxan Signed Ranks Test is included in the battery of assessments to ensure that the courses achieve a statistically significant increase in participants' beliefs about their personal science teaching efficacy. The research design also includes the analysis of concept maps and content mastery assignments to assist in documentation of a teacher's transition from mastery of novice to expert knowledge. Content-based, course-specific pre and post knowledge surveys are included in the battery of assessments. In the analysis of on-line discussions, the project employs a textual analysis technique outlined in "The Rhetoric of Social Intervention," (RSI) (Opt and Gring 2009). RSI provides a promising analytical framework, especially when examining the development of understanding of scientific topics with societal implications, such as sustainability and climate change. The session provides a description of the integrated research design and data collection and analysis in the first year of this project.

  2. Space-Based Sensor Web for Earth Science Applications: An Integrated Architecture for Providing Societal Benefits

    NASA Technical Reports Server (NTRS)

    Habib, Shahid; Talabac, Stephen J.

    2004-01-01

    There is a significant interest in the Earth Science research and user remote sensing community to substantially increase the number of useful observations relative to the current frequency of collection. The obvious reason for such a push is to improve the temporal, spectral, and spatial coverage of the area(s) under investigation. However, there is little analysis available in terms of the benefits, costs and the optimal set of sensors needed to make the necessary observations. Classic observing system solutions may no longer be applicable because of their point design philosophy. Instead, a new intelligent data collection system paradigm employing both reactive and proactive measurement strategies with adaptability to the dynamics of the phenomena should be developed. This is a complex problem that should be carefully studied and balanced across various boundaries including: science, modeling, applications, and technology. Modeling plays a crucial role in making useful predictions about naturally occurring or human-induced phenomena In particular, modeling can serve to mitigate the potentially deleterious impacts a phenomenon may have on human life, property, and the economy. This is especially significant when one is interested in learning about the dynamics of, for example, the spread of forest fires, regional to large-scale air quality issues, the spread of the harmful invasive species, or the atmospheric transport of volcanic plumes and ash. This paper identifies and examines these challenging issues and presents architectural alternatives for an integrated sensor web to provide observing scenarios driving the requisite dynamic spatial, spectral, and temporal characteristics to address these key application areas. A special emphasis is placed on the observing systems and its operational aspects in serving the multiple users and stakeholders in providing societal benefits. We also address how such systems will take advantage of technological advancement in small spacecraft and emerging information technologies, and how sensor web options may be realized and made affordable. Specialized detector subsystems and precision flying techniques may still require substantial innovation, development time and cost: we have presented the considerations for these issues. Finally, data and information gathering and compression techniques are also briefly described.

  3. A Synergy Framework for the integration of Earth Observation technologies into Disaster Risk Reduction

    NASA Astrophysics Data System (ADS)

    Gaetani, Francesco; Petiteville, Ivan; Pisano, Francesco; Rudari, Roberto; St Pierre, Luc

    2015-04-01

    Earth observations and space-based applications have seen a considerable advance in the last decade, and such advances should find their way in applications related to DRR, climate change and sustainable development, including in the indicators to monitor advances in these areas. The post-2015 framework for disaster risk reduction, as adopted by the 3rd WCDRR is a action-oriented framework for disaster risk reduction that builds on modalities of cooperation linking local, national, regional and global efforts. Earth observations from ground and space platforms and related applications will play a key role in facilitating the implementation of the HFA2 and represent a unique platform to observe and assess how risks have changed in recent years, as well as to track the reduction in the level of exposure of communities. The proposed white paper focuses mainly on Earth Observation from space but it also addresses the use of other sources of data ( airborne, marine, in-situ, socio-economic and model outputs) in combination to remote sensing data. Earth observations (EO) and Space-based technologies can play a crucial role in contributing to the generation of relevant information to support informed decision-making regarding risk and vulnerability reduction and to address the underlying factors of disaster risk. For example, long series of Earth observation data collected over more than 30 years already contribute to track changes in the environment and in particular, environmental degradation around the world. Earth observation data is key to the work of the scientific community. Whether due to inadequate land-use policies, lack of awareness or understanding regarding such degradation, or inadequate use of natural resources including water and the oceans; Earth observation technologies are now routinely employed by many Ministries of Environment and Natural Resources worldwide to monitor the extent of degradation and a basis to design and enact new environmental management policies. This White Paper is the premise of a global partnership as a way to enhance the use of Earth observation and Space-based technologies worldwide in the context of the post-2015 disaster risk reduction framework. This document outlines several issues pertaining to such a global partnership including efforts conducted by international stakeholders, recent advances in the use of Earth observation and Space-based technologies, challenges that need to be addressed, policies, and potential aims.

  4. Use of Persistent Identifiers to link Heterogeneous Data Systems in the Integrated Earth Data Applications (IEDA) Facility

    NASA Astrophysics Data System (ADS)

    Hsu, L.; Lehnert, K. A.; Carbotte, S. M.; Arko, R. A.; Ferrini, V.; O'hara, S. H.; Walker, J. D.

    2012-12-01

    The Integrated Earth Data Applications (IEDA) facility maintains multiple data systems with a wide range of solid earth data types from the marine, terrestrial, and polar environments. Examples of the different data types include syntheses of ultra-high resolution seafloor bathymetry collected on large collaborative cruises and analytical geochemistry measurements collected by single investigators in small, unique projects. These different data types have historically been channeled into separate, discipline-specific databases with search and retrieval tailored for the specific data type. However, a current major goal is to integrate data from different systems to allow interdisciplinary data discovery and scientific analysis. To increase discovery and access across these heterogeneous systems, IEDA employs several unique IDs, including sample IDs (International Geo Sample Number, IGSN), person IDs (GeoPass ID), funding award IDs (NSF Award Number), cruise IDs (from the Marine Geoscience Data System Expedition Metadata Catalog), dataset IDs (DOIs), and publication IDs (DOIs). These IDs allow linking of a sample registry (System for Earth SAmple Registration), data libraries and repositories (e.g. Geochemical Research Library, Marine Geoscience Data System), integrated synthesis databases (e.g. EarthChem Portal, PetDB), and investigator services (IEDA Data Compliance Tool). The linked systems allow efficient discovery of related data across different levels of granularity. In addition, IEDA data systems maintain links with several external data systems, including digital journal publishers. Links have been established between the EarthChem Portal and ScienceDirect through publication DOIs, returning sample-level objects and geochemical analyses for a particular publication. Linking IEDA-hosted data to digital publications with IGSNs at the sample level and with IEDA-allocated dataset DOIs are under development. As an example, an individual investigator could sign up for a GeoPass account ID, write a proposal to NSF and create a data plan using the IEDA Data Management Plan Tool. Having received the grant, the investigator then collects rock samples on a scientific cruise from dredges and registers the samples with IGSNs. The investigator then performs analytical geochemistry on the samples, and submits the full dataset to the Geochemical Resource Library for a dataset DOI. Finally, the investigator writes an article that is published in Science Direct. Knowing any of the following IDs: Investigator GeoPass ID, NSF Award Number, Cruise ID, Sample IGSNs, dataset DOI, or publication DOI, a user would be able to navigate to all samples, datasets, and publications in IEDA and external systems. Use of persistent identifiers to link heterogeneous data systems in IEDA thus increases access, discovery, and proper citation of hard-earned investigator datasets.

  5. Structural and optical properties of rare earth-doped (Ba0.77Ca0.23)1-x(Sm, Nd, Pr, Yb)xTiO3

    NASA Astrophysics Data System (ADS)

    Moraes, A. P. A.; Filho, A. G. Souza; Freire, P. T. C.; Filho, J. Mendes; M'Peko, J. C.; Hernandes, A. C.; Antonelli, E.; Blair, Michael W.; Muenchausen, Ross E.; Jacobsohn, Luiz G.; Paraguassu, W.

    2011-06-01

    The structural, dielectric, and vibrational properties of pure and rare earth (RE)-doped Ba0.77Ca0.23TiO3 (BCT23; RE = Nd, Sm, Pr, Yb) ceramics obtained via solid-state reaction were investigated. The pure and RE-doped BCT23 ceramics sintered at 1450 °C in air for 4 h showed a dense microstructure in all ceramics. The use of RE ions as dopants introduced lattice-parameter changes that manifested in the reduction of the volume of the unit cell. RE-doped BCT23 samples exhibit a more homogenous microstructure due to the absence of a Ti-rich phase in the grain boundaries as demonstrated by scanning electron microscopy imaging. The incorporation of REs led to perturbations of the local symmetry of TiO6 octahedra and the creation of a new Raman mode. The results of Raman scattering measurements indicated that the Curie temperature of the ferroelectric phase transition depends on the RE ion and ion content, with the Curie temperature shifting toward lower values as the RE content increases, with the exception of Yb3+ doping, which did not affect the ferroelectric phase transition temperature. The phase transition behavior is explained using the standard soft mode model. Electronic paramagnetic resonance measurements showed the existence of Ti vacancies in the structure of RE-doped BCT23. Defects are created via charge compensation mechanisms due to the incorporation of elements with a different valence state relative to the ions of the pure BCT23 host. It is concluded that the Ti vacancies are responsible for the activation of the Raman mode at 840 cm-1, which is in agreement with lattice dynamics calculations.

  6. Continuous monitoring of a large active earth flow using an integrated GPS - automatic total station approach

    NASA Astrophysics Data System (ADS)

    Corsini, A.

    2009-04-01

    Landslide monitoring has evolved as a crucial tool in civil protection to mitigate and prevent disasters. The research presents an approach to continuous monitoring of a large-scale active earth flow using a system that integrates surface measurements obtained by a GPS and an automatic total station. With the data obtained from the system the landslide can be monitored in near-real-time and surface displacements can be directly utilized to provide early warning of slope movements and to study the behavior of the landslide, e.g. to predict timing and mechanisms of future failure. The Valoria landslide located in the northern Apennines of Italy was reactivated in 2001, 2005 and 2007 damaging roads and endangering houses. A monitoring system was installed in 2007-2008 in the frame of a civil protection plan aimed at risk mitigation. The system consists of an automatic total station measuring about 40 prisms located in the landslide to a maximum distance of 1.800 km; one double-frequency GPS receiver connects in streaming by wireless communication with 4 single-frequency GPS in side the flow. Until December 2007 the monitoring network was operated with periodic static surveying followed by the data post-processing. From September 2007 until March 2008 the landslide deformation was evaluated by periodic surveys with the total station and the GPS system. This first measure showed that the displacements were influenced by the rainfall events and by the snow melting. The total displacements measured vary from centimeter scale in the crown zone, where retrogressive movements were in progress, to over 50 m in the flow track zone. Starting in March 2008 data acquisition by the total station system and GPS were automated in order to allow continuous and near-real-time data processing. The displacement data collected in one and a half year of continuous operation show different acceleration and deceleration phases as a result of the pore water pressure distribution inside the landslide. From March 2008, the total station and the GPS receiver were predisposed for the continuous monitoring. The successive deformation continued constantly and some monitored points recorded decimeter of cumulative displacements in May. In June the displacements progressively decreased due to the absence of the precipitation. Abundant rainfalls in July 2008 (200 mm of rainfall in 50 days) drove a new instability in the landslide. As a result some landslide sectors experienced accelerations measuring total displacements between one decimeter and ten meters in 20 days. Following this event acceleration was recorded at the end of October 2008, when 550 mm of cumulative rain fell in 40 days. During this event the velocity of the material varied between cm/day to m/day and the maximum reacted displacement was 15 m. Through the monitoring with data acquisition every 3 hours it was also possible to evaluate the continuous transfer of mass from the upper part of the slope to lower part. Measurements showed the reactivation of a downslope portion only one day after reactivation occurred upslope at a distance 200 m. The utilized monitoring system has proven reliable for continuous monitoring of an active earth flow with large deformations ranging up to meters for day also during the paroxysmal phases. Moreover, the complex behavior of the flow in the active phase and in each acceleration and deceleration phase was highlighted. For instance, the timing and intensity of movement propagation downslope as an effect of mass transfer and successive loading of lower slope portions was evidenced many times. This information cannot be obtained with borehole monitoring systems which are normally damaged when displacement exceeds some decimeters, nor can it be computed with comparable spatial coverage and data availability timing using other high precision methods, such as laser scanners or ground-based SAR. Another advantage of the adopted monitoring approach over other techniques is the wide angle of operation provided by the strategically beneficial location of the master

  7. Observations from Integrated Ground Motion Using EarthScope's USArray Transportable Array

    NASA Astrophysics Data System (ADS)

    West, J. D.; Fouch, M. J.

    2012-12-01

    Integrated Ground Motion (IGM) is a new method for visualizing and investigating long-term changes in seismic background levels. These new time series present an opportunity to evaluate variations in background seismic levels on intermediate time scales longer than those usually considered in processing seismic event data, but shorter than the time scales typically utilized when measuring the power spectral density (PSD) function of a seismic channel or instrument. Example uses for this new method include determining relationships between weather and seismic noise, detection of uncataloged small seismic and slow slip events, detection and characterization of remotely triggered seismicity, detection and monitoring of induced seismicity and detection of non-seismic signals. Here we apply the IGM processing method to broadband seismic data from the EarthScope USArray Transportable Array (TA) [www.usarray.org], and present some preliminary observations of the observed patterns in seismicity. We generate IGM time series from raw broadband seismic data by filtering and evaluating the envelope of a sliding time window. We further process the resulting IGM time series to remove peaks from short-duration seismic events by clipping the series at the 95th percentile value and normalizing each resulting series on a 0-1 scale. For this initial evaluation, we process IGM from overlapping 15-minute windows sampled every 5 minutes from four weeks of TA data for the western US in early 2008, bandpass filtering over four different ranges: 7-19 Hz, 1-8 Hz, 1-20 sec, and 20-100 sec. We create a series of animations overlaying the IGM values on a map of the western US and compressing the time scale to 2 hours/second. We observe that IGM in the 7-19 Hz and 1-8 Hz bands is primarily influenced by diurnal variations in background seismic levels, which generally overwhelm the signals from small (M<1.5) local earthquakes. Small earthquakes are somewhat more visible in the 1-8 Hz band. In our test data set, both the 1-8 Hz and 7-19 Hz IGM series also show a series of signal sources which appear to move at ~200 m/s and are visible over only a few stations; we speculate that these sources represent low-flying military test flights. IGM in the 1-20 second band appears to be influenced by a combination of local and teleseismic earthquakes plus large, long-term variations in background levels. Since this is the frequency band occupied by primary and secondary microseism, we hypothesize that the longer-term variations are mainly weather and oceanic wave related, and plan to test for correlation with weather and wave-height data. IGM in the 20-100 second band appears to be primarily related to large-magnitude (M>5) teleseismic events, although we observe some longer-term elevated IGM levels in the Pacific Northwest which may be due to either low-frequency slip events or oceanic winter storm-related noise sources.

  8. Earth Science Research Discovery, Integration, 3D Visualization and Analysis using NASA World Wind

    Microsoft Academic Search

    N. Alameh; P. Hogan

    2008-01-01

    NASA plays a leadership role in the world of Advanced Information Technologies. Part of our mission is to leverage those technologies to increase the usability of the growing amount of earth observation produced by the science community. NASA World Wind open source technology provides a complete 3D visualization platform that is being continually advanced by NASA, its partners and the

  9. CIM-EARTH: Community Integrated Model of Economic and Resource Trajectories for Humankind

    Microsoft Academic Search

    I. Foster; J. Elliott; T. Munson; K. Judd; E. J. Moyer; A. H. Sanstad; Hoover Inst

    2010-01-01

    We report here on the development of an open source software framework termed CIM-EARTH that is intended to aid decision-making in climate and energy policy. Numerical modeling in support of evaluating policies to address climate change is difficult not only because of inherent uncertainties but because of the differences in scale and modeling approach required for various subcomponents of the

  10. Path Integral Monte Carlo Study Confirms a Highly Ordered Snowball in 4He Nanodroplets Doped with an Ar+ Ion

    NASA Astrophysics Data System (ADS)

    Tramonto, F.; Salvestrini, P.; Nava, M.; Galli, D. E.

    2015-01-01

    By means of the exact Path Integral Monte Carlo method we have performed a detailed microscopic study of $^4$He nanodroplets doped with an argon ion, Ar$^+$, at $T=0.5$ K. We have computed density profiles, energies, dissociation energies and characterized the local order around the ion for nanodroplets with a number of 4He atoms ranging from 10 to 64 and also 128. We have found the formation of a stable solid structure around the ion, a "snowball", consisting of 3 concentric shells in which the 4He atoms are placed on at the vertices of platonic solids: the first inner shell is an icosahedron (12 atoms); the second one is a dodecahedron with 20 atoms placed on the faces of the icosahedron of the first shell; the third shell is again an icosahedron composed of 12 atoms placed on the faces of the dodecahedron of the second shell. The "magic numbers" implied by this structure, 12, 32 and 44 helium atoms, have been observed in a recent experimental study [Bartl et al, J. Phys. Chem. A 118, 2014] of these complexes; the dissociation energy curve computed in the present work shows jumps in correspondence with those found in the nanodroplets abundance distribution measured in that experiment, strengthening the agreement between theory and experiment. The same structures were predicted in Ref. [Galli et al, J. Phys. Chem. A 115, 2011] in a study regarding Na$^+$@$^4$He$_n$ when n>30; a comparison between Ar$^+$@$^4$He$_n$ and Na$^+$@$^4$He$_n$ complexes is also presented.

  11. Optical spectra of undoped and rare-earth-(=Pr, Nd, Eu, and Er) doped transparent ceramic Y sub 3 Al sub 5 O sub 12

    SciTech Connect

    Sekita, M.; Haneda, H.; Shirasaki, S. (National Institute for Research in Inorganic Materials, Namiki, Tsukuba-shi, Ibaraki 305, Japan (JP)); Yanagitani, T. (Takuma Works, Konoshima Chemical Co. Ltd., Kouda, Takuma-chou, Mitoyo-gun, Kagawa (Japan))

    1991-03-15

    Undoped and rare-earth- (Pr, Nd, Eu, and Er) doped transparent Y{sub 3}Al{sub 5}O{sub 12} ceramics have been prepared, and their optical spectra have been measured. It is found that absorption coefficient of the undoped ceramic Y{sub 3}Al{sub 5}O{sub 12} is almost independent of wavelength with 0.258 cm{sup {minus}1}, which gives transmittance of the undoped ceramic Y{sub 3}Al{sub 5}O{sub 12} to be, for example, 95% for a 2-mm height. Peaks in the absorption and emission spectra of Pr:Y{sub 3}Al{sub 5}O{sub 12} are assigned to the transitions in 4{ital f}{sup 2} configuration. The transitions from the multiplets with total angular momentum {ital J}=0 to multiplets with even {ital J} momentum are strong as predicted by Judd--Ofelt theory. The overall and detail structure of the absorption and emission spectra of Nd:Y{sub 3}Al{sub 5}O{sub 12} is the same as those in a previous publication. However, the absorption coefficient at nonabsorbing wavelengths by Nd{sup 3+} is reduced from more than 1.7 to 0.25 cm{sup {minus}1}. A simple estimation of the population inversion threshold of the Nd:Y{sub 3}Al{sub 5}O{sub 12} ceramic reveals that the threshold is still about 25 times larger than that of single-crystal Nd:Y{sub 3}Al{sub 5}O{sub 12}. Peaks in the absorption and emission spectra of Er:Y{sub 3}Al{sub 5}O{sub 12} ceramic are assigned to the transitions in 4{ital f}{sup 11} configuration. The transition energies agree well with those reported for single-crystal Er:Y{sub 3}Al{sub 5}O{sub 12} and the other hosts within 30 cm{sup {minus}1}. A Stark splitting scheme for some multiplets has been constructed. Peaks in the emission, absorption, and excitation spectra of Eu:Y{sub 3}Al{sub 5}O{sub 12} ceramic are assigned to the transitions in 4{ital f}{sup 6} configuration.

  12. Earth Sciences Earth Sciences

    E-print Network

    Royal Holloway, University of London

    Earth Sciences Earth Sciences Undergraduate Studies #12;Department of Earth Sciences2 Royal;3Department of Earth Sciences Earth Sciences The Department of Earth Sciences at Royal Holloway.ac.uk/studyhere Contents Why study Earth Sciences? 4 Earth Sciences at Royal Holloway 5 Admissions and entry requirements 6

  13. Microwave-assisted one-pot synthesis of water-soluble rare-earth doped fluoride luminescent nanoparticles with tunable colors

    PubMed Central

    Mi, Cong-Cong; Tian, Zhen-huang; Han, Bao-fu; Mao, Chuan-bin; Xu, Shu-kun

    2012-01-01

    Polyethyleneimine (PEI) functionalized multicolor luminescent LaF3 nanoparticles were synthesized via a novel microwave-assisted method, which can achieve fast and uniform heating under eco-friendly and energy efficient conditions. The as-prepared nanoparticles possess a pure hexagonal structure with an average size of about 12 nm. When doped with different ions (Tb3+ and Eu3+), the morphology and structure of the nanoparticles were not changed, whereas the optical properties varied with doped ions and their molar ratio, and as a result emission of four different colors (green, yellow, orange and red) were achieved by simply switching the types of doping ions (Eu3+ versus Tb3 +) and the molar ratio of the two doping ions. PMID:22879690

  14. Thermal neutron imaging with rare-earth-ion-doped LiCaAlF 6 scintillators and a sealed 252Cf source

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Noriaki; Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Kamada, Kei; Fukuda, Kentaro; Suyama, Toshihisa; Watanabe, Kenichi; Yamazaki, Atsushi; Chani, Valery; Yoshikawa, Akira

    2011-10-01

    Thermal neutron imaging with Ce-doped LiCaAlF 6 crystals has been performed. The prototype of the neutron imager using a Ce-doped LiCaAlF 6 scintillating crystal and a position sensitive photomultiplier tube (PSPMT) which had 64 multi-channel anode was developed. The Ce-doped LiCaAlF 6 single crystal was grown by the Czochralski method. A plate with dimensions of a diameter of 50×2 mm 2 was cut from the grown crystal, polished, and optically coupled to PSPMT by silicone grease. The 252Cf source (<1 MBq) was sealed with 43 mm of polyethylene for neutron thermalization. Alphabet-shaped Cd pieces with a thickness of 2 mm were used as a mask for the thermal neutrons. After corrections for the pedestals and gain of each pixel, we successfully obtained two-dimensional neutron images using Ce-doped LiCaAlF 6.

  15. Physicochemical properties of rare earth doped ceria Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) as an electrolyte material for IT-SOFC/SOEC

    NASA Astrophysics Data System (ADS)

    Chaubey, Nityanand; Wani, B. N.; Bharadwaj, S. R.; Chattopadhyaya, M. C.

    2013-06-01

    Nanosized crystallites of rare earth doped ceria Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) a promising electrolyte material for Intermediate Temperature - Solid Oxide Fuel Cells/electrolysis cells have been synthesized by standard ceramic route. Detection of impurities in the samples was done by FTIR spectroscopy. X-ray diffraction studies were used for the determination of phase purity, crystal structure and average crystallite size of the samples. Kinetics involved in phase formation has been discussed. Raman study showed a major band around 465 cm-1 in all the samples, which is attributed to the cubic fluorite structure of ceria. It was also found that for samples Ce0.9Ln0.1O1.95 (Ln = Nd, Sm, Gd) the frequency of F2g shifts to lower value. Electrochemical impedance spectroscopy has been used to measure the ionic conductivity of the samples at elevated temperatures. The Gd doped sample showed the highest grain boundary and total conductivity in comparison to Sm and Nd doped sample. Bulk thermal expansion behavior, sintered densities and micro structural features of the samples have also been studied.

  16. Modeling of optical amplifier waveguide based on silicon nanostructures and rare earth ions doped silica matrix gain media by a finite-difference time-domain method: comparison of achievable gain with Er3+ or Nd3+ ions dopants

    NASA Astrophysics Data System (ADS)

    Cardin, Julien; Fafin, Alexandre; Dufour, Christian; Gourbilleau, Fabrice

    2015-03-01

    A comparative study of the gain achievement is performed in a waveguide optical amplifier whose active layer is constituted by a silica matrix containing silicon nanograins acting as sensitizer of either neodymium ions (Nd3+) or erbium ions (Er3+). Due to the large difference between population levels characteristic times (ms) and finite-difference time step (10-17s), the conventional auxiliary differential equation and finite-difference time-domain (ADE-FDTD) method is not appropriate to treat such systems. Consequently, a new two loops algorithm based on ADE-FDTD method is presented in order to model this waveguide optical amplifier. We investigate the steady states regime of both rare earth ions and silicon nanograins levels populations as well as the electromagnetic field for different pumping powers ranging from 1 to 104 mW/mm2 . Furthermore, the three dimensional distribution of achievable gain per unit length has been estimated in this pumping range. The Nd3+ doped waveguide shows a higher gross gain per unit length at 1064 nm (up to 30 dB/cm-1) than the one with Er3+ doped active layer at 1532 nm (up to 2 dB/cm-1). Considering the experimental background losses found on those waveguides we demonstrate that a significant positive net gain can only be achieved with the Nd3+ doped waveguide. The developed algorithm is stable and applicable to optical gain materials with emitters having a wide range of characteristic lifetimes.

  17. Molecular dynamics simulation and crystal-field theory: Predicting the optical spectra and structure of rare-earth doped inorganic glasses

    Microsoft Academic Search

    Guy Cormier

    1993-01-01

    Simulated structural models were developed for two doped inorganic glasses, Na2O-2SiO2-Eu(III) and SiO2-Eu(III). The simulated structure of the base glasses and the local environment of the doped Eu(III) ions were investigated with the help of radial distribution functions, cumulative distribution functions, and bond angle distributions of the various atomic species found in both glasses. A successful validation of the simulated

  18. Sun-, Earth- and Moon-integrated simulation ray tracing for observation from space using ASAP

    NASA Astrophysics Data System (ADS)

    Breault, Robert P.; Kim, Sug-Whan; Yang, Seul-Ki; Ryu, Dongok

    2014-09-01

    The Space Optics Laboratory at Yonsei University, Korea, in cooperation with Breault Research Organization (BRO) in Tucson, Arizona, have invested significant research and development efforts into creating large scale ray tracing techniques for simulating "reflected" light from the earth with an artificial satellite. This presentation describes a complex model that combines the sun, the earth and an orbiting optical instrument combined into a real scale nonsequential ray tracing computation using BRO's Advanced Systems Analysis Program, ASAP®. The Sun is simulated as a spherically emitting light source of 695,500 km in diameter. The earth also is simulated as a sphere with its characteristics defined as target objects to be observed and defined with appropriate optical properties. They include the atmosphere, land and ocean elements, each having distinctive optical properties expressed by single or combined characteristics of refraction, reflection and scattering. The current embodiment has an atmospheric model consisting of 33 optical layers, a land model with 6 different albedos and the ocean simulated with sun glint characteristics. A space-based optical instrument, with an actual opto-mechanical prescription, is defined in an orbit of several hundreds to thousands of miles in altitude above the earth's surface. The model allows for almost simultaneous evaluations of the imaging and radiometric performances of the instrument. Several real-life application results are reported suggesting that this simulation approach not only provides valuable information that can greatly improve the space optical instrument performance but also provides a simulation tool for scientists to evaluate all phases of a space mission.

  19. Earth Systems Science Earth Systems Science at UNH

    E-print Network

    Pringle, James "Jamie"

    Earth Systems Science Earth Systems Science at UNH THE UNH Institute for the Study of Earth, Oceans, and Space (EOS) Earth Systems Research Center is dedicated to understanding the Earth as an integrative scientists and students study the Earth's ecosystems, atmosphere, water, and ice using field measurements

  20. Photoinduced phenomena in chalcogenide glasses doped with metals

    E-print Network

    Boolchand, Punit

    on relaxation of photodarkening in a-As2Se3 doped with Sn and rare-earth (RE) ions (Dy, Pr, Hon, Sm3 Nd, Er3 for chalcogenide glasses doped with rare-earth ions as perspective materials for fibre optics amplifiers operating and the kinetics ofphotodarkening in amonhous As2Se3:Sn thin films at %) and and AsSe3 doped with rare-earth ions

  1. Vacuum ultraviolet spectroscopic properties of rare earth (RE=Ce,Tb,Eu,Tm,Sm)-doped hexagonal KCaGd(PO4)2 phosphate

    NASA Astrophysics Data System (ADS)

    Zhang, Z. J.; Yuan, J. L.; Duan, C. J.; Xiong, D. B.; Chen, H. H.; Zhao, J. T.; Zhang, G. B.; Shi, C. S.

    2007-11-01

    Hexagonal KCaGd(PO4)2:RE3+ (RE =Ce,Tb,Eu,Tm,Sm) were synthesized by coprecipitation method and their vacuum ultraviolet-ultraviolet (VUV-UV) spectroscopic properties were investigated. The bands at about 165nm in the VUV excitation spectra are attributed to the host lattice absorptions. For Ce3+-doped samples, the bands at 207, 256, 275, and 320nm are assigned to the 4f-5d transitions of Ce3+ in KCaGd(PO4)2. For Tb3+-doped sample, the bands at 203 and 222nm are related to the 4f-5d spin-allowed transitions. For Eu3+-doped sample, the O2--Eu3+ charge-transfer band (CTB) at 229nm is observed, and the fine emission spectrum of Eu3+ indicates that Eu3+ ions prefer to occupy Gd3+ or Ca2+ sites in the host lattice. For Tm3+- and Sm3+-doped samples, the O2--Tm3+ and O2--Sm3+ CTBs are observed to be at 176 and 186nm, respectively. From the standpoints of the absorption band, color purity, and luminescent intensity, Tb3+-doped KCaGd(PO4)2 is a potential candidate for 172nm excited green plasma display phosphors.

  2. On an improved sub-regional water resources management representation for integration into earth system models

    NASA Astrophysics Data System (ADS)

    Voisin, N.; Li, H.; Ward, D.; Huang, M.; Wigmosta, M.; Leung, L. R.

    2013-03-01

    Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of earth system models in hydrologic and climate predictions, as well as impact studies at regional to global scales. Emerging large-scale research reservoir models use generic operating rules that are flexible for coupling with earth system models. Those generic operating rules have been successful in reproducing the overall regulated flow at large basin scales. This study investigates the uncertainties of the reservoir models from different implementations of the generic operating rules using the complex multi-objective Columbia River Regulation System in northwestern United States as an example to understand their effects on not only regulated flow but also reservoir storage and fraction of the demand that is met. Numerical experiments are designed to test new generic operating rules that combine storage and releases targets for multi-purpose reservoirs and to compare the use of reservoir usage priorities, withdrawals vs. consumptive demand, as well as natural vs. regulated mean flow for calibrating operating rules. Overall the best performing implementation is the use of the combined priorities (flood control storage targets and irrigation release targets) operating rules calibrated with mean annual natural flow and mean monthly withdrawals. The options of not accounting for groundwater withdrawals, or on the contrary, of assuming that all remaining demand is met through groundwater extractions, are discussed.

  3. On an improved sub-regional water resources management representation for integration into earth system models

    NASA Astrophysics Data System (ADS)

    Voisin, N.; Li, H.; Ward, D.; Huang, M.; Wigmosta, M.; Leung, L. R.

    2013-09-01

    Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of earth system models in hydrologic and climate predictions, as well as impact studies at regional to global scales. Emerging large-scale research reservoir models use generic operating rules that are flexible for coupling with earth system models. Those generic operating rules have been successful in reproducing the overall regulated flow at large basin scales. This study investigates the uncertainties of the reservoir models from different implementations of the generic operating rules using the complex multi-objective Columbia River Regulation System in northwestern United States as an example to understand their effects on not only regulated flow but also reservoir storage and fraction of the demand that is met. Numerical experiments are designed to test new generic operating rules that combine storage and releases targets for multi-purpose reservoirs and to compare the use of reservoir usage priorities and predictors (withdrawals vs. consumptive demands, as well as natural vs. regulated mean flow) for configuring operating rules. Overall the best performing implementation is with combined priorities rules (flood control storage targets and irrigation release targets) set up with mean annual natural flow and mean monthly withdrawals. The options of not accounting for groundwater withdrawals, or on the contrary, of assuming that all remaining demand is met through groundwater extractions, are discussed.

  4. On an improved sub-regional water resources management representation for integration into earth system models

    SciTech Connect

    Voisin, Nathalie; Li, Hongyi; Ward, Duane L.; Huang, Maoyi; Wigmosta, Mark S.; Leung, Lai-Yung R.

    2013-09-30

    Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of earth system models in hydrologic and climate predictions, as well as impact studies at regional to global scales. Emerging large-scale research reservoir models use generic operating rules that are flexible for coupling with earth system models. Those generic operating rules have been successful in reproducing the overall regulated flow at large basin scales. This study investigates the uncertainties of the reservoir models from different implementations of the generic operating rules using the complex multi-objective Columbia River Regulation System in northwestern United States as an example to understand their effects on not only regulated flow but also reservoir storage and fraction of the demand that is met. Numerical experiments are designed to test new generic operating rules that combine storage and releases targets for multi-purpose reservoirs and to compare the use of reservoir usage priorities, withdrawals vs. consumptive demand, as well as natural vs. regulated mean flow for calibrating operating rules. Overall the best performing implementation is the use of the combined priorities (flood control storage targets and irrigation release targets) operating rules calibrated with mean annual natural flow and mean monthly withdrawals. The challenge of not accounting for groundwater withdrawals, or on the contrary, assuming that all remaining demand is met through groundwater extractions, is discussed.

  5. Selective Emitter Pumped Rare Earth Laser

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor); Patton, Martin O. (Inventor)

    2001-01-01

    A selective emitter pumped rare earth laser provides an additional type of laser for use in many laser applications. Rare earth doped lasers exist which are pumped with flashtubes or laser diodes. The invention uses a rare earth emitter to transform thermal energy input to a spectral band matching the absorption band of a rare earth in the laser in order to produce lasing.

  6. Distributed Earth observation data integration and on-demand services based on a collaborative framework of geospatial data service gateway

    NASA Astrophysics Data System (ADS)

    Xie, Jibo; Li, Guoqing

    2015-04-01

    Earth observation (EO) data obtained by air-borne or space-borne sensors has the characteristics of heterogeneity and geographical distribution of storage. These data sources belong to different organizations or agencies whose data management and storage methods are quite different and geographically distributed. Different data sources provide different data publish platforms or portals. With more Remote sensing sensors used for Earth Observation (EO) missions, different space agencies have distributed archived massive EO data. The distribution of EO data archives and system heterogeneity makes it difficult to efficiently use geospatial data for many EO applications, such as hazard mitigation. To solve the interoperable problems of different EO data systems, an advanced architecture of distributed geospatial data infrastructure is introduced to solve the complexity of distributed and heterogeneous EO data integration and on-demand processing in this paper. The concept and architecture of geospatial data service gateway (GDSG) is proposed to build connection with heterogeneous EO data sources by which EO data can be retrieved and accessed with unified interfaces. The GDSG consists of a set of tools and service to encapsulate heterogeneous geospatial data sources into homogenous service modules. The GDSG modules includes EO metadata harvesters and translators, adaptors to different type of data system, unified data query and access interfaces, EO data cache management, and gateway GUI, etc. The GDSG framework is used to implement interoperability and synchronization between distributed EO data sources with heterogeneous architecture. An on-demand distributed EO data platform is developed to validate the GDSG architecture and implementation techniques. Several distributed EO data achieves are used for test. Flood and earthquake serves as two scenarios for the use cases of distributed EO data integration and interoperability.

  7. Effect of Knowledge Integration Activities on Students' Perception of the Earth's Crust as a Cyclic System.

    ERIC Educational Resources Information Center

    Kali, Yael; Orion, Nir; Eylon, Bat-Sheva

    2003-01-01

    Characterizes students' understanding of the rock cycle system. Examines effects of a knowledge integration activity on their system thinking. Interprets answers to an open-ended test using a systems thinking continuum ranging from a completely static view of the system to an understanding of the system's cyclic nature. Reports meaningful…

  8. Earth Observation Remote Sensing and GIS Services for Monitoring of Integration Systems

    Microsoft Academic Search

    S. Kurnaz; R. B. Rustamov

    2007-01-01

    Today availability of using the high resolution of space imagery creates a positive environment on application of space technology for monitoring of integrated systems in different areas of industry and commercial purposes. They are an airborne, unmanned aerial vehicles (UAV) and satellite Synthetic Aperture Radar and LIDAR multi-spectral and hyper-spectral sensors. One of the advance methods of feasibility study of

  9. Fast integration of low orbiter's trajectory perturbed by the earth's non-sphericity

    E-print Network

    Hwang, Cheinway

    -major axis of a reference ellipsoid, "gnm and "nm are the spherical harmonic coecients, and "nmsin from EGM96 to harmonic degree 360, orbit integrations were per- formed for a low orbiter at an altitude FFT Á Perturbation Á Spherical harmonics 1 Introduction There are many satellite missions that require

  10. Effect of knowledge integration activities on students' perception of the earth's crust as a cyclic system

    Microsoft Academic Search

    Yael Kali; Nir Orion; Bat-Sheva Eylon

    2003-01-01

    Systems thinking is regarded as a high-order thinking skill required in scientific, technological, and everyday domains. However, little is known about systems thinking in the context of science education. In the current research, students' understanding of the rock cycle system after a learning program was characterized, and the effect of a concluding knowledge integration activity on their systems thinking was

  11. Entrainment of bed material by Earth-surface mass flows: Review and reformulation of depth-integrated theory

    NASA Astrophysics Data System (ADS)

    Iverson, Richard M.; Ouyang, Chaojun

    2015-03-01

    Earth-surface mass flows such as debris flows, rock avalanches, and dam-break floods can grow greatly in size and destructive potential by entraining bed material they encounter. Increasing use of depth-integrated mass and momentum conservation equations to model these erosive flows motivates a review of the underlying theory. Our review indicates that many existing models apply depth-integrated conservation principles incorrectly, leading to spurious inferences about the role of mass and momentum exchanges at flow-bed boundaries. Model discrepancies can be rectified by analyzing conservation of mass and momentum in a two-layer system consisting of a moving upper layer and static lower layer. Our analysis shows that erosion or deposition rates at the interface between layers must, in general, satisfy three jump conditions. These conditions impose constraints on valid erosion formulas, and they help determine the correct forms of depth-integrated conservation equations. Two of the three jump conditions are closely analogous to Rankine-Hugoniot conditions that describe the behavior of shocks in compressible gasses, and the third jump condition describes shear traction discontinuities that necessarily exist across eroding boundaries. Grain-fluid mixtures commonly behave as compressible materials as they undergo entrainment, because changes in bulk density occur as the mixtures mobilize and merge with an overriding flow. If no bulk density change occurs, then only the shear traction jump condition applies. Even for this special case, however, accurate formulation of depth-integrated momentum equations requires a clear distinction between boundary shear tractions that exist in the presence or absence of bed erosion.

  12. Entrainment of bed material by Earth-surface mass flows: review and reformulation of depth-integrated theory

    USGS Publications Warehouse

    Iverson, Richard M.; Chaojun Ouyang

    2015-01-01

    Earth-surface mass flows such as debris flows, rock avalanches, and dam-break floods can grow greatly in size and destructive potential by entraining bed material they encounter. Increasing use of depth-integrated mass- and momentum-conservation equations to model these erosive flows motivates a review of the underlying theory. Our review indicates that many existing models apply depth-integrated conservation principles incorrectly, leading to spurious inferences about the role of mass and momentum exchanges at flow-bed boundaries. Model discrepancies can be rectified by analyzing conservation of mass and momentum in a two-layer system consisting of a moving upper layer and static lower layer. Our analysis shows that erosion or deposition rates at the interface between layers must in general satisfy three jump conditions. These conditions impose constraints on valid erosion formulas, and they help determine the correct forms of depth-integrated conservation equations. Two of the three jump conditions are closely analogous to Rankine-Hugoniot conditions that describe the behavior of shocks in compressible gasses, and the third jump condition describes shear traction discontinuities that necessarily exist across eroding boundaries. Grain-fluid mixtures commonly behave as compressible materials as they undergo entrainment, because changes in bulk density occur as the mixtures mobilize and merge with an overriding flow. If no bulk density change occurs, then only the shear-traction jump condition applies. Even for this special case, however, accurate formulation of depth-integrated momentum equations requires a clear distinction between boundary shear tractions that exist in the presence or absence of bed erosion.

  13. Synthesis and characterization of rare-earth doped SrBi{sub 2}Nb{sub 2}O{sub 9} phase in lithium borate based nanocrystallized glasses

    SciTech Connect

    Harihara Venkataraman, B. [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Fujiwara, Takumi [Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Komatsu, Takayuki, E-mail: komatsu@mst.nagaokaut.ac.j [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan)

    2009-06-15

    Glass composites comprising of un-doped and samarium-doped SrBi{sub 2}Nb{sub 2}O{sub 9} nanocrystallites are fabricated in the glass system 16.66SrO-16.66[(1-x)Bi{sub 2}O{sub 3}-xSm{sub 2}O{sub 3}]-16.66Nb{sub 2}O{sub 5}-50Li{sub 2}B{sub 4}O{sub 7} (0<=x<=0.5, in mol%) via the melt quenching technique. The glassy nature of the as-quenched samples is established by differential thermal analyses. Transmission electron microscopic studies reveal the presence of about 15 nm sized spherical crystallites of the fluorite-like SrBi{sub 1.9}Sm{sub 0.1}Nb{sub 2}O{sub 9} phase in the samples heat treated at 530 deg. C. The formation of layered perovskite-type un-doped and samarium-doped SrBi{sub 2}Nb{sub 2}O{sub 9} nanocrystallites with an orthorhombic structure through the intermediate fluorite phase is confirmed by X-ray powder diffraction and micro-Raman spectroscopic studies. The influence of samarium doping on the lattice parameters, lattice distortions, and the Raman peak positions of SrBi{sub 2}Nb{sub 2}O{sub 9} perovskite phase is clarified. The dielectric constants of the perovskite SrBi{sub 2}Nb{sub 2}O{sub 9} and SrBi{sub 1.9}Sm{sub 0.1}Nb{sub 2}O{sub 9} nanocrystals are relatively larger than those of the corresponding fluorite-like phase and the precursor glass. - Graphical Abstract: This figure shows the XRD patterns at room temperature for the as-quenched and heat treated samples in Sm{sub 2}O{sub 3}-doped (x=0.1) glass. Based on these results, it is concluded that the formation of samarium-doped perovskite SBN phase takes place via an intermediate fluorite-like phase in the crystallization of this glass.

  14. Vacuum ultraviolet spectroscopic properties of rare earth (RE=Ce,Tb,Eu,Tm,Sm)-doped hexagonal KCaGd(PO{sub 4}){sub 2} phosphate

    SciTech Connect

    Zhang, Z. J.; Yuan, J. L.; Duan, C. J.; Xiong, D. B.; Chen, H. H.; Zhao, J. T.; Zhang, G. B.; Shi, C. S. [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China) and Graduate School of Chinese Academy of Science, Beijing 100039 (China); National Synchrotron Radiation Laboratory, University of Science and Technology of China, Heifei 230026 (China)

    2007-11-01

    Hexagonal KCaGd(PO{sub 4}){sub 2}:RE{sup 3+} (RE=Ce,Tb,Eu,Tm,Sm) were synthesized by coprecipitation method and their vacuum ultraviolet-ultraviolet (VUV-UV) spectroscopic properties were investigated. The bands at about 165 nm in the VUV excitation spectra are attributed to the host lattice absorptions. For Ce{sup 3+}-doped samples, the bands at 207, 256, 275, and 320 nm are assigned to the 4f-5d transitions of Ce{sup 3+} in KCaGd(PO{sub 4}){sub 2}. For Tb{sup 3+}-doped sample, the bands at 203 and 222 nm are related to the 4f-5d spin-allowed transitions. For Eu{sup 3+}-doped sample, the O{sup 2-}-Eu{sup 3+} charge-transfer band (CTB) at 229 nm is observed, and the fine emission spectrum of Eu{sup 3+} indicates that Eu{sup 3+} ions prefer to occupy Gd{sup 3+} or Ca{sup 2+} sites in the host lattice. For Tm{sup 3+}- and Sm{sup 3+}-doped samples, the O{sup 2-}-Tm{sup 3+} and O{sup 2-}-Sm{sup 3+} CTBs are observed to be at 176 and 186 nm, respectively. From the standpoints of the absorption band, color purity, and luminescent intensity, Tb{sup 3+}-doped KCaGd(PO{sub 4}){sub 2} is a potential candidate for 172 nm excited green plasma display phosphors.

  15. Earth tides

    SciTech Connect

    Harrison, J.C.

    1984-01-01

    Nineteen papers on gravity, tilt, and strain tides are compiled into this volume. Detailed chapters cover the calculation of the tidal forces and of the Earth's response to them, as well as actual observations of earth tides. Partial Contents: On Earth tides. The tidal forces: Tidal Forces. New Computations of the Tide-Generating Potential. Corrected Tables of Tidal Harmonics. The Theory of Tidal Deformations. Body Tides on an Elliptical, Rotating, Elastic and Oceanless Earth, Deformation of the Earth by Surface Loads. Gravimetric Tidal Loading Computed from Integrated Green's Functions. Tidal Friction in the Solid Earth. Loading Tides Versus Body Tides. Lunar Tidal Acceleration from Earth Satellite Orbit Analysis. Observations: gravity. Tidal Gravity in Britain: Tidal Loading and the Spatial Distribution of the Marine Tide. Tidal Loading along a Profile Europe-East Africa-South Asia-Australia and the Pacific Ocean. Detailed Gravity-Tide Spectrum between One and Four Cycles per Day. Observations: tilt and strain. Cavity and Topographic Effects in Tilt and Strain Measurement. Observations of Local Elastic Effects on Earth Tide Tilts and Strains.

  16. Towards Designing an Integrated Earth Observation System for the Provision of Solar Energy Resource and Assessment

    NASA Technical Reports Server (NTRS)

    Stackouse, Paul W., Jr.; Renne, D.; Beyer, H.-G.; Wald, L.; Meyers, R.; Perez, R.; Suri, M.

    2006-01-01

    The GEOSS strategic plan specifically targets the area of improved energy resource management due to the importance of these to the economic and social viability of every nation of the world. With the world s increasing demand for energy resources, the need for new alternative energy resources grows. This paper overviews a new initiative within the International Energy Agency that addresses needs to better manage and develop solar energy resources worldwide. The goal is to provide the solar energy industry, the electricity sector, governments, and renewable energy organizations and institutions with the most suitable and accurate information of the solar radiation resources at the Earth's surface in easily-accessible formats and understandable quality metrics. The scope of solar resource assessment information includes historic data sets and currently derived data products using satellite imagery and other means. Thus, this new task will address the needs of the solar energy sector while at the same time will serve as a model that satisfies GEOSS objectives and goals.

  17. Research priorities in land use and land-cover change for the Earth system and integrated assessment modelling

    SciTech Connect

    Hibbard, Kathleen A.; Janetos, Anthony C.; Van Vuuren, Detlef; Pongratz, Julia; Rose, Steven K.; Betts, Richard; Herold, Martin; Feddema, Johannes J.

    2010-11-15

    This special issue has highlighted recent and innovative methods and results that integrate observations and AQ3 modelling analyses of regional to global aspect of biophysical and biogeochemical interactions of land-cover change with the climate system. Both the Earth System and the Integrated Assessment modeling communities recognize the importance of an accurate representation of land use and land-cover change to understand and quantify the interactions and feedbacks with the climate and socio-economic systems, respectively. To date, cooperation between these communities has been limited. Based on common interests, this work discusses research priorities in representing land use and land-cover change for improved collaboration across modelling, observing and measurement communities. Major research topics in land use and land-cover change are those that help us better understand (1) the interaction of land use and land cover with the climate system (e.g. carbon cycle feedbacks), (2) the provision of goods and ecosystem services by terrestrial (natural and anthropogenic) land-cover types (e.g. food production), (3) land use and management decisions and (4) opportunities and limitations for managing climate change (for both mitigation and adaptation strategies).

  18. INTEGRATING EARTH OBSERVATION AND FIELD DATA INTO A LYME DISEASE MODEL TO MAP AND PREDICT RISKS TO BIODIVERSITY AND HUMAN HEALTH

    EPA Science Inventory

    DW-75-92243901 Title: Integrating Earth Observation and Field Data into a Lyme Disease Model to Map and Predict Risks to Biodiversity and Human HealthDurland Fish, Maria Diuk-Wasser, Joe Roman, Yongtao Guan, Brad Lobitz, Rama Nemani, Joe Piesman, Montira J. Pongsiri, F...

  19. Habitability of Super-Earth Planets around Main-Sequence Stars including Red Giant Branch Evolution: Models based on the Integrated System Approach

    Microsoft Academic Search

    M. Cuntz; W. von Bloh; K.-P. Schroeder; C. Bounama; S. Franck

    2011-01-01

    In a previous study published in Astrobiology, we focused on the evolution of habitability of a 10 M_E super-Earth planet orbiting a star akin to the Sun. This study was based on a concept of planetary habitability in accordance to the integrated system approach that describes the photosynthetic biomass production taking into account a variety of climatological, biogeochemical, and geodynamical

  20. Integration of fluorine-doped silicon oxide in copper pilot line for 0.12-?m technology

    Microsoft Academic Search

    J. P Reynard; C Verove; E Sabouret; P Motte; B Descouts; C Chaton; J Michailos; K Barla

    2002-01-01

    The FSG (fluorine-doped silicon glass) was introduced as dielectric for copper interconnects in order to take advantage of its lower dielectric constant. With a gain of 18% in the constant value, it makes the shrink of metal dimension possible for 0.12-?m technology devices with limited cross-talks or delays in the information transmission. In spite of its strong sensitivity to water

  1. Building Capacity to Integrate NASA Earth Science into Water Resources Management Applications in the Context of a Changing Climate

    NASA Astrophysics Data System (ADS)

    Prados, A. I.; Mehta, A. V.

    2011-12-01

    The NASA Applied Sciences program provides technical capacity building activities to enable decision-makers to integrate NASA Earth Science into environmental management activities. This includes workshops tailored to end-user needs by working directly with agencies to 1) identify environmental management activities that could benefit from NASA Earth Science and 2) conducting workshops that teach the NASA products and decision-support tools best suited to the identified application area. Building on a successful 3-year effort on air pollution monitoring for environmental applications, the project has expanded into water resources. Climate Change has dramatically increased demand for observational and predictive data in support of decision making activities related to water supply and demand. However, a gap remains between NASA products and applied research and the entities who stand to benefit from their utilization. To fill this gap, the project has developed short courses on 1) impacts of climate change on water resources 2) hands-on exercises on access and interpretation of NASA imagery relevant to water resources management via the use of decision-support web tools and software and 3) case studies on the application of NASA products in the field. The program is currently focused on two areas 1) precipitation products over the central and southern U.S. that help communities and agencies improve flooding forecasts and 2) snow and snow/water equivalent products over the western U.S and Latin America that can provide end-users with improved stream flow prediction in Spring within a framework of decreasing snow availability.

  2. Superconductivity and phase diagram in iron-based arsenic-oxides ReFeAsO1?? (Re = rare-earth metal) without fluorine doping

    Microsoft Academic Search

    Zhi-An Ren; Guang-Can Che; Xiao-Li Dong; Jie Yang; Wei Lu; Wei Yi; Xiao-Li Shen; Zheng-Cai Li; Li-Ling Sun; Fang Zhou; Zhong-Xian Zhao

    2008-01-01

    Here we report a new class of superconductors prepared by high-pressure synthesis in the quaternary family ReFeAsO1?? (Re=Sm, Nd, Pr, Ce, La) without fluorine doping. The onset superconducting critical temperature (Tc) in these compounds increases with the reduction of the Re atom size, and the highest Tc obtained so far is 55 K in SmFeAsO1??. For the NdFeAsO1?? compound with

  3. Tin oxide thick film by doping rare earth for detecting traces of CO{sub 2}: Operating in oxygen-free atmosphere

    SciTech Connect

    Xiong, Ya; Zhang, Guozhu; Zhang, Shunping; Zeng, Dawen; Xie, Changsheng, E-mail: csxie@mail.hust.edu.cn

    2014-04-01

    Highlights: • La, Gd, and Lu doped SnO{sub 2} with their sensing properties toward CO{sub 2} were compared. • The microstructures of SnO{sub 2}-based nanoparticles were elaborately characterized. • La-SnO{sub 2} thick film shows superior response toward trace ppm CO{sub 2}. • Our sensing material can be recommended to employ in oxygen-free environment. - Abstract: SnO{sub 2} thick films doped with atomic ratios ranging from 0 up to 8 at.% La, 8 at.% Gd, 8 at.% Lu were fabricated, respectively, via hydrothermal and impregnation methods. The crystal phase, morphology, and chemical composition of the SnO{sub 2}-based nanoparticles were characterized by XRD, FE-SEM, EDX, HRTEM and XPS. Sensing properties of La-SnO{sub 2}, Gd-SnO{sub 2}, Lu-SnO{sub 2} films, as well as the pure SnO{sub 2} film, were analyzed toward CO{sub 2} in the absence of O{sub 2}. It was found that the optimal doping element was La and the best doping ratio was 4 at.%. The maximum response appeared at an operating temperature of 250 °C, on which condition the 4 at.% La-SnO{sub 2} exhibited a remarkable improvement of response from 5.12 to 29.8 when increasing CO{sub 2} concentration from 50 to 500 ppm. Furthermore, the working mechanism underlying such enhancement in CO{sub 2}-sensing functions by La additive in the absence of O{sub 2} was proposed and discussed.

  4. Expedition Earth and Beyond: Using NASA Data Resources and Integrated Educational Strategies to Promote Authentic Research in the Classroom

    NASA Technical Reports Server (NTRS)

    Graffi, Paige Valderrama; Stefanov, William; Willis, Kim; Runco, Sue

    2009-01-01

    Teachers in today s classrooms are bound by state required skills, education standards, and high stakes testing. How can they gain skills and confidence to replace units or individual activities with curriculum that incorporates project and inquiry-based learning and promotes authentic research in the classroom? The key to promoting classroom authentic research experiences lies in educator professional development that is structured around teacher needs. The Expedition Earth and Beyond Program is a new geosciences program based at the NASA Johnson Space Center designed to engage, inspire and educate teachers and students in grades 5-14. The program promotes authentic research experiences for classrooms and uses strategies that will help NASA reach its education goals while still allowing educators to teach required standards. Teachers will have access to experts in terrestrial and planetary remote sensing and geoscience; this will enhance their use of content, structure, and relevant experiences to gain the confidence and skills they need to actively engage students in authentic research experiences. Integrated and powerful educational strategies are used to build skills and confidence in teachers. The strategies are as follows: 1) creating Standards-aligned, inquiry-based curricular resources as ready-to-use materials that can be modified by teachers to fit their unique classroom situation; 2) providing ongoing professional development opportunities that focus on active experiences using curricular materials, inquiry-based techniques and expanding content knowledge; 3) connecting science experts to classrooms to deepen content knowledge and provide relevance to classroom activities and real world applications; 4) facilitating students sharing research with their peers and scientists reinforcing their active participation and contributions to research. These components of the Expedition Earth and Beyond Education Program will be enhanced by providing exciting and diverse research opportunities that are inspired by views of Earth from space taken by astronauts on board the International Space Station. The interest and connection to viewing our home planet from space will inevitably spark questions that will drive students to pursue their research investigations, as well as forming a basis for comparisons to the exploration of other planetary bodies in our solar system.

  5. Svalbard Integrated Arctic Earth Observing System (sios): Facilitating Easy Access to Multidisciplinary Arctic Data Through the Brokering Approach.

    NASA Astrophysics Data System (ADS)

    Bye, B. L.; Godøy, Ø.

    2014-12-01

    Environmental and climate changes are important elements of our global challenges. They are observed at a global scale and in particular in the Arctic. In order to give better estimates of the future changes, the Arctic has to be monitored and analyzed by a multi-disciplinary observation system that will improve Earth System Models. The best chance to achieve significant results within a relatively short time frame is found in regions with a large natural climate gradient, and where processes sensitive to the expected changes are particularly important. Svalbard and the surrounding ocean areas fulfil all these criteria. The vision for SIOS is to be a regional observational system for long term acquisition and proliferation of fundamental knowledge on global environmental change within an Earth System Science perspective in and around Svalbard. SIOS will systematically develop and implement methods for how observational networks are to be construed. The distributed SIOS data management system (SDMS) will be implemented through a combination of technologies tailored to the multi-disciplinary nature of the Arctic data. One of these technologies is The Brokering approach or "Framework". The Brokering approach provides a series of services such as discovery, access, transformation and semantics support to enable translation from one discipline/culture to another. This is exactly the challenges the SDMS will have to handle and thus the Brokering approach is integrated in the design of the system. A description of the design strategy for the SDMS that includes The Brokering approach will be presented. The design and implementation plans for the SDMS are based on research done in the EU funded ESFRI project SIOS and examples of solutions for interoperable systems producing Arctic datasets and products coordinated through SIOS will be showcased. The reported experience from SIOS brokering approach will feed into the process of developing a sustainable brokering governance in the framework of Research Data Alliance. It will also support the Global Earth Observation System of Systems (GEOSS). This is a contribution to increase our global capacity to create interoperable systems that provide multi-disciplinary dataset and products.

  6. Expedition Earth and Beyond: Using NASA data resources and integrated educational strategies to promote authentic research in the classroom

    NASA Astrophysics Data System (ADS)

    Graff, P. V.; Stefanov, W.; Willis, K.; Runco, S.

    2009-12-01

    Teachers in today’s classrooms are bound by state required skills, education standards, and high stakes testing. How can they gain skills and confidence to replace units or individual activities with curriculum that incorporates project and inquiry-based learning and promotes authentic research in the classroom? The key to promoting classroom authentic research experiences lies in educator professional development that is structured around teacher needs. The Expedition Earth and Beyond Program is a new geosciences program based at the NASA Johnson Space Center designed to engage, inspire and educate teachers and students in grades 5-14. The program promotes authentic research experiences for classrooms and uses strategies that will help NASA reach its education goals while still allowing educators to teach required standards. Teachers will have access to experts in terrestrial and planetary remote sensing and geoscience; this will enhance their use of content, structure, and relevant experiences to gain the confidence and skills they need to actively engage students in authentic research experiences. Integrated and powerful educational strategies are used to build skills and confidence in teachers. The strategies are as follows: 1) creating Standards-aligned, inquiry-based curricular resources as ready-to-use materials that can be modified by teachers to fit their unique classroom situation; 2) providing ongoing professional development opportunities that focus on active experiences using curricular materials, inquiry-based techniques and expanding content knowledge; 3) connecting science experts to classrooms to deepen content knowledge and provide relevance to classroom activities and real world applications; 4) facilitating students sharing research with their peers and scientists reinforcing their active participation and contributions to research. These components of the Expedition Earth and Beyond Education Program will be enhanced by providing exciting and diverse research opportunities that are inspired by views of Earth from space taken by astronauts on board the International Space Station. The interest and connection to viewing our home planet from space will inevitably spark questions that will drive students to pursue their research investigations, as well as forming a basis for comparisons to the exploration of other planetary bodies in our solar system.

  7. Rare earth ceramic scintillator

    SciTech Connect

    DiBianca, F. A.; Cusano, D. A.; Georges, J.-P. J.; Greskovich, C. D.

    1985-06-25

    An improved scintillator for a solid state radiation detector useful in CT (computed tomography), DR (digital radiography), and related technologies. The scintillator, rather than being grown as a single crystal, is formed by means of hot pressing or sintering, as a polycrystalline ceramic. Rare earth oxides doped with rare earth activators are selected to yield a cubic crystal structure of high density and transmittance, which satisfies radiation detector requirements better than crystals utilized heretofore.

  8. Multidisciplinary integrated field campaign to an acidic Martian Earth analogue with astrobiological interest: Rio Tinto

    NASA Astrophysics Data System (ADS)

    Gómez, F.; Walter, N.; Amils, R.; Rull, F.; Klingelhöfer, A. K.; Kviderova, J.; Sarrazin, P.; Foing, B.; Behar, A.; Fleischer, I.; Parro, V.; Garcia-Villadangos, M.; Blake, D.; Martin Ramos, J. D.; Direito, S.; Mahapatra, P.; Stam, C.; Venkateswaran, K.; Voytek, M.

    2011-07-01

    Recently reported results from latest Mars Orbiters and Rovers missions are transforming our opinion about the red planet. That dry and inhospitable planet reported in the past is becoming a wetter planet with high probabilities of water existence in the past. Nowadays, some results seem to indicate the presence of water beneath the Mars surface. But also mineralogy studies by NASA Opportunity Rover report iron oxides and hydroxides precipitates on Endurance Crater. Sedimentary deposits have been identified at Meridiani Planum. These deposits must have generated in a dune aqueous acidic and oxidizing environment. Similarities appear when we study Rio Tinto, and acidic river under the control of iron. The discovery of extremophiles on Earth widened the window of possibilities for life to develop in the Universe, and as a consequence on Mars and other planetary bodies with astrobiological interest. The compilation of data produced by the ongoing missions offers an interested view for life possibilities to exist: signs of an early wet Mars and rather recent volcanic activity as well as ground morphological characteristics that seem to be promoted by liquid water. The discovery of important accumulations of sulfates and the existence of iron minerals such as jarosite in rocks of sedimentary origin has allowed specific terrestrial models to come into focus. Río Tinto (Southwestern Spain, Iberian Pyritic Belt) is an extreme acidic environment, product of the chemolithotrophic activity of micro-organisms that thrive in the massive pyrite-rich deposits of the Iberian Pyritic Belt. Some particular protective environments should house the organic molecules and bacterial life forms in harsh environments such as Mars surface supporting microniches inside precipitated minerals or inside rocks. Terrestrial analogues could help us to afford the comprehension of habitability (on other planetary bodies). We are reporting here the multidisciplinary study of some endolithic niches inside salt deposits used by phototrophs for taking advantage of sheltering particular light wavelengths. These acidic salts deposits located in Río Tinto shelter life forms that are difficult to visualize by eye. This interdisciplinary field analogue campaign was conducted in the framework of the CAREX FP7 EC programme.

  9. carleton.ca Earth Sciences

    E-print Network

    Dawson, Jeff W.

    carleton.ca Earth Sciences #12;Earth is our home. It is a dynamic planet, integrating and recording spectrometers or electron microprobes--earth scientists investigate Earth's evolution to help understand future today and for the future is enhanced by the expertise of economic geologists. Knowledge of the Earth

  10. Earth: Earth Science and Health

    NASA Technical Reports Server (NTRS)

    Maynard, Nancy G.

    2001-01-01

    A major new NASA initiative on environmental change and health has been established to promote the application of Earth science remote sensing data, information, observations, and technologies to issues of human health. NASA's Earth Sciences suite of Earth observing instruments are now providing improved observations science, data, and advanced technologies about the Earth's land, atmosphere, and oceans. These new space-based resources are being combined with other agency and university resources, data integration and fusion technologies, geographic information systems (GIS), and the spectrum of tools available from the public health community, making it possible to better understand how the environment and climate are linked to specific diseases, to improve outbreak prediction, and to minimize disease risk. This presentation is an overview of NASA's tools, capabilities, and research advances in this initiative.

  11. Earth materials and earth dynamics

    SciTech Connect

    Bennett, K; Shankland, T. [and others

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  12. Evaluating and improving hydrologic processes in the community land model for integrated earth system modeling

    NASA Astrophysics Data System (ADS)

    Hannah, D. M.; Khamis, K.; Blaen, P. J.; Hainie, S.; Mellor, C.; Brown, L. E.; Milner, A. M.

    2011-12-01

    High climatic sensitivity and low anthropogenic influence make glacierized river basins important environments for examining hydrological and ecological response to global change. This paper synthesises findings from previous and ongoing research in glacierized Alpine and Arctic river basins (located in the French Pyrenees, New Zealand, Swedish Lapland and Svalbard), which adopts an interdisciplinary approach to investigate the climate-cryosphere-hydrology-ecology cascade. Data are used to advance hypotheses concerning the consequences of climate change/ variability on glacier river system hydrology and ecology. Aquatic ecosystems in high latitude and altitude environments are influenced strongly by cryospheric and hydrological processes due to links between atmospheric forcing, snowpack/ glacier mass-balance, river runoff, physico-chemistry and biota. In the current phase of global warming, many glaciers are retreating. Using downscaled regional climate projections as inputs to a distributed hydrological model for a study basin in the French Pyrenees (i.e. an environment at the contemporary limit of valley glaciation), we show how shrinking snow and ice-masses may alter space-time dynamics in basin runoff. Notably, the timing of peak snow- and ice-melt may shift; and the proportion of stream flow sourced from rainfall-runoff (cf. meltwater) may increase. Across our range of Alpine and Arctic study basins, we quantify observed links between relative water source contributions (% meltwater : % groundwater), physico-chemical habitat (e.g. water temperature, electrical conductivity, suspended sediment and channel stability) and benthic communities. At the site scale, results point towards increased community diversity (taxonomic and functional) as meltwater contributions decline and physico-chemical habitat becomes less harsh. However, basin-scale biodiversity may be reduced due to less spatio-temporal heterogeneity in water source contributions and habitats, and the extinction of cold stenothermic specialists. Similar integrated, long-term research into hydroecological connections in other glacierized river basins is vital: (1) to enable robust projections of stream hydrology (water source contributions and physico-chemical habitat) and ecological response under scenarios of future climate/ variability, and (2) to develop conservation strategies for these fragile Alpine and Arctic freshwater ecosystems.

  13. An integrated, open-source set of tools for urban vulnerability monitoring from Earth observation data

    NASA Astrophysics Data System (ADS)

    De Vecchi, Daniele; Harb, Mostapha; Dell'Acqua, Fabio; Aurelio Galeazzo, Daniel

    2015-04-01

    Aim: The paper introduces an integrated set of open-source tools designed to process medium and high-resolution imagery with the aim to extract vulnerability indicators [1]. Problem: In the context of risk monitoring [2], a series of vulnerability proxies can be defined, such as the extension of a built-up area or buildings regularity [3]. Different open-source C and Python libraries are already available for image processing and geospatial information (e.g. OrfeoToolbox, OpenCV and GDAL). They include basic processing tools but not vulnerability-oriented workflows. Therefore, it is of significant importance to provide end-users with a set of tools capable to return information at a higher level. Solution: The proposed set of python algorithms is a combination of low-level image processing and geospatial information handling tools along with high-level workflows. In particular, two main products are released under the GPL license: source code, developers-oriented, and a QGIS plugin. These tools were produced within the SENSUM project framework (ended December 2014) where the main focus was on earthquake and landslide risk. Further development and maintenance is guaranteed by the decision to include them in the platform designed within the FP 7 RASOR project . Conclusion: With the lack of a unified software suite for vulnerability indicators extraction, the proposed solution can provide inputs for already available models like the Global Earthquake Model. The inclusion of the proposed set of algorithms within the RASOR platforms can guarantee support and enlarge the community of end-users. Keywords: Vulnerability monitoring, remote sensing, optical imagery, open-source software tools References [1] M. Harb, D. De Vecchi, F. Dell'Acqua, "Remote sensing-based vulnerability proxies in the EU FP7 project SENSUM", Symposium on earthquake and landslide risk in Central Asia and Caucasus: exploiting remote sensing and geo-spatial information management, 29-30th January 2014, Bishkek, Kyrgyz Republic. [2] UNISDR, "Living with Risk", Geneva, Switzerland, 2004. [3] P. Bisch, E. Carvalho, H. Degree, P. Fajfar, M. Fardis, P. Franchin, M. Kreslin, A. Pecker, "Eurocode 8: Seismic Design of Buildings", Lisbon, 2011. (SENSUM: www.sensum-project.eu, grant number: 312972 ) (RASOR: www.rasor-project.eu, grant number: 606888 )

  14. Preparation and luminescence of nano-sized In2O3 and rare-earth co-doped SiO2 thin films

    Microsoft Academic Search

    Neng Wan; Tao Lin; Jun Xu; Ling Xu; Kunji Chen

    2008-01-01

    The sol-gel method was used to prepare SiO2 thin films co-doped with In2O3 nano-particles and Eu3+. The formation of nano-sized In2O3 particles after annealing at 900 °C was confirmed by the x-ray diffraction technique. A novel phase transition from a hexagonal rhombic centered to a body centered cubic structure of In2O3 nano-particles was observed at around 1100 °C. It is

  15. Incubational domain characterization in lightly doped ceria

    SciTech Connect

    Li Zhipeng, E-mail: Zhipeng@email.unc.edu [Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States); Mori, Toshiyuki [Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); John Auchterlonie, Graeme [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072 (Australia); Zou Jin [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072 (Australia); Division of Materials, University of Queensland, St. Lucia, Brisbane, QLD 4072 (Australia); Drennan, John [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072 (Australia)

    2012-08-15

    Microstructures of both Gd- and Y-doped ceria with different doping level (i.e., 10 at% and 25 at%) have been comprehensively characterized by means of high resolution transmission electron microscopy and selected area electron diffraction. Coherent nano-sized domains can be widely observed in heavily doped ceria. Nevertheless, it was found that a large amount of dislocations actually exist in lightly doped ceria instead of heavily doped ones. Furthermore, incubational domains can be detected in lightly doped ceria, with dislocations located at the interfaces. The interactions between such linear dislocations and dopant defects have been simulated accordingly. As a consequence, the formation mechanism of incubational domains is rationalized in terms of the interaction between intrinsic dislocations of doped ceria and dopant defects. This study offers the insights into the initial state and related mechanism of the formation of nano-sized domains, which have been widely observed in heavily rare-earth-doped ceria in recent years. - Graphical abstract: Interactions between dislocations and dopants lead to incubational domain formation in lightly doped ceria. Highlights: Black-Right-Pointing-Pointer Microstructures were characterized in both heavily and light Gd-/Y-doped ceria. Black-Right-Pointing-Pointer Dislocations are existed in lightly doped ceria rather than heavily doped one. Black-Right-Pointing-Pointer Interactions between dislocations and dopant defects were simulated. Black-Right-Pointing-Pointer Formation of dislocation associated incubational domain is rationalized.

  16. Effect of lanthanum doping on the electrical properties of sol-gel derived ferroelectric lead-zirconate-titanate for ultra-large-scale integration dynamic random access memory applications

    Microsoft Academic Search

    C. Sudhama; J. Kim; J. Lee; V. Chikarmane; W. Shepherd; E. R. Myers

    1993-01-01

    Thin films of lead-zirconate-titanate [(PZT) PbZr{sub 0.5}Ti{sub 0.5})Oâ] possess demonstrably adequate charge storage densities and endurance to read\\/write cycling for ultra-large-scale integration dynamic random access memory (DRAM) applications. Lanthanum (donor) doping is expected to reduce the (p-type) conductivity to acceptable levels (<10⁻⁶ A\\/cm²). In this study, six thin films of 200 nm sol-gel derived lanthanum-doped PZT, with the [La]\\/([La] +

  17. Origins of conductivity improvement in fluoride-enhanced silicon doping of ZnO films.

    PubMed

    Rashidi, Nazanin; Vai, Alex T; Kuznetsov, Vladimir L; Dilworth, Jonathan R; Edwards, Peter P

    2015-05-21

    Fluoride in spray pyrolysis precursor solutions for silicon-doped zinc oxide (SiZO) transparent conductor thin films significantly improves their electrical conductivity by enhancing silicon doping efficiency and not, as previously assumed, by fluoride doping. Containing only earth-abundant elements, SiZO thus prepared rivals the best solution-processed indium-doped ZnO in performance. PMID:25879727

  18. Absorption and photoluminescence of Ga 0.017Ge 0.25As 0.083S 0.65 glasses doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Iovu, M. S.; Andriesh, A. M.; Lupan, E. V.; Ciornea, V. I.; Syrbu, N. N.

    2007-08-01

    The visible luminescence from Pr 3+, Dy 3+, Nd 3+, Sm 3+ and codoped with Ho 3+ and Dy 3+ ions embedded in Ga 0.017Ge 0.25As 0.083S 0.65 glass hosts at room temperature and at T=10 K is reported, when pumping with an Ar +-ion laser at ?=488 nm. Fluorescence emissions at 1.3 ?m was observed for Dy 3+ and both at 1.3 and at 1.5 ?m for Pr 3+ doped glasses with wavelength pumping at 950 nm. Energy transfer from Ho 3+: 5F 3 level to Dy 3+: 4F 9/2 level increase the visible emission efficiency at 650 nm in the codoped glasses. The investigated Ga 0.017Ge 0.25As 0.083S 0.65 glasses doped with Pr 3+ are promising amplifier materials for 1.3 and 1.5 ?m fiber optic telecommunication windows.

  19. Flat earth upward continuation

    Microsoft Academic Search

    John V. Shebalin

    1979-01-01

    For a thorough understanding of flat earth upward continuation, Poisson's integral equation is transformed from a coordinate system with spherical symmetry to one with planar symmetry. The two separate cases of infinite and finite flat earths are considered. In resulting exact forms a functional factor in the integrands is isolated, a factor which allows the translation of a spherical earth

  20. The EOS Aqua/Aura Experience: Lessons Learned on Design, Integration, and Test of Earth-Observing Satellites

    NASA Technical Reports Server (NTRS)

    Nosek, Thomas P.

    2004-01-01

    NASA and NOAA earth observing satellite programs are flying a number of sophisticated scientific instruments which collect data on many phenomena and parameters of the earth's environment. The NASA Earth Observing System (EOS) Program originated the EOS Common Bus approach, which featured two spacecraft (Aqua and Aura) of virtually identical design but with completely different instruments. Significant savings were obtained by the Common Bus approach and these lessons learned are presented as information for future program requiring multiple busses for new diversified instruments with increased capabilities for acquiring earth environmental data volume, accuracy, and type.

  1. Effect of Mn doping on structural and magnetic susceptibility of C-type rare earth nano oxides Er{sub 2?x}Mn{sub x}O{sub 3}

    SciTech Connect

    Heiba, Zein K. [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt) [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Taif University, Faculty of Science, Physics Department (Saudi Arabia); Mohamed, Mohamed Bakr, E-mail: mbm1977@yahoo.com [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Fuess, H. [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)] [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ? Er{sub 2?x}Mn{sub x}·O{sub 3} (0.0 ? x ? 0.20) prepared by sol–gel method. ? The change in lattice parameter is not linear with x due to the change in crystallite size with doping. ? Anomalous concentration dependence is found in magnetic susceptibility. ? The effective magnetic moment ?{sub eff} is found to decrease with composition parameter x. ? Superexchange interactions between Er ions depending on the amount of Mn or Er in different sites. -- Abstract: The manganese doped rare earth oxides Er{sub 2?x}Mn{sub x} O{sub 3} (0.0 ? x ? 0.20) were synthesized by a sol–gel process and analyzed by X-ray diffraction using Rietveld refinement methods. A single phase solid solution is formed up to x = 0.15 while for x ? 0.2 a manganese oxide phase appears in the diffraction pattern. Preferential cationic distribution between the non-equivalent sites 8b and 24d of space group Ia3{sup ¯} is found for all samples but to a different extent. The octahedral volume and average bond length of Er{sub 1}-O for 8b site decrease while both octahedral volume and bond length of Er{sub 2}-O for 24d site increase. Magnetization measurements were done in the temperature range 5–300 K. The effective magnetic moment ?{sub eff} is found to decrease with composition parameter x, except for sample x = 0.05 where the magnetization is enhanced. The Curie-Weiss paramagnetic temperatures indicate antiferromagnetic interaction.

  2. Information Technology Infusion Case Study: Integrating Google Earth(Trademark) into the A-Train Data Depot

    NASA Technical Reports Server (NTRS)

    Smith, Peter; Kempler, Steven; Leptoukh, Gregory; Chen, Aijun

    2010-01-01

    This poster paper represents the NASA funded project that was to employ the latest three dimensional visualization technology to explore and provide direct data access to heterogeneous A-Train datasets. Google Earth (tm) provides foundation for organizing, visualizing, publishing and synergizing Earth science data .

  3. The Use of the Integrated Medical Model for Forecasting and Mitigating Medical Risks for a Near-Earth Asteroid Mission

    NASA Technical Reports Server (NTRS)

    Kerstman, Eric; Saile, Lynn; Freire de Carvalho, Mary; Myers, Jerry; Walton, Marlei; Butler, Douglas; Lopez, Vilma

    2011-01-01

    Introduction The Integrated Medical Model (IMM) is a decision support tool that is useful to space flight mission managers and medical system designers in assessing risks and optimizing medical systems. The IMM employs an evidence-based, probabilistic risk assessment (PRA) approach within the operational constraints of space flight. Methods Stochastic computational methods are used to forecast probability distributions of medical events, crew health metrics, medical resource utilization, and probability estimates of medical evacuation and loss of crew life. The IMM can also optimize medical kits within the constraints of mass and volume for specified missions. The IMM was used to forecast medical evacuation and loss of crew life probabilities, as well as crew health metrics for a near-earth asteroid (NEA) mission. An optimized medical kit for this mission was proposed based on the IMM simulation. Discussion The IMM can provide information to the space program regarding medical risks, including crew medical impairment, medical evacuation and loss of crew life. This information is valuable to mission managers and the space medicine community in assessing risk and developing mitigation strategies. Exploration missions such as NEA missions will have significant mass and volume constraints applied to the medical system. Appropriate allocation of medical resources will be critical to mission success. The IMM capability of optimizing medical systems based on specific crew and mission profiles will be advantageous to medical system designers. Conclusion The IMM is a decision support tool that can provide estimates of the impact of medical events on human space flight missions, such as crew impairment, evacuation, and loss of crew life. It can be used to support the development of mitigation strategies and to propose optimized medical systems for specified space flight missions. Learning Objectives The audience will learn how an evidence-based decision support tool can be used to help assess risk, develop mitigation strategies, and optimize medical systems for exploration space flight missions.

  4. Effect of rare-earth composition on microstructure and pinning properties of Zr-doped (Gd,Y)Ba2Cu3Ox superconducting tapes

    NASA Astrophysics Data System (ADS)

    Selvamanickam, V.; Chen, Y.; Zhang, Y.; Guevara, A.; Shi, T.; Yao, Y.; Majkic, G.; Lei, C.; Galtsyan, E.; Miller, D. J.

    2012-04-01

    The effect of changing Gd + Y content from 1.2 to 1.6 in the precursor of (Gd,Y)Ba2Cu3O7 superconducting thin film tapes made by metal organic chemical vapor deposition (MOCVD) at a constant Gd:Y ratio and a fixed Zr content of 7.5% has been studied. The influence of changing the Gd:Y ratio from Gd = 0 to Y= 0 in 0.2 mol steps at a constant Gd + Y content of 1.2 in the precursor has also been investigated at a fixed Zr content of 7.5%. The critical current of these films is found to vary significantly as a function of rare-earth content as well as a function of rare-earth type. Even for a fixed Zr content, it is found that the critical current in the orientation of magnetic field parallel to the a-b plane and that in the orientation of field perpendicular to the a-b plane can be systematically varied with changing Gd + Y content as well as with changing Gd:Y ratio. The nanoscale defect structures along the a-b plane and along the c-axis are found to be sensitive to these changes in rare-earth content and type.

  5. Characterizing an Integrated Annual Global Measure of the Earth's Maximum Land Surface Temperatures from 2003 to 2012 Reveals Strong Biogeographic Influences

    NASA Astrophysics Data System (ADS)

    Mildrexler, D. J.; Zhao, M.; Running, S. W.

    2014-12-01

    Land Surface Temperature (LST) is a good indicator of the surface energy balance because it is determined by interactions and energy fluxes between the atmosphere and the ground. The variability of land surface properties and vegetation densities across the Earth's surface changes these interactions and gives LST a unique biogeographic influence. Natural and human-induced disturbances modify the surface characteristics and alter the expression of LST. This results in a heterogeneous and dynamic thermal environment. Measurements that merge these factors into a single global metric, while maintaining the important biophysical and biogeographical factors of the land surface's thermal environment are needed to better understand integrated temperature changes in the Earth system. Using satellite-based LST we have developed a new global metric that focuses on one critical component of LST that occurs when the relationship between vegetation density and surface temperature is strongly coupled: annual maximum LST (LSTmax). A 10 year evaluation of LSTmax histograms that include every 1-km pixel across the Earth's surface reveals that this integrative measurement is strongly influenced by the biogeographic patterns of the Earth's ecosystems, providing a unique comparative view of the planet every year that can be likened to the Earth's thermal maximum fingerprint. The biogeographical component is controlled by the frequency and distribution of vegetation types across the Earth's land surface and displays a trimodal distribution. The three modes are driven by ice covered polar regions, forests, and hot desert/shrubland environments. In ice covered areas the histograms show that the heat of fusion results in a convergence of surface temperatures around the melting point. The histograms also show low interannual variability reflecting two important global land surface dynamics; 1) only a small fraction of the Earth's surface is disturbed in any given year, and 2) when considered at the global scale, the positive and negative climate forcings resulting from the aggregate effects of the loss of vegetation to disturbances and the regrowth from natural succession are roughly in balance. Changes in any component of the histogram can be tracked and would indicate a major change in the Earth system.

  6. Effects of PbF2 doping on structure and spectroscopic properties of Ga2O3-GeO2-Bi2O3-PbO glasses doped with rare earths

    NASA Astrophysics Data System (ADS)

    Zhang, Q. Y.; Li, T.; Shi, D. M.; Yang, G. F.; Yang, Z. M.; Jiang, Z. H.; Buddhudu, S.

    2006-02-01

    We report an intense room-temperature blue upconversion in Tm3+/Yb+3-codoped Ga2O3-GeO2-Bi2O3-PbO(PbF2) glasses upon excitation with a convenient 980 nm laser diode. Effects of PbF2 doping on the thermal stability, structure, and upconversion properties of Tm3+/Yb3+-codoped gallate-germanium-bismuth-lead glasses have been investigated. We find that the presence of PbF2 provides two potentials: shortening the ultraviolet cutoff band and decreasing the phonon energy of host glasses. The blue-upconversion intensity has a cubelike dependence on incident pump-laser power, indicating a three-photon process. Energy-transfer process and nonradiative phonon-assisted decay could be responsible for the population of the 1G4 emitting level of the Tm3+. The results indicate the potential possibility towards the development of an oxide-based blue-upconversion glass-fiber laser.

  7. Energies of 4f^N and 4f^N-15d States Relative to Host Bands in Rare-earth-doped Fluorides

    Microsoft Academic Search

    C. W. Thiel; M.-F. Joubert; A. Tkachuk

    2005-01-01

    Energies of 4f^N states relative to crystal band states were measured for rare-earth ions in the optical host materials LiYF4, Na0.4Y0.6F2.2, and LaF3 using x-ray photoemission spectroscopy. Spectra were modeled to determine the valence band maximum and 4f^ electron binding energies in each material. These results were combined with 4f^N to 4f^N-15d transition energies to determine 5d binding energies for

  8. The characterization and mechanism of long afterglow in alkaline earth aluminates phosphors co-doped by Eu 2O 3 and Dy 2O 3

    Microsoft Academic Search

    Yuanhua Lin; Zhongtai Zhang; Zilong Tang; Junying Zhang; Zishan Zheng; Xiao Lu

    2001-01-01

    Long afterglow alkaline earth aluminates MAl2O4:Eu, Dy (M: Ca, Sr, Ba) phosphors were prepared at high temperature and weak reductive atmosphere. The excitation and emission spectra of these phosphors indicated that all of them are broad band, and the main emission peaks around 445, 496 and 518nm of CaAl2O4:Eu, Dy, BaAl2O4:Eu, Dy and SrAl2O4:Eu, Dy, respectively, are due to 5d?4f

  9. Enhancement of Ferroelectricity in Rare Earth and Manganese Ions Co-doped BiFeO3 Thin Films via Chemical Solution Deposition Method

    Microsoft Academic Search

    C. M. Raghavan; J. W. Kim; S. S. Kim; M. H. Kim; T. K. Song

    2012-01-01

    The structural and electrical properties of BiFeO3 (BFO) and rare earth metal ions (Re) co-substituted (Bi0.9Re0.1)(Fe0.9Mn0.1)O3-? (Re = Nd, Sm, Ce and Tb) thin films prepared on Pt(111)\\/Ti\\/SiO2\\/Si(100) substrates via a chemical solution deposition method were investigated. The significant decrease of leakage current density and improved ferroelectric properties were observed from the co-substituted thin films. The largest remnant polarization (2Pr)

  10. EarthLabs: Teacher's Guide

    NSDL National Science Digital Library

    The EarthLabs project provides a national model for rigorous and engaging Earth and environmental science labs. The activities in each EarthLabs topic represent a lab sequence for an integrated instructional unit. Six topics are available: corals, cryosphere, drought, earth system science, fisheries and hurricanes. There are six to nine labs within each topic with complete directions.

  11. Distributed Infrastructure Enabling Effective Integration of Earth Observation Information Resources for Collective Solution of Archiving, Searching, Processing and EO Data Analyzing Tasks

    NASA Astrophysics Data System (ADS)

    Savorskiy, V. P.; Lupyan, E. A.; Kaevitser, V. I.; Smirnov, M. T.; Ermakov, D. M.; Balashov, I. V.; Bourtsev, M. A.; Efremov, V. Yu; Proshin, A. A.; Tolpin, V. A.; Uvarov, L. A.; Flitman, E. V.

    2012-07-01

    Numerous applications of Earth observation (EO) data for Earth resource exploration both for land use management purposes and for fundamental research goals require as much as possible independent EO data sets provided for a number of data consumers, i.e. for collective (shared) data usage. In addition data distribution procedures should be accompanied with sophisticated information services enabling correct interpretation and application of provided data. As a result data providers should be able to convert data in a lot of consumer-proper formats and in some cases it should require additional data processing before data shipping. Presented work proposes basic infrastructure for collective (shared) EO data usage that enables above mentioned integration of information resources contained in typical Russian EO centers. Paper reveals architecture design, description of basic infrastructure elements, and examples of real implementations.

  12. Role of rare-earth Ba2+ doping in governing the superconducting and mechanical characteristics of Bi Sr Ca Cu O

    NASA Astrophysics Data System (ADS)

    Khalil, S. M.

    2005-08-01

    The effect of barium doping on the superconducting and mechanical properties in the Bi2Sr2Ca2BaxCu5Oy (BSCCO) system has been investigated by thermoelectric power (TEP), Vickers microhardness (VHN), x-ray diffraction (XRD), and scanning electron microscope (SEM) analysis. Barium was incorporated with x ranging from 0.0 to 0.82. The temperature variation of the thermopower (Seebeck coefficient) S shows that the critical transition temperature Tc0 is enhanced (to 93 K) up to x = 0.45 and then disappears for x = 0.82. The results have also suggested an increased interaction of electrons and holes with phonons at low temperatures. The enhancement of Tc0 is ascribed to the improvement in electric connection between superconducting grains. XRD data show that the high-Tc (2:2:2:3) phase increases and the low-Tc (2:2:1:2) phase decreases as the barium concentration changes from x = 0.0 to 0.45. SEM analysis of a sample (x = 0.45) shows that plate-like grains (2223 phase) are formed. Also, an appropriate level of Ba dopant improves the microhardness and fracture toughness remarkably. The optimum dopant level of Ba from the point of view of mechanical properties is x = 0.45. The improvement of mechanical characteristics is due to the fact that Ba2+ can fill the intergrain spaces, and thereby reinforce the coupling between granules. From the above results, it is inferred that the added Ba has the positive effect of decomposing the structure of the low-Tc phase, leading to the production of BaBiO3 and BaCuO2 and enhancing the high-Tc phase creation.

  13. Earth Sciences Environmental Earth Sciences,

    E-print Network

    Brierley, Andrew

    94 Earth Sciences­ Environmental Earth Sciences, Geology Degree options MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint placement. * The Geology and Environmental Earth Sciences degrees are accredited by the Geological Society

  14. Integrating Science Content and Pedagogy in the Earth, Life, and Physical Sciences: A K-8 Pre-Service Teacher Preparation Continuum at the University of Delaware

    NASA Astrophysics Data System (ADS)

    Madsen, J.; Allen, D.; Donham, R.; Fifield, S.; Ford, D.; Shipman, H.; Dagher, Z.

    2007-12-01

    University of Delaware faculty in the geological sciences, biological sciences, and the physics and astronomy departments have partnered with faculty and researchers from the school of education to form a continuum for K- 8 pre-service teacher preparation in science. The goal of the continuum is to develop integrated understandings of content and pedagogy so that these future teachers can effectively use inquiry-based approaches in teaching science in their classrooms. Throughout the continuum where earth science content appears an earth system science approach, with emphasis on inquiry-based activities, is employed. The continuum for K-8 pre-service teachers includes a gateway content course in the earth, life, or physical sciences taken during the freshman year followed by integrated science content and methods courses taken during the sophomore year. These integrated courses, called the Science Semester, were designed and implemented with funding from the National Science Foundation. During the Science Semester, traditional content and pedagogy subject matter boundaries are crossed to stress shared themes that teachers must understand to teach standards-based science. Students work collaboratively on multidisciplinary problem-based learning (PBL) activities that place science concepts in authentic contexts and build learning skills. They also critically explore the theory and practice of elementary science teaching, drawing on their shared experiences of inquiry learning during the Science Semester. The PBL activities that are the hallmark of the Science Semester provide the backdrop through which fundamental earth system interactions can be studied. For example in a PBL investigation that focuses on kids, cancer, and the environment, the hydrologic cycle with emphasis on surface runoff and ground water contamination is studied. Those students seeking secondary certification in science will enroll, as a bridge toward their student teaching experience, in an additional content course within a science discipline that is concurrently taught with a science methods course. Emphasizing inquiry-based activities, these bridge courses also focus on developing integrated understandings of the sciences. The continuum extends beyond the student teaching experience by tracking cohorts of science teachers during their in-service years. With funding from the National Science Foundation's Teacher Professional Continuum program, we are conducting research on this inquiry-based professional development approach for K-8 teachers across this continuum.

  15. Practicing ESD at School: Integration of Formal and Nonformal Education Methods Based on the Earth Charter (Belarusian Experience)

    ERIC Educational Resources Information Center

    Savelava, Sofia; Savelau, Dmitry; Cary, Marina Bakhnova

    2010-01-01

    The Earth Charter represents the philosophy and ethics necessary to create a new period of human civilization. Understanding and adoption of this new vision is the most important mission of education for sustainable development (ESD). This article argues that for successful implementation of ESD principles at school, the school education system…

  16. EarthScope's Plate Boundary Observatory in Alaska: Building on Existing Infrastructure to Provide a Platform for Integrated Research and Hazard-monitoring Efforts

    NASA Astrophysics Data System (ADS)

    Boyce, E. S.; Bierma, R. M.; Willoughby, H.; Feaux, K.; Mattioli, G. S.; Enders, M.; Busby, R. W.

    2014-12-01

    EarthScope's geodetic component in Alaska, the UNAVCO-operated Plate Boundary Observatory (PBO) network, includes 139 continuous GPS sites and 41 supporting telemetry relays. These are spread across a vast area, from northern AK to the Aleutians. Forty-five of these stations were installed or have been upgraded in cooperation with various partner agencies and currently provide data collection and transmission for more than one group. Leveraging existing infrastructure normally has multiple benefits, such as easier permitting requirements and costs savings through reduced overall construction and maintenance expenses. At some sites, PBO-AK power and communications systems have additional capacity beyond that which is needed for reliable acquisition of GPS data. Where permits allow, such stations could serve as platforms for additional instrumentation or real-time observing needs. With the expansion of the Transportable Array (TA) into Alaska, there is increased interest to leverage existing EarthScope resources for station co-location and telemetry integration. Because of the complexity and difficulty of long-term O&M at PBO sites, however, actual integration of GPS and seismic equipment must be considered on a case-by-case basis. UNAVCO currently operates two integrated GPS/seismic stations in collaboration with the Alaska Earthquake Center, and three with the Alaska Volcano Observatory. By the end of 2014, PBO and TA plan to install another four integrated and/or co-located geodetic and seismic systems. While three of these are designed around existing PBO stations, one will be a completely new TA installation, providing PBO with an opportunity to expand geodetic data collection in Alaska within the limited operations and maintenance phase of the project. We will present some of the design considerations, outcomes, and lessons learned from past and ongoing projects to integrate seismometers and other instrumentation at PBO-Alaska stations. Developing the PBO network as a platform for ongoing research and hazard monitoring equipment may also continue to serve the needs of the research community and the public beyond the sun-setting and completion of EarthScope science plan in 2018.

  17. Earth as a System

    NSDL National Science Digital Library

    WGBH/Boston

    This short video uses animated imagery from satellite remote sensing systems to illustrate that Earth is a complex, evolving body characterized by ceaseless change. Adapted from NASA, this visualization helps explain why understanding Earth as an integrated system of components and processes is essential to science education.

  18. Mapping of integrated radon emanation for detection of long-distance migration of gases within the earth: Techniques and principles

    Microsoft Academic Search

    Robert L. Fleischer; Antonio Mogro-Campero

    1978-01-01

    Integrated measurements of radon concentrations within the ground but close to the surface are being used extensively in search for premonitory signals from earthquakes and in exploration for uranium. We present a description of the different components of the radon signals that may be present and describe methods for separating them. We also show quantitatively what signals the different radon-integrating

  19. Ceria co-doping: Synergistic or average effect? Mario Burbano,1

    E-print Network

    Paris-Sud XI, Université de

    -75005 Paris, France Ceria (CeO2) co-doping has been suggested as a means to achieve ionic conductivities- trolytes, in particular those based on doped ceria (CeO2). Fluorite-structured materials, such as CeO2, Zr with lower valent cations[13]. For example, CeO2 is usually doped with Rare Earth cations (RE = lanthanides

  20. Creep and Fatigue Behavior of SnAg Solders With Lanthanum Doping

    Microsoft Academic Search

    Min Pei; Jianmin Qu

    2008-01-01

    In this paper, extensive testing was conducted to study the effects of Lanthanum (La) doping on the creep and fatigue behavior of SnAg lead free solder alloys. Variables considered in this paper include doping amount, aging temperature, and aging time. The experimental data show that rare earth element (RE) doping increases SnAg solders creep resistance by about 15%. Meanwhile, RE

  1. Observation of frequency doubling in tantalum doped silica fibres

    NASA Technical Reports Server (NTRS)

    Driscoll, T. J.; Lawandy, N. M.; Killian, A.; Rienhart, L.; Morse, T. F.

    1991-01-01

    Second harmonic conversion efficients of 3 x 0,0001 in tantalum-doped silica fibers prepared by the seeding technique are reported. A series of experiments were conducted to characterize the frequency doubling in this fiber and to compare the results to the behavior observed in germanosilicate and rare earth-doped aluminosilicate fibers.

  2. Spectral hole burning measurement thulium-doped fiber amplifiers

    Microsoft Academic Search

    Fabien Roy; Dominique Bayart; Céline Heerdt; André Le Sauze; Pascal Baniel

    2002-01-01

    An accurate technique was implemented to measure spectral hole burning in rare-earth amplifiers at room temperature, showing that thulium-doped fiber amplifiers exhibit hole depths four times lower than those of C-band erbium-doped fiber amplifiers.

  3. Solid-State Syntheses of Rare-Earth-Doped Sr1-xLn2x\\/3MgP2O7 (Ln = Gd, Eu, Dy, Sm, Pr, and Nd; x = 0.05) by Metathesis Reactions and their Spectroscopic Characterization

    Microsoft Academic Search

    Radha Velchuri; B. Vijaya Kumar; V. Rama Devi; D. Jaya Prakash; M. Vithal

    2011-01-01

    Rare-earth–doped strontium magnesium diphosphates of composition Sr1-xLn2x\\/3MgP2O7 (Ln = Gd, Eu, Dy, Sm, Pr, and Nd; x = 0.05) were prepared by metathesis reaction. These diphosphates were characterized by powder X-ray diffraction (XRD), energy dispersive spectra (EDS), and infrared spectroscopy. All these compounds were found to crystallize in monoclinic lattice with P21\\/n space group. The compositions of all the samples were confirmed from their

  4. A model of recent vertical movements of the earth's surface in Lithuania: integration of geodetic levelling data and geological parameters

    NASA Astrophysics Data System (ADS)

    Zakarevi?ius, Algimantas; Šliaupa, Saulius; Anik?nien?, Asta; D?nas, Žydr?nas; Šliaupien?, Rasa

    2008-01-01

    The precise geodetic levelling reveals the recent activity of the vertical movements of the earth's crust. However, the main shortcoming of the levelling networks is scarceness of the measurement tracks that cannot be compensated for by a high density of the levelling sites within the tracks. The pattern and trends of vertical movements between the measured lines remain unknown. A special approach has been developed to allow prediction of vertical movements within the test grounds. It is based on the multicomponent statistical correlation of the levelling data with the significant geological parameters. The correlations between among parameters were derived separately for each particular test ground and then combined into one common model. It allowed compilation of a rather detailed map of vertical movements in Lithuania during the past 30-40 years. The rate of vertical movements of the earth's surface, obtained from the geodetic levelling, varies from -2.7 mm to 3.5 mm/y. The closest correlation of the recent movements was identified for the topography and the sub-Quaternary surface. It indicates that the major morphological features of Lithuania have a tectonic background. Furthermore, a close correlation was obtained with the gravity and in some parts with the magnetic fields which reflect the deep structure of the earth's crust. A close correlation suggests that the heterogeneity of the crust is important for the distribution of its vertical movements. The application of the close correlation with the geoparameters allowed a considerable improvement of the map of the vertical movements in Lithuania.

  5. Ceria co-doping: Synergistic or average effect?

    E-print Network

    Burbano, Mario; Marrocchelli, Dario; Salanne, Mathieu; Watson, Graeme W

    2014-01-01

    Ceria (CeO$_{2}$) co-doping has been suggested as a means to achieve ionic conductivities that are significantly higher than those in singly-doped systems. Rekindled interest in this topic over the last decade has given rise to claims of much improved performance. The present study makes use of computer simulations to investigate the bulk ionic conductivity of Rare Earth (RE) doped ceria, where RE = Sc, Gd, Sm, Nd and La. The results from the singly doped systems are compared to those from ceria co-doped with Nd/Sm and Sc/La. The pattern that emerges from the conductivity data is consistent with the dominance of local lattice strains from individual defects, rather than the synergistic co-doping effect reported recently and, as a result no enhancement in the conductivity of co-doped samples is observed.

  6. Integration of (208) oriented epitaxial Hf-doped Bi4Ti3O12 with (0002) GaN using SrTiO3\\/TiO2 buffer layer

    Microsoft Academic Search

    W. B. Luo; J. Zhu; Y. R. Li; X. P. Wang; Y. Zhang

    2009-01-01

    Hf-doped Bi4Ti3O12 (BTH) ferroelectric films with excellent electrical properties were epitaxially integrated with GaN semiconductor using (111) SrTiO3 (STO)\\/rutile (200) TiO2 as buffer layer. The STO\\/TiO2 buffer layer was deposited by laser molecular beam epitaxy. The structural characteristics of the buffer layer were in situ and ex situ characterized by reflective high energy electron diffraction, x-ray diffraction (XRD), and high

  7. Expedition Earth and Beyond: Engaging Classrooms in Student-Led Research Using NASA Data, Access to Scientists, and Integrated Educational Strategies

    NASA Technical Reports Server (NTRS)

    Graff, P. V.; Stefanov, W. L.; Willis, K. J.; Runco, S.; McCollum, T.; Baker, M.; Lindgren, C.; Mailhot, M.

    2011-01-01

    Classroom teachers are challenged with engaging and preparing today s students for the future. Activities are driven by state required skills, education standards, and high-stakes testing. Providing educators with standards-aligned, inquiry-based activities that will help them engage their students in student-led research in the classroom will help them teach required standards, essential skills, and help inspire their students to become motivated learners. The Astromaterials Research and Exploration Science (ARES) Education Program, classroom educators, and ARES scientists at the NASA Johnson Space Center created the Expedition Earth and Beyond education program to help teachers promote student-led research in their classrooms (grades 5-14) by using NASA data, providing access to scientists, and using integrated educational strategies.

  8. Development of response models for the Earth Radiation Budget Experiment (ERBE) sensors. Part 2: Analysis of the ERBE integrating sphere ground calibration

    NASA Technical Reports Server (NTRS)

    Halyo, Nesim; Taylor, Deborah B.

    1987-01-01

    An explicit solution of the spectral radiance leaving an arbitrary point on the wall of a spherical cavity with diffuse reflectivity is obtained. The solution is applicable to spheres with an arbitrary number of openings of any size and shape, an arbitrary number of light sources with possible non-diffuse characteristics, a non-uniform sphere wall temperature distribution, non-uniform and non-diffuse sphere wall emissivity and non-uniform but diffuse sphere wall spectral reflectivity. A general measurement equation describing the output of a sensor with a given field of view, angular and spectral response measuring the sphere output is obtained. The results are applied to the Earth Radiation Budget Experiment (ERBE) integrating sphere. The sphere wall radiance uniformity, loading effects and non-uniform wall temperature effects are investigated. It is shown that using appropriate interpretation and processing, a high-accuracy short-wave calibration of the ERBE sensors can be achieved.

  9. Microstructure and electroluminescent performance of chemical vapor deposited zinc sulfide doped with manganese films for integration in thin film electroluminescent devices

    NASA Astrophysics Data System (ADS)

    Topol, Anna Wanda

    Zinc sulfide (ZnS) doped with manganese (Mn), ZnS:Mn, is widely recognized as the brightest and most effective electroluminescent (EL) phosphor used in current thin film electroluminescent (TFEL) devices. ZnS acts as a host lattice for the luminescent activator, Mn, leading to a highly efficient yellow-orange EL emission, and resulting in a wide array of applications in monochrome, multi-color and full color displays. Although this wide band dap (3.7 eV) material can be prepared by several deposition techniques, the chemical vapor deposition (CVD) is the most promising for TFEL applications in terms of viable deposition rates, high thickness and composition uniformity, and excellent yield over large area panels. This study describes the development and optimization of a CVD ZnS:Mn process using diethylzinc [(C2H5)2Zn, DEZ], di-pi-cyclopentadienylmanganese [(C5H5)2Mn, CPMn], and hydrogen sulfide [H2S] as the chemical sources for, respectively, Zn, Mn, and S. The effects of key deposition parameters on resulting Film microstructure and performance are discussed, primarily in the context of identifying an optimized process window for best electroluminescence behavior. In particular, substrate temperature was observed to play a key role in the formation of high quality crystalline ZnS:Mn films leading to improved brightness and EL efficiency. Further investigations of the influence of temperature treatment on the structural characteristics and EL performance of the CVD ZnS:Mn film were carried out. In this study, the influence of post-deposition annealing both in-situ and ex-situ annealing processes, on chemical, structural, and electroluminescent characteristics of the phosphor layer are described. The material properties of the employed dielectric are among the key factors determining the performance, stability and reliability of the TFEL display and therefore, the choice of dielectric material for use in ACTFEL displays is crucial. In addition, the luminous efficiency depends on the density of the interface states and their depth at the insulator-phosphor interfaces. Hence, critical integration issues are discussed in terms of the incorporation of ZnS:Mn films in dielectricsemiconductor-dielectric (DSD) structures with silicon nitride (SiNx) and aluminum titanium oxide (ATO) as top and bottom insulators.

  10. Allowance for the influence of geopotential in the high-precision numerical integration of artificial-earth-satellite orbits

    Microsoft Academic Search

    Iu. D. Stepin

    1982-01-01

    The paper considers the influence of discarded terms of the geopotential expansion on the error in the prediction of satellite orbit position in the case of high-precision numerical integration in rectangular coordinates. Upper summation bounds are presented, which assure the achievement of prescribed prediction precision for various orbits and time intervals.

  11. Earth's Three

    E-print Network

    Hacker, Randi

    2010-11-17

    Broadcast Transcript: From Mongolia, land of fermented mare's milk, comes this beguiling morsel of nomadic oral tradition. It's called yertonciin gorav or Earth's Three. Earth's three what? Well, Earth's three top things in a number of categories...

  12. Earth's Atmosphere

    NSDL National Science Digital Library

    2012-08-03

    This problem set is about the methods scientists use to compare the abundance of the different elements in Earth's atmosphere. Answer key is provided. This is part of Earth Math: A Brief Mathematical Guide to Earth Science and Climate Change.

  13. Earth Sciences Environmental Earth Sciences,

    E-print Network

    Brierley, Andrew

    84 Earth Sciences­ Environmental Earth Sciences, Geology MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint Honours Degrees) and among the most research-intensive in Europe. Features * The Department of Earth and Environmental

  14. Peru Water Resources: Integrating NASA Earth Observations into Water Resource Planning and Management in Perus La Libertad Region

    NASA Technical Reports Server (NTRS)

    Padgett-Vasquez, Steve; Steentofte, Catherine; Holbrook, Abigail

    2014-01-01

    Developing countries often struggle with providing water security and sanitation services to their populations. An important aspect of improving security and sanitation is developing a comprehensive understanding of the country's water budget. Water For People, a non-profit organization dedicated to providing clean drinking water, is working with the Peruvian government to develop a water budget for the La Libertad region of Peru which includes the creation of an extensive watershed management plan. Currently, the data archive of the necessary variables to create the water management plan is extremely limited. Implementing NASA Earth observations has bolstered the dataset being used by Water For People, and the METRIC (Mapping EvapoTranspiration at High Resolution and Internalized Calibration) model has allowed for the estimation of the evapotranspiration values for the region. Landsat 8 imagery and the DEM (Digital Elevation Model) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor onboard Terra were used to derive the land cover information, and were used in conjunction with local weather data of Cascas from Peru's National Meteorological and Hydrological Service (SENAMHI). Python was used to combine input variables and METRIC model calculations to approximate the evapotranspiration values for the Ochape sub-basin of the Chicama River watershed. Once calculated, the evapotranspiration values and methodology were shared Water For People to help supplement their decision support tools in the La Libertad region of Peru and potentially apply the methodology in other areas of need.

  15. Vector Diffraction Integrals for Solving Inverse Problems of Radio-Holographic Sensing of the Earth's Surface and Atmosphere

    NASA Astrophysics Data System (ADS)

    Pavelyev, A. G.

    2004-01-01

    Vector relationships between the fields on a certain surface confining an inhomogeneous three-dimensional volume and the fields inside this volume are obtained by the Stratton-Chu method developed for the case of homogeneous media. The vector relationships allow us to solve the direct and inverse problems of determining the fields inside an inhomogeneous medium given the field on its boundary. The vector equations take into acount the polarization changes of direct and inverse waves propagated in an inhomogeneous medium. In the case of a two-dimensional homogeneous medium, the vector equations reduce to the previously obtained scalar equations used in the approximation of spherical symmetry to describe the process of backward wave propagation during the atmospheric and ionospheric radio-occultation monitoring. It is shown that the Green's function of the scalar wave equation in an inhomogeneous medium should be used as the reference signal for solving the inverse problem of radio-occultation monitoring. This validates the method of focused synthetic aperture previously used for high-accuracy retrieval of the vertical refractive-index profiles in the ionosphere and atmosphere. In this method, the reference-signal phase was determined from a model which describes with sufficient accuracy the radiophysical parameters of a refracting medium in the region of radio-occultation sensing. The obtained equations can be used for the high-accuracy solving of inverse problems of radio-holographic sensing of the Earth's atmosphere and surface by precision signals from radio-navigation satellites.

  16. Use of geochemical signatures, including rare earth elements, in mosses and lichens to assess spatial integration and the influence of forest environment

    NASA Astrophysics Data System (ADS)

    Gandois, L.; Agnan, Y.; Leblond, S.; Séjalon-Delmas, N.; Le Roux, G.; Probst, A.

    2014-10-01

    In order to assess the influence of local environment and spatial integration of Trace Metals (TM) by biomonitors, Al, As, Cd, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Sb, Sn, V and Zn and some rare earth element (REE) concentrations have been measured in lichens and mosses collected in three French forest sites located in three distinct mountainous areas, as well as in the local soil and bedrock, and in both bulk deposition (BD) and throughfall (TF). Similar enrichment factors (EF) were calculated using lichens and mosses and local bedrock for most elements, except for Cs, Mn, Ni, Pb, and Cu which were significantly (KW, p < 0.05) more enriched in mosses. Similar REE ratios were measured in soils, bedrock, lichens and mosses at each study sites, indicating a regional integration of atmospheric deposition by both biomonitors. Both TM signature and REE composition of mosses revealed that this biomonitor is highly influenced by throughfall composition, and reflect atmospheric deposition interaction with the forest canopy. This explained the higher enrichment measured in mosses for elements which concentration in deposition were influenced by the canopy, either due to leaching (Mn), direct uptake (Ni), or dry deposition dissolution (Pb, Cu, Cs).

  17. Influence of Al\\/Nd ratio on light-emitting properties of Nd-doped glass prepared by sol-gel process

    Microsoft Academic Search

    Qing Xiang; Yan Zhou; Yee Loy Lam; BoonSiew Ooi; YuenChuen Chan; ChanHin Kam

    1999-01-01

    For rare earth doped silica-based glasses derived by sol-gel process, Al was used as a modifier in order to improve the dispersion of the rare earth ion in silica lattices, and thus, make the higher rare earth doped silica glasses without clustering possible. In this research, the influence of the ratio of Al to Nd on the fluorescence intensity and

  18. From land use to land cover: Restoring the afforestation signal in a coupled integrated assessment - earth system model and the implications for CMIP5 RCP simulations

    SciTech Connect

    Di Vittorio, Alan; Chini, Louise M.; Bond-Lamberty, Benjamin; Mao, Jiafu; Shi, Xiaoying; Truesdale, John E.; Craig, Anthony P.; Calvin, Katherine V.; Jones, Andrew D.; Collins, William D.; Edmonds, James A.; Hurtt, George; Thornton, Peter E.; Thomson, Allison M.

    2014-11-27

    Climate projections depend on scenarios of fossil fuel emissions and land use change, and the IPCC AR5 parallel process assumes consistent climate scenarios across Integrated Assessment and Earth System Models (IAMs and ESMs). To facilitate consistency, CMIP5 used a novel land use harmonization to provide ESMs with seamless, 1500-2100 land use trajectories generated by historical data and four IAMs. However, we have identified and partially addressed a major gap in the CMIP5 land coupling design. The CMIP5 Community ESM (CESM) global afforestation is only 22% of RCP4.5 afforestation from 2005 to 2100. Likewise, only 17% of the Global Change Assessment Model’s (GCAM’s) 2040 RCP4.5 afforestation signal, and none of the pasture loss, were transmitted to CESM within a newly integrated model. This is a critical problem because afforestation is necessary for achieving the RCP4.5 climate stabilization. We attempted to rectify this problem by modifying only the ESM component of the integrated model, enabling CESM to simulate 66% of GCAM’s afforestation in 2040, and 94% of GCAM’s pasture loss as grassland and shrubland losses. This additional afforestation increases vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, implying different climate scenarios between CMIP5 GCAM and CESM. Similar inconsistencies likely exist in other CMIP5 model results, primarily because land cover information is not shared between models, with possible contributions from afforestation exceeding model-specific, potentially viable forest area. Further work to harmonize land cover among models will be required to adequately rectify this problem.

  19. From land use to land cover: Restoring the afforestation signal in a coupled integrated assessment - earth system model and the implications for CMIP5 RCP simulations

    NASA Astrophysics Data System (ADS)

    Di Vittorio, Alan; Chini, Louise; Bond-Lamberty, Ben; Mao, Jiafu; Shi, Xiaoying; Truesdale, John; Craig, Anthony; Calvin, Kate; Jones, Andrew; Collins, William; Edmonds, Jae; Hurtt, George; Thornton, Peter; Thomson, Allison

    2015-04-01

    Climate projections depend on scenarios of fossil fuel emissions and land use change, and the IPCC AR5 parallel process assumes consistent climate scenarios across Integrated Assessment and Earth System Models (IAMs and ESMs). The CMIP5 project used a novel "land use harmonization" based on the Global Land use Model (GLM) to provide ESMs with consistent 1500-2100 land use trajectories generated by historical data and four IAMs. A direct coupling of the Global Change Assessment Model (GCAM), GLM, and the Community ESM (CESM) has allowed us to characterize and partially address a major gap in the CMIP5 land coupling design: the lack of a corresponding land cover harmonization. For RCP4.5, CESM global afforestation is only 22% of GCAM's 2005 to 2100 afforestation. Likewise, only 17% of GCAM's 2040 afforestation, and zero pasture loss, were transmitted to CESM within the directly coupled model. This is a problem because GCAM relied on afforestation to achieve RCP4.5 climate stabilization. GLM modifications and sharing forest area between GCAM and GLM within the directly coupled model did not increase CESM afforestation. Modifying the land use translator in addition to GLM, however, enabled CESM to include 66% of GCAM's afforestation in 2040, and 94% of GCAM's pasture loss as grassland and shrubland losses. This additional afforestation increases CESM vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, which demonstrates that CESM without additional afforestation simulates a different RCP4.5 scenario than prescribed by GCAM. Similar land cover inconsistencies exist in other CMIP5 model results, primarily because land cover information is not shared between models. Further work to harmonize land cover among models will be required to increase fidelity between IAM scenarios and ESM simulations and realize the full potential of scenario-based earth system simulations.

  20. From land use to land cover: restoring the afforestation signal in a coupled integrated assessment-earth system model and the implications for CMIP5 RCP simulations

    NASA Astrophysics Data System (ADS)

    Di Vittorio, A. V.; Chini, L. P.; Bond-Lamberty, B.; Mao, J.; Shi, X.; Truesdale, J.; Craig, A.; Calvin, K.; Jones, A.; Collins, W. D.; Edmonds, J.; Hurtt, G. C.; Thornton, P.; Thomson, A.

    2014-11-01

    Climate projections depend on scenarios of fossil fuel emissions and land use change, and the Intergovernmental Panel on Climate Change (IPCC) AR5 parallel process assumes consistent climate scenarios across integrated assessment and earth system models (IAMs and ESMs). The CMIP5 (Coupled Model Intercomparison Project Phase 5) project used a novel "land use harmonization" based on the Global Land use Model (GLM) to provide ESMs with consistent 1500-2100 land use trajectories generated by historical data and four IAMs. A direct coupling of the Global Change Assessment Model (GCAM), GLM, and the Community ESM (CESM) has allowed us to characterize and partially address a major gap in the CMIP5 land coupling design: the lack of a corresponding land cover harmonization. For RCP4.5, CESM global afforestation is only 22% of GCAM's 2005 to 2100 afforestation. Likewise, only 17% of GCAM's 2040 afforestation, and zero pasture loss, were transmitted to CESM within the directly coupled model. This is a problem because GCAM relied on afforestation to achieve RCP4.5 climate stabilization. GLM modifications and sharing forest area between GCAM and GLM within the directly coupled model did not increase CESM afforestation. Modifying the land use translator in addition to GLM, however, enabled CESM to include 66% of GCAM's afforestation in 2040, and 94% of GCAM's pasture loss as grassland and shrubland losses. This additional afforestation increases CESM vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, which demonstrates that CESM without additional afforestation simulates a different RCP4.5 scenario than prescribed by GCAM. Similar land cover inconsistencies exist in other CMIP5 model results, primarily because land cover information is not shared between models. Further work to harmonize land cover among models will be required to increase fidelity between IAM scenarios and ESM simulations and realize the full potential of scenario-based earth system simulations.

  1. Integrated corner reflector InSAR, SI and GPS characterization of complex earth slide deformations, Little Smoky River, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Froese, C. R.; Poncos, V.; Murhagan, K.; Hawkins, R.; Skirrow, R.; Singhroy, V.

    2009-04-01

    Since the construction of the highway across the Little Smoky River in 1957, slope movements on both valley walls have lead to significant ongoing maintenance for both the highway and the bridge crossing. As the river has changed courses over it's period of incision, numerous landslides of different ages and orientations impact on the road infrastructure. In addition, downcutting into the thick infill of glacial sediments has lead to large, compound earth slides moving in both translational and rotational components. Previous studies associated with road maintenance and repair has relied on conventional point source geotechnical instrumentation, slope inclinometers, at discrete locations. As the landslides impacting on the road are on the scale of many kilometers in width and length the point source readings adjacent to the highway have not allowed for proper characterization of deformation rates on other portions of the valley walls. As options are currently being considered for re-alignment of the highway, data on the relative state of stability of other portions of the valley walls are critical. In order to provide a better global view of the state of stability of the valley walls of the Little Smoky River a series of 18 corner reflectors were installed at strategic locations along the valley walls. This included locations where reflectors were co-located with conventional geotechnical instrumentation and areas where no monitoring had been previously attempted. Each reflector was aimed for optimal orientation for readings with Radarsat F2N ascending beam mode on a 24 day return cycle. During the initial installation period in October 2006, GPS readings were taken on all reflectors with second epoch of readings conducted in August 2008. As well, during this time period bi-annual slope inclinometer readings were collected to provide indications of the horizontal component of the displacements. These two set of ground data were compared, along with observations of slope morphology in order to interpret the InSAR line-of-sight observations and provide a more complete picture of deformations on the valley walls.

  2. Skylab explores the Earth

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Data from visual observations are integrated with results of analyses of approxmately 600 of the nearly 2000 photographs taken of Earth during the 84-day Skylab 4 mission to provide additional information on (1) Earth features and processes; (2) operational procedures and constraints in observing and photographing the planet; and (3) the use of man in real-time analysis of oceanic and atmospheric phenomena.

  3. Electrical, magnetic, and magneto-electrical properties in quasi-two-dimensional K{sub 0.58}RhO{sub 2} single crystals doped with rare-earth elements

    SciTech Connect

    Zhang, Bin-Bin; Dong, Song-Tao; Yao, Shu-Hua, E-mail: shyao@nju.edu.cn, E-mail: ybchen@nju.edu.cn; Zhang, Shan-Tao; Gu, Zheng-Bin; Zhou, Jian; Lu, Ming-Hui; Chen, Yan-Feng [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China); Chen, Y. B., E-mail: shyao@nju.edu.cn, E-mail: ybchen@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Shi, Y. G. [Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-08-11

    In this Letter, we studied the electrical transport, magnetic property, magnetoresistance and anomalous Hall properties of La-, Sm-, Ho-, and Dy-doped quasi-two dimensional K{sub 0.58}RhO{sub 2} single crystals. At low temperature (<10?K), a significant magnetoresistance (36%) can be observed in these samples. Accordingly, the “glassy ferromagnetism” is revealed by temperature-dependent magnetization in these samples. The significant magnetoresistance is related to the granular ferromagnetism. The unconventional anomalous Hall effect is also observed in magnetic atoms doped samples. Our finding shields more light on the magnetic, magnetoresistance, and anomalous Hall properties of quasi-two-dimensional material systems doped with magnetic ions.

  4. Microstructure and electroluminescent performance of chemical vapor deposited zinc sulfide doped with manganese films for integration in thin film electroluminescent devices

    Microsoft Academic Search

    Anna Wanda Topol

    2001-01-01

    Zinc sulfide (ZnS) doped with manganese (Mn), ZnS:Mn, is widely recognized as the brightest and most effective electroluminescent (EL) phosphor used in current thin film electroluminescent (TFEL) devices. ZnS acts as a host lattice for the luminescent activator, Mn, leading to a highly efficient yellow-orange EL emission, and resulting in a wide array of applications in monochrome, multi-color and full

  5. Theoretical analysis of fiber lasers emitting around 810 nm based on thulium-doped silica fibers with enhanced 3

    E-print Network

    Boyer, Edmond

    Theoretical analysis of fiber lasers emitting around 810 nm based on thulium-doped silica fibers-earth doped fiber lasers are situated around 1, 1.5 and 2 µm. In this paper we investigate thulium-doped fiber shown that with modification of local environment of the thulium ions by alumina, the fluorescence

  6. Rare earth ion diffusion in AgBr crystals

    Microsoft Academic Search

    L. Nagli; A German; A Katzir

    1999-01-01

    The luminescence of silver bromide crystals doped with rare earth ions (Nd3+ and Er3+) was investigated in the visible and near infrared spectral ranges. Crystal doping was produced by growing in the melt and by a diffusion method. The diffusion profile of rare earth ions in AgBr crystals was measured by the luminescence method. The luminescence parameters of AgBr crystals

  7. The quickest, lowest-cost lunar resource assessment program: Integrated high-tech Earth-based astronomy

    NASA Astrophysics Data System (ADS)

    Pieters, Carle M.

    1992-12-01

    Science and technology applications for the Moon have not fully kept pace with technical advancements in sensor development and analytical information extraction capabilities. Appropriate unanswered questions for the Moon abound, but until recently there has been little motivation to link sophisticated technical capabilities with specific measurement and analysis projects. Over the last decade enormous technical progress has been made in the development of (1) CCD photometric array detectors; (2) visible to near-infrared imaging spectrometers; (3)infrared spectroscopy; (4) high-resolution dual-polarization radar imaging at 3.5, 12, and 70 cm; and equally important (5) data analysis and information extraction techniques using compact powerful computers. Parts of each of these have been tested separately, but there has been no programmatic effort to develop and optimize instruments to meet lunar science and resource assessment needs (e.g., specific wavelength range, resolution, etc.) nor to coordinate activities so that the symbiotic relation between different kinds of data can be fully realized. No single type of remotely acquired data completely characterizes the lunar environment, but there has been little opportunity for integration of diverse advanced sensor data for the Moon. Two examples of technology concepts for lunar measurements are given. Using VIS/near-IR spectroscopy, the mineral composition of surface material can be derived from visible and near-infrared radiation reflected from the surface. The surface and subsurface scattering properties of the Moon can be analyzed using radar backscattering imaging.

  8. The Quickest, Lowest-cost Lunar Resource Assessment Program: Integrated High-tech Earth-based Astronomy

    NASA Technical Reports Server (NTRS)

    Pieters, Carle M.

    1992-01-01

    Science and technology applications for the Moon have not fully kept pace with technical advancements in sensor development and analytical information extraction capabilities. Appropriate unanswered questions for the Moon abound, but until recently there has been little motivation to link sophisticated technical capabilities with specific measurement and analysis projects. Over the last decade enormous technical progress has been made in the development of (1) CCD photometric array detectors; (2) visible to near-infrared imaging spectrometers; (3)infrared spectroscopy; (4) high-resolution dual-polarization radar imaging at 3.5, 12, and 70 cm; and equally important (5) data analysis and information extraction techniques using compact powerful computers. Parts of each of these have been tested separately, but there has been no programmatic effort to develop and optimize instruments to meet lunar science and resource assessment needs (e.g., specific wavelength range, resolution, etc.) nor to coordinate activities so that the symbiotic relation between different kinds of data can be fully realized. No single type of remotely acquired data completely characterizes the lunar environment, but there has been little opportunity for integration of diverse advanced sensor data for the Moon. Two examples of technology concepts for lunar measurements are given. Using VIS/near-IR spectroscopy, the mineral composition of surface material can be derived from visible and near-infrared radiation reflected from the surface. The surface and subsurface scattering properties of the Moon can be analyzed using radar backscattering imaging.

  9. Broadband near infrared emission in antimony-germanate glass co-doped with erbium and thulium ions

    NASA Astrophysics Data System (ADS)

    Dorosz, Dominik; Zmojda, Jacek; Kochanowicz, Marcin

    2014-07-01

    Antimony-germanate glasses co-doped with Er/Tm ions as a material for active waveguides application have been investigated. In result of optimizations of rare earths, concentration wide (??FWHM=420 nm) luminescence emission in the range of 1.4 to 1.9 ?m was obtained for molar composition of 1%Er2O3: 0.25%TmO. The influence of the molar ratio of active ions on the luminescence spectra has been investigated. Luminescent properties of fabricated glass indicate that elaborated glass is promising material for broad tunable integrated laser sources and broadband optical amplifiers.

  10. Faraday rotation and photoluminescence in heavily Tb3+-doped GeO2-B2O3-Al2O3-Ga2O3 glasses for fiber-integrated magneto-optics

    PubMed Central

    Gao, Guojun; Winterstein-Beckmann, Anja; Surzhenko, Oleksii; Dubs, Carsten; Dellith, Jan; Schmidt, Markus A.; Wondraczek, Lothar

    2015-01-01

    We report on the magneto-optical (MO) properties of heavily Tb3+-doped GeO2-B2O3-Al2O3-Ga2O3 glasses towards fiber-integrated paramagnetic MO devices. For a Tb3+ ion concentration of up to 9.7 × 1021?cm?3, the reported glass exhibits an absolute negative Faraday rotation of ~120?rad/T/m at 632.8?nm. The optimum spectral ratio between Verdet constant and light transmittance over the spectral window of 400–1500?nm is found for a Tb3+ concentration of ~6.5 × 1021?cm?3. For this glass, the crystallization stability, expressed as the difference between glass transition temperature and onset temperature of melt crystallization exceeds 100?K, which is a prerequisite for fiber drawing. In addition, a high activation energy of crystallization is achieved at this composition. Optical absorption occurs in the NUV and blue spectral region, accompanied by Tb3+ photoluminescence. In the heavily doped materials, a UV/blue-to-green photo-conversion gain of ~43% is achieved. The lifetime of photoluminescence is ~2.2?ms at a stimulated emission cross-section ?em of ~1.1 × 10?21?cm2 for ~ 5.0 × 1021?cm?3 Tb3+. This results in an optical gain parameter ?em*? of ~2.5 × 10?24?cm2s, what could be of interest for implementation of a Tb3+ fiber laser. PMID:25754819

  11. Faraday rotation and photoluminescence in heavily Tb3+-doped GeO2-B2O3-Al2O3-Ga2O3 glasses for fiber-integrated magneto-optics

    NASA Astrophysics Data System (ADS)

    Gao, Guojun; Winterstein-Beckmann, Anja; Surzhenko, Oleksii; Dubs, Carsten; Dellith, Jan; Schmidt, Markus A.; Wondraczek, Lothar

    2015-03-01

    We report on the magneto-optical (MO) properties of heavily Tb3+-doped GeO2-B2O3-Al2O3-Ga2O3 glasses towards fiber-integrated paramagnetic MO devices. For a Tb3+ ion concentration of up to 9.7 × 1021 cm-3, the reported glass exhibits an absolute negative Faraday rotation of ~120 rad/T/m at 632.8 nm. The optimum spectral ratio between Verdet constant and light transmittance over the spectral window of 400-1500 nm is found for a Tb3+ concentration of ~6.5 × 1021 cm-3. For this glass, the crystallization stability, expressed as the difference between glass transition temperature and onset temperature of melt crystallization exceeds 100 K, which is a prerequisite for fiber drawing. In addition, a high activation energy of crystallization is achieved at this composition. Optical absorption occurs in the NUV and blue spectral region, accompanied by Tb3+ photoluminescence. In the heavily doped materials, a UV/blue-to-green photo-conversion gain of ~43% is achieved. The lifetime of photoluminescence is ~2.2 ms at a stimulated emission cross-section ?em of ~1.1 × 10-21 cm2 for ~ 5.0 × 1021 cm-3 Tb3+. This results in an optical gain parameter ?em*? of ~2.5 × 10-24 cm2s, what could be of interest for implementation of a Tb3+ fiber laser.

  12. Integration of light attenuation measurements from Earth Observation into 3D Geobiochemical models of the North Sea.

    NASA Astrophysics Data System (ADS)

    van der Woerd, Hans; Blaas, Meinte; Peters, Steef W. M.; Eleveld, Marieke; Garcia Triana, Ivan D. T. F.

    2013-04-01

    The FP7 CoBiOS project aims to develop a near-real-time information system to diagnose high-biomass blooms in the Baltic Sea and North Sea. The core information in such a system will result from integration of ocean colour remote sensing with 3D geobiochemical modelling. A key parameter is the description of available solar energy in these complex waters, where optically active substances such as silt, algae and dissolved organic material all contribute to the light extinction. A new approach is presented to consistently define the light extinction coefficient Kd of the downward irradiance over PAR from an EO perspective and a numerical modelling perspective. An analysis of a few hundred in-situ Kd-profiles in the North Sea demonstrates that irradiance extinction by the various substances as a function of their PAR-representative absorption and scattering properties works better than a linear model of 'specific extinction' coefficients. In addition to adopting consistent coefficients, it is recommended to apply a nonlinear approach to couple absorption and scattering properties for deriving Kd [1,2]. This approach enables obtaining a consistently defined set of Kd values that will facilitate assimilation of geobiochemical models with ocean colour observations. [1] Lee, Z.P., Du, K.P., Arnone, R. 2005. A model for the diffuse attenuation coefficient of downwelling irradiance J. Geophys. Res., 110, C02016, doi:10.1029/2004JC002275, 2005 [2] Van der Woerd, H.J., Pasterkamp, R. 2008. HYDROPT: A fast and flexible method to retrieve chlorophyll-a from multi-spectral satellite observation of optical-complex coastal waters. Rem. Sens. Env. 112, 1795-1807

  13. First steps of integrated spatial modeling of titanium, zirconium, and rare earth element resources within the Coastal Plain sediments of the southeastern United States

    USGS Publications Warehouse

    Ellefsen, Karl J.; Van Gosen, Bradley S.; Fey, David L.; Budahn, James R.; Smith, Steven M.; Shah, Anjana K.

    2015-01-01

    The Coastal Plain of the southeastern United States has extensive, unconsolidated sedimentary deposits that are enriched in heavy minerals containing titanium, zirconium, and rare earth element resources. Areas favorable for exploration and development of these resources are being identified by geochemical data, which are supplemented with geological, geophysical, hydrological, and geographical data. The first steps of this analysis have been completed. The concentrations of lanthanum, yttrium, and titanium tend to decrease as distance from the Piedmont (which is the likely source of these resources) increases and are moderately correlated with airborne measurements of equivalent thorium concentration. The concentrations of lanthanum, yttrium, and titanium are relatively high in those watersheds that adjoin the Piedmont, south of the Cape Fear Arch. Although this relation suggests that the concentrations are related to the watersheds, it may be simply an independent regional trend. The concentration of zirconium is unrelated to the distance from the Piedmont, the equivalent thorium concentration, and the watershed. These findings establish a foundation for more sophisticated analyses using integrated spatial modeling.

  14. Reducing Loss of Life and Property from Disasters: A Societal Benefit Area of the Strategic Plan for U.S. Integrated Earth Observation System (IEOS)

    USGS Publications Warehouse

    Helz, Rosalind L.; Gaynor, John E.

    2007-01-01

    Natural and technological disasters, such as hurricanes and other extreme weather events, earthquakes, volcanic eruptions, landslides and debris flows, wildland and urban-interface fires, floods, oil spills, and space-weather storms, impose a significant burden on society. Throughout the United States, disasters inflict many injuries and deaths, and cost the nation $20 billion each year (SDR, 2003). Disasters in other countries can affect U.S. assets and interests overseas (e.g. the eruption of Mt. Pinatubo in the Philippines, which effectively destroyed Clark Air Force Base). Also, because they have a disproportionate impact on developing countries, disasters are major barriers to sustainable development. Improving our ability to assess, predict, monitor, and respond to hazardous events is a key factor in reducing the occurrence and severity of disasters, and relies heavily on the use of information from well-designed and integrated Earth observation systems. To fully realize the benefits gained from the observation systems, the information derived must be disseminated through effective warning systems and networks, with products tailored to the needs of the end users and the general public.

  15. Theoretical study of native and rare-earth defect complexes in -PbF2 Huitian Jiang, Aurora Costales,* Miguel A. Blanco,

    E-print Network

    Pandey, Ravi

    ARTICLES Theoretical study of native and rare-earth defect complexes in -PbF2 Huitian Jiang, Aurora manuscript received 31 January 2000 Native and rare-earth-doped point-defects in -PbF2 are studied data. In the rare-earth doped PbF2, a site preference of the charge-compensating fluorine interstitial

  16. Integrating Ideas for International Data Collaborations Through The Committee on Earth Observation Satellites (CEOS) International Directory Network (IDN)

    NASA Technical Reports Server (NTRS)

    Olsen, Lola M.

    2006-01-01

    The capabilities of the International Directory Network's (IDN) version MD9.5, along with a new version of the metadata authoring tool, "docBUILDER", will be presented during the Technology and Services Subgroup session of the Working Group on Information Systems and Services (WGISS). Feedback provided through the international community has proven instrumental in positively influencing the direction of the IDN s development. The international community was instrumental in encouraging support for using the IS0 international character set that is now available through the directory. Supporting metadata descriptions in additional languages encourages extended use of the IDN. Temporal and spatial attributes often prove pivotal in the search for data. Prior to the new software release, the IDN s geospatial and temporal searches suffered from browser incompatibilities and often resulted in unreliable performance for users attempting to initiate a spatial search using a map based on aging Java applet technology. The IDN now offers an integrated Google map and date search that replaces that technology. In addition, one of the most defining characteristics in the search for data relates to the temporal and spatial resolution of the data. The ability to refine the search for data sets meeting defined resolution requirements is now possible. Data set authors are encouraged to indicate the precise resolution values for their data sets and subsequently bin these into one of the pre-selected resolution ranges. New metadata authoring tools have been well received. In response to requests for a standalone metadata authoring tool, a new shareable software package called "docBUILDER solo" will soon be released to the public. This tool permits researchers to document their data during experiments and observational periods in the field. interoperability has been enhanced through the use of the Open Archives Initiative s (OAI) Protocol for Metadata Harvesting (PMH). Harvesting of XML content through OAI-MPH has been successfully tested with several organizations. The protocol appears to be a prime candidate for sharing metadata throughout the international community. Data services for visualizing and analyzing data have become valuable assets in facilitating the use of data. Data providers are offering many of their data-related services through the directory. The IDN plans to develop a service-based architecture to further promote the use of web services. During the IDN Task Team session, ideas for further enhancements will be discussed.

  17. Synthesis and evaluation of ultra-pure rare-earth-coped glass for laser refrigeration

    SciTech Connect

    Patterson, Wendy M [Los Alamos National Laboratory; Hehlen, Markus P [Los Alamos National Laboratory; Epstein, Richard I [Los Alamos National Laboratory; Sheik-bahae, Mansoor [UNM

    2009-01-01

    Significant progress has been made in synthesizing and characterizing ultra-pure, rare-earth doped ZIBLAN (ZrF{sub 4}-InF{sub 3}BaF{sub 2}-LaF{sub 3}-AlF{sub 3}-NaF) glass capable of laser refrigeration. The glass was produced from fluorides which were purified and subsequently treated with hydrofluoric gas at elevated temperatures to remove impurities before glass formation. Several Yb3 +-doped samples were studied with degrees of purity and composition with successive iterations producing an improved material. We have developed a non-invasive, spectroscopic technique, two band differential luminescence thermometry (TBDLT), to evaluate the intrinsic quality of the ytterbium doped ZIBLAN used for laser cooling experiments. TBDLT measures local temperature changes within an illuminated volume resulting solely from changes in the relative thermal population of the excited state levels. This TBDLT technique utilizes two commercially available band pass filters to select and integrate the 'difference regions' of interest in the luminescence spectra. The goal is to determine the minimum temperature to which the ytterbium sample can cool on the local scale, unphased by surface heating. This temperature where heating and cooling are exactly balanced is the zero crossing temperature (ZCT) and can be used as a measure for the presence of impurities and the overall quality of the laser cooling material. Overall, favorable results were obtained from 1 % Yb3+-doped glass, indicating our glasses are desirable for laser refrigeration.

  18. Erbium-doped nanoparticles in silica-based optical Wilfried Blanc*, Valrie Mauroy, Bernard

    E-print Network

    Boyer, Edmond

    .dussardier@unice.fr *Corresponding author Abstract: Developing of new rare-earth (RE)-doped optical fibres for power amplifiers to modify some spectroscopic properties of rare-earth ions in silica- based fibers based alkaline earth elements, in low concentration into silica, one can obtain a glass with an immiscibility gap

  19. High-speed integrated circuits using i-AlGaAs\\/n-GaAs doped-channel hetero-MISFET's (DMT's)

    Microsoft Academic Search

    HIKARU HIDA; H. Toyoshima; Y. Ogawa

    1987-01-01

    High-speed ring oscillators and divide-by-two circuits have been fabricated by using i-AlGaAs\\/n-GaAs doped-channel hetero-MISFET's (DMT's) and saturated resistors in direct-coupled FET logic (DCFL) circuit architecture for the first time. The maximum operating frequency is 3.72 GHz for dual-clocked master-slave flip-flop frequency dividers based on eight NOR gates, which consist of 0.8-µm gate enhancement-mode DMT's with 370-mS\\/mm maximum transconductance. A 25-stage

  20. Earth Observing System AM1 mission to Earth

    Microsoft Academic Search

    Yoram J. Kaufman; David D. Herring; K. Jon Ranson; G. James Collatz

    1998-01-01

    In 1998, NASA launches EOS-AMI, the first of a series of the Earth Observing System (EOS) satellites. EOS will monitor the evolution of the state of the earth for 18 years, starting with the morning observations of EOS-AM1 (10:30 a.m. equatorial crossing time). An integrated view of the earth, as planned by EOS, is needed to study the interchange of