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Sample records for germanium bromides

  1. Germanium

    SciTech Connect

    Major-Sosias, M.A.

    1996-01-01

    Germanium is an important semiconductor material, or metalloid which, by definition, is a material whose electrical properties are halfway between those of metallic conductors and electrical insulators. This paper describes the properties, sources, and market for germanium.

  2. Lanthanum Bromide Detectors for Safeguards Measurements

    SciTech Connect

    Wright, J.

    2011-05-25

    Lanthanum bromide has advantages over other popular inorganic scintillator detectors. Lanthanum bromide offers superior resolution, and good efficiency when compared to sodium iodide and lanthanum chloride. It is a good alternative to high purity germanium detectors for some safeguards applications. This paper offers an initial look at lanthanum bromide detectors. Resolution of lanthanum bromide will be compared lanthanum chloride and sodium-iodide detectors through check source measurements. Relative efficiency and angular dependence will be looked at. Nuclear material spectra, to include plutonium and highly enriched uranium, will be compared between detector types.

  3. Cyanogen bromide

    Integrated Risk Information System (IRIS)

    Cyanogen bromide ; CASRN 506 - 68 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  4. Vinyl bromide

    Integrated Risk Information System (IRIS)

    Vinyl bromide ; CASRN 593 - 60 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  5. Methyl Bromide Poisoning

    PubMed Central

    Rathus, E. M.; Landy, P. J.

    1961-01-01

    Seven cases of methyl bromide poisoning which occurred amongst workers engaged on a fumigation project are described. The methods adopted for investigation of the environmental situation are discussed and the measurement of blood bromide levels on random samples of workers is suggested as an index of the effectiveness of equipment and working methods. PMID:13739738

  6. Mineral commodity profiles: Germanium

    USGS Publications Warehouse

    Butterman, W.C.; Jorgenson, John D.

    2005-01-01

    Overview -- Germanium is a hard, brittle semimetal that first came into use a half-century ago as a semiconductor material in radar units and as the material from which the first transistor was made. Today it is used principally as a component of the glass in telecommunications fiber optics; as a polymerization catalyst for polyethylene terephthalate (PET), a commercially important plastic; in infrared (IR) night vision devices; and as a semiconductor and substrate in electronics circuitry. Most germanium is recovered as a byproduct of zinc smelting, although it also has been recovered at some copper smelters and from the fly ash of coal-burning industrial powerplants. It is a highly dispersed element, associated primarily with base-metal sulfide ores. In the United States, germanium is recovered from zinc smelter residues and manufacturing scrap and is refined by two companies at four germanium refineries. One of the four refineries is dedicated to processing scrap. In 2000, producers sold zone-refined (high-purity) germanium at about $1,250 per kilogram and electronic-grade germanium dioxide (GeO2) at $800 per kilogram. Domestic refined production was valued at $22 million. Germanium is a critical component in highly technical devices and processes. It is likely to remain in demand in the future at levels at least as high as those of 2000. U.S. resources of germanium are probably adequate to meet domestic needs for several decades.

  7. Germanium detector passivated with hydrogenated amorphous germanium

    DOEpatents

    Hansen, William L.; Haller, Eugene E.

    1986-01-01

    Passivation of predominantly crystalline semiconductor devices (12) is provided for by a surface coating (21) of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating (21) of amorphous germanium onto the etched and quenched diode surface (11) in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices (12), which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating (21) compensates for pre-existing undesirable surface states as well as protecting the semiconductor device (12) against future impregnation with impurities.

  8. Lithium drifted germanium system

    NASA Technical Reports Server (NTRS)

    Fjarlie, E. J.

    1969-01-01

    General characteristics of the lithium-drifted germanium photodiode-Dewar-preamplifier system and particular operating instructions for the device are given. Information is included on solving operational problems.

  9. Bridgman Growth of Germanium

    NASA Technical Reports Server (NTRS)

    Szofran, F. R.; Volz, M. P.; Cobb, S. D.; Motakef, S.

    1997-01-01

    The high-magnetic-field crystal growth facility at the Marshall Space Flight Center will be briefly described. This facility has been used to grow bulk germanium by the Bridgman technique in magnetic fields up to 5 Tesla. The results of investigations of ampoule material on the interface shape and thermal field applied to the melt on stability against convection will be discussed.

  10. Germanium detector vacuum encapsulation

    NASA Technical Reports Server (NTRS)

    Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

    1991-01-01

    This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

  11. Bromide affecting drinking water mutagenicity.

    PubMed

    Myllykangas, T; Nissinen, T K; Mäki-Paakkanen, J; Hirvonen, A; Vartiainen, T

    2003-11-01

    The effect of bromide on the mutagenicity of artificially recharged groundwater and purified artificially recharged groundwater after chlorine, ozone, hydrogen peroxide, permanganate, and UV treatments alone and in various combinations was studied. The highest mutagenicity was observed after chlorination, while hydrogen peroxide-ozone-chlorine treatment produced the lowest value for both waters. Chlorinated waters, which were spiked with bromide, had up to 3.7 times more mutagenic activity than waters without bromide after every preoxidation method. 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was found to correspond as much as 76% of the overall mutagenicity in the waters not spiked with bromide. MX formation was found to be lower when the treated water contained bromide, implicating the formation of brominated MX analogues. Trihalomethane formation increased when the treated water contained bromide. PMID:13129514

  12. Germanium-76 Sample Analysis

    SciTech Connect

    Kouzes, Richard T.; Engelhard, Mark H.; Zhu, Zihua

    2011-04-01

    The MAJORANA DEMONSTRATOR is a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay (0νββ). The DEMONSTRATOR will utilize 76Ge from Russia, and the first one gram sample was received from the supplier for analysis on April 24, 2011. The Environmental Molecular Sciences facility, a DOE user facility at PNNL, was used to make the required isotopic and chemical purity measurements that are essential to the quality assurance for the MAJORANA DEMONSTRATOR. The results of this first analysis are reported here.

  13. Aqueous Zinc Bromide Waste Solidification

    SciTech Connect

    Langton, C.A.

    2002-07-23

    The goal of this study was to select one or more commercially available aqueous sorbents to solidify the zinc bromide solution stored in C-Area, identify the polymer to zinc bromide solution ratio (waste loading) for the selected sorbents, and identify processing issues that require further testing in pilot-scale testing.

  14. Tiotropium Bromide: An Update

    PubMed Central

    Heredia, Josep Lluis

    2009-01-01

    Tiotropium bromide is a once-daily inhaled anticholinergic bronchodilator. It works by blocking the muscarinic receptors in airway smooth muscle. Tiotropium has a wide therapeutic margin, due to its poor gastrointestinal absorption and its very low systemic bioavailability. The drug is mainly indicated in COPD patients. Clinically relevant outcomes such as significant improvements in spirometry, hyperinflation, dyspnea, heath status, acute exacerbations and mortality have been consistently observed in tiotropium clinical trials, and the drug has been shown to reduce the risk of mortality due to cardiac-vascular disease and respiratory failure. The main side effect reported is dryness of the mouth. Some subgroups of asthmatics also seem to respond to anticholinergic drugs: among them, those with the Arg/Arg genotype for the β2-adrenergic receptor and those with a high percentage of neutrophils in sputum. PMID:19461900

  15. Germanium: An aqueous processing review

    SciTech Connect

    Lier, R.J.M. van; Dreisinger, D.B.

    1995-08-01

    In industrial aqueous solutions, germanium generally occurs in trace amounts amid high concentrations of other metals, such as zinc, copper and iron. Separation of germanium from these metals as well as its isolation from gallium and indium pose a real challenge to the hydrometallurgist. After a brief discussion of the aqueous chemistry of germanium, this paper reviews the flowsheet of the Apex Mine in Utah. The Apex property was the only mine in the world to be operated primarily for production of gallium and germanium, but apparently closed due to great operating difficulties. Several process variants proposed for the treatment of the Apex ore, including bioleaching methods, are addressed. Following a more general description of the behavior of germanium in hydrometallurgical zinc processing streams, available technology for its recovery from aqueous solutions is summarized. Precipitation, solvent extraction, ion exchange, electrowinning, ion flotation and liquid-membrane separation are all outlined in terms of the aqueous chemistry of germanium. Finally, the production of high purity germanium dioxide and metal is briefly discussed. 61 refs.

  16. Germanium geochemistry and mineralogy

    USGS Publications Warehouse

    Bernstein, L.R.

    1985-01-01

    Germanium is enriched in the following geologic environments: 1. (1) iron meteorites and terrestrial iron-nickel; 2. (2) sulfide ore deposits, particularly those hosted by sedimentary rocks; 3. (3) iron oxide deposits; 4. (4) oxidized zones of Ge-bearing sulfide deposits; 5. (5) pegmatites, greisens, and skarns; and 6. (6) coal and lignitized wood. In silicate melts, Ge is highly siderophile in the presence of native iron-nickel; otherwise, it is highly lithophile. Among silicate minerals, Ge is concentrated in those having less polymerized silicate tetrahedra such as olivine and topaz. In deposits formed from hydrothermal solutions, Ge tends to be enriched mostly in either sulfides or in fluorine-bearing phases; it is thus concentrated both in some hydrothermal sulfide deposits and in pegmatites, greisens, and skarns. In sulfide deposits that formed from solutions having low to moderate sulfur activity, Ge is concentrated in sphalerite in amounts up to 3000 ppm. Sulfide deposits that formed from solutions having higher sulfur activity allowed Ge to either form its own sulfides, particularly with Cu, or to substitute for As, Sn, or other metals in sulfosalts. The Ge in hydrothermal fluids probably derives from enrichment during the fractional crystallization of igneous fluids, or is due to the incorporation of Ge from the country rocks, particularly from those containing organic material. Germanium bonds to lignin-derivative organic compounds that are found in peat and lignite, accounting for its common concentration in coals and related organic material. Germanium is precipitated from water together with iron hydroxide, accounting for its concentration in some sedimentary and supergene iron oxide deposits. It also is able to substitute for Fe in magnetite in a variety of geologic environments. In the oxidized zone of Ge-bearing sulfide deposits, Ge is concentrated in oxides, hydroxides, and hydroxy-sulfates, sometimes forming its own minerals. It is particularly

  17. Slow Crack Growth of Germanium

    NASA Technical Reports Server (NTRS)

    Salem, Jon

    2016-01-01

    The fracture toughness and slow crack growth parameters of germanium supplied as single crystal beams and coarse grain disks were measured. Although germanium is anisotropic (A=1.7), it is not as anisotropic as SiC, NiAl, or Cu, as evidence by consistent fracture toughness on the 100, 110, and 111 planes. Germanium does not exhibit significant slow crack growth in distilled water. (n=100). Practical values for engineering design are a fracture toughness of 0.7 MPam and a Weibull modulus of m=6+/-2. For well ground and reasonable handled coupons, fracture strength should be greater than 30 MPa.

  18. Hafnium germanium telluride

    PubMed Central

    Jang, Gyung-Joo; Yun, Hoseop

    2008-01-01

    The title hafnium germanium telluride, HfGeTe4, has been synthesized by the use of a halide flux and structurally characterized by X-ray diffraction. HfGeTe4 is isostructural with stoichiometric ZrGeTe4 and the Hf site in this compound is also fully occupied. The crystal structure of HfGeTe4 adopts a two-dimensional layered structure, each layer being composed of two unique one-dimensional chains of face-sharing Hf-centered bicapped trigonal prisms and corner-sharing Ge-centered tetra­hedra. These layers stack on top of each other to complete the three-dimensional structure with undulating van der Waals gaps. PMID:21202163

  19. Nitrogen in germanium

    NASA Astrophysics Data System (ADS)

    Chambouleyron, I.; Zanatta, A. R.

    1998-07-01

    The known properties of nitrogen as an impurity in, and as an alloy element of, the germanium network are reviewed in this article. Amorphous and crystalline germanium-nitrogen alloys are interesting materials with potential applications for protective coatings and window layers for solar conversion devices. They may also act as effective diffusion masks for III-V electronic devices. The existing data are compared with similar properties of other group IV nitrides, in particular with silicon nitride. To a certain extent, the general picture mirrors the one found in Si-N systems, as expected from the similar valence structure of both elemental semiconductors. However, important differences appear in the deposition methods and alloy composition, the optical properties of as grown films, and the electrical behavior of nitrogen-doped amorphous layers. Structural studies are reviewed, including band structure calculations and the energies of nitrogen-related defects, which are compared with experimental data. Many important aspects of the electronic structure of Ge-N alloys are not yet completely understood and deserve a more careful investigation, in particular the structure of defects associated with N inclusion. The N doping of the a-Ge:H network appears to be very effective, the activation energy of the most effectively doped samples becoming around 120 meV. This is not the case with N-doped a-Si:H, the reasons for the difference remaining an open question. The lack of data on stoichiometric β-Ge3N4 prevents any reasonable assessment on the possible uses of the alloy in electronic and ceramic applications.

  20. Local structure of germanium-sulfur, germanium-selenium, and germanium-tellurium vitreous alloys

    SciTech Connect

    Bordovsky, G. A.; Terukov, E. I.; Anisimova, N. I.; Marchenko, A. V.; Seregin, P. P.

    2009-09-15

    {sup 119}Sn and {sup 129}Te ({sup 129}I) Moessbauer spectroscopy showed that chalcogen-enriched Ge{sub 100-y}X{sub y} (X = S, Se, Te) glasses are constructed of structural units including two-coordinated chalcogen atoms in chains such as Ge-X-Ge- and Ge-X-X-Ge-. Germanium in these glasses is only tetravalent and four-coordinated, and only chalcogen atoms are in the local environment of germanium atoms. Chalcogen-depleted glasses are constructed of structural units including two-coordinated (in Ge-X-Ge- chains) and three-coordinated chalcogen atoms (in -Ge-X-Ge- chains). Germanium in these glasses stabilizes in both the tetravalent four-coordinated and divalent three-coordinated states, and only chalcogen atoms are in the local environment of germanium atoms.

  1. Resonant germanium nanoantenna photodetectors.

    PubMed

    Cao, Linyou; Park, Joon-Shik; Fan, Pengyu; Clemens, Bruce; Brongersma, Mark L

    2010-04-14

    On-chip optical interconnection is considered as a substitute for conventional electrical interconnects as microelectronic circuitry continues to shrink in size. Central to this effort is the development of ultracompact, silicon-compatible, and functional optoelectronic devices. Photodetectors play a key role as interfaces between photonics and electronics but are plagued by a fundamental efficiency-speed trade-off. Moreover, engineering of desired wavelength and polarization sensitivities typically requires construction of space-consuming components. Here, we demonstrate how to overcome these limitations in a nanoscale metal-semiconductor-metal germanium photodetector for the optical communications band. The detector capitalizes on antenna effects to dramatically enhance the photoresponse (>25-fold) and to enable wavelength and polarization selectivity. The electrical design featuring asymmetric metallic contacts also enables ultralow dark currents (approximately 20 pA), low power consumption, and high-speed operation (>100 GHz). The presented high-performance photodetection scheme represents a significant step toward realizing integrated on-chip communication and manifests a new paradigm for developing miniaturized optoelectronics components. PMID:20230043

  2. Surface Passivation of Germanium Nanowires

    SciTech Connect

    Adhikari, Hemant; Sun, Shiyu; Pianetta, Piero; Chidsey, Chirstopher E.D.; McIntyre, Paul C.; /SLAC, SSRL

    2005-05-13

    The surface of single crystal, cold-wall CVD-grown germanium nanowires was studied by synchrotron radiation photoemission spectroscopy (SR-PES) and also by conventional XPS. The as-grown germanium nanowires seem to be hydrogen terminated. Exposure to laboratory atmosphere leads to germanium oxide growth with oxidation states of Ge{sup 1+}, Ge{sup 2+}, Ge{sup 3+}, while exposure to UV light leads to a predominance of the Ge{sup 4+} oxidation state. Most of the surface oxide could be removed readily by aqueous HF treatment which putatively leaves the nanowire surface hydrogen terminated with limited stability in air. Alternatively, chlorine termination could be achieved by aq. HCl treatment of the native oxide-coated nanowires. Chlorine termination was found to be relatively more stable than the HF-last hydrogen termination.

  3. The Germanium Dichotomy in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Humayun, M.; Yang, S.; Righter, K.; Zanda, B.; Hewins, R. H.

    2016-01-01

    Germanium is a moderately volatile and siderophile element that follows silicon in its compatibility during partial melting of planetary mantles. Despite its obvious usefulness in planetary geochemistry germanium is not analyzed routinely, with there being only three prior studies reporting germanium abundances in Martian meteorites. The broad range (1-3 ppm) observed in Martian igneous rocks is in stark contrast to the narrow range of germanium observed in terrestrial basalts (1.5 plus or minus 0.1 ppm). The germanium data from these studies indicates that nakhlites contain 2-3 ppm germanium, while shergottites contain approximately 1 ppm germanium, a dichotomy with important implications for core formation models. There have been no reliable germanium abundances on chassignites. The ancient meteoritic breccia, NWA 7533 (and paired meteorites) contains numerous clasts, some pristine and some impact melt rocks, that are being studied individually. Because germanium is depleted in the Martian crust relative to chondritic impactors, it has proven useful as an indicator of meteoritic contamination of impact melt clasts in NWA 7533. The germanium/silicon ratio can be applied to minerals that might not partition nickel and iridium, like feldspars. We report germanium in minerals from the 3 known chassignites, 2 nakhlites and 5 shergottites by LAICP- MS using a method optimized for precise germanium analysis.

  4. Bromide Adsorption by Reference Minerals and Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bromide, Br-, adsorption behavior was investigated on amorphous Al and Fe oxide, montmorillonite, kaolinite, and temperate and tropical soils. Bromide adsorption decreased with increasing solution pH with minimal adsorption occurring above pH 7. Bromide adsorption was higher for amorphous oxides t...

  5. Germanium Nanocrystal Solar Cells

    NASA Astrophysics Data System (ADS)

    Holman, Zachary Charles

    Greenhouse gas concentrations in the atmosphere are approaching historically unprecedented levels from burning fossil fuels to meet the ever-increasing world energy demand. A rapid transition to clean energy sources is necessary to avoid the potentially catastrophic consequences of global warming. The sun provides more than enough energy to power the world, and solar cells that convert sunlight to electricity are commercially available. However, the high cost and low efficiency of current solar cells prevent their widespread implementation, and grid parity is not anticipated to be reached for at least 15 years without breakthrough technologies. Semiconductor nanocrystals (NCs) show promise for cheap multi-junction photovoltaic devices. To compete with photovoltaic materials that are currently commercially available, NCs need to be inexpensively cast into dense thin films with bulk-like electrical mobilities and absorption spectra that can be tuned by altering the NC size. The Group II-VI and IV-VI NC communities have had some success in achieving this goal by drying and then chemically treating colloidal particles, but the more abundant and less toxic Group IV NCs have proven more challenging. This thesis reports thin films of plasma-synthesized Ge NCs deposited using three different techniques, and preliminary solar cells based on these films. Germanium tetrachloride is dissociated in the presence of hydrogen in a nonthermal plasma to nucleate Ge NCs. Transmission electron microscopy and X-ray diffraction indicate that the particles are nearly monodisperse (standard deviations of 10-15% the mean particle diameter) and the mean diameter can be tuned from 4-15 nm by changing the residence time of the Ge NCs in the plasma. In the first deposition scheme, a Ge NC colloid is formed by reacting nanocrystalline powder with 1-dodecene and dispersing the functionalized NCs in a solvent. Films are then formed on substrates by drop-casting the colloid and allowing it to dry

  6. Radiation damage of germanium detectors

    NASA Technical Reports Server (NTRS)

    Pehl, R. H.

    1978-01-01

    Energetic particles can produce interstitial-vacancy pairs in a crystal by knocking the atoms from their normal positions. Detectors are unique among semiconductor devices in depending on very low concentrations of electrically active impurities, and also on efficient transport of holes and electrons over relatively large distances. Because the dense regions of damage produced by energetic particles may result in donors and/or acceptors, and also provide trapping sites for holes and electrons, detectors are very sensitive to radiation damage. In addition to these effects occurring within the detector, radiation may also change the characteristics of the exposed surfaces causing unpredictable effects on the detector leakage current. Radiation-induced surface degradation has rarely, if ever, been observed for germanium detectors. The possibility of minimizing hole trapping in charge collection by the use of a high-purity germanium coaxial detector configured with the p (+) contact on the coaxial periphery is discussed.

  7. Calibration of Germanium Resistance Thermometers

    NASA Technical Reports Server (NTRS)

    Ladner, D.; Urban, E.; Mason, F. C.

    1987-01-01

    Largely completed thermometer-calibration cryostat and probe allows six germanium resistance thermometers to be calibrated at one time at superfluid-helium temperatures. In experiments involving several such thermometers, use of this calibration apparatus results in substantial cost savings. Cryostat maintains temperature less than 2.17 K through controlled evaporation and removal of liquid helium from Dewar. Probe holds thermometers to be calibrated and applies small amount of heat as needed to maintain precise temperature below 2.17 K.

  8. Epitaxial Deposition Of Germanium Doped With Gallium

    NASA Technical Reports Server (NTRS)

    Huffman, James E.

    1994-01-01

    Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

  9. Mineral resource of the month: germanium

    USGS Publications Warehouse

    Guberman, David

    2010-01-01

    The article provides information on germanium, an element with electrical properties between those of a metal and an insulator. Applications of germanium include its use as a component of the glass in fiber-optic cable, in infrared optics devices and as a semiconductor and substrate used in electronic and solar applications. Germanium was first isolated by German chemist Clemens Winkler in 1886 and was named after Winkler's native country. In 2008, the leading sources of primary germanium from coal or zinc include Canada, China and Russia.

  10. Germanium recycling in the United States in 2000

    USGS Publications Warehouse

    Jorgenson, John D.

    2006-01-01

    This report describes the recycling flow of germanium in the United States in 2000, as well as other germanium material flow streams. Germanium was recycled mostly from new scrap that was generated during the manufacture of germanium-containing fiber optic cables and from new and old scrap products of germanium-containing infrared imaging devices. In 2000, about 11.5 metric tons of germanium was recycled, about 40 percent of which was derived from old scrap. The germanium recycling rate was estimated to be 50 percent, and germanium scrap recycling efficiency, 76 percent.

  11. Mineral resource of the month: germanium

    USGS Publications Warehouse

    Jorgenson, John D.

    2003-01-01

    Germanium is a hard, brittle semimetal that first came into use over a half-century ago as a semiconductor material in radar units and in the first transistor ever made. Most germanium is recovered as a byproduct of zinc smelting, but it has also been recovered at some copper smelters and from the fly ash of coal-burning industrial power plants.

  12. APPLICATION OF GERMANIUM DETECTORS TO ENVIRONMENTAL MONITORING

    EPA Science Inventory

    Gamma-ray spectroscopy is one of the most economical and wide-ranging tools for monitoring the environment for radiological impact. This report examines the problems involved in applying germanium detectors to the analysis of environmental samples. All aspects of germanium spectr...

  13. Reactions of germanium tetrahalides with ketene acetals

    SciTech Connect

    Efimova, I.V.; Kazankova, M.A.; Lutsenko, I.F.

    1985-05-01

    Recently, the authors reported that alkyl vinyl ethers and terminal alkynes are readily germylated by germanium tetrahalides in the presence of a tertiary amine. To extend the range of applicability of this reaction and to obtain additional information on its mechanism, the authors study reactions of ketene acetals with germanium tetrachloride and tetrabromide in the presence of triethylamine.

  14. Germanium multiphase equation of state

    SciTech Connect

    Crockett, Scott D.; Lorenzi-Venneri, Giulia De; Kress, Joel D.; Rudin, Sven P.

    2014-05-07

    A new SESAME multiphase germanium equation of state (EOS) has been developed using the best available experimental data and density functional theory (DFT) calculations. The equilibrium EOS includes the Ge I (diamond), the Ge II (β-Sn) and the liquid phases. The foundation of the EOS is based on density functional theory calculations which are used to determine the cold curve and the Debye temperature. Results are compared to Hugoniot data through the solid-solid and solid-liquid transitions. We propose some experiments to better understand the dynamics of this element

  15. MAJORANA Collaboration's experience with germanium detectors

    SciTech Connect

    Mertens, S.; Abgrall, N.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Brudanin, V.; Busch, M.; Buuck, M.; Byram, D.; Caldwell, A. S.; Chan, Y. -D.; Christofferson, C. D.; Cuesta, C.; Detwiler, J. A.; Efremenko, Yu; Ejiri, H.; Elliott, S. R.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guinn, I.; Guiseppe, V. E.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Jasinski, B. R.; Keeter, K. J.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; MacMullin, J.; Martin, R. D.; Meijer, S. J.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Ronquest, M. C.; Shanks, B.; Shirchenko, M.; Snyder, N.; Tedeschi, D.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C. -H.; Yumatov, V.

    2015-05-01

    The goal of the Majorana Demonstrator project is to search for 0νββ decay in 76Ge. Of all candidate isotopes for 0νββ, 76Ge has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0νββ, the high purity germanium crystal acts simultaneously as source and detector. Furthermore, p-type germanium detectors provide excellent energy resolution and a specially designed point contact geometry allows for sensitive pulse shape discrimination. This paper will summarize the experiences the MAJORANA collaboration made with enriched germanium detectors manufactured by ORTEC®®. The process from production, to characterization and integration in MAJORANA mounting structure will be described. A summary of the performance of all enriched germanium detectors will be given.

  16. MAJORANA Collaboration's experience with germanium detectors

    DOE PAGESBeta

    Mertens, S.; Abgrall, N.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Brudanin, V.; Busch, M.; Buuck, M.; Byram, D.; Caldwell, A. S.; et al

    2015-05-01

    The goal of the Majorana Demonstrator project is to search for 0νββ decay in 76Ge. Of all candidate isotopes for 0νββ, 76Ge has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0νββ, the high purity germanium crystal acts simultaneously as source and detector. Furthermore, p-type germanium detectors provide excellent energy resolution and a specially designed point contact geometry allows for sensitive pulse shape discrimination. This paper will summarize the experiences the MAJORANA collaboration made with enriched germanium detectors manufactured by ORTEC®®. The process from production, to characterization and integration in MAJORANAmore » mounting structure will be described. A summary of the performance of all enriched germanium detectors will be given.« less

  17. Measuring methyl bromide emissions from fields

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.; Yates, M.V.

    1995-12-31

    Methyl bromide is used extensively for pest control. Recent evidence suggests that methyl bromide may react with stratospheric ozone and, due to the Clean Air Act, is scheduled for phase-out within the next 5 to 10 years. As indicated in a recent report from The National Agricultural Pesticide Impact Assessment Program, there will be substantial economic impact on the agricultural community if the use of methyl bromide is restricted. There are several areas of uncertainty concerning the agricultural use of methyl bromide. Foremost is the quantification of mass emitted to the atmosphere from agricultural fields. To address this, two field experiments were conducted to directly measure methyl bromide emissions. In the first experiment, methyl bromide was injected at approximately 25 cm depth and the soil was covered with 1 mil high-density polyethylene plastic. The second experiment was similar except that methyl bromide was injected at approximately 68 cm depth and the soil was not covered. From these experiments, the emission rate into the atmosphere and the subsurface transport of methyl bromide was determined. Both experiments include a field-scale mass balance to verify the accuracy of the flux-measurement methods as well as to check data consistency. The volatilization rate and mass lost was determined from estimates of the degradation and from several atmospheric and chamber flux methods.

  18. 77 FR 35295 - Methyl Bromide; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... AGENCY 40 CFR Part 180 RIN 2070-ZA16 Methyl Bromide; Pesticide Tolerances AGENCY: Environmental... methyl bromide in or on cotton, undelinted seed under the Federal Food, Drug, and Cosmetic Act (FFDCA.... Background In the Federal Register of April 6, 2012 (77 FR 20752) (FRL-9345- 1), EPA issued a proposed...

  19. METHYL BROMIDE ALTERNATIVES FOR VINEYARD REPLANT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil fumigation with methyl bromide is needed by grape growers in central California to control soilborne pests. However, use of methyl bromide is banned and soil fumigation with other chemicals subjects to strict regulations to protect human health and air quality. The objective was to determine,...

  20. Interfacial properties of germanium nitride dielectric layers in germanium

    NASA Astrophysics Data System (ADS)

    Meiners, L. G.

    The first year's effort on this project has been primarily devoted to the design and construction of a low-pressure chemical vapor deposition system for growth of the germanium nitride layers. The gas manifold layout is shown schematically, as is the reactor assembly, and the vacuum pumping assembly. The generator-cavity system is capable of delivering 0-600 W of microwave power at 2.45 GHz. The power generating section has been constructed from components contained in a portable home microwave oven and the cavity was assembled from easily machinable pieces. The cw magnetron source was mounted directly on a cylindrical microwave cavity. The plasma was contained in an on-axis 20-mm o.d. quartz tube. Design tradeoffs and operating information are discussed.

  1. Neurological manifestation of methyl bromide intoxication.

    PubMed

    Suwanlaong, Kanokrat; Phanthumchinda, Kammant

    2008-03-01

    Methyl bromide is a highly toxic gas with poor olfactory warning properties. It is widely used as insecticidal fumigant for dry foodstuffs and can be toxic to central and peripheral nervous systems. Most neurological manifestations of methyl bromide intoxication occur from inhalation. Acute toxicity characterized by headache, dizziness, abdominal pain, nausea, vomiting and visual disturbances. Tremor, convulsion, unconsciousness and permanent brain damage may occur in severe poisoning. Chronic exposure can cause neuropathy, pyramidal and cerebellar dysfunction, as well as neuropsychiatric disturbances. The first case of methyl bromide intoxication in Thailand has been described. The patient was a 24-year-old man who worked in a warehouse of imported vegetables fumigated with methyl bromide. He presented with unstable gait, vertigo and paresthesia of both feet, for two weeks. He had a history of chronic exposure to methyl bromide for three years. His fourteen co-workers also developed the same symptoms but less in severity. Neurological examination revealed ataxic gait, decreased pain and vibratory sense on both feet, impaired cerebellar signs and hyperactive reflex in all extremities. The serum concentration of methyl bromide was 8.18 mg/dl. Electrophysilogical study was normal. Magnetic resonance imaging of the brain (MRI) revealed bilateral symmetrical lesion of abnormal hypersignal intensity on T2 and fluid-attenuation inversion recovery (FLAIR) sequences at bilateral dentate nuclei of cerebellum and periventricular area of the fourth ventricle. This incident stresses the need for improvement of worker education and safety precautions during all stages of methyl bromide fumigation. PMID:18575299

  2. Solution synthesis of germanium nanocrystals

    DOEpatents

    Gerung, Henry; Boyle, Timothy J.; Bunge, Scott D.

    2009-09-22

    A method for providing a route for the synthesis of a Ge(0) nanometer-sized material from. A Ge(II) precursor is dissolved in a ligand heated to a temperature, generally between approximately 100.degree. C. and 400.degree. C., sufficient to thermally reduce the Ge(II) to Ge(0), where the ligand is a compound that can bond to the surface of the germanium nanomaterials to subsequently prevent agglomeration of the nanomaterials. The ligand encapsulates the surface of the Ge(0) material to prevent agglomeration. The resulting solution is cooled for handling, with the cooling characteristics useful in controlling the size and size distribution of the Ge(0) materials. The characteristics of the Ge(II) precursor determine whether the Ge(0) materials that result will be nanocrystals or nanowires.

  3. High Efficiency Germanium Immersion Gratings

    SciTech Connect

    Kuzmenko, P J; Davis, P J; Little, S L; Little, L M; Bixler, J V

    2006-05-01

    We have fabricated several germanium immersion gratings by single crystal, single point diamond flycutting on an ultra-precision lathe. Use of a dead sharp tool produces groove corners less than 0.1 micron in radius and consequently high diffraction efficiency. We measured first order efficiencies in immersion of over 80% at 10.6 micron wavelength. Wavefront error was low averaging 0.06 wave rms (at 633 nm) across the full aperture. The grating spectral response was free of ghosts down to our detection limit of 1 part in 10{sup 4}. Scatter should be low based upon the surface roughness. Measurement of the spectral line profile of a CO{sub 2} laser sets an upper bound on total integrated scatter of 0.5%.

  4. High efficiency germanium immersion gratings

    NASA Astrophysics Data System (ADS)

    Kuzmenko, Paul J.; Davis, Pete J.; Little, Steve L.; Little, Liesl M.; Bixler, Jay V.

    2006-06-01

    We have fabricated several germanium immersion gratings by single crystal, single point diamond flycutting on an ultra-precision lathe. Use of a dead sharp tool produces groove corners less than 0.1 micron in radius and consequently high diffraction efficiency. We measured first order efficiencies in immersion of over 80% at 10.6 micron wavelength. Wavefront error was low averaging 0.06 wave rms (at 633 nm) across the full aperture. The grating spectral response was free of ghosts down to our detection limit of 1 part in 104. Scatter should be low based upon the surface roughness. Measurement of the spectral line profile of a CO II laser sets an upper bound on total integrated scatter of 0.5%.

  5. Potassium bromide method of infrared sampling

    USGS Publications Warehouse

    Milkey, R.G.

    1958-01-01

    In the preparation of potassium bromide pressed windows for use in the infrared analysis of solids, severe grinding of the potassium bromide powder may produce strong absorption bands that could interfere seriously with the spectra of the sample. These absorption bands appear to be due to some crystal alteration of the potassium bromide as a result of the grinding process. They were less apt to occur when the coarser powder, which had received a relatively gentle grinding, was used. Window blanks prepared from the coarser powders showed smaller adsorbed water peaks and generally higher over-all transmittance readings than windows pressed from the very fine powders.

  6. Germanium: giving microelectronics an efficiency boost

    USGS Publications Warehouse

    Mercer, Celestine N.

    2015-01-01

    Germanium is an essentially nontoxic element, with the exception of only a few compounds. However, if dissolved concentrations in drinking water are as high as one or more parts per million chronic diseases may occur.

  7. Germanium Resistance Thermometer For Subkelvin Temperatures

    NASA Technical Reports Server (NTRS)

    Castles, Stephen H.

    1993-01-01

    Improved germanium resistance thermometer measures temperatures as small as 0.01 K accurately. Design provides large area for electrical connections (to reduce electrical gradients and increase sensitivity to changes in temperatures) and large heat sink (to minimize resistance heating). Gold pads on top and bottom of germanium crystal distribute electrical current and flow of heat nearly uniformly across crystal. Less expensive than magnetic thermometers or superconducting quantum interference devices (SQUID's) otherwise used.

  8. Emission of methyl bromide from biomass burning

    SciTech Connect

    Manoe, S.; Andreae, M.O. )

    1994-03-04

    Bromine is, per atom, far more efficient than chlorine in destroying stratospheric ozone, and methyl bromide is the single largest source of stratospheric bromine. The two main previously known sources of this compound are emissions from the ocean and from the compound's use as an agricultural pesticide. Laboratory biomass combustion experiments showed that methyl bromide was emitted in the smoke from various fuels tested. Methyl bromide was also found in smoke plumes from wildfires in savannas, chaparral, and boreal forest. Global emissions of methyl bromide from biomass burning are estimated to be in the range of 10 to 50 gigagrams per year, which is comparable to the amount produced by ocean emission and pesticide use and represents a major contribution ([approximately]30 percent) to the stratospheric bromine budget.

  9. Growth and characterization of lead bromide crystals

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Gottlieb, M.; Henningsen, T.; Hopkins, R. H.; Mazelsky, R.; Glicksman, M. E.; Coriell, S. R.; Santoro, G. J.; Duval, W. M. B.

    1992-01-01

    Lead(II) bromide was purified by a combination of directional freezing and zone-refining methods. Differential thermal analysis of the lead bromide showed that a destructive phase transformation occurs below the melting temperature. This transformation causes extensive cracking, making it very difficult to grow a large single crystal. Energy of phase transformation for pure lead bromide was determined to be 24.67 cal/g. To circumvent this limitation, crystals were doped by silver bromide which decreased the energy of phase transformation. The addition of silver helped in achieving the size, but enhanced the inhomogeneity in the crystal. The acoustic attenuation constant was almost identical for the pure and doped (below 3000 ppm) crystals.

  10. Dangling bonds and vacancies in germanium

    NASA Astrophysics Data System (ADS)

    Weber, J. R.; Janotti, A.; Van de Walle, C. G.

    2013-01-01

    The quest for metal-oxide-semiconductor field-effect transistors (MOSFETs) with higher carrier mobility has triggered great interest in germanium-based MOSFETs. Still, the performance of germanium-based devices lags significantly behind that of their silicon counterparts, possibly due to the presence of defects such as dangling bonds (DBs) and vacancies. Using screened hybrid functional calculations we investigate the role of DBs and vacancies in germanium. We find that the DB defect in germanium has no levels in the band gap; it acts as a negatively charged acceptor with the (0/-1) transition level below the valence-band maximum (VBM). This explains the absence of electron-spin-resonance observations of DBs in germanium. The vacancy in germanium has a much lower formation energy than the vacancy in silicon and is stable in a number of charge states, depending on the position of the Fermi level. We find the (0/-1) and (-1/-2) transition levels at 0.16 and 0.38 eV above the VBM; the spacing of these levels is explained based on the strength of intraorbital repulsion. We compare these results with calculations for silicon, as well as with available experimental data.

  11. Investigation of drug interactions with pinaverium bromide.

    PubMed

    Devred, C; Godeau, P; Guerot, C; Librez, P; Mougeot, G; Orsetti, A; Segrestaa, J M

    1986-01-01

    A series of studies was carried out at 6 centres to investigate possible drug interaction between the spasmolytic, pinaverium bromide, and cardiac glycosides, anticoagulants and hypoglycaemic agents given to patients as part of the long-term treatment of their condition. The results of clinical and laboratory investigations did not show any evidence of pinaverium bromide interfering with the action or activity of any of the drugs studied. PMID:3084176

  12. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations... bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. (a) Bromoacetone must...

  13. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations... bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. (a) Bromoacetone must...

  14. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations... bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. (a) Bromoacetone must...

  15. Recovery of germanium-68 from irradiated targets

    DOEpatents

    Phillips, Dennis R.; Jamriska, Sr., David J.; Hamilton, Virginia T.

    1993-01-01

    A process for selective separation of germanium-68 from proton irradiated molybdenum targets is provided and includes dissolving the molybdenum target in a hydrogen peroxide solution to form a first ion-containing solution, contacting the first ion-containing solution with a cationic resin whereby ions selected from the group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium and rubidium remain in a second ion-containing solution while ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium and zirconium are selectively adsorbed by the first resin, adjusting the pH of the second ion-containing solution to within a range of from about 0.7 to about 3.0, adjusting the soluble metal halide concentration in the second ion-containing solution to a level adapted for subsequent separation of germanium, contacting the pH-adjusted, soluble metal halide-containing second ion-containing solution with a dextran-based material whereby germanium ions are separated by the dextran-based material, and recovering the germanium from the dextran-based material, preferably by distillation.

  16. Recovery of germanium-68 from irradiated targets

    SciTech Connect

    Phillips, D.R.; Jamriska, D.J. Sr.; Hamilton, V.T.

    1992-12-31

    This invention is comprised of a process for selective separation of germanium-68 from proton irradiated molybdenum targets is provided and includes dissolving the molybdenum target in a hydrogen peroxide solution to form a first ion-containing solution, contacting the first ion-containing solution with a cationic resin whereby ions selected from the group consisting of molybdenum, niobium, technetium, selenium,vanadium, arsenic, germanium, zirconium and rubidium remain in a second ion-containing solution while ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium and zirconium are selectively adsorbed by the first resin, adjusting the pH of the second ion-containing solution to within a range of from about 0.7 to about 3.0, adjusting the soluble metal halide concentration in the second ion-containing solution to a level adapted for subsequent separation of germanium, contacting the pH-adjusted, soluble metal halide-containing second ion-containing solution with a dextran-based material whereby germanium ions are separated by the dextran-based material, and recovering the germanium from the dextran-based material, preferably by distillation.

  17. Recovery of germanium-68 from irradiated targets

    SciTech Connect

    Phillips, D.R.; Jamriska, D.J. Sr.; Hamilton, V.T.

    1993-03-02

    A process for selective separation of germanium-68 from proton irradiated molybdenum targets is provided and includes dissolving the molybdenum target in a hydrogen peroxide solution to form a first ion-containing solution, contacting the first ion-containing solution with a cationic resin whereby ions selected from the group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium and rubidium remain in a second ion-containing solution while ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium and zirconium are selectively adsorbed by the first resin, adjusting the pH of the second ion-containing solution to within a range of from about 0.7 to about 3.0, adjusting the soluble metal halide concentration in the second ion-containing solution to a level adapted for subsequent separation of germanium, contacting the pH-adjusted, soluble metal halide-containing second ion-containing solution with a dextran-based material whereby germanium ions are separated by the dextran-based material, and recovering the germanium from the dextran-based material, preferably by distillation.

  18. Front End Spectroscopy ASIC for Germanium Detectors

    NASA Astrophysics Data System (ADS)

    Wulf, Eric

    Large-area, tracking, semiconductor detectors with excellent spatial and spectral resolution enable exciting new access to soft (0.2-5 MeV) gamma-ray astrophysics. The improvements from semiconductor tracking detectors come with the burden of high density of strips and/or pixels that require high-density, low-power, spectroscopy quality readout electronics. CMOS ASIC technologies are a natural fit to this requirement and have led to high-quality readout systems for all current semiconducting tracking detectors except for germanium detectors. The Compton Spectrometer and Imager (COSI), formerly NCT, at University of California Berkeley and the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) at Goddard Space Flight Center utilize germanium cross-strip detectors and are on the forefront of NASA's Compton telescope research with funded missions of long duration balloon flights. The development of a readout ASIC for germanium detectors would allow COSI to replace their discrete electronics readout and would enable the proposed Gamma-Ray Explorer (GRX) mission utilizing germanium strip-detectors. We propose a 3-year program to develop and test a germanium readout ASIC to TRL 5 and to integrate the ASIC readout onto a COSI detector allowing a TRL 6 demonstration for the following COSI balloon flight. Our group at NRL led a program, sponsored by another government agency, to produce and integrate a cross-strip silicon detector ASIC, designed and fabricated by Dr. De Geronimo at Brookhaven National Laboratory. The ASIC was designed to handle the large (>30 pF) capacitance of three 10 cm^2 detectors daisy-chained together. The front-end preamplifier, selectable inverter, shaping times, and gains make this ASIC compatible with a germanium cross-strip detector as well. We therefore have the opportunity and expertise to leverage the previous investment in the silicon ASIC for a new mission. A germanium strip detector ASIC will also require precise timing of the signals at

  19. Extrinsic germanium Blocked Impurity Bank (BIB) detectors

    NASA Technical Reports Server (NTRS)

    Krabach, Timothy N.; Huffman, James E.; Watson, Dan M.

    1989-01-01

    Ge:Ga blocked-impurity-band (BIB) detectors with long wavelength thresholds greater than 190 microns and peak quantum efficiencies of 4 percent, at an operating temperature of 1.8 K, have been fabricated. These proof of concept devices consist of a high purity germanium blocking layer epitaxially grown on a Ga-doped Ge substrate. This demonstration of BIB behavior in germanium enables the development of far infrared detector arrays similar to the current silicon-based devices. Present efforts are focussed on improving the chemical vapor deposition process used to create the blocking layer and on the lithographic processing required to produce monolithic detector arrays in germanium. Approaches to test the impurity levels in both the blocking and active layers are considered.

  20. [The clinical pharmacological profile of pinaverium bromide].

    PubMed

    Guslandi, M

    1994-04-01

    Pinaverium bromide is a locally acting spasmolytic agent of the digestive tract. Its mechanism of action relies upon inhibition of calcium ion entrance into smooth muscle cells (calcium-antagonist effect). In humans pinaverium facilitates gastric emptying and decreases intestinal transit time in patients with constipation. Pinaverium is very effective in improving symptoms of irritable bowel syndrome (abdominal pain, gas, diarrhea or constipation). In this respect the drug proved to be significantly superior to placebo, at least as effective as trimebutine and on the whole more active than otilonium and prifinium bromide, being always extremely well tolerated. PMID:8028745

  1. Effects of pinaverium bromide on Oddi's sphincter.

    PubMed

    DiSomma, C; Reboa, G; Patrone, M G; Mortola, G P; Sala, G; Ciampini, M

    1986-01-01

    Twelve to 15 days after cholecystectomy, endocholedochal pressure was measured in ten patients before and one hour after oral administration of 15 mg of pinaverium bromide (six patients) or placebo. The mean endocholedochal pressure was 7.1 +/- 0.25 mmHg before and 3.1 +/- 0.2 mmHg after pinaverium (P less than 0.01), and 7.0 +/- 0.2 and 6.8 +/- 1.2 mmHg in the placebo-treated patients. The results suggest that pinaverium bromide has a specific effect on the common bile duct and probably on Oddi's sphincter. PMID:3815457

  2. Silicon and germanium nanocrystals: properties and characterization

    PubMed Central

    Carvalho, Alexandra; Coutinho, José

    2014-01-01

    Summary Group-IV nanocrystals have emerged as a promising group of materials that extends the realm of application of bulk diamond, silicon, germanium and related materials beyond their traditional boundaries. Over the last two decades of research, their potential for application in areas such as optoelectronic applications and memory devices has been progressively unraveled. Nevertheless, new challenges with no parallel in the respective bulk material counterparts have arisen. In this review, we consider what has been achieved and what are the current limitations with regard to growth, characterization and modeling of silicon and germanium nanocrystals and related materials. PMID:25383290

  3. Germanium-overcoated niobium Dayem bridges

    NASA Technical Reports Server (NTRS)

    Holdeman, L. B.; Peters, P. N.

    1976-01-01

    Overcoating constriction microbridges with semiconducting germanium provides additional thermal conductivity at liquid-helium temperatures to reduce the effects of self-heating in these Josephson junctions. Microwave-induced steps were observed in the I-V characteristics of an overcoated Dayem bridge fabricated in a 15-nm-thick niobium film; at least 20 steps could be counted at 4.2 K. No steps were observed in the I-V characteristics of the bridge prior to overcoating. In addition, the germanium overcoat can protect against electrical disturbances at room temperature.

  4. Neutron-transmutation-doped germanium bolometers

    NASA Technical Reports Server (NTRS)

    Palaio, N. P.; Rodder, M.; Haller, E. E.; Kreysa, E.

    1983-01-01

    Six slices of ultra-pure germanium were irradiated with thermal neutron fluences between 7.5 x 10 to the 16th and 1.88 x 10 to the 18th per sq cm. After thermal annealing the resistivity was measured down to low temperatures (less than 4.2 K) and found to follow the relationship rho = rho sub 0 exp(Delta/T) in the hopping conduction regime. Also, several junction FETs were tested for noise performance at room temperature and in an insulating housing in a 4.2 K cryostat. These FETs will be used as first stage amplifiers for neutron-transmutation-doped germanium bolometers.

  5. Germanium-Based Nanomaterials for Rechargeable Batteries.

    PubMed

    Wu, Songping; Han, Cuiping; Iocozzia, James; Lu, Mingjia; Ge, Rongyun; Xu, Rui; Lin, Zhiqun

    2016-07-01

    Germanium-based nanomaterials have emerged as important candidates for next-generation energy-storage devices owing to their unique chemical and physical properties. In this Review, we provide a review of the current state-of-the-art in germanium-based materials design, synthesis, processing, and application in battery technology. The most recent advances in the area of Ge-based nanocomposite electrode materials and electrolytes for solid-state batteries are summarized. The limitations of Ge-based materials for energy-storage applications are discussed, and potential research directions are also presented with an emphasis on commercial products and theoretical investigations. PMID:27281435

  6. Methyl Bromide Alternatives for Vineyard Replant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The project is part of the USDA-ARS Pacific Area-Wide Pest Management Program for Methyl Bromide Alternatives. This is the first year of a three-year project. The research was initiated in summer 2007 with a field study planned for October 2007 at the USDA-ARS San Joaquin Valley Agricultural Scienc...

  7. METHYL BROMIDE ALTERNATIVES FOR CALIFORNIA STRAWBERRY NURSERIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of methyl bromide (MB) alternative fumigants on soil pests, plant productivity in nursery and fruiting fields, as well as production costs, were evaluated in California strawberry nurseries by an interdisciplinary team. Our trials followed nursery stock through low and high elevation ph...

  8. Zinc Bromide Waste Solution Treatment Options

    SciTech Connect

    Langston, C.A.

    2001-01-16

    The objective of this effort was to identify treatment options for 20,000 gallons of low-level radioactively contaminated zinc bromide solution currently stored in C-Area. These options will be relevant when the solutions are declared waste.

  9. Challenges in Weed Management Without Methyl Bromide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide has been used for several decades for pre-plant soil fumigation in high value agricultural and horticultural crops because it can provide broad-spectrum control of insects, nematodes, pathogens, and weeds. However, MeBr has been identified as a powerful ozone-depleting chemical and i...

  10. Methyl bromide emissions from tarped fields

    SciTech Connect

    Cicerone, R.J.; Williams, J.; Wang, N.Y.

    1995-12-31

    Once in the stratosphere, bromine atoms can destroy ozone effectively. Because of this potential effect, certain organobromine compounds including methyl bromide (MeBr) are being controlled or eliminated by national and international regulations. It would be valuable to determine the fraction of MeBr used in soil fumigations that subsequently enters the atmosphere to better assess the need for, and value of, strong regulations. We have designed and conducted several experiments accompanying field fumigations with MeBr/chloropicrin mixtures. In each of three field-fumigation experiments new Irvine, CA in which the fumigated field was covered immediately with plastic tarping, we have deployed static flux chambers on top of the tarping and measured escape fluxes of MeBr. After tarp removal, the same chambers were replaced on the bare soil to continue the measurements. We have also measured soil bromide contents before and after the fumigation. One experiment yielded an escape fraction of 80 to 87% (with 19% remaining as bromide) while the other two experiments yielded escape fractions of 30 to 35% (with about 70% remaining as bromide). This paper will summarize stratospheric bromine chemistry, describe the field experiments and discuss factors that influence emissions, including soil pH, moisture and organic content and injection technique. We acknowledge TriCal, Inc. for many helpful discussions and for professional field applications of MeBr.

  11. Can Georgia growers replace methyl bromide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The price and availability of methyl bromide is limiting its use on Georgia farms; the need for an alternative is essential for sustainable vegetable production in GA. Three alternatives were evaluated in on-farm trials in the spring 2007 in Tift, Colquitt and Echols Counties. Treatments were replic...

  12. Electron tunnelling into amorphous germanium and silicon.

    NASA Technical Reports Server (NTRS)

    Smith, C. W.; Clark, A. H.

    1972-01-01

    Measurements of tunnel conductance versus bias, capacitance versus bias, and internal photoemission were made in the systems aluminum-oxide-amorphous germanium and aluminium-oxide-amorphous silicon. A function was extracted which expresses the deviation of these systems from the aluminium-oxide-aluminium system.

  13. Dopant precipitation in silicon-germanium alloys.

    NASA Technical Reports Server (NTRS)

    Raag, V.

    1972-01-01

    The model commonly used to describe dopant precipitation in silicon-germanium alloys is discussed. The results of an experimental program are fit to the model in order to determine the long-term behavior of the thermoelectric properties of the n-type 80 at. % Si/20 at. % Ge alloy. Thermoelectric property projections to twelve years of operating time are given.

  14. Method for copper staining of germanium crystals

    NASA Technical Reports Server (NTRS)

    Rivet, E. J.

    1969-01-01

    Proper conditions for copper staining of germanium crystals include a low solution temperature of 3 degrees C, illumination of the sample by infrared light, and careful positioning of the light source relative to the sample so as to minimize absorption of the infrared light.

  15. Hydrogenated amorphous silicon-germanium alloys

    SciTech Connect

    Luft, W.

    1988-02-01

    This report describes the effects of the germanium fraction in hydrogenated amorphous silicon-germanium alloys on various parameters, especially those that are indicators of film quality, and the impact of deposition methods, feedgas mixtures, and other deposition parameters on a SiGe:H and a-SiGe:H:F film characteristics and quality. Literature data show the relationship between germanium content, hydrogen content, deposition method (various glow discharges and CVD), feedgas lmixture, and other parameters and properties, such as optical band gap, dark and photoconductivities, photosensitivity, activation energy, Urbach parameter, and spin density. Some of these are convenient quality indicators; another is the absence of microstructure. Examining RF glow discharge with both a diode and triode geometry, DC proximity glow discharge, microwave glow discharge, and photo-CVD, using gas mixtures such as hydrogen-diluted and undiluted mixtures of silane/germane, disilane/germane, silane/germaniumtetrafluoride, and others, it was observed that hydrogen dilution (or inert gas dilution) is essential in achieving high photosensitivity in silicon-germanium alloys (in contradistinction to amorphous hydrogenated silicon). Hydrogen dilution results in a higher photosensitivity than do undiluted gas mixtures. 81 refs., 42 figs., 7 tabs.

  16. Germanium JFET for Cryogenic Readout Electronics

    NASA Technical Reports Server (NTRS)

    Das, N. C.; Monroy, C.; Jhabvala, M.; Shu, P.

    1999-01-01

    The n-channel Germanium junction field effect transistor (Ge-JFET) was designed and fabricated for cryogenic applications. The Ge-JFET exhibits superior noise performance at liquid nitrogen temperature (77 K). From the device current voltage characteristics of n-channel JFETs, it is seen that transconductance increases monotonically with the lowering of temperature to 4.2 K (liquid helium temperature).

  17. A comparison of the action of otilonium bromide and pinaverium bromide: study conducted under clinical control.

    PubMed

    Defrance, P; Casini, A

    1991-11-01

    We studied 40 patients with irritable bowel syndrome (IBS) which received in a simple-blind fashion otilonium and pinaverium bromide (15 days each drug). During each 15-day period we evaluated: number of pain episodes, intensity of pain, number of bowel movements, side effects. Otilonium bromide, (OB), compared with pinaverium bromide was able to significantly (p less than 0.05) reduce the number of pain attacks, whereas no significant differences were found between the 2 groups as regards the other parameters. The occurrence of side effects was similar in the two treatment courses. We can conclude that the two types of treatment were similarly useful in IBS, although OB seems more effective than pinaverium bromide. PMID:1756286

  18. EVALUATION OF PROPARGYL BROMIDE AS A SOIL FUMIGANT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cut flower and bulb industry has relied heavily upon the use of methyl bromide as a key soil treatment for soilborne pest control. Due to the phase-out of methyl bromide it is important to develop alternatives to manage pests now managed by methyl bromide. The emphasis of this work was to eval...

  19. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  20. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  1. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  2. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  3. WEED CONTROL IN THE LIFE AFTER METHYL BROMIDE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetable growers are losing the soil fumigant methyl bromide. Efforts are on-going to extend the deadline for using methyl bromide until suitable alternatives are developed. Regardless of whether the deadline is extended or not, growers need to begin to study alternatives to methyl bromide and be...

  4. 75 FR 5582 - Methyl Bromide; Amendments to Terminate Uses

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-03

    ... AGENCY Methyl Bromide; Amendments to Terminate Uses AGENCY: Environmental Protection Agency (EPA). ACTION... requested by the registrants and accepted by the Agency, of products containing the pesticide methyl bromide... Requests from the registrants listed in Table 2 to amend to terminate post-harvest methyl bromide uses...

  5. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Methyl bromide; tolerances for... § 180.124 Methyl bromide; tolerances for residues. (a) General. A tolerance is established for residues of the fumigant methyl bromide, including metabolites and degradates, in or on the commodity in...

  6. 7 CFR 305.6 - Methyl bromide fumigation treatment schedules.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Methyl bromide fumigation treatment schedules. 305.6..., fumigation with methyl bromide for sapote fruit fly. Regulated citrus fruits originating inside an area... equal concentrations of methyl bromide throughout the chamber, a fan should be placed near the point...

  7. Measurements of atmospheric methyl bromide and bromoform

    SciTech Connect

    Cicerone, R.J.; Heidt, L.E.; Pollock, W.H.

    1988-04-20

    We have measured gaseous methyl bromide (CH/sub 3/Br) and bromoform (CHBr/sub 3/) in air samples that were gathered approximately weekly from five ground-level sites: Point Barrow, Alaska; Mauna Loa Observatory and Cape Kumukahi, Hawaii; Matatula, Samoa; and Kaitorete Spit, New Zealand. Approximately 750 samples have been analyzed for CH/sub 3/Br between January 1985 and October 1987 and 990 samples have been analyzed for CHBr/sub 3/ between early 1984 and September 1987, all by gas chromatography/mass spectroscopy. Methyl bromide concentrations are typically 10--11 parts per trillion (ppt) by volume; there are no clear indications of temporal increases. Bromoform concentrations are typically 2--3 ppt, but large seasonal variations are seen at Point Barrow. copyright American Geophysical Union 1988

  8. Removal of bromide and natural organic matter by anion exchange.

    PubMed

    Hsu, Susan; Singer, Philip C

    2010-04-01

    Bromide removal by anion exchange was explored for various water qualities, process configurations, and resin characteristics. Simulated natural waters containing different amounts of natural organic matter (NOM), bicarbonate, chloride, and bromide were treated with a polyacrylate-based magnetic ion exchange (MIEX) resin on a batch basis to evaluate the effectiveness of the resin for removal of bromide. While bromide removal was achieved to some degree, alkalinity (bicarbonate), dissolved organic carbon (DOC), and chloride were shown to inhibit bromide removal in waters with bromide concentrations of 100 and 300 microg/L. Water was also treated using a two-stage batch MIEX process. Two-stage treatment resulted in only a slight improvement in bromide removal compared to single-stage treatment, presumably due to competition with the high concentration of chloride which is present along with bromide in natural waters. In view of the relatively poor bromide removal results for the MIEX resin, a limited set of experiments was performed using polystyrene resins. DOC and bromide removal were compared by treating model waters with MIEX and two polystyrene resins, Ionac A-641 and Amberlite IRA910. The two polystyrene resins were seen to be more effective for bromide removal, while the MIEX resin was more effective at removing DOC. PMID:20045170

  9. [Research advances in methyl bromide in the ocean].

    PubMed

    Du, Hui-na; Xie, Wen-xia; Cui, Yu-qian; Chen, Jian-lei; Ye, Si-yuan

    2014-12-01

    Methyl bromide is an important atmospheric trace gas, which plays significant roles in the global warming and atmospheric chemistry. The ocean plays important and complex roles in the global biogeochemical cycles of methyl bromide, not only the source of atmospheric methyl bromide, but also the sink. Therefore, developing the chemical research of the soluble methyl bromide in the ocean, will not only have a certain guiding significance to the atmospheric ozone layer protection, but also provide a theoretical basis for estimating methyl bromide's contribution to the global environmental change on global scale. This paper reviewed the research advances on methyl bromide in the ocean, from the aspects of the biogeochemical cycle of methyl bromide in the ocean, the analysis and determination method, the concentration distribution, the sea-to-air flux and its sources and sinks in the atmosphere. Some deficiencies in the current studies were put forward, and the directions of the future studies were prospected. PMID:25876424

  10. Methyl bromide: Ocean sources, ocean sinks, and climate sensitivity

    SciTech Connect

    Anbar, A.D.; Yung, Y.L.; Chavez, F.P.

    1996-03-01

    This study was performed to examine conflicting conclusions of two previously published studies which estimated the size of oceanic sources of methyl bromide. In addition, the sensitivity of atmospheric methyl bromide to climatic variations was examined. A steady state mass balance model was used to reexamine data from the previous studies. Linear scaling of methyl bromide production rates to chlorophyll content provided agreement between the two models. The results suggest that the open ocean is a small net sink for atmospheric methyl bromide, rather than a large net source. A high rate of biological production of methyl bromide in seawater is also strongly indicated. A coupled ocean-atmosphere model indicated that methyl bromide variations induced by climatic change can be larger than those resulting from 25% variations in anthropogenic sources. Quantifying marine production rates of methyl bromide is suggested as a necessary step in assessing stratospheric ozone loss. 63 refs., 10 figs., 2 tabs.

  11. Lattice vibrations in lead bromide and chloride

    NASA Astrophysics Data System (ADS)

    Carabatos-Nédelec, C.; Bréhat, F.; Wyncke, B.

    Lead bromide and lead chloride lattice dynamics studies by polarized IR reflectivity and Raman scattering are reported at room temperature and at 10 K. Reflectivity spectra from 20 to 300 cm -1 have been fitted with a model of the factorized form of the dielectric function. The lattice modes frequencies, damping factors and oscillators strengths are given, as well as the effective charges of the polar modes. The study concludes the ionic character of the compounds.

  12. Methyl bromide users search for science

    SciTech Connect

    Winegar, E.D.

    1995-01-01

    Workers, neighbors and the ozone are protected by regulation from this chemical, but those needing it complain that a solid foundation is lacking for the rules. Although not yet featured on {open_quotes}60 Minutes,{close_quotes} the pesticide methyl bromide is gaining widespread attention because of its central position in debates about worker health and safety, environmental toxics exposure and global ozone depletion.

  13. Methyl bromide volatility measurements from treated fields

    SciTech Connect

    Majewski, M.S.; Woodrow, J.E.; Seiber, J.N. |

    1995-12-31

    Methyl bromide is used as an agricultural soil fumigant and concern is growing over the role it may play in the depletion of stratospheric ozone. Methyl bromide is applied using various techniques and little is known about how much of the applied fumigant volatilizes into the atmosphere after application. The post-application volatilization losses of methyl bromide from two fields using different application practices were measured using an aerodynamic-gradient technique. One field was covered with a high-barrier plastic film tarp during application and the other was left uncovered, but the furrows made by the injection shanks were bedded over. The cumulative volatilization losses from the tarped field were 22% of the nominal application within the first 5 days of the experiment and about 32% of the nominal application within 9 days including the one day after the tarp was removed on day 8. The nontarped field lost 89%of the nominal application by volatilization in 5 days. The error associated, with each flux measurement, as well as variations in daily flux losses with differing sampling period lengths show the degree of variability inherent in this type of study.

  14. Methyl bromide fate in fumigated soils

    SciTech Connect

    Anderson, T.A.; Rice, P.J.; Cink, J.H.

    1995-12-31

    Although widespread use of methyl bromide (MeBr) as a sail and structure fumigant has previously been recognized as a potential significant source of atmospheric MeBr, losses have not been well quantified. Our research indicates that, in laboratory studies, MeBr is volatilized rapidly from fumigated soils and that volatility increases with temperature (35{degrees}C > 25{degrees}C and 15{degrees}C) and moisture (0.03 bar and 0.3 bar > 1 bar > 3 bar). Degradation of MeBr in soil, as indicated by production of bromide ion, was also directly related to temperature and moisture. Most of the soil degradation of MeBr in these studies appears to be abiotic based on the observation of toxicity (reduced microbial respiration) in fumigated soils. We also determined the transformation and movement of MeBr in undisturbed soil columns. These studies also indicated that MeBT volatilizes rapidly (> 50% in 48 h) from soil. In addition, MeBr was not detected in the leachate from the soil columns, however, bromide ion was detected at levels above background 48 h after fumigation and peaked at 5 weeks.

  15. Bromate oxidized from bromide during sonolytic ozonation.

    PubMed

    Lu, Ning; Wu, Xue-Fei; Zhou, Ji-Zhi; Huang, Xin; Ding, Guo-Ji

    2015-01-01

    Sonolytic ozonation (US/O3) is an effective way to degrade many pollutants in drinking water as the elevated mass transfer rate of ozone gas and the enhanced forming of hydroxyl radicals (OH). This work investigated the formation of bromate (BrO3(-)) from bromide (Br(-)) in sonolytic ozonation. At neutral pH, the bromate conversion rate ([BrO3(-)]/[Br(-)]0) was increased to 60% by ultrasound at continuous ozone flow (0-0.2Lmin(-1)), much higher than that without ultrasound or without bubbling. This indicates that the promoting effect of sonolysis on BrO3(-) formation is mainly due to the sonolytic decomposition of ozone and the enhancement of gas-liquid transfer. The [BrO3(-)]/[Br(-)]0 was increased with increasing pH. In addition, the reduction of HOBr/OBr(-) with ultrasound demonstrates that bromate may be inhibited as the bromide was formed with the H2O2 generation under ultrasound. This suggests the competition between bromate and bromide during the US/O3 led to the inhibition of bromate formation at high ozone flow. Therefore, our result reveals that the bromate formation under ultrasound is improved remarkably in US/O3 in quick treatment with proper ozone flow (<0.2Lmin(-1)). PMID:24931426

  16. Spin transport in p-type germanium.

    PubMed

    Rortais, F; Oyarzún, S; Bottegoni, F; Rojas-Sánchez, J-C; Laczkowski, P; Ferrari, A; Vergnaud, C; Ducruet, C; Beigné, C; Reyren, N; Marty, A; Attané, J-P; Vila, L; Gambarelli, S; Widiez, J; Ciccacci, F; Jaffrès, H; George, J-M; Jamet, M

    2016-04-27

    We report on the spin transport properties in p-doped germanium (Ge-p) using low temperature magnetoresistance measurements, electrical spin injection from a ferromagnetic metal and the spin pumping-inverse spin Hall effect method. Electrical spin injection is carried out using three-terminal measurements and the Hanle effect. In the 2-20 K temperature range, weak antilocalization and the Hanle effect provide the same spin lifetime in the germanium valence band (≈1 ps) in agreement with predicted values and previous optical measurements. These results, combined with dynamical spin injection by spin pumping and the inverse spin Hall effect, demonstrate successful spin accumulation in Ge. We also estimate the spin Hall angle θ(SHE) in Ge-p (6-7 x 10(-4) at room temperature, pointing out the essential role of ionized impurities in spin dependent scattering. PMID:26988255

  17. Constraining neutrino electromagnetic properties by germanium detectors

    NASA Astrophysics Data System (ADS)

    Chen, Jiunn-Wei; Chi, Hsin-Chang; Huang, Keh-Ning; Li, Hau-Bin; Liu, C.-P.; Singh, Lakhwinder; Wong, Henry T.; Wu, Chih-Liang; Wu, Chih-Pan

    2015-01-01

    The electromagnetic properties of neutrinos, which are either trivial or negligible in the context of the Standard Model, can probe new physics and have significant implications in astrophysics and cosmology. The current best direct limits on the neutrino millicharges and magnetic moments are both derived from data taken with germanium detectors with low thresholds at keV levels. In this paper, we discuss in detail a robust, ab initio method: the multiconfiguration relativistic random-phase approximation, that enables us to reliably understand the germanium detector response at the sub-keV level, where atomic many-body physics matters. By using existing data with sub-keV thresholds, limits on the reactor antineutrino's millicharge, magnetic moment, and charge radius squared are derived. The projected sensitivities for next-generation experiments are also given and discussed.

  18. A Germanium-Based, Coded Aperture Imager

    SciTech Connect

    Ziock, K P; Madden, N; Hull, E; William, C; Lavietes, T; Cork, C

    2001-10-31

    We describe a coded-aperture based, gamma-ray imager that uses a unique hybrid germanium detector system. A planar, germanium strip detector, eleven millimeters thick is followed by a coaxial detector. The 19 x 19 strip detector (2 mm pitch) is used to determine the location and energy of low energy events. The location of high energy events are determined from the location of the Compton scatter in the planar detector and the energy is determined from the sum of the coaxial and planar energies. With this geometry, we obtain useful quantum efficiency in a position-sensitive mode out to 500 keV. The detector is used with a 19 x 17 URA coded aperture to obtain spectrally resolved images in the gamma-ray band. We discuss the performance of the planar detector, the hybrid system and present images taken of laboratory sources.

  19. Spin transport in p-type germanium

    NASA Astrophysics Data System (ADS)

    Rortais, F.; Oyarzún, S.; Bottegoni, F.; Rojas-Sánchez, J.-C.; Laczkowski, P.; Ferrari, A.; Vergnaud, C.; Ducruet, C.; Beigné, C.; Reyren, N.; Marty, A.; Attané, J.-P.; Vila, L.; Gambarelli, S.; Widiez, J.; Ciccacci, F.; Jaffrès, H.; George, J.-M.; Jamet, M.

    2016-04-01

    We report on the spin transport properties in p-doped germanium (Ge-p) using low temperature magnetoresistance measurements, electrical spin injection from a ferromagnetic metal and the spin pumping-inverse spin Hall effect method. Electrical spin injection is carried out using three-terminal measurements and the Hanle effect. In the 2-20 K temperature range, weak antilocalization and the Hanle effect provide the same spin lifetime in the germanium valence band (≈1 ps) in agreement with predicted values and previous optical measurements. These results, combined with dynamical spin injection by spin pumping and the inverse spin Hall effect, demonstrate successful spin accumulation in Ge. We also estimate the spin Hall angle {θ\\text{SHE}} in Ge-p (6-7× {{10}-4} ) at room temperature, pointing out the essential role of ionized impurities in spin dependent scattering.

  20. The first spectroscopic observation of germanium carbide

    NASA Astrophysics Data System (ADS)

    Ruiz, Jose I.

    Electronic spectroscopy was used to obtain gas phase spectrum of the germanium carbide molecule in emission from a corona excited supersonic expansion source. The (2) 3pi -- X 3pi electronic transition was observed around the 21250 cm-1 region. In this system, vibrational bands and the rotational lines of the O = 0, 1, and 2 components were obtained and analyzed. The equilibrium transition energy is found at 21120.3 cm-1 and the fundamental vibrational frequency for the lowest energy ground state O = 2 component is 795.3 cm -1. This is the first spectroscopic observation of germanium carbide. An unsuccessful attempt to obtain the first electronic emission spectrum of aluminum boride is also described.

  1. Electronic structure of intrinsic defects in crystalline germanium telluride.

    SciTech Connect

    Thompson, Aidan Patrick; Pineda, Andrew C.; Umrigar, Cyrus J.; Hjalmarson, Harold Paul; Schultz, Peter Andrew; Edwards, Arthur H.; Martin, Marcus Gary

    2005-05-01

    Germanium telluride undergoes rapid transition between polycrystalline and amorphous states under either optical or electrical excitation. While the crystalline phases are predicted to be semiconductors, polycrystalline germanium telluride always exhibits p-type metallic conductivity. We present a study of the electronic structure and formation energies of the vacancy and antisite defects in both known crystalline phases. We show that these intrinsic defects determine the nature of free-carrier transport in crystalline germanium telluride. Germanium vacancies require roughly one-third the energy of the other three defects to form, making this by far the most favorable intrinsic defect. While the tellurium antisite and vacancy induce gap states, the germanium counterparts do not. A simple counting argument, reinforced by integration over the density of states, predicts that the germanium vacancy leads to empty states at the top of the valence band, thus giving a complete explanation of the observed p-type metallic conduction.

  2. Xenon Filled Silicon Germanium Thermoelectric Generators

    NASA Technical Reports Server (NTRS)

    Dewinter, F.

    1972-01-01

    An analysis is presented that shows the desirability and feasibility of using a xenon fill in the initial stages of operation of a silicon-germanium radioisotope thermoelectric generator to be used in outer-planetary exploration. The xenon cover gas offers protection against oxidation and against material sublimation, and allows the generator to deliver required power throughout the prelaunch and launch phases. The protective mechanisms afforded by the xenon cover gas and the mechanization of a xenon supply system are also discussed.

  3. Germanium films by polymer-assisted deposition

    SciTech Connect

    Jia, Quanxi; Burrell, Anthony K.; Bauer, Eve; Ronning, Filip; McCleskey, Thomas Mark; Zou, Guifu

    2013-01-15

    Highly ordered Ge films are prepared directly on single crystal Si substrates by applying an aqueous coating solution having Ge-bound polymer onto the substrate and then heating in a hydrogen-containing atmosphere. A coating solution was prepared by mixing water, a germanium compound, ethylenediaminetetraacetic acid, and polyethyleneimine to form a first aqueous solution and then subjecting the first aqueous solution to ultrafiltration.

  4. Large Cryogenic Germanium Detector. Final Report

    SciTech Connect

    Mandic, Vuk

    2013-02-13

    The goal of this project was to investigate possible ways of increasing the size of cryogenic Ge detectors. This project identified two possible approaches to increasing the individual cryogenic Ge detector size. The first approach relies on using the existing technology for growing detector-grade (high-purity) germanium crystals of dislocation density 100-7000 cm{sup -2}. The second approach is to consider dislocation-free Ge crystals.

  5. On the geological availability of germanium

    NASA Astrophysics Data System (ADS)

    Frenzel, Max; Ketris, Marina P.; Gutzmer, Jens

    2014-04-01

    Based on a detailed statistical analysis of chemical data published in the scientific literature, estimates were made of the minimum amounts of recoverable Ge contained within sulphidic zinc ores and coals, given current processing technologies. It is expected that at least 119 kt (˜7 kt in zinc ores and ˜112 kt in coal) of recoverable germanium exist within proven reserves (at present stage of knowledge) at grades in excess of 100 ppm in sphalerite and 200 ppm in coal, while at least 440 kt (˜50 kt in zinc ores and ˜390 kt in coal) should become recoverable in the future, being associated to coal reserves at 8-200 ppm Ge and zinc resources containing in excess of 100 ppm Ge in sphalerite. Mississippi Valley Type (MVT) deposits are expected to be the most important hosts of germanium-rich sphalerite, while both brown and hard coals are expected to be equally important as hosts of germanium. The approach taken in this publication shows that reliable minimum estimates for the availability of by-product metals lacking suitable reserve/resource data may be attained by using robust statistical methods and geochemical data published in the scientific literature

  6. Bottom-up assembly of metallic germanium

    PubMed Central

    Scappucci, Giordano; Klesse, Wolfgang M.; Yeoh, LaReine A.; Carter, Damien J.; Warschkow, Oliver; Marks, Nigel A.; Jaeger, David L.; Capellini, Giovanni; Simmons, Michelle Y.; Hamilton, Alexander R.

    2015-01-01

    Extending chip performance beyond current limits of miniaturisation requires new materials and functionalities that integrate well with the silicon platform. Germanium fits these requirements and has been proposed as a high-mobility channel material, a light emitting medium in silicon-integrated lasers, and a plasmonic conductor for bio-sensing. Common to these diverse applications is the need for homogeneous, high electron densities in three-dimensions (3D). Here we use a bottom-up approach to demonstrate the 3D assembly of atomically sharp doping profiles in germanium by a repeated stacking of two-dimensional (2D) high-density phosphorus layers. This produces high-density (1019 to 1020 cm−3) low-resistivity (10−4Ω · cm) metallic germanium of precisely defined thickness, beyond the capabilities of diffusion-based doping technologies. We demonstrate that free electrons from distinct 2D dopant layers coalesce into a homogeneous 3D conductor using anisotropic quantum interference measurements, atom probe tomography, and density functional theory. PMID:26256239

  7. Germanium-76 Sample Analysis: Revision 3

    SciTech Connect

    Kouzes, Richard T.; Zhu, Zihua; Engelhard, Mark H.

    2011-09-19

    The MAJORANA DEMONSTRATOR is a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay (0{nu}{beta}{beta}). The DEMONSTRATOR will utilize 76Ge from Russia. The first one-gram sample was received from the supplier for analysis on April 24, 2011. The second one-gram sample was received from the supplier for analysis on July 12, 2011. The third sample, which came from the first large shipment of germanium from the vendor, was received from Oak Ridge National Laboratory (ORNL) on September 13, 2011. The Environmental Molecular Sciences facility, a DOE user facility at PNNL, was used to make the required isotopic and chemical purity measurements that are essential to the quality assurance for the MAJORANA DEMONSTRATOR. The results of these analyses are reported here. The isotopic composition of a sample of natural germanium was also measured twice. Differences in the result between these two measurements led to a re-measurement of the second 76Ge sample.

  8. Bottom-up assembly of metallic germanium

    NASA Astrophysics Data System (ADS)

    Scappucci, Giordano; Klesse, Wolfgang M.; Yeoh, Lareine A.; Carter, Damien J.; Warschkow, Oliver; Marks, Nigel A.; Jaeger, David L.; Capellini, Giovanni; Simmons, Michelle Y.; Hamilton, Alexander R.

    2015-08-01

    Extending chip performance beyond current limits of miniaturisation requires new materials and functionalities that integrate well with the silicon platform. Germanium fits these requirements and has been proposed as a high-mobility channel material, a light emitting medium in silicon-integrated lasers, and a plasmonic conductor for bio-sensing. Common to these diverse applications is the need for homogeneous, high electron densities in three-dimensions (3D). Here we use a bottom-up approach to demonstrate the 3D assembly of atomically sharp doping profiles in germanium by a repeated stacking of two-dimensional (2D) high-density phosphorus layers. This produces high-density (1019 to 1020 cm-3) low-resistivity (10-4Ω · cm) metallic germanium of precisely defined thickness, beyond the capabilities of diffusion-based doping technologies. We demonstrate that free electrons from distinct 2D dopant layers coalesce into a homogeneous 3D conductor using anisotropic quantum interference measurements, atom probe tomography, and density functional theory.

  9. Synthesis and characterization of germanium nanowires and germanium/silicon radially heterostructured nanowires

    NASA Astrophysics Data System (ADS)

    Goldthorpe, Irene Anne

    Semiconductor nanowires offer new opportunities to study physical phenomena in low-dimensional nanostructures. They also possess technologically useful properties for applications in electronics, optics, sensing, and thermoelectrics. Germanium nanowires are of particular interest, because of germanium's compatibility with standard silicon integrated circuit fabrication processes, its high electronic carrier mobilities, and the low temperature required for germanium nanowire growth. In this work, epitaxially-aligned germanium nanowires are grown on silicon substrates by chemical vapor deposition through the vapor-liquid-solid mechanism. Uniform nanowire diameters between 5 and 50 nm are obtained through the use of monodisperse gold colloids as catalysts. The crystallographic orientation of the nanowires, their strain, and their heteroepitaxial relationship with the substrate are characterized with transmission electron microscopy (TEM) and x-ray diffraction (XRD). A process for removing the gold catalysts from the tips of the germanium nanowires is demonstrated. Silicon shells are then heteroepitaxially deposited around the wires to fabricate radial heterostructures. These shells passivate the germanium nanowire surface, create electronic band offsets to confine holes away the surface where they can scatter or recombine, and induce strain which could allow for the engineering of properties such as band gap and carrier mobilities. However, analogous to planar heteroepitaxy, surface roughening and misfit dislocations can relax this strain. The effects of coaxial dimensions on strain relaxation in these structures are analyzed quantitatively by TEM and synchrotron XRD, and these results are related to continuum elasticity models. Lessons learned generated two successful strategies for synthesizing coherent core-shell nanowires with large misfit strain: chlorine surface passivation and growth of nanowires with low-energy sidewall facets. Both approaches avoid the strain

  10. Europium-doped barium bromide iodide

    SciTech Connect

    Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

    2009-10-21

    Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

  11. Advanced hydrogen electrode for hydrogen-bromide battery

    NASA Technical Reports Server (NTRS)

    Kosek, Jack A.; Laconti, Anthony B.

    1987-01-01

    Binary platinum alloys are being developed as hydrogen electrocatalysts for use in a hydrogen bromide battery system. These alloys were varied in terms of alloy component mole ratio and heat treatment temperature. Electrocatalyst evaluation, performed in the absence and presence of bromide ion, includes floating half cell polarization studies, electrochemical surface area measurements, X ray diffraction analysis, scanning electron microscopy analysis and corrosion measurements. Results obtained to date indicate a platinum rich alloy has the best tolerance to bromide ion poisoning.

  12. Germanium: From Its Discovery to SiGe Devices

    SciTech Connect

    Haller, E.E.

    2006-06-14

    Germanium, element No.32, was discovered in 1886 by Clemens Winkler. Its first broad application was in the form of point contact Schottky diodes for radar reception during WWII. The addition of a closely spaced second contact led to the first all-solid-state electronic amplifier device, the transistor. The relatively low bandgap, the lack of a stable oxide and large surface state densities relegated germanium to the number 2 position behind silicon. The discovery of the lithium drift process, which made possible the formation of p-i-n diodes with fully depletable i-regions several centimeters thick, led germanium to new prominence as the premier gamma-ray detector. The development of ultra-pure germanium yielded highly stable detectors which have remained unsurpassed in their performance. New acceptors and donors were discovered and the electrically active role of hydrogen was clearly established several years before similar findings in silicon. Lightly doped germanium has found applications as far infrared detectors and heavily Neutron Transmutation Doped (NTD) germanium is used in thermistor devices operating at a few milliKelvin. Recently germanium has been rediscovered by the silicon device community because of its superior electron and hole mobility and its ability to induce strains when alloyed with silicon. Germanium is again a mainstream electronic material.

  13. Anisotropy-Driven Spin Relaxation in Germanium

    NASA Astrophysics Data System (ADS)

    Li, Pengke; Li, Jing; Qing, Lan; Dery, Hanan; Appelbaum, Ian

    2013-12-01

    A unique spin depolarization mechanism, induced by the presence of g-factor anisotropy and intervalley scattering, is revealed by spin-transport measurements on long-distance germanium devices in a magnetic field longitudinal to the initial spin orientation. The confluence of electron-phonon scattering (leading to Elliott-Yafet spin flips) and this previously unobserved physics enables the extraction of spin lifetime solely from spin-valve measurements, without spin precession, and in a regime of substantial electric-field-generated carrier heating. We find spin lifetimes in Ge up to several hundreds of nanoseconds at low temperature, far beyond any other available experimental results.

  14. Analog/Digital System for Germanium Thermometer

    NASA Technical Reports Server (NTRS)

    Woodhouse, Christopher

    1988-01-01

    Electronic system containing analog and digital circuits makes high-precision, four-wire measurements of resistance of each germanium resistance thermometer (GRT) in array of devices, using alternating current (ac) of 1 micro-A. At end measurement interval, contents of negative register subtracted from positive one, resulting in very-narrow-band synchronous demodulation of carrier wave and suppression of out-of-band noise. Microprocessor free to perform other duties after measurement complete. Useful in noisy terrestrial environments encountered in factories.

  15. Tensile strain mapping in flat germanium membranes

    SciTech Connect

    Rhead, S. D. Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R.; Shah, V. A.; Kachkanov, V.; Dolbnya, I. P.; Reparaz, J. S.; Sotomayor Torres, C. M.

    2014-04-28

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.

  16. The first spectroscopic observation of germanium carbide

    NASA Astrophysics Data System (ADS)

    Brazier, Christopher R.; Ruiz, José I.

    2011-11-01

    The gas phase spectrum of the germanium carbide radical has been observed at low temperature in emission from a corona excited supersonic expansion source. Many vibrational bands involving the Ω = 0, 1, and 2 components of the (2) 3Π-X 3Π system were recorded and analyzed. The equilibrium transition energy is found at 21120.3 cm -1, in good agreement with theoretical predictions. The fundamental vibrational frequency for the lowest energy ground state Ω = 2 component is 795.3 cm -1.

  17. All-inorganic Germanium nanocrystal films by cationic ligand exchange

    DOE PAGESBeta

    Wheeler, Lance M.; Nichols, Asa W.; Chernomordik, Boris D.; Anderson, Nicholas C.; Beard, Matthew C.; Neale, Nathan R.

    2016-01-21

    In this study, we introduce a new paradigm for group IV nanocrystal surface chemistry based on room temperature surface activation that enables ionic ligand exchange. Germanium nanocrystals synthesized in a gas-phase plasma reactor are functionalized with labile, cationic alkylammonium ligands rather than with traditional covalently bound groups. We employ Fourier transform infrared and 1H nuclear magnetic resonance spectroscopies to demonstrate the alkylammonium ligands are freely exchanged on the germanium nanocrystal surface with a variety of cationic ligands, including short inorganic ligands such as ammonium and alkali metal cations. This ionic ligand exchange chemistry is used to demonstrate enhanced transport inmore » germanium nanocrystal films following ligand exchange as well as the first photovoltaic device based on an all-inorganic germanium nanocrystal absorber layer cast from solution. This new ligand chemistry should accelerate progress in utilizing germanium and other group IV nanocrystals for optoelectronic applications.« less

  18. Investigation of intrinsic gettering for germanium doped Czochralski silicon wafer

    NASA Astrophysics Data System (ADS)

    Chen, Jiahe; Yang, Deren; Ma, Xiangyang; Wang, Weiyan; Zeng, Yuheng; Que, Duanlin

    2007-06-01

    The intrinsic gettering (IG) effects in a germanium-doped Czochralski (GCz) silicon wafer have been investigated through a processing simulation of dynamic random access memory making and an evaluation on IG capability for copper contamination. It has been suggested that both the good quality defect-free denuded zones (DZs) and the high-density bulk microdefect (BMD) regions could be generated in GCz silicon wafer during device fabrication. Meanwhile, it was also indicated that the tiny oxygen precipitates were hardly presented in DZs of silicon wafer with the germanium doping. Furthermore, it was found in GCz silicon wafer that the BMDs were higher in density but smaller in size in contrast to that in conventional Cz silicon wafer. Promoted IG capability for metallic contamination was therefore induced in the germanium-doped Cz silicon wafer. A mechanism of the germanium doping on oxygen precipitation in Cz silicon was discussed, which was based on the hypothesis of germanium-related complexes.

  19. Germanium resistance thermometer calibration at superfluid helium temperatures

    SciTech Connect

    Mason, F.C.

    1985-01-01

    The rapid increase in resistance of high purity semi-conducting germanium with decreasing temperature in the superfluid helium range of temperatures makes this material highly adaptable as a very sensitive thermometer. Also, a germanium thermometer exhibits a highly reproducible resistance versus temperature characteristic curve upon cycling between liquid helium temperatures and room temperature. These two factors combine to make germanium thermometers ideally suited for measuring temperatures in many cryogenic studies at superfluid helium temperatures. One disadvantage, however, is the relatively high cost of calibrated germanium thermometers. In space helium cryogenic systems, many such thermometers are often required, leading to a high cost for calibrated thermometers. The construction of a thermometer calibration cryostat and probe which will allow for calibrating six germanium thermometers at one time, thus effecting substantial savings in the purchase of thermometers is considered.

  20. All-Inorganic Germanium Nanocrystal Films by Cationic Ligand Exchange.

    PubMed

    Wheeler, Lance M; Nichols, Asa W; Chernomordik, Boris D; Anderson, Nicholas C; Beard, Matthew C; Neale, Nathan R

    2016-03-01

    We introduce a new paradigm for group IV nanocrystal surface chemistry based on room temperature surface activation that enables ionic ligand exchange. Germanium nanocrystals synthesized in a gas-phase plasma reactor are functionalized with labile, cationic alkylammonium ligands rather than with traditional covalently bound groups. We employ Fourier transform infrared and (1)H nuclear magnetic resonance spectroscopies to demonstrate the alkylammonium ligands are freely exchanged on the germanium nanocrystal surface with a variety of cationic ligands, including short inorganic ligands such as ammonium and alkali metal cations. This ionic ligand exchange chemistry is used to demonstrate enhanced transport in germanium nanocrystal films following ligand exchange as well as the first photovoltaic device based on an all-inorganic germanium nanocrystal absorber layer cast from solution. This new ligand chemistry should accelerate progress in utilizing germanium and other group IV nanocrystals for optoelectronic applications. PMID:26796765

  1. Experience from operating germanium detectors in GERDA

    NASA Astrophysics Data System (ADS)

    Palioselitis, Dimitrios; GERDA Collaboration

    2015-05-01

    Phase I of the Germanium Detector Array (GERDA) experiment, searching for the neutrinoless double beta (0νββ) decay of 76Ge, was completed in September 2013. The most competitive half-life lower limit for the 0νββ decay of 76Ge was set (T-0ν1/2 > 2.1 · 1025 yr at 90% C.L.). GERDA operates bare Ge diodes immersed in liquid argon. During Phase I, mainly refurbished semi-coaxial high purity Ge detectors from previous experiments were used. The experience gained with handling and operating bare Ge diodes in liquid argon, as well as the stability and performance of the detectors during GERDA Phase I are presented. Thirty additional new enriched BEGe-type detectors were produced and will be used in Phase II. A subgroup of these detectors has already been used successfully in GERDA Phase I. The present paper gives an overview of the production chain of the new germanium detectors, the steps taken to minimise the exposure to cosmic radiation during manufacturing, and the first results of characterisation measurements in vacuum cryostats.

  2. Germanium avalanche receiver for low power interconnects

    NASA Astrophysics Data System (ADS)

    Virot, Léopold; Crozat, Paul; Fédéli, Jean-Marc; Hartmann, Jean-Michel; Marris-Morini, Delphine; Cassan, Eric; Boeuf, Frédéric; Vivien, Laurent

    2014-09-01

    Recent advances in silicon photonics have aided the development of on-chip communications. Power consumption, however, remains an issue in almost all integrated devices. Here, we report a 10 Gbit per second waveguide avalanche germanium photodiode under low reverse bias. The avalanche photodiode scheme requires only simple technological steps that are fully compatible with complementary metal oxide semiconductor processes and do not need nanometre accuracy and/or complex epitaxial growth schemes. An intrinsic gain higher than 20 was demonstrated under a bias voltage as low as -7 V. The Q-factor relating to the signal-to-noise ratio at 10 Gbit per second was maintained over 20 dB without the use of a trans-impedance amplifier for an input optical power lower than -26 dBm thanks to an aggressive shrinkage of the germanium multiplication region. A maximum gain over 140 was also obtained for optical powers below -35 dBm. These results pave the way for low-power-consumption on-chip communication applications.

  3. High-purity germanium crystal growing

    SciTech Connect

    Hansen, W.L.; Haller, E.E.

    1982-10-01

    The germanium crystals used for the fabrication of nuclear radiation detectors are required to have a purity and crystalline perfection which is unsurpassed by any other solid material. These crystals should not have a net electrically active impurity concentration greater than 10/sup 10/cm/sup -3/ and be essentially free of charge trapping defects. Such perfect crystals of germanium can be grown only because of the highly favorable chemical and physical properties of this element. However, ten years of laboratory scale and commercial experience has still not made the production of such crystals routine. The origin and control of many impurities and electrically active defect complexes is now fairly well understood but regular production is often interrupted for long periods due to the difficulty of achieving the required high purity or to charge trapping in detectors made from crystals seemingly grown under the required conditions. The compromises involved in the selection of zone refining and crystal grower parts and ambients is discussed and the difficulty in controlling the purity of key elements in the process is emphasized. The consequences of growing in a hydrogen ambient are discussed in detail and it is shown how complexes of neutral defects produce electrically active centers.

  4. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Methyl bromide; tolerances for residues. 180.124 Section 180.124 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.124 Methyl bromide; tolerances...

  5. An Ill Wind: Methyl Bromide Use Near California Schools, 1998.

    ERIC Educational Resources Information Center

    Ross, Zev; Walker, Bill

    A California study investigates the use of the toxic pesticide methyl bromide near the state's public schools, explains why proposed safety rules have failed to protect children and others from exposure, and examines regions at particular exposure risk. Study results show an increasing exposure to methyl bromide near schools already at risk while…

  6. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Methyl bromide; tolerances for residues. 180.124 Section 180.124 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.124 Methyl bromide; tolerances...

  7. Interaction of methyl bromide with soil.

    PubMed

    Tao, Ting; Maciel, Gary E

    2002-02-15

    Because methyl bromide (CH3Br) is a widely used agricultural fumigant for soil disinfection, it is important to know the chemical behavior and fate of CH3Br as a result of its use for soil treatment. A solid-state 13C NMR study of 13CH3Br-treated soil and soil-component samples shows that methylation of soil organic matter may be the major pathway for degradation of CH3Br in soils. Adsorption of CH3Br on a dried clay like Ca-montmorillonite or kaolinite does not contribute directly to the degradation of CH3Br. The results are interpreted in terms of the chemical structures of separated soil fractions and the nature of the separation procedure. PMID:11878373

  8. Degradation of methyl bromide in anaerobic sediments

    USGS Publications Warehouse

    Oremland, R.S.; Miller, L.G.; Strohmaler, F.E.

    1994-01-01

    Methyl bromide (MeBr) was anaerobically degraded in saltmarsh sediments after reaction with sulfide. The product of this nucleophilic substitution reaction was methanethiol, which underwent further chemical and bacterial reactions to form dimethyl sulfide. These two gases appeared transiently during sediment incubations because they were metabolized by methanogenic and sulfate-reducing bacteria. A second, less significant reaction of MeBr was the exchange with chloride, forming methyl chloride, which was also susceptible to attack by sulfide. Incubation of 14C-labeled methyl iodide as an analogue of MeBr resulted in the formation of 14CH4 and 14CO2 and also indicated that sulfate-reducing bacteria as well as methanogens metabolized the methylated sulfur intermediates. These results suggest that exposed sediments with abundant free sulfide, such as coastal salt-marshes, may constitute a sink for atmospheric MeBr.

  9. Single ion dynamics in molten sodium bromide

    SciTech Connect

    Alcaraz, O.; Trullas, J.; Demmel, F.

    2014-12-28

    We present a study on the single ion dynamics in the molten alkali halide NaBr. Quasielastic neutron scattering was employed to extract the self-diffusion coefficient of the sodium ions at three temperatures. Molecular dynamics simulations using rigid and polarizable ion models have been performed in parallel to extract the sodium and bromide single dynamics and ionic conductivities. Two methods have been employed to derive the ion diffusion, calculating the mean squared displacements and the velocity autocorrelation functions, as well as analysing the increase of the line widths of the self-dynamic structure factors. The sodium diffusion coefficients show a remarkable good agreement between experiment and simulation utilising the polarisable potential.

  10. Glycopyrronium bromide for the treatment of chronic obstructive pulmonary disease.

    PubMed

    Riario-Sforza, Gian Galeazzo; Ridolo, Erminia; Riario-Sforza, Edoardo; Incorvaia, Cristoforo

    2015-02-01

    Glycopyrronium bromide is a new long-acting muscarinic antagonist to be used once-daily, which is approved as a bronchodilator for the symptomatic maintenance treatment of adult patients with chronic obstructive pulmonary disease (COPD). In the Glycopyrronium bromide in chronic Obstructive pulmonary disease airWays trials, treatment with inhaled glycopyrronium bromide at 50 μg once daily achieved a significantly better lung function than placebo, as measured by the trough forced expiratory volume in 1 s in patients with moderate-to-severe COPD. The lung function improvement was maintained for up to 52 weeks. Other improved indexes were dyspnea scores, health status, exacerbation rates and time of exercise endurance. Studies comparing the efficacy of glycopyrronium versus tiotropium bromide found substantial equivalence of the two drugs. Glycopyrronium was generally well tolerated. These data add inhaled glycopyrronium bromide to the treatment of patients with moderate to severe COPD as an effective once-daily LAMA. PMID:25547422

  11. Atmosphere-plant canopy interactions of methyl bromide

    SciTech Connect

    Taylor, G.E. Jr.; Leonard, T.D.; Gustin, M.S.

    1995-12-31

    In the planetary boundary layer, parcels of air containing background and elevated concentrations of methyl bromide commonly pass through plant canopies in managed (agriculture) and natural (forests, grasslands) ecosystems. It is hypothesized that leaf surfaces are a significant sink or methyl bromide on a local and regional scale and that failure to account for this sink results in a significant overestimation of methyl bromide transport to the stratosphere. Using highly controlled environments, studies are investigating the reactivity of leaf surfaces for methyl bromide at elevated and global background concentrations. Estimates of pathway resistances are being calculated and sites of deposition determined. The results indicate that plant canopies are a significant unrecognized sink for methyl bromide in the atmosphere.

  12. Preparation and characterization of hydrogenated amorphous germanium and hydrogenated amorphous germanium carbide thin films

    NASA Astrophysics Data System (ADS)

    Wu, Hai-Sheng

    1989-02-01

    Hydrogenated amorphous germanium (a-Ge:H) and germanium carbide (a-Ge(1-x)Cx:H) films were prepared by rf sputtering of a polycrystalline Ge target in a vacuum approximately 4 x 10 to the 7th Torr at various rf power 50 less than or equal to P less than or equal to 600 W (0.27 to 3.3 W/sq cm), target-substrate distance 1 less than or equal to d less than or equal to 7 minutes, varying partial pressures of Ar, H2, and C3H8, and flow rates f. The vibrational and opto-electronic properties such as infrared (IR) absorption, optical gap, electron-spin-resonance (ESR) signals, and conductivities vary with deposition conditions. The photoconductivity sigma sub ph, in particular, was carefully monitored as a function of the deposition conditions to optimize it.

  13. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...

  14. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...

  15. Oxygen defect processes in silicon and silicon germanium

    NASA Astrophysics Data System (ADS)

    Chroneos, A.; Sgourou, E. N.; Londos, C. A.; Schwingenschlögl, U.

    2015-06-01

    Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

  16. Sputtered germanium/silicon devices for photonics applications

    NASA Astrophysics Data System (ADS)

    Nujhat, N.; Papouloute, J.-P.; DeBerry, M.; Jiang, L.; Korivi, N. S.

    2015-08-01

    We report on the ongoing investigation of magnetron sputtered germanium on silicon for photonics applications. Direct current (DC) magnetron sputtering has been used to deposit germanium layers on silicon at low growth temperatures and medium range vacuum levels. Standard photolithography has been used to make germanium photodetectors for the 1550 nm wavelength range. Electrical characterization, more specifically current-voltage measurements indicate that the devices function as intended. Sputtered silicon waveguides have also been fabricated and evaluated for possible applications in photonics integration. The sputtering-based developments in our present research are expected to provide for a flexible and economically viable manufacturing process for such devices.

  17. Ultra High-Rate Germanium (UHRGe) Modeling Status Report

    SciTech Connect

    Warren, Glen A.; Rodriguez, Douglas C.

    2012-06-07

    The Ultra-High Rate Germanium (UHRGe) project at Pacific Northwest National Laboratory (PNNL) is conducting research to develop a high-purity germanium (HPGe) detector that can provide both the high resolution typical of germanium and high signal throughput. Such detectors may be beneficial for a variety of potential applications ranging from safeguards measurements of used fuel to material detection and verification using active interrogation techniques. This report describes some of the initial radiation transport modeling efforts that have been conducted to help guide the design of the detector as well as a description of the process used to generate the source spectrum for the used fuel application evaluation.

  18. Oxygen defect processes in silicon and silicon germanium

    SciTech Connect

    Chroneos, A.; Sgourou, E. N.; Londos, C. A.; Schwingenschlögl, U.

    2015-06-15

    Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

  19. Synthesis of silicon and germanium nanowires.

    SciTech Connect

    Clement, Teresa J.; Hsu, Julia W. P.

    2007-11-01

    The vapor-liquid-solid growth process for synthesis of group-IV semiconducting nanowires using silane, germane, disilane and digermane precursor gases has been investigated. The nanowire growth process combines in situ gold seed formation by vapor deposition on atomically clean silicon (111) surfaces, in situ growth from the gaseous precursor(s), and real-time monitoring of nanowire growth as a function of temperature and pressure by a novel optical reflectometry technique. A significant dependence on precursor pressure and growth temperature for the synthesis of silicon and germanium nanowires is observed, depending on the stability of the specific precursor used. Also, the presence of a nucleation time for the onset of nanowire growth has been found using our new in situ optical reflectometry technique.

  20. Interactions of germanium atoms with silica surfaces

    NASA Astrophysics Data System (ADS)

    Stanley, Scott K.; Coffee, Shawn S.; Ekerdt, John G.

    2005-11-01

    GeH 4 is thermally cracked over a hot filament depositing 0.7-15 ML Ge onto 2-7 nm SiO 2/Si(1 0 0) at substrate temperatures of 300-970 K. Ge bonding changes are analyzed during annealing with X-ray photoelectron spectroscopy. Ge, GeH x, GeO, and GeO 2 desorption is monitored through temperature programmed desorption in the temperature range 300-1000 K. Low temperature desorption features are attributed to GeO and GeH 4. No GeO 2 desorption is observed, but GeO 2 decomposition to Ge through high temperature pathways is seen above 750 K. Germanium oxidization results from Ge etching of the oxide substrate. With these results, explanations for the failure of conventional chemical vapor deposition to produce Ge nanocrystals on SiO 2 surfaces are proposed.

  1. Electron paramagnetic resonance at dislocations in germanium

    SciTech Connect

    Pakulis, E.J.

    1982-06-01

    The first observation of the paramagnetic resonance of electrons at dislocations in germanium single crystals is reported. Under subband gap optical excitation, two sets of lines are detected: four lines about the <111> axes with g/sub perpendicular to/ = 0.34 and g/sub parallel/ = 1.94, and 24 lines with g/sub perpendicular to/ = 0.73 and g/sub parallel/ = 1.89 about <111> axes with the six-fold 1.2/sup 0/ distortion. This represents the first measurement of the disortion angle of a dislocation dangling bond. The possibility that the distortion results from a Peierls transition along the dislocation line is discussed.

  2. Thermodynamic properties of germanium/carbon microclusters

    NASA Astrophysics Data System (ADS)

    Wielgus, Pawel; Roszak, Szczepan; Majumdar, Devashis; Leszczynski, Jerzy

    2005-12-01

    Theoretical studies on the GenCm (n =1,2; m =1-3) microclusters have been performed using the state of the art calculations. Several alternative structures of these clusters were studied to locate the lowest-energy isomers. It is observed that the structures of the complexes result from the competition between ionic Ge-C, conjugated covalent C-C, and metallic Ge-Ge bonds. The ionization of the molecules enhances the ionic character of the Ge-C bond and has significant structural consequences. Using theoretically determined partition functions, thermodynamic data are computed and experimental enthalpies are enhanced. The ab initio atomization energies of germanium carbides compare well with corrected experimental functions. The experimental appearance potentials are well reproduced by the theoretical ionization potentials.

  3. Germanium Detectors in Homeland Security at PNNL

    SciTech Connect

    Stave, Sean C.

    2015-05-01

    Neutron and gamma-ray detection is used for non-proliferation and national security applications. While lower energy resolution detectors such as NaI(Tl) have their place, high purity germanium (HPGe) also has a role to play. A detection with HPGe is often a characterization due to the very high energy resolution. However, HPGe crystals remain small and expensive leaving arrays of smaller crystals as an excellent solution. PNNL has developed two similar HPGe arrays for two very different applications. One array, the Multisensor Aerial Radiation Survey (MARS) detector is a fieldable array that has been tested on trucks, boats, and helicopters. The CASCADES HPGe array is an array designed to assay samples in a low background environment. The history of HPGe arrays at PNNL and the development of MARS and CASCADES will be detailed in this paper along with some of the other applications of HPGe at PNNL.

  4. Germanium detectors in homeland security at PNNL

    SciTech Connect

    Stave, S.

    2015-05-01

    Neutron and gamma-ray detection is used for non-proliferation and national security applications. While lower energy resolution detectors such as NaI(Tl) have their place, high purity germanium (HPGe) also has a role to play. A detection with HPGe is often a characterization due to the very high energy resolution. However, HPGe crystals remain small and expensive leaving arrays of smaller crystals as an excellent solution. PNNL has developed two similar HPGe arrays for two very different applications. One array, the Multisensor Aerial Radiation Survey (MARS) detector is a fieldable array that has been tested on trucks, boats, and helicopters. The CASCADES HPGe array is an array designed to assay samples in a low background environment. The history of HPGe arrays at PNNL and the development of MARS and CASCADES will be detailed in this paper along with some of the other applications of HPGe at PNNL.

  5. Germanium detectors in homeland security at PNNL

    DOE PAGESBeta

    Stave, S.

    2015-05-01

    Neutron and gamma-ray detection is used for non-proliferation and national security applications. While lower energy resolution detectors such as NaI(Tl) have their place, high purity germanium (HPGe) also has a role to play. A detection with HPGe is often a characterization due to the very high energy resolution. However, HPGe crystals remain small and expensive leaving arrays of smaller crystals as an excellent solution. PNNL has developed two similar HPGe arrays for two very different applications. One array, the Multisensor Aerial Radiation Survey (MARS) detector is a fieldable array that has been tested on trucks, boats, and helicopters. The CASCADESmore » HPGe array is an array designed to assay samples in a low background environment. The history of HPGe arrays at PNNL and the development of MARS and CASCADES will be detailed in this paper along with some of the other applications of HPGe at PNNL.« less

  6. Tin impurity centers in glassy germanium chalcogenides

    SciTech Connect

    Bordovsky, G. A.; Gladkikh, P. V.; Kozhokar, M. Yu.; Marchenko, A. V.; Seregin, P. P.; Terukov, E. I.

    2011-10-15

    Tin atoms produced by radioactive decay of {sup 119mm}Sn and {sup 119}Sn impurity atoms in the structure of Ge{sub x}S{sub 1-x} and Ge{sub x}Se{sub 1-x} glasses are stabilized in the form of Sn{sup 2+} and Sn{sup 4+} ions and correspond to ionized states of the amphoteric two-electron center with negative correlation energy (Sn{sup 2+} is an ionized acceptor, and Sn{sup 4+} is an ionized donor), whereas the neutral state of the Sn{sup 3+} center appears to be unstable. {sup 119}Sn atoms produced by radioactive decay of {sup 119m}Te impurity atoms in the structure of Ge{sub x}S{sub 1-x} and Ge{sub x}Se{sub 1-x} glasses are stabilized at both chalcogen sites (they are electrically inactive) and germanium sites.

  7. Electromechanically cooled germanium radiation detector system

    NASA Astrophysics Data System (ADS)

    Lavietes, Anthony D.; Joseph Mauger, G.; Anderson, Eric H.

    1999-02-01

    We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of high energy resolution performance and exceptional detection efficiency. Logistical difficulties associated with providing the required liquid nitrogen (LN) for cooling is the primary reason that these systems are found mainly in laboratories. The EMC-HPGe detector system described in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It incorporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degradation from microphonics. All standard isotopic analysis codes, including MGA and MGA++ [1], GAMANL [2], GRPANL [3]and MGAU [4], typically used with HPGe detectors can be used with this system with excellent results. Several national and international Safeguards organisations including the International Atomic Energy Agency (IAEA) and U.S. Department of Energy (DOE) have expressed interest in this system. The detector was combined with custom software and demonstrated as a rapid Field Radiometric Identification System (FRIS) for the U.S. Customs Service [5]. The European Communities' Safeguards Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent applications, and results will be highlighted.

  8. Reduction of Defects in Germanium-Silicon

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Crystals grown without contact with a container have far superior quality to otherwise similar crystals grown in direct contact with a container. In addition to float-zone processing, detached- Bridgman growth is a promising tool to improve crystal quality, without the limitations of float zoning or the defects introduced by normal Bridgman growth. Goals of this project include the development of the detached Bridgman process to be reproducible and well understood and to quantitatively compare the defect and impurity levels in crystals grown by these three methods. Germanium (Ge) and germanium-silicon (Ge-Si) alloys are being used. At MSFC, we are responsible for the detached Bridgman experiments intended to differentiate among proposed mechanisms of detachment, and to confirm or refine our understanding of detachment. Because the contact angle is critical to determining the conditions for detachment, the sessile drop method was used to measure the contact angles as a function of temperature and composition for a large number of substrates made of potential ampoule materials. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. Etch pit density (EPD) measurements of normal and detached Bridgman-grown Ge samples show a two order of magnitude improvement in the detached-grown samples. The nature and extent of detachment is determined by using profilometry in conjunction with optical and electron microscopy. The stability of detachment has been analyzed, and an empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed. We have investigated the effects on detachment of ampoule material, pressure difference above and below the melt, and Si concentration; samples that are nearly completely detached can be grown repeatedly in pBN. Current work is concentrated on developing a

  9. Selective oxidation of bromide in wastewater brines from hydraulic fracturing.

    PubMed

    Sun, Mei; Lowry, Gregory V; Gregory, Kelvin B

    2013-07-01

    Brines generated from oil and natural gas production, including flowback water and produced water from hydraulic fracturing of shale gas, may contain elevated concentrations of bromide (~1 g/L). Bromide is a broad concern due to the potential for forming brominated disinfection byproducts (DBPs) during drinking water treatment. Conventional treatment processes for bromide removal is costly and not specific. Selective bromide removal is technically challenging due to the presence of other ions in the brine, especially chloride as high as 30-200 g/L. This study evaluates the ability of solid graphite electrodes to selectively oxidize bromide to bromine in flowback water and produced water from a shale gas operation in Southwestern PA. The bromine can then be outgassed from the solution and recovered, as a process well understood in the bromine industry. This study revealed that bromide may be selectively and rapidly removed from oil and gas brines (~10 h(-1) m(-2) for produced water and ~60 h(-1) m(-2) for flowback water). The electrolysis occurs with a current efficiency between 60 and 90%, and the estimated energy cost is ~6 kJ/g Br. These data are similar to those for the chlor-alkali process that is commonly used for chlorine gas and sodium hydroxide production. The results demonstrate that bromide may be selectively removed from oil and gas brines to create an opportunity for environmental protection and resource recovery. PMID:23726709

  10. Synthesis and thermoluminescence of boron-doped germanium nanowires

    NASA Astrophysics Data System (ADS)

    Zahedifar, M.; Hosseinmardi, F.; Eshraghi, L.; Ganjipour, B.

    2011-03-01

    Boron doped germanium nanowires were synthesized using chemical vapor deposition (CVD) with Au nanoparticles as nucleating centers, germanium tetrachloride as the source of germanium and B 2H 6 gas as source of boron impurity. Au nanoparticles were deposited on Si using 3-aminopropyltriethylsilane (APTES). The single crystal Ge nanowires with diameters ranging from 19 to 200 nm were grown in a controllable manner. Effects of Au nanoparticle size, argon gas flow, temperature and duration of growth on diameter and length of nanowires were investigated. This is the first report on thermoluminescence (TL) properties of boron doped germanium nanowires. Glow curves were fitted using computerized glow curve deconvolution program and seven overlapped peaks were obtained. Further the response of synthesized nanowires to different dose levels of UV was studied and linear response regime was determined.

  11. Transport Phenomena in Liquid Phase Diffusion Growth of Silicon Germanium

    NASA Astrophysics Data System (ADS)

    Armour, Neil Alexander

    Silicon Germanium, SiGe, is an important emerging semiconductor material. In order to optimize growth techniques for SiGe production, such as Liquid Phase Diffusion, LPD, or Melt Replenishment Czochralski, a good understanding of the transport phenomena in the melt is required. In the context of the Liquid Phase Diffusion growth technique, the transport phenomena of silicon in a silicon-germanium melt has been explored. Experiments isolating the dissolution and transport of silicon into a germanium melt have been conducted under a variety of flow conditions. Preliminary modeling of these experiments has also been conducted and agreement with experiments has been shown. In addition, full LPD experiments have also been conducted under varying flow conditions. Altered flow conditions were achieved through the application of a variety of magnetic fields. Through the experimental and modeling work better understanding of the transport mechanisms at work in a silicon-germanium melt has been achieved.

  12. Reaction studies of hot silicon, germanium and carbon atoms

    SciTech Connect

    Gaspar, P.P.

    1986-11-15

    Research has been continued on hot silicon, germanium and carbon atoms. Progress in the period November 16, 1985 to November 15, 1986 is reviewed in the following areas: (1) Recoil atom reaction studies. (2) Reactions of thermally generated free atoms.

  13. Near-infrared emission from mesoporous crystalline germanium

    NASA Astrophysics Data System (ADS)

    Boucherif, Abderraouf; Korinek, Andreas; Aimez, Vincent; Arès, Richard

    2014-10-01

    Mesoporous crystalline germanium was fabricated by bipolar electrochemical etching of Ge wafer in HF-based electrolyte. It yields uniform mesoporous germanium layers composed of high density of crystallites with an average size 5-7 nm. Subsequent extended chemical etching allows tuning of crystallites size while preserving the same chemical composition. This highly controllable nanostructure exhibits photoluminescence emission above the bulk Ge bandgap, in the near-infrared range (1095-1360nm) with strong evidence of quantum confinement within the crystallites.

  14. Near-infrared emission from mesoporous crystalline germanium

    SciTech Connect

    Boucherif, Abderraouf; Aimez, Vincent; Arès, Richard; Korinek, Andreas

    2014-10-15

    Mesoporous crystalline germanium was fabricated by bipolar electrochemical etching of Ge wafer in HF-based electrolyte. It yields uniform mesoporous germanium layers composed of high density of crystallites with an average size 5-7 nm. Subsequent extended chemical etching allows tuning of crystallites size while preserving the same chemical composition. This highly controllable nanostructure exhibits photoluminescence emission above the bulk Ge bandgap, in the near-infrared range (1095-1360nm) with strong evidence of quantum confinement within the crystallites.

  15. Lithium bromide chiller technology in gas processing

    SciTech Connect

    Huey, M.A.; Leppin, D.

    1995-12-31

    Lithium Bromide (LiBr) Absorption Chillers have been in use for more than half a century, mainly in the commercial air conditioning industry. The Gas Research Institute and EnMark Natural Gas Company co-funded a field test to determine the viability of this commercial air conditioning technology in the gas industry. In 1991, a 10 MMCFC natural gas conditioning plant was constructed in Sherman, Texas. The plant was designed to use a standard, off-the-shelf chiller from Trane with a modified control scheme to maintain tight operating temperature parameters. The main objective was to obtain a 40 F dewpoint natural gas stream to meet pipeline sales specifications. Various testing performed over the past three years has proven that the chiller can be operated economically and on a continuous basis in an oilfield environment with minimal operation and maintenance costs. This paper will discuss how a LiBr absorption chiller operates, how the conditioning plant performed during testing, and what potential applications are available for LiBr chiller technology.

  16. Promoting Cell Proliferation Using Water Dispersible Germanium Nanowires

    PubMed Central

    Bezuidenhout, Michael; Liu, Pai; Singh, Shalini; Kiely, Maeve

    2014-01-01

    Group IV Nanowires have strong potential for several biomedical applications. However, to date their use remains limited because many are synthesised using heavy metal seeds and functionalised using organic ligands to make the materials water dispersible. This can result in unpredicted toxic side effects for mammalian cells cultured on the wires. Here, we describe an approach to make seedless and ligand free Germanium nanowires water dispersible using glutamic acid, a natural occurring amino acid that alleviates the environmental and health hazards associated with traditional functionalisation materials. We analysed the treated material extensively using Transmission electron microscopy (TEM), High resolution-TEM, and scanning electron microscope (SEM). Using a series of state of the art biochemical and morphological assays, together with a series of complimentary and synergistic cellular and molecular approaches, we show that the water dispersible germanium nanowires are non-toxic and are biocompatible. We monitored the behaviour of the cells growing on the treated germanium nanowires using a real time impedance based platform (xCELLigence) which revealed that the treated germanium nanowires promote cell adhesion and cell proliferation which we believe is as a result of the presence of an etched surface giving rise to a collagen like structure and an oxide layer. Furthermore this study is the first to evaluate the associated effect of Germanium nanowires on mammalian cells. Our studies highlight the potential use of water dispersible Germanium Nanowires in biological platforms that encourage anchorage-dependent cell growth. PMID:25237816

  17. Modified silicon-germanium alloys with improved performance. [thermoelectric material

    NASA Technical Reports Server (NTRS)

    Pisharody, R. K.; Garvey, L. P.

    1978-01-01

    This paper discusses the results of a program on the modification of silicon-germanium alloys by means of small extraneous material additions in order to improve their figures-of-merit. A review of the properties that constitute the figure-of-merit indicates that it is the relatively high thermal conductivity of silicon-germanium alloys that is responsible for their low values of figure-of-merit. The intent of the effort discussed in this paper is therefore the reduction of the thermal conductivity of silicon-germanium alloys by minor alloy additions and/or changes in the basic structure of the material. Because Group III and V elements are compatible with silicon and germanium, the present effort in modifying silicon-germanium alloys has concentrated on additions of gallium phosphide. A significant reduction in thermal conductivity, approximately 40 to 50 percent, has been demonstrated while the electrical properties are only slightly affected as a result. The figure-of-merit of the resultant material is enhanced over that of silicon-germanium alloys and when fully optimized is potentially better than that of any other presently available thermoelectric material.

  18. Protective infrared antireflection coating based on sputtered germanium carbide

    NASA Astrophysics Data System (ADS)

    Gibson, Des; Waddell, Ewan; Placido, Frank

    2011-09-01

    This paper describes optical, durablility and environmental performance of a germanium carbide based durable antireflection coating. The coating has been demonstrated on germanium and zinc selenide infra-red material however is applicable to other materials such as zinc sulphide. The material is deposited using a novel reactive closed field magnetron sputtering technique, offering significant advantages over conventional evaporation processes for germanium carbide such as plasma enhanced chemical vapour deposition. The sputtering process is "cold", making it suitable for use on a wide range of substrates. Moreover, the drum format provide more efficient loading for high throughput production. The use of the closed field and unbalanced magnetrons creates a magnetic confinement that extends the electron mean free path leading to high ion current densities. The combination of high current densities with ion energies in the range ~30eV creates optimum thin film growth conditions. As a result the films are dense, spectrally stable, supersmooth and low stress. Films incorporate low hydrogen content resulting in minimal C-H absorption bands within critical infra-red passbands such as 3 to 5um and 8 to 12um. Tuning of germanium carbide (Ge(1-x)Cx) film refractive index from pure germanium (refractive index 4) to pure germanium carbide (refractive index 1.8) will be demonstrated. Use of film grading to achieve single and dual band anti-reflection performance will be shown. Environmental and durability levels are shown to be suitable for use in harsh external environments.

  19. Method of fabricating germanium and gallium arsenide devices

    NASA Technical Reports Server (NTRS)

    Jhabvala, Murzban (Inventor)

    1990-01-01

    A method of semiconductor diode fabrication is disclosed which relies on the epitaxial growth of a precisely doped thickness layer of gallium arsenide or germanium on a semi-insulating or intrinsic substrate, respectively, of gallium arsenide or germanium by either molecular beam epitaxy (MBE) or by metal-organic chemical vapor deposition (MOCVD). The method involves: depositing a layer of doped or undoped silicon dioxide on a germanium or gallium arsenide wafer or substrate, selectively removing the silicon dioxide layer to define one or more surface regions for a device to be fabricated thereon, growing a matched epitaxial layer of doped germanium or gallium arsenide of an appropriate thickness using MBE or MOCVD techniques on both the silicon dioxide layer and the defined one or more regions; and etching the silicon dioxide and the epitaxial material on top of the silicon dioxide to leave a matched epitaxial layer of germanium or gallium arsenide on the germanium or gallium arsenide substrate, respectively, and upon which a field effect device can thereafter be formed.

  20. Monolayer formation of luminescent germanium nanoparticles on silica surface in aqueous buffer solution.

    PubMed

    Shirahata, Naoto

    2014-03-01

    The present paper reports monolayer formation of germanium nanoparticles (Ge NPs) on silica substrate. The NPs were prepared by hydride reduction of GeCl4, which is encapsulated with an inverse micelle of dimethyldioctylammonium bromide, with lithium aluminum hydride, and subsequent hydrogermylation of allylamine in the presence of platinum catalyst. The resultant NPs showed the blue photoluminescence property. Due to the terminal amine, the NPs were soluble highly in aqueous buffer solution. To fabricate a monolayer of Ge NPs, the chemical reactivity of the NPs was studied using a multi-functional microarray in which different kinds of siloxane monolayers were periodically aligned on a silica substrate. We observed using fluorescence microscope whether the terminal amines of the NPs recognize the specific monolayers in the microarray. In terms of fluorescence observation, the entire surface of the monolayer-covered microsize-domains emits uniformly the blue light. This suggests a high degree of coverage of the luminescent NPs covering over the monolayer regions in the microarray, and implies the non-occurrence of quenching through energy transfer between adjacent NPs. PMID:24745276

  1. Health and Environmental Effects Profile for methyl bromide

    SciTech Connect

    Not Available

    1986-06-01

    The Health and Environmental Effects Profile for methyl bromide was prepared to support listings of hazardous constituents of a wide range of waste streams under Section 3001 of the Resource Conservation and Recovery Act (RCRA) and to provide health-related limits for emergency actions under Section 101 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Both published literature and information obtained from Agency program office files were evaluated as they pertained to potential human health, aquatic life, and environmental effects. Quantitative estimates are presented provided sufficient data are available. Methyl bromide has been determined to be a systemic toxicant. An Acceptable Daily Intake (ADI), for methyl bromide is 0.0014 mg/kg/day for oral exposure. The Reportable Quantity (RQ) value for methyl bromide is 100.

  2. Kinetics and Mechanism of the Chlorate-Bromide Reaction.

    PubMed

    Sant'Anna, Rafaela T P; Faria, Roberto B

    2015-11-01

    The chlorate-bromide reaction, ClO3(-) + 6Br(-) + 6H(+) → 3Br2 + Cl(-) + 3H2O, was followed at the Br3(-)/Br2 isosbestic point (446 nm). A fifth-order rate law was found: (1)/3 d[Br2]/dt = k[ClO3(-)][Br(-)][H(+)](3) (k = 5.10 × 10(-6) s(-1) L(4) mol(-4)) at 25 °C and I = 2.4 mol L(-1). At high bromide concentrations, the bromide order becomes close to zero, indicating a saturation profile on bromide concentration, similar to the chloride saturation profile observed in the chlorate-chloride reaction. A mechanism is proposed that considers the formation of the intermediate BrOClO2(2-), similar to the intermediate ClOClO2(2-) proposed in the mechanism of the chlorate-chloride reaction. PMID:26467822

  3. The oceans: A source or a sink of methyl bromide?

    SciTech Connect

    Pilinis, C.; King, D.B.; Saltzman, E.S.

    1996-04-15

    The global ocean/atmosphere flux of methyl bromide has been estimated from shipboard measurements of the saturation anomaly. When such data are extrapolated globally on the basis of constant saturation anomaly, the ocean is a net sink for methyl bromide [Lobert et al.]. The same data can also be extrapolated on the basis of steady-state production rate of methyl bromide in the water column, allowing regional and seasonal variations in temperature to affect the saturation anomaly. The authors have carried out this type of extrapolation, and they found that the oceans are a strong net source of methyl bromide to the atmosphere. The difference arises mainly due to slow degradation rates in water of higher latitudes. A reduction of the applied production rate by more than 35% is needed in order to switch the ocean from a source to a sink of methyl bromide. These results demonstrate the sensitivity of current estimates of oceanic flux to assumptions about methyl bromide production and destruction in the water column. 19 refs., 2 fig.

  4. The toxic chemistry of methyl bromide.

    PubMed

    Bulathsinghala, A T; Shaw, I C

    2014-01-01

    Methyl bromide (MeBr) is a chemically reactive compound that has found use as a fire retardant and fumigant used for wood, soil, fruits and grains. Its use is banned in many countries because of its ozone-depleting properties. Despite this ban, the use of MeBr persists in some parts of the world (e.g. New Zealand) due to its important role in maintaining strict biosecurity of exported and imported products. Its high chemical reactivity leads to a broad toxicological profile ranging from acute respiratory toxicity following inhalation exposure, through carcinogenicity to neurotoxicty. In this article, we discuss the chemistry of MeBr in the context of its mechanisms of toxicity. The chemical reactivity of MeBr clearly underlies its toxicity. Bromine (Br) is electronegative and a good leaving group; the δ+ carbon thus facilitates electrophilic methylation of biological molecules including glutathione (GSH) via its δ- sulphur atom, leading to downstream effects due to GSH depletion. DNA alkylation, either directly by MeBr or indirectly due to reduction in GSH-mediated detoxification of reactive alkylating chemical species, might explain the carcinogenicity of MeBr. The neurotoxicity of MeBr is much more difficult to understand, but we speculate that methyl phosphates formed in cells might contribute to its neurone-specific toxicity via cholinesterase inhibition. Finally, evidence reviewed shows that it is unlikely for Br⁻ liberated by the metabolism of MeBr to have any toxicological effect because the Br⁻ dose is very low. PMID:23800997

  5. Optical properties of colloidal germanium nanocrystals

    SciTech Connect

    WILCOXON,JESS P.; PROVENCIO,PAULA P.; SAMARA,GEORGE A.

    2000-05-01

    Highly crystalline germanium (Ge) nanocrystals in the size range 2--10 nm were grown in inverse micelles and purified and size-separated by high pressure liquid chromatography with on-line optical and electrical diagnostics. The nanocrystals retain the diamond structure of bulk Ge down to at least 2.0 nm (containing about 150 Ge atoms). The background- and impurity-free extinction and photoluminescence (PL) spectra of these nanocrystals revealed rich structure which was interpreted in terms of the bandstructure of Ge shifted to higher energies by quantum confinement. The shifts ranged from {minus}0.1 eV to over 1 eV for the various transitions. PL in the range 350--700 nm was observed from nanocrystals 2--5 nm in size. The 2.0 nm nanocrystals yielded the most intense PL (at 420 nm) which is believed to be intrinsic and attributed to direct recombination at {Gamma}. Excitation at high energy (250 nm) populates most of the conduction bands resulting in competing recombination channels and the observed broad PL spectra.

  6. Tunnel current across linear homocatenated germanium chains

    SciTech Connect

    Matsuura, Yukihito

    2014-01-28

    The electronic transport properties of germanium oligomers catenating into linear chains (linear Ge chains) have been theoretically studied using first principle methods. The conduction mechanism of a Ge chain sandwiched between gold electrodes was analyzed based on the density of states and the eigenstates of the molecule in a two-probe environment. Like that of silicon chains (Si chains), the highest occupied molecular orbital of Ge chains contains the extended σ-conjugation of Ge 4p orbitals at energy levels close to the Fermi level; this is in contrast to the electronic properties of linear carbon chains. Furthermore, the conductance of a Ge chain is expected to decrease exponentially with molecular length L. The decay constant β, which is defined as e{sup −βL}, of a Ge chain is similar to that of a Si chain, whereas the conductance of the Ge chains is higher than that of Si chains even though the Ge–Ge bond length is longer than the Si–Si bond length.

  7. Detached Growth of Germanium and Germaniumsilicon

    NASA Technical Reports Server (NTRS)

    Dold, P.; Schweizer, M.; Szofran, F.; Benz, K. W.

    1999-01-01

    Up to now, detached growth was observed mainly under microgravity, i.e. under the absence of hydrostatic pressure that hinders the formation of a free melt meniscus. the detached growth of germanium doped with gallium was obtained under 1 g conditions, the growth was performed in quartz-glass ampoule. Part of the crystal grew without wall contact, the detached growth was observed in-situ with a CCD-camera as well as after the growth process in form of growth lines and the formation of <111> facets on the crystal surface. GeSi crystal (oriientation: <111>, maximum silicon content: 4 at%, seed material: Ge) was grown in a pBN crucible (excluding the possibility of in-situ monitoring of the growth process). The grown crystal exhibits three growth facets, indicating also wall free growth. Surface analysis of the crystals (NDIC, SEM) and characterization of crystal segregation (EDAX, resistivity measurement) and defect structure (EPD, x-ray diffraction measurements) will be presented.

  8. Assessment of Ethidium bromide and Ethidium monoazide bromide removal from aqueous matrices by adsorption on cupric oxide nanoparticles.

    PubMed

    Fakhri, Ali

    2014-06-01

    The present study was undertaken to develop an effective adsorbent and to study the adsorption of Ethidium bromide and Ethidium monoazide bromide from aqueous solution using the CuO nanoparticles. The characteristics of CuO nanoparticles were determined and found to have a surface area 89.59m(2)/g. Operational parameters such as pH, contact time and adsorbent concentration, initial concentration and temperature were also studied. The amount of removal increases with the increase in pH from one to seven and reaches the maximum when the pH is nine. Adsorption data fitted well with the Langmuir, Freundlich and Florry-Huggins models. The results show that the best fit was achieved with the Langmuir isotherm equation with maximum adsorption capacities of 0.868 and 0.662mg/g for Ethidium bromide and Ethidium monoazide bromide, respectively. The adsorption process was found to follow pseudo-second-order kinetics. The calculated thermodynamic parameters, namely ΔG, ΔH and ΔS showed that adsorption of Ethidium bromide and Ethidium monoazide bromide was spontaneous and endothermic under examined conditions. PMID:24630576

  9. Preparation and characterization of hydrogenated amorphous germanium and hydrogenated amorphous germanium carbide thin films

    SciTech Connect

    Wu, Hai-Sheng

    1989-02-01

    Hydrogenated amorphous germanium (a-Ge:H) and germanium carbide (a-Ge/sub 1-x/C/sub x/:H) films were prepared by rf sputtering of a polycrystalline Ge target in a vacuum /approximately/ 4 /times/ 10/sup /minus/7/ Torr at various rf power 50 less than or equal to P less than or equal to 600 W (0. 27-3.3 W/cm/sup 2/), target-substrate distance 1 less than or equal to d less than or equal to 7'', varying partial pressures of Ar, H/sub 2/, and C/sub 3/H/sub 8/, and flow rates f. The vibrational and opto-electronic properties such as infrared (IR) absorption, optical gap, electron-spin-resonance (ESR) signals, and conductivities vary with deposition conditions. The photoconductivity sigma/sub ph/, in particular, was carefully monitored as a function of the deposition conditions to optimize it. 96 refs., 49 figs., 7 tabs.

  10. Preparation and characterization of hydrogenated amorphous germanium and hydrogenated amorphous germanium-carbide thin films

    SciTech Connect

    Wu, H.S.

    1988-01-01

    Hydrogenated amorphous germanium (a-Ge:H) and germanium carbide (a-Ge{sub 1{minus}x}C{sub x}:H) films were prepared by rf sputtering of a polycrystalline Ge target in a vacuum {approximately}4 {times} 10{sup {minus}7} Torr at various rf power, target-substrate distance, varying partial pressures of Ar, H{sub 2}, and C{sub 3}H{sub 8}, and flow rates. The vibrational and opto-electronic properties such as infrared (IR) absorption, optical gap, electron-spin-resonance (ESR) signals, and conductivities vary with deposition conditions. The photoconductivity, in particular, was carefully monitored as a function of the deposition conditions to optimize it. The concentration of Ge-H bonds and the optical gap generally decrease as P is increased. Results of annealing showed the enhanced segregation effect of Ge-C bonds {ge} 300{degree}C. The evolution of bonded hydrogen with temperature is studied. Deposition rates of a-Ge:H films are estimated and compared. The thermalization curve for a Ge target is constructed. Deposition rate was found to decrease exponentially with increasing target-substrate distances to decrease with increasing partial pressures of H{sub 2} and C{sub 3}H{sub 8} and increasing flow rates. Hydrogen incorporation markedly increased photoconductivity.

  11. Determination of the Wetting Angle of Germanium and Germanium-Silicon Melts on Different Substrate Materials

    NASA Technical Reports Server (NTRS)

    Kaiser, Natalie; Croell, Arne; Szofran, F. R.; Cobb. S. D.; Dold, P.; Benz, K. W.

    1999-01-01

    During Bridgman growth of semiconductors detachment of the crystal and the melt meniscus has occasionally been observed, mainly under microgravity (microg) conditions. An important factor for detached growth is the wetting angle of the melt with the crucible material. High contact angles are more likely to result in detachment of the growing crystal from the ampoule wall. In order to achieve detached growth of germanium (Ge) and germanium-silicon (GeSi) crystals under 1g and microg conditions, sessile drop measurements were performed to determine the most suitable ampoule material as well as temperature dependence of the surface tension for GeSi. Sapphire, fused quartz, glassy carbon, graphite, SiC, pyrolytic Boron Nitride (pBN), AIN, and diamond were used as substrates. Furthermore, different cleaning procedures and surface treatments (etching, sandblasting, etc.) of the same substrate material and their effect on the wetting behavior were studied during these experiments. pBN and AIN substrates exhibited the highest contact angles with values around 170 deg.

  12. Disposition of ( UC)methyl bromide in rats after inhalation

    SciTech Connect

    Bond, J.A.; Dutcher, J.S.; Medinsky, M.A.; Henderson, R.F.; Birnbaum, L.S.

    1985-01-01

    The purpose of this investigation was to determine the disposition and metabolism of ( UC)methyl bromide in rats after inhalation. Male Fischer-344 rats were exposed nose only to a vapor concentration of 337 nmol ( UC)methyl bromide/liter air (9.0 ppm, 25C, 620 torr) for 6 hr. Urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Elimination of UC as UCO2 was the major route of excretion with about 47% (3900 nmol/rat) of the total ( UC)methyl bromide absorbed excreted by this route. CO2 excretion exhibited a biphasic elimination pattern with 85% of the UCO2 being excreted with a half-time of 3.9 +/- 0.1 hr (anti x +/- SE) and 15% excreted with a half-time of 11.4 +/- 0.2 hr. Half-times for elimination of UC in urine and feces were 9.6 +/- 0.1 and 16.1 +/- 0.1 hr, respectively. By 65 hr after exposure, about 75% of the initial radioactivity had been excreted with 25% remaining in the body. Radioactivity was widely distributed in tissues immediately following exposure with lung (250 nmol equivalents/g), adrenal (240 nmol equivalents/g), and nasal turbinates (110 nmol equivalents/g) containing the highest concentrations of UC. Radioactivity in livers immediately after exposure accounted for about 17% of the absorbed methyl bromide. Radioactivity in all other tissues examined accounted for about 10% of the absorbed methyl bromide. Elimination half-times of UC from tissues were on the order of 1.5 to 8 hr. In all tissues examined, over 90% of the UC in the tissues was methyl bromide metabolities. The data from this study indicate that after inhalation methyl bromide is rapidly metabolized in tissues and readily excreted. 22 references, 4 figures, 4 tables.

  13. Single-molecule conductance in atomically precise germanium wires.

    PubMed

    Su, Timothy A; Li, Haixing; Zhang, Vivian; Neupane, Madhav; Batra, Arunabh; Klausen, Rebekka S; Kumar, Bharat; Steigerwald, Michael L; Venkataraman, Latha; Nuckolls, Colin

    2015-09-30

    While the electrical conductivity of bulk-scale group 14 materials such as diamond carbon, silicon, and germanium is well understood, there is a gap in knowledge regarding the conductivity of these materials at the nano and molecular scales. Filling this gap is important because integrated circuits have shrunk so far that their active regions, which rely so heavily on silicon and germanium, begin to resemble ornate molecules rather than extended solids. Here we unveil a new approach for synthesizing atomically discrete wires of germanium and present the first conductance measurements of molecular germanium using a scanning tunneling microscope-based break-junction (STM-BJ) technique. Our findings show that germanium and silicon wires are nearly identical in conductivity at the molecular scale, and that both are much more conductive than aliphatic carbon. We demonstrate that the strong donor ability of C-Ge σ-bonds can be used to raise the energy of the anchor lone pair and increase conductance. Furthermore, the oligogermane wires behave as conductance switches that function through stereoelectronic logic. These devices can be trained to operate with a higher switching factor by repeatedly compressing and elongating the molecular junction. PMID:26373928

  14. Application of germanium carbide in durable multilayer IR coatings

    NASA Astrophysics Data System (ADS)

    Kelly, Chris J.; Orr, James S.; Gordon, H.; Traub, Leonard T.; Lettington, Alan H.

    1990-08-01

    Infrared transparent amorphous hydrogenated alloys of germanium and carbon (germanium carbide) have been deposited by plasma assisted chemical vapour deposition (PACVD) using germane (GeH4 ) and butane (C 4Hid as the feedstocks and by reactive sputtering of germanium with a CH1g-Ar plasma. The effects of varying various deposition conditions have been assessed on a number of coating properties . Germanium Carbide has good environmental durability and can be deposited in thick layers. Using PACVD it can be deposited with any refractive index in the range 2 to 4 while the sputtering process is limited to indices in the range 3 to 4 . One advantage of the sputtering process is the high deposition rates achievable which can be up to '-lOum/h compared with lum/h for the PACVD process. When used in conjunction with "diamond-like" carbon (a-'C:H) , germanium carbide offers the prospect of rnultilayer antireflection coatings for 8 to 12 urn optics with durabilities which hitherto have been impossible to achieve. Antireflection coatings for zinc sulphide windows which are subject to hostile environmental conditions have been investigated and the performance of the coatings is presented. The factors affecting the practical realisation of these coatings on a production scale are discussed.

  15. Low temperature exfoliation process in hydrogen-implanted germanium layers

    NASA Astrophysics Data System (ADS)

    Ferain, I. P.; Byun, K. Y.; Colinge, C. A.; Brightup, S.; Goorsky, M. S.

    2010-03-01

    The feasibility of transferring hydrogen-implanted germanium to silicon with a reduced thermal budget is demonstrated. Germanium samples were implanted with a splitting dose of 5×1016 H2+ cm-2 at 180 keV and a two-step anneal was performed. Surface roughness and x-ray diffraction pattern measurements, combined with cross-sectional TEM analysis of hydrogen-implanted germanium samples were carried out in order to understand the exfoliation mechanism as a function of the thermal budget. It is shown that the first anneal performed at low temperature (≤150 °C for 22 h) enhances the nucleation of hydrogen platelets significantly. The second anneal is performed at 300 °C for 5 min and is shown to complete the exfoliation process by triggering the formation of extended platelets. Two key results are highlighted: (i) in a reduced thermal budget approach, the transfer of hydrogen-implanted germanium is found to follow a mechanism similar to the transfer of hydrogen-implanted InP and GaAs, (ii) such a low thermal budget (<300 °C) is found to be suitable for directly bonded heterogeneous substrates, such as germanium bonded to silicon, where different thermal expansion coefficients are involved.

  16. Investigation of germanium Raman lasers for the mid-infrared.

    PubMed

    De Leonardis, Francesco; Troia, Benedetto; Soref, Richard A; Passaro, Vittorio M N

    2015-06-29

    In this paper we present a detailed theoretical investigation of integrated racetrack Raman lasers based on the germanium material system operating in the mid-infrared beyond the germanium two-photon absorption cut-off wavelength of 3.17 μm. The effective Raman gain has been estimated in waveguides based on germanium-on-silicon, germanium-on-SOI and germanium-on-Si3N4 technology platforms as a function of their crystallographic orientations. Furthermore, general design guidelines have been determined by means of a comparative analysis of Raman laser performance, i.e. the threshold power, polarization and directionality of the excited Stokes signals as a function of racetrack cavity length and directional-coupler dimensions. Finally, the emitted Raman laser power has been evaluated as a function of overall propagation losses and operative wavelengths up to 3.8 μm, while the time dynamics of Raman lasers has been simulated assuming continuous and pulse waves as input pump signals. PMID:26191733

  17. Reaction studies of hot silicon, germanium and carbon atoms

    SciTech Connect

    Gaspar, P.P.

    1990-11-01

    The goal of this project was to increase the authors understanding of the interplay between the kinetic and electronic energy of free atoms and their chemical reactivity by answering the following questions: (1) what is the chemistry of high-energy carbon silicon and germanium atoms recoiling from nuclear transformations; (2) how do the reactions of recoiling carbon, silicon and germanium atoms take place - what are the operative reaction mechanisms; (3) how does the reactivity of free carbon, silicon and germanium atoms vary with energy and electronic state, and what are the differences in the chemistry of these three isoelectronic atoms This research program consisted of a coordinated set of experiments capable of achieving these goals by defining the structures, the kinetic and internal energy, and the charge states of the intermediates formed in the gas-phase reactions of recoiling silicon and germanium atoms with silane, germane, and unsaturated organic molecules, and of recoiling carbon atoms with aromatic molecules. The reactions of high energy silicon, germanium, and carbon atoms created by nuclear recoil were studied with substrates chosen so that their products illuminated the mechanism of the recoil reactions. Information about the energy and electronic state of the recoiling atoms at reaction was obtained from the variation in end product yields and the extent of decomposition and rearrangement of primary products (usually reactive intermediates) as a function of total pressure and the concentration of inert moderator molecules that remove kinetic energy from the recoiling atoms and can induce transitions between electronic spin states. 29 refs.

  18. First-principles calculations of multivacancies in germanium

    NASA Astrophysics Data System (ADS)

    Sholihun; Ishii, Fumiyuki; Saito, Mineo

    2016-01-01

    We carry out density-functional-theory calculations to study the stability of germanium multivacancies. We use supercells containing 216 atomic sites and simulate two configurations called the “part of hexagonal ring” (PHR) and fourfold configurations of the tri-, tetra-, and pentavacancies. We find that the fourfold configurations of the tetra- and pentavacancies are the most stable and these configurations are also the most stable in the case of silicon. However, we find that the PHR and fourfold configurations have similar energies in the case of the germanium trivacancy. These results are in contrast to those of the silicon trivacancy; the fourfold configuration has substantially lower energy than the PHR configuration. This difference between germanium and silicon is expected to originate from the fact that the four bonds in the fourfold configurations in the germanium trivacancy are weaker than those in the silicon one. By calculating dissociation energies, we find that the silicon tetravacancy is not easy to dissociate, whereas the germanium tetravacancy is not very stable compared with the silicon one.

  19. POSITION SENSITIVE GERMANIUM DETECTORS FOR GAMMA-RAY IMAGING AND SPECTROSCOPY

    EPA Science Inventory

    Gamma-ray imaging with position-sensitive germanium detectors offers the advantages of excellent energy resolution, high detection efficiency, and potentially good sptial resolution. The development of the amorphous-semiconductor electrical contact technology for germanium detec...

  20. UV photodissociation of methyl bromide and methyl bromide cation studied by velocity map imaging

    SciTech Connect

    Blanchet, Valerie; Samartzis, Peter C.; Wodtke, Alec M.

    2009-01-21

    We employ the velocity map imaging technique to measure kinetic energy and angular distributions of state selected CH{sub 3} (v{sub 2}=0,1,2,3) and Br ({sup 2}P{sub 3/2}, {sup 2}P{sub 1/2}) photofragments produced by methyl bromide photolysis at 215.9 nm. These results show unambiguously that the Br and Br* forming channels result in different vibrational excitations of the umbrella mode of the methyl fragment. Low energy structured features appear on the images, which arise from CH{sub 3}Br{sup +} photodissociation near 330 nm. The excess energy of the probe laser photon is channeled into CH{sub 3}{sup +} vibrational excitation, most probably in the {nu}{sub 4} degenerate bend.

  1. Hydrogenated nanocrystalline silicon germanium thin films

    NASA Astrophysics Data System (ADS)

    Yusoff, A. R. M.; Syahrul, M. N.; Henkel, K.

    2007-08-01

    Hydrogenated nanocrystalline silicon germanium thin films (nc-SiGe:H) is an interesting alternative material to replace hydrogenated nanocrystalline silicon (nc-Si:H) as the narrow bandgap absorber in an a-Si/a-SiGe/nc-SiGe(nc-Si) triple-junction solar cell due to its higher optical absorption in the wavelength range of interest. In this paper, we present results of optical, structural investigations and electrical characterization of nc-SiGe:H thin films made by hot-wire chemical vapor deposition (HWCVD) with a coil-shaped tungsten filament and with a disilane/germane/hydrogen gas mixture. The optical band gaps of a-SiGe:H and nc-SiGe:H thin-films, which are deposited with the same disilane/germane/hydrogen gas mixture ratio of 3.4:1.7:7, are about 1.58 eV and 2.1 eV, respectively. The nc-SiGe:H thin film exhibits a larger optical absorption coefficient of about 2-4 in the 600-900 nm range when compared to nc-Si:H thin film. Therefore, a thinner nc-SiGe:H layer of sim500 nm thickness may be sufficient for the narrow bandgap absorber in an a-Si based multiple-junction solar cell. We enhanced the transport properties as measured by the photoconductivity frequency mixing technique. These improved alloys do not necessarily show an improvement in the degree of structural heterogeneity on the nanometer scale as measured by small-angle X-ray scattering. Decreasing both the filament temperature and substrate temperature produced a film with relatively low structural heterogeneity while photoluminescence showed an order of magnitude increase in defect density for a similar change in the process.

  2. Stability of Detached Grown Germanium Single Crystals

    NASA Technical Reports Server (NTRS)

    Schweizer, M.; Volz, M. P.; Cobb, S. D.; Vujisic, L.; Szofran, F. R.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Detachment of the melt meniscus from the crucible during semiconductor Bridgman growth experiments has been observed in recent years, especially under microgravity experiments. Under earth conditions, the hydrostatic pressure counteracts the mechanism, whereby it is more difficult to achieve detached Bridgman growth. Attempts to get stable detached growth under terrestrial conditions have been discussed in the literature and have been the subject of recent experiments in our own group. The advantage of crystals grown without wall contact is obvious: In general, they possess a higher crystal quality than conventional Bridgman grown crystals with wall contact. However, due to the interaction of different parameters such as the wetting behavior of the melt with the crucible, and the dependence of the growth angle with the shape of the melt meniscus, the mechanism leading to detachment is very complicated and not completely understood. We have grown several doped and undoped Germanium crystals with the detached Bridgman and the normal Bridgman growth technique. Pyrolytic boron nitride containers were used for all growth experiments. In the detached grown crystals the typical gap thickness between the pBN crucible and the crystal is in the range of 10 to 100 micrometers, which was determined by performing profilometer measurements. Etch pit density measurements were also performed and a comparison between detached and attached grown crystals will be given. An interesting feature was detected on the surface of a detached grown crystal. Strong surface striations with an average axial distance of 0.5 mm were observed around the whole circumference. The maximum fluctuation of the gap thickness is in the range of 5-10 micrometers. These variations of the detached gap along the crystal axis can be explained by a kind of stiction of the melt/crucible interface and thus by a variation of the meniscus shape. This phenomenon leading to the fluctuation of the gap thickness will be

  3. Stability of Detached Grown Germanium Single Crystals

    NASA Technical Reports Server (NTRS)

    Schweizer, M.; Volz, M. P.; Cobb, S. D.; Motakef, S.; Szofran, F. R.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Detachment of the melt meniscus from the crucible during semiconductor Bridgman growth experiments has been observed in recent years especially, under microgravity experiments. Under earth conditions, the hydrostatic pressure counteracts the mechanism, whereby it is more difficult to achieve detached Bridgman growth. Attempts to get stable detached growth under terrestrial conditions have been discussed in the literature and have been the subject of recent experiments in our own group. The advantage of crystals grown without wall contact is obvious: In general, they possess a higher crystal quality than conventional Bridgman grown crystals with wall contact. However, due to the interaction of different parameters such as the wetting behavior of the melt with the crucible, and the dependence of the growth angle with the shape of the melt meniscus, the mechanism leading to detachment is very complicated and not completely understood. We have grown several doped and undoped Germanium crystals with the detached Bridgman and the normal Bridgman growth technique. Pyrolytic boron nitride containers were used for all growth experiments. In the detached grown crystals the typical gap thickness between the pBN crucible and the crystal is in the range of 10 to 100 microns, which was determined by performing profilometer measurements. Etch pit density measurements were also performed and a comparison between detached and attached grown crystals will be given. An interesting feature was detected on the surface of a detached grown crystal. Strong surface striations with an average axial distance of 0.5mm were observed around the whole circumference. The maximum fluctuation of the gap thickness is in the range of 5-10 microns. These variations of the detached gap along the crystal axis can be explained by a kind of stiction of the melt/crucible interface and thus by a variation of the meniscus shape. This phenomenon leading to the fluctuation of the gap thickness will be

  4. Zinc Bromide Combustion: Implications for the Consolidated Incinerator Facility

    SciTech Connect

    Oji, L.N.

    1998-12-16

    In the nuclear industry, zinc bromide (ZnBr2) is used for radiation shielding. At Savannah River Site (SRS) zinc bromide solution, in appropriate configurations and housings, was used mainly for shielding in viewing windows in nuclear reactor and separation areas. Waste stream feeds that will be incinerated at the CIF will occasionally include zinc bromide solution/gel matrices.The CIF air pollution systems control uses a water-quench and steam atomizer scrubber that collects salts, ash and trace metals in the liquid phase. Water is re-circulated in the quench unit until a predetermined amount of suspended solids or dissolved salts are present. After reaching the threshold limit, "dirty liquid", also called "blowdown", is pumped to a storage tank in preparation for treatment and disposal. The air pollution control system is coupled to a HEPA pre-filter/filter unit, which removes particulate matter from the flue gas stream (1).The objective of this report is to review existing literature data on the stability of zinc bromide (ZnBr2) at CIF operating temperatures (>870 degrees C (1600 degrees F) and determine what the combustion products are in the presence of excess air. The partitioning of the combustion products among the quencher/scrubber solution, bottom ash and stack will also be evaluated. In this report, side reactions between zinc bromide and its combustion products with fuel oil were not taken into consideration.

  5. Cross-Coupling of Aromatic Bromides with Allylic Silanolate Salts

    PubMed Central

    Denmark, Scott E; Werner, Nathan S.

    2009-01-01

    The sodium salts of allyldimethylsilanol and 2-butenyldimethylsilanol undergo palladium-catalyzed cross-coupling with a wide variety of aryl bromides to afford allylated and crotylated arenes. The coupling of both silanolates required extensive optimization to deliver the expected products in high yields. The reaction of the allyldimethylsilanolate takes place at 85 °C in DME with allylpalladium chloride dimer (2.5 mol %) to afford 7–95% yields of the allylation products. Both electron-rich and sterically-hindered bromides reacted smoothly, whereas electron-poor bromides cross-coupled in poor yield because of a secondary isomerization to the 1-propenyl isomer (and subsequent polymerization). The 2-butenyldimethylsilanolate (E/Z, 80:20) required additional optimization to maximize the formation of the branched (γ-substitution product). A remarkable influence of added alkenes (dibenzylideneacetone and norbornadiene) led to good selectivities for electron-rich and electron-poor bromides in 4–83% yields. However, bromides containing coordinating groups (particularly in the ortho position) gave lower, and in one case even reversed, selectivity. Configurationally homogeneous E-silanolates gave slightly higher γ-selectivity than the pure Z-silanolates. A unified mechanistic picture involving initial γ-transmetalation followed by direct reductive elimination or σ–π isomerization can rationalize all of the observed trends. PMID:18998687

  6. Effect of Bromide-Hypochlorite Bactericides on Microorganisms1

    PubMed Central

    Shere, Lewis; Kelley, Maurice J.; Richardson, J. Harold

    1962-01-01

    A new principle in compounding stable, granular bactericidal products led to unique combinations of a water-soluble inorganic bromide salt with a hypochlorite-type disinfectant of either inorganic or organic type. Microbiological results are shown for an inorganic bactericide composed of chlorinated trisodium phosphate containing 3.1% “available chlorine” and 2% potassium bromide, and for an organic bactericide formulated from sodium dichloroisocyanurate so as to contain 13.4% “available chlorine” and 8% potassium bromide. Comparison of these products with their nonbromide counterparts are reported for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus lactis, Aerobacter aerogenes, and Proteus vulgaris. Test methods employed were the Chambers test, the A.O.A.C. Germicidal and Detergent Sanitizer-Official test, and the Available Chlorine Germicidal Equivalent Concentration test. The minimal killing concentrations for the bromide-hypochlorite bactericides against this variety of organisms were reduced by a factor 2 to 24 times those required for similar hypochlorite-type disinfectants not containing the bromide. PMID:13977149

  7. Electrophysiological study of intravenous pinaverium bromide in cardiology.

    PubMed

    Guerot, C; Khemache, A; Sebbah, J; Noel, B

    1988-01-01

    Pinaverium bromide is a musculotropic spasmolytic agent which acts by inhibiting transmembrane calcium movements, an effect similar to that of verapamil. Because of this, an investigation was carried out to see if it had any electrophysiological effects in patients with various cardiac disorders. In an open study, 10 patients received 2 mg pinaverium bromide intravenously. In a double-blind study, 10 patients received 4 mg pinaverium bromide intravenously and 10 patients placebo. Patients included those with either normal or pathological basal conduction, such as bundle-branch block and 1st degree atrioventricular block. Measurements were made of electrophysiological parameters before and 10 minutes after injection. The results showed that neither of the two doses of pinaverium bromide had any effect on atrial excitability, sino-atrial conduction, node and trunk atrioventricular conduction or on intraventricular conduction. No significant difference was seen in comparison with placebo. Pinaverium bromide had no anti-arrhythmic properties in these studies. Local, cardiac and general clinical tolerability was good in all patients. PMID:3219882

  8. Simulations for Tracking Cosmogenic Activation in Germanium and Copper

    SciTech Connect

    Aguayo, Estanislao; Kouzes, Richard T.; Orrell, John L.

    2011-11-01

    High-purity germanium (HPGe) detectors housed in copper cryostats and shielding materials are used in measurements of the extraordinarily rare nuclear decay process, neutrinoless double-beta decay (0νββ), and for dark matter searches. Cosmogenic production of 68Ge and 60Co in the germanium and copper represent an irreducible background to these experiments as the subsequent decays of these isotopes can mimic the signals of interest. These radioactive isotopes can be removed by chemical and/or isotopic separation, but begin to grow-in to the material after separation until the material is moved deep underground. This work is motivated by the need to have a reliable, experimentally benchmarked simulation tool for evaluating shielding materials used during transportation and near-surface manufacturing of experiment components. The resulting simulations tool has been used to enhance the effectiveness of an existing transport shield used to ship enriched germanium from the separations facility to the detector manufacturing facility.

  9. Moth's eye anti-reflection gratings on germanium freeform surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Meng; Shultz, Jason A.; Owen, Joseph D.; Davies, Matthew A.; Suleski, Thomas J.

    2014-09-01

    Germanium is commonly used for optical components in the infrared, but the high refractive index of germanium causes significant losses due to Fresnel reflections. Anti-reflection (AR) surfaces based on subwavelength "moth's eye" gratings provide one means to significantly increase optical transmission. As found in nature, these gratings are conformal to the curved surfaces of lenslets in the eye of the moth. Engineered optical systems inspired by biological examples offer possibilities for increased performance and system miniaturization, but also introduce significant challenges to both design and fabrication. In this paper, we consider the design and fabrication of conformal moth's eye AR structures on germanium freeform optical surfaces, including lens arrays and Alvarez lenses. Fabrication approaches and limitations based on both lithography and multi-axis diamond machining are considered. Rigorous simulations of grating performance and approaches for simulation of conformal, multi-scale optical systems are discussed.

  10. Germanium FCC structure from a colloidal crystal template

    SciTech Connect

    Miguez, H.; Meseguer, F.; Lopez, C.; Holgado, M.; Andreasen, G.; Mifsud, A.; Fornes, V.

    2000-05-16

    Here, the authors show a method to fabricate a macroporous structure in which the pores, essentially identical, arrange regularly in a face-centered cubic (FCC) lattice. The result is a network of air spheres in a germanium medium. This structure presents the highest dielectric contrast ({epsilon}{sub Ge}/{epsilon}{sub air} = 16) ever achieved in the optical regime in such periodic structures, which could result in important applications in photonics. The authors employ solid silica colloidal crystals (opals) as templates within which a cyclic germanium growth process is carried out. Thus, the three-dimensional periodicity of the host is inherited by the guest. Afterward, the silica is removed and a germanium opal replica is obtained.

  11. Next Generation Device Grade Silicon-Germanium on Insulator

    PubMed Central

    Littlejohns, Callum G.; Nedeljkovic, Milos; Mallinson, Christopher F.; Watts, John F.; Mashanovich, Goran Z.; Reed, Graham T.; Gardes, Frederic Y.

    2015-01-01

    High quality single crystal silicon-germanium-on-insulator has the potential to facilitate the next generation of photonic and electronic devices. Using a rapid melt growth technique we engineer tailored single crystal silicon-germanium-on-insulator structures with near constant composition over large areas. The proposed structures avoid the problem of laterally graded SiGe compositions, caused by preferential Si rich solid formation, encountered in straight SiGe wires by providing radiating elements distributed along the structures. This method enables the fabrication of multiple single crystal silicon-germanium-on-insulator layers of different compositions, on the same Si wafer, using only a single deposition process and a single anneal process, simply by modifying the structural design and/or the anneal temperature. This facilitates a host of device designs, within a relatively simple growth environment, as compared to the complexities of other methods, and also offers flexibility in device designs within that growth environment. PMID:25656076

  12. Silicon-germanium technology program of the Jet Propulsion Laboratory.

    NASA Technical Reports Server (NTRS)

    De Winter, F.; Stapfer, G.

    1972-01-01

    The outer planetary exploration missions studied by the Jet Propulsion Laboratory require silicon-germanium radioisotope thermoelectric generators (RTGs) in which the factors of safety are as low as is compatible with the reliable satisfaction of the power needs. Work on silicon germanium sublimation performed at the Jet Propulsion Laboratory is presented. Analytical modeling work on the solid-diffusion process involved in the steady-state (free) sublimation of silicon germanium is described. Analytical predictions are made of the sublimation suppression which can be achieved by using a cover gas. A series of accelerated (high-temperature) tests which were performed on simulated hardware (using four SiGe couples) to study long-term sublimation and reaction mechanisms are also discussed.

  13. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart...

  14. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart...

  15. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart...

  16. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart...

  17. 40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... primary and secondary germanium and gallium subcategory. 421.180 Section 421.180 Protection of Environment... POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium Subcategory § 421.180 Applicability: Description of the primary and secondary germanium and gallium subcategory. The provisions of this subpart...

  18. Deposition and characterizations of ultrasmooth silver thin films assisted with a germanium wetting layer

    NASA Astrophysics Data System (ADS)

    Zhang, Junce; Fryauf, David M.; Diaz Leon, Juan J.; Garrett, Matthew; VJ, Logeeswaran; Islam, Saif M.; Kobayashi, Nobuhiko P.

    2015-08-01

    In this paper, silver thin films deposited on SiO2 substrates with a germanium wetting layer fabricated by electron-beam evaporation were studied. The characterization methods of XTEM, FTIR, XRD and XRR were used to study the structural properties of silver thin films with various thicknesses of germanium layers. Silver films deposited with very thin (1-5nm) germanium wetting layers show about one half of improvement in the crystallite sizes comparing silver films without germanium layer. The surface roughness of silver thin films significantly decrease with a thin germanium wetting layer, reaching a roughness minimum around 1-5nm of germanium, but as the germanium layer thickness increases, the silver thin film surface roughness increases. The relatively higher surface energy of germanium and bond dissociation energy of silver-germanium were introduced to explain the effects the germanium layer made to the silver film deposition. However, due to the Stranski-Krastanov growth mode of germanium layer, germanium island formation started with increased thickness (5-15nm), which leads to a rougher surface of silver films. The demonstrated silver thin films are very promising for large-scale applications as molecular anchors, optical metamaterials, plasmonic devices, and several areas of nanophotonics.

  19. Nanocrystal Inks without Ligands: Stable Colloids of Bare Germanium Nanocrystals

    SciTech Connect

    Holman, Zachary C.; Kortshagen, Uwe R.

    2011-05-11

    Colloidal semiconductor nanocrystals typically have ligands attached to their surfaces that afford solubility in common solvents but hinder charge transport in nanocrystal films. Here, an alternative route is explored in which bare germanium nanocrystals are solubilized by select solvents to form stable colloids without the use of ligands. A survey of candidate solvents shows that germanium nanocrystals are completely solubilized by benzonitrile, likely because of electrostatic stabilization. Films cast from these dispersions are uniform, dense, and smooth, making them suitable for device applications without postdeposition treatment.

  20. Characterisation of two AGATA asymmetric high purity germanium capsules

    NASA Astrophysics Data System (ADS)

    Colosimo, S. J.; Moon, S.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Harkness-Brennan, L.; Judson, D. S.; Lazarus, I. H.; Nolan, P. J.; Simpson, J.; Unsworth, C.

    2015-02-01

    The AGATA spectrometer is an array of highly segmented high purity germanium detectors. The spectrometer uses pulse shape analysis in order to track Compton scattered γ-rays to increase the efficiency of nuclear spectroscopy studies. The characterisation of two high purity germanium detector capsules for AGATA of the same A-type has been performed at the University of Liverpool. This work will examine the uniformity of performance of the two capsules, including a comparison of the resolution and efficiency as well as a study of charge collection. The performance of the capsules shows good agreement, which is essential for the efficient operation of the γ-ray tracking array.

  1. LETTER TO THE EDITOR: Structure of densified amorphous germanium dioxide

    NASA Astrophysics Data System (ADS)

    Micoulaut, Matthieu

    2004-03-01

    Classical molecular dynamics simulations are used to study the structure of densified germanium dioxide (GeO2). It is found that the coordination number of germanium changes with increasing density (pressure) while pressure released systems exhibit only a marked angular change in local structure as compared to the virgin system. The structural modification with pressure appears to be stepwise and gradually affects long-range (through the reduction of the long-range correlations as seen from the shift of the first sharp diffraction peak), intermediate-range (by angular reduction) and finally short-range structure (by tetrahedron distortion).

  2. The GALATEA test-facility for high purity germanium detectors

    NASA Astrophysics Data System (ADS)

    Abt, I.; Caldwell, A.; Dönmez, B.; Garbini, L.; Irlbeck, S.; Majorovits, B.; Palermo, M.; Schulz, O.; Seitz, H.; Stelzer, F.

    2015-05-01

    GALATEA is a test facility designed to investigate bulk and surface effects in high purity germanium detectors. A vacuum tank houses a cold volume with the detector inside. A system of three precision motorized stages allows an almost complete scan of the detector. The main feature of GALATEA is that there is no material between source and detector. This allows the usage of alpha and beta sources to study surface effects. A 19-fold segmented true-coaxial germanium detector was used for commissioning. A first analysis of data obtained with an alpha source is presented here.

  3. The Novel Synthesis of Silicon and Germanium Nanocrystallites

    SciTech Connect

    Kauzlarich, S M; Liu, Q; Yin, S C; Lee, W H; Taylor, B

    2001-04-03

    Interest in the synthesis of semiconductor nanoparticles has been generated by their unusual optical and electronic properties arising from quantum confinement effects. We have synthesized silicon and germanium nanoclusters by reacting Zintl phase precursors with either silicon or germanium tetrachloride in various solvents. Strategies have been investigated to stabilize the surface, including reactions with RLi and MgBrR (R = alkyl). This synthetic method produces group IV nanocrystals with passivated surfaces. These nanoparticle emit over a very large range in the visible region. These particles have been characterized using HRTEM, FTIR, UV-Vis, solid state NMR, and fluorescence. The synthesis and characterization of these nanoclusters will be presented.

  4. Large-size germanium crystal growth for rare event physics

    NASA Astrophysics Data System (ADS)

    Mei, Dongming; Wang, Guojian; Mei, Hao; Guan, Yutong; Yang, Gang; Govani, Jayesh; Cubed Collaboration

    2014-09-01

    Cosmogenic production in germanium crystals grown on the surface can limit the sensitivity for the next generation deep underground experiments in searching for rare event physics beyond the Standard Model. One of the best solutions to eliminate unwanted cosmogenics is to produce the germanium crystals and detectors in an underground environment. The goal of this project is to create state-of-the-art detectors to advance neutrinoless double-beta decay and dark matter exploration research and technology while simultaneously paving the way for infrastructure to support an underground laboratory for zone refining, crystal growth, and detector fabrication. The greatest challenge in the growth of germanium crystals is a lack of precise control of individual crystal properties such as the impurity distribution, the dislocation density, and the crystalline structure. With knowledge gained from the pioneers in the field of crystal growth, the researchers have developed a novel technique to grow detector-grade crystals. In this paper, we will report detector-grade large-size germanium crystal growth at the University of South Dakota. Cosmogenic production in germanium crystals grown on the surface can limit the sensitivity for the next generation deep underground experiments in searching for rare event physics beyond the Standard Model. One of the best solutions to eliminate unwanted cosmogenics is to produce the germanium crystals and detectors in an underground environment. The goal of this project is to create state-of-the-art detectors to advance neutrinoless double-beta decay and dark matter exploration research and technology while simultaneously paving the way for infrastructure to support an underground laboratory for zone refining, crystal growth, and detector fabrication. The greatest challenge in the growth of germanium crystals is a lack of precise control of individual crystal properties such as the impurity distribution, the dislocation density, and the

  5. Tensile-strained germanium microdisks with circular Bragg reflectors

    NASA Astrophysics Data System (ADS)

    El Kurdi, M.; Prost, M.; Ghrib, A.; Elbaz, A.; Sauvage, S.; Checoury, X.; Beaudoin, G.; Sagnes, I.; Picardi, G.; Ossikovski, R.; Boeuf, F.; Boucaud, P.

    2016-02-01

    We demonstrate the combination of germanium microdisks tensily strained by silicon nitride layers and circular Bragg reflectors. The microdisks with suspended lateral Bragg reflectors form a cavity with quality factors up to 2000 around 2 μm. This represents a key feature to achieve a microlaser with a quasi-direct band gap germanium under a 1.6% biaxial tensile strain. We show that lowering the temperature significantly improves the quality factor of the quasi-radial modes. Linewidth narrowing is observed in a range of weak continuous wave excitation powers. We finally discuss the requirements to achieve lasing with these kind of structures.

  6. Silicon germanium semiconductive alloy and method of fabricating same

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor)

    2008-01-01

    A silicon germanium (SiGe) semiconductive alloy is grown on a substrate of single crystalline Al.sub.2O.sub.3. A {111} crystal plane of a cubic diamond structure SiGe is grown on the substrate's {0001} C-plane such that a <110> orientation of the cubic diamond structure SiGe is aligned with a <1,0,-1,0> orientation of the {0001} C-plane. A lattice match between the substrate and the SiGe is achieved by using a SiGe composition that is 0.7223 atomic percent silicon and 0.2777 atomic percent germanium.

  7. Cetyltrimethyl ammonium bromide assisted hydrothermal growth of hematite hollow cubes

    SciTech Connect

    Wang, Wei-Wei; Yao, Jia-Liang

    2010-11-15

    Hematite hollow cubes have been prepared by forced hydrolysis of ferric chloride solutions under hydrothermal conditions. The effects of reaction time, reaction temperature and cetyltrimethyl ammonium bromide on the transformation process from akageneite to hematite were investigated in detail. The products were characterized by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. It is found that cetyltrimethyl ammonium bromide was a critical factor influencing the phase transformation process of akageneite and the final morphology of the as-prepared products. With cetyltrimethyl ammonium bromide, hematite hollow cubes and porous spheres were obtained. Otherwise only dense cubes were observed even prolonging reaction time or increasing reaction temperature. The mechanism was proposed.

  8. Investigation of pyridine/propargyl bromide reaction and strong fluorescence enhancements of the resultant poly(propargyl pyridinium bromide).

    PubMed

    Zhou, Changming; Gao, Yong; Chen, Daoyong

    2012-09-20

    Poly(propargyl pyridinium bromide), a kind of conjugated polyelectrolyte with polyacetylene as the backbone and pyridinium as side groups, was synthesized simply via reaction between pyridine and propargyl bromide under mild conditions. The resultant polymer was characterized by (1)H NMR, elemental analysis, FT-IR, and GPC-MALLS. An alkyne group was confirmed as the end group of the polymer chains by the alkyne/azide click chemistry, which reveals that the polymerization is terminated by the reaction between propargyl bromide and carbon anions. It is known that monosubstituted polyacetylenes reported have very weak fluorescence intensities, which limit their applications. As a monosubstituted polyacetylene, the freshly prepared poly(propargyl pyridinium bromide) also has a very weak fluorescence. However, we confirmed that addition of some anions to the polymer solution in DMF or DMSO leads to the fluorescence enhancements up to 25 times. Besides, heating the polymer solution at a temperature between 70 and 130 °C for longer than 0.5 h greatly enhanced the fluorescence intensity. The interaction with the anions or the heating enhances the effective exciton confinement within the conjugated backbone and thus results in the fluorescence enhancements. After the fluorescence enhancements, poly(propargyl pyridinium bromide) has relatively strong fluorescence emissions, which will make it promising in fluorescence-based applications. PMID:22928912

  9. Detached Bridgman Growth of Germanium and Germanium-Silicon Alloy Crystals

    NASA Technical Reports Server (NTRS)

    Szofran, F. R.; Volz, M. P.; Schweizer, M.; Cobb, S. D.; Motakef, S.; Croell, A.; Dold, P.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Earth based experiments on the science of detached crystal growth are being conducted on germanium and germanium-silicon alloys (2 at% Si average composition) in preparation for a series of experiments aboard the International Space Station (ISS). The purpose of the microgravity experiments includes differentiating among proposed mechanisms contributing to detachment, and confirming or refining our understanding of the detachment mechanism. Because large contact angle are critical to detachment, sessile drop measurements were used to determine the contact angles as a function of temperature and composition for a large number of substrates made of potential ampoule materials. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. The contact angles were 173 deg (Ge) and 165 deg (GeSi) for pBN. For fused silica, the contact angle decreases from 150 deg to an equilibrium value of 117 deg (Ge) or from 129 deg to an equilibrium value of 100 deg (GeSi) over the duration of the experiment. The nature and extent of detachment is determined by using profilometry in conjunction with optical and electron microscopy. The stability of detachment has been analyzed, and an empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed. Results in this presentation will show that we have established the effects on detachment of ampoule material, pressure difference above and below the melt, and silicon concentration; samples that are nearly completely detached can be grown repeatedly in pBN.

  10. Oxidation of manganese(II) during chlorination: role of bromide.

    PubMed

    Allard, S; Fouche, L; Dick, J; Heitz, A; von Gunten, U

    2013-08-01

    The oxidation of dissolved manganese(II) (Mn(II)) during chlorination is a relatively slow process which may lead to residual Mn(II) in treated drinking waters. Chemical Mn(II) oxidation is autocatalytic and consists of a homogeneous and a heterogeneous process; the oxidation of Mn(II) is mainly driven by the latter process. This study demonstrates that Mn(II) oxidation during chlorination is enhanced in bromide-containing waters by the formation of reactive bromine species (e.g., HOBr, BrCl, Br2O) from the oxidation of bromide by chlorine. During oxidation of Mn(II) by chlorine in bromide-containing waters, bromide is recycled and acts as a catalyst. For a chlorine dose of 1 mg/L and a bromide level as low as 10 μg/L, the oxidation of Mn(II) by reactive bromine species becomes the main pathway. It was demonstrated that the kinetics of the reaction are dominated by the adsorbed Mn(OH)2 species for both chlorine and bromine at circumneutral pH. Reactive bromine species such as Br2O and BrCl significantly influence the rate of manganese oxidation and may even outweigh the reactivity of HOBr. Reaction orders in [HOBr]tot were found to be 1.33 (±0.15) at pH 7.8 and increased to 1.97 (±0.17) at pH 8.2 consistent with an important contribution of Br2O which is second order in [HOBr]tot. These findings highlight the need to take bromide, and the subsequent reactive bromine species formed upon chlorination, into account to assess Mn(II) removal during water treatment with chlorine. PMID:23859083

  11. Intensification of sonochemical degradation of malachite green by bromide ions.

    PubMed

    Moumeni, Ouarda; Hamdaoui, Oualid

    2012-05-01

    Sonochemical oxidation has been investigated as a viable advanced oxidation process (AOP) for the destruction of various pollutants in water. Ultrasonic irradiation generates ()OH radicals that can recombine, react with other gaseous species present in the cavity, or diffuse out of the bubble into the bulk liquid medium where they are able to react with solute molecules. The extent of degradation of an organic dye such as malachite green (MG) is limited by the quantity of hydroxyl radicals diffused from cavitation bubbles. In this work, the effect of bromide ions on sonolytic degradation of MG was investigated. The obtained results clearly demonstrated the considerable enhancement of sonochemical destruction of MG in the presence of bromide. No significant differences were observed in the presence of chloride and sulfate, excluding the salting-out effect. Positive effect of bromide ions, which increases with increasing bromide level and decreasing MG concentration, is due to the generation of dibromine radical anion (Br(2)(-)) formed by reaction of Br(-) with ()OH radicals followed by rapid complexation with another anion. The generated Br(2)(-) radicals, reactive but less than ()OH, are likely able to migrate far from the cavitation bubbles towards the solution bulk and are suitable for degradation of an organic dye such as MG. Additionally, Br(2)(-) radicals undergo radical-radical recombination at a lesser extent than hydroxyl radicals and would be more available than ()OH for substrate degradation, both at the bubble surface and in the solution bulk. This effect compensates for the lower reactivity of Br(2)(-) compared to ()OH toward organic substrate. Addition of bromide to natural and sea waters induces a slight positive effect on MG degradation. In the absence of bromide, ultrasonic treatment for the removal of MG was promoted in complex matrices such as natural and sea waters. PMID:21911308

  12. Methyl bromide emissions from a covered field: II. Volatilization

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.

    1996-01-01

    An experiment to investigate the environmental fate and transport of methyl bromide in agricultural fields is described. The methyl bromide volatilization rate was determined as a function of time for conditions where methyl bromide was applied at a rate of 843 kg in a 3.5-ha (i.e., 240 kg/ha) field covered with plastic at a depth of 25 cm. Three methods were used to estimate the methyl bromide volatilization rate, including: the aerodynamic, theoretical profile shape and integrated horizontal flux methods. The highest methyl bromide volatilization rates were at the beginning of the experiment. Within the first 24 h, approximately 36% of the applied methyl bromide mass was lost. Diurnally, the largest volatilization rates occurred during the day when temperatures were high and the atmosphere was unstable. Cooler temperatures, light winds, and neutral to stable atmospheric conditions were present at night, reducing the flux. The total emission calculated using these methods was found to be approximately 64% ({+-} 10%) of the applied mass. A mass balance was calculated using each flux estimation technique and several methods for analyzing the data. The average mass recovery using all the flux methods was 867 kg ({+-}83 kg), which was 102.8% ({+-}9.8%) of the applied (i.e., 843 kg). The range in the mass balance percent (i.e., percent of applied mass that is measured) is from 88 to 112%. The averaged mass balance percent for the aerodynamic method, which involved using the measured data directly, was approximately 100.8%. The total emission calculated using the aerodynamic method was found to be approximately 62% ({+-}11%) of the applied mass. 29 refs., 7 figs., 1 tab.

  13. Photochemistry of alkyl bromides trapped in water ice films

    NASA Astrophysics Data System (ADS)

    Schrems, O.; Okaikwei, B.; Bluszcz, Th.

    2012-04-01

    Photochemical reactions of atmospheric trace gases taking place at the surface of atmospheric ice particles and in bulk ice are important in stratospheric and tropospheric chemistry but also in polar and alpine snowpack chemistry. Consequently, the understanding of the uptake und incorporation of atmospheric trace gases in water ice as well as their interactions with water molecules is very important for the understanding of processes which occur in ice particles and at the air/ice interface. Reactive atmospheric trace gases trapped in ice are subject of photochemical reactions when irradiated with solar UV radiation. Among such compounds bromine species are highly interesting due to their potential of depleting ozone both in the stratosphere and troposphere. Organic bromine gases can carry bromine to the stratosphere. Methyl bromide (CH3Br) is the largest bromine carrier to the stratosphere. It has both natural and anthropogenic sources. In this contribution we will present the results of our laboratory studies of alkyl bromides (methyl, bromide (CH3Br), dimethyl bromide (CH2Br2), n-propyl bromide (C3H7Br), 1,2-dibromoethane C2H4Br2)), trapped in water ice. We have simulated the UV photochemistry of these brominated alkanes isolated in ice films kept at 16 K and for comparison in solid argon matrices. The photoproducts formed in the ice have been identified by means of FTIR spectroscopy. Reflection absorption infrared spectroscopy (RAIRS) is especially useful to study nascent ice surfaces, kinetics of adsorption/decomposition, and heterogeneous catalysis. Among the observed photoproducts we could identify carbon monoxide and carbon dioxide for each alkyl bromide studied. The photoproduct HBr is dissociated in the bulk ice. Based on the experimental observations possible reaction mechanisms will be discussed.

  14. Versatile Route to Arylated Fluoroalkyl Bromide Building Blocks.

    PubMed

    Kaplan, Peter T; Vicic, David A

    2016-02-19

    New difunctionalized and fluoroalkylated silyl reagents have been prepared that react with silver and copper salts to afford active catalysts that can be used to synthesize arylated fluoroalkyl bromide building blocks. It has been shown that the [(phen)Ag(CF2)nBr] intermediates are capable of transferring both the phenanthroline ligand and the fluoroalkyl bromide chain to copper iodide, eliminating the need for a preligated copper salt precursor. The methodology is compatible with various chain lengths of the fluoroalkyl halide functionality. PMID:26820388

  15. Investigation of possible interaction between pinaverium bromide and digoxin.

    PubMed

    Weitzel, O; Seidel, G; Engelbert, S; Berksoy, M; Eberhardt, G; Bode, R

    1983-01-01

    A single-blind study was carried out in 25 patients, who were receiving maintenance therapy for congestive heart failure with digoxin, to investigate the effect on steady-state plasma digoxin levels of concomitant administration of the spasmolytic, pinaverium bromide (50 mg 3-times daily). Patients received pinaverium bromide for 12 days followed by placebo for a further 7 days. Assessment of the results in 21 patients showed no evidence of any statistically significant variations in plasma digoxin levels during either treatment period or in the clinical observations which might indicate drug interaction. PMID:6653138

  16. Action of pinaverium bromide on calmodulin-regulated functions.

    PubMed

    Wuytack, F; De Schutter, G; Casteels, R

    1985-08-01

    Pinaverium bromide at concentrations below 10(-5) M did not inhibit calmodulin-dependent enzymes such as phosphodiesterase and the Ca transport ATPase of the plasma membrane. At higher concentrations the compound interacted with the stimulation of those enzymes by calmodulin and also inhibited the calmodulin-independent activity. A similar inhibitory action was observed for the NaK ATPase. It is concluded that the inhibitory action of pinaverium bromide on smooth muscle concentration at concentrations below 10(-5) M was due to its interaction with the voltage-dependent Ca channels and not to its interference with the calmodulin-dependent activation of the contractile proteins. PMID:2995077

  17. Magnesium Lewis Acid Assisted Oxidative Bromoetherification Involving Bromine Transfer from Alkyl Bromides with Aldehydes by Umpolung of Bromide.

    PubMed

    Moriyama, Katsuhiko; Nishinohara, Chihiro; Togo, Hideo

    2016-08-16

    An oxidative bromoetherification involving a bromine transfer from alkyl bromides upon reacting them with aldehydes in a Grignard reaction with a concurrent oxidation of bromide was developed to provide substituted tetrahydrofurans in high yields. This reaction, which proceeds through two types of bromine transfer, was promoted by the addition of a Brønsted acid. Mechanistic studies suggested that a magnesium Lewis acid activates hypobromate, which is generated in situ from the reaction of bromide and Oxone to improve the electrophilicity of the bromonium ion (Br(+) ) for the oxidative bromoetherification of alkenyl alcohols. Furthermore, the magnesium Lewis acid catalyzed oxidative bromoetherification of an alkenyl alcohol proceeded to provide a cyclization product in 92 % yield. PMID:27304660

  18. Nickel-Catalyzed Reductive Cross-Coupling of Aryl Bromides with Alkyl Bromides: Et3N as the Terminal Reductant.

    PubMed

    Duan, Zhengli; Li, Wu; Lei, Aiwen

    2016-08-19

    Reductive cross-coupling has emerged as a direct method for the construction of carbon-carbon bonds. Most cobalt-, nickel-, and palladium-catalyzed reductive cross-coupling reactions to date are limited to stoichiometric Mn(0) or Zn(0) as the reductant. One nickel-catalyzed cross-coupling paradigm using Et3N as the terminal reductant is reported. By using this photoredox catalysis and nickel catalysis approach, a direct Csp(2)-Csp(3) reductive cross-coupling of aryl bromides with alkyl bromides is achieved under mild conditions without stoichiometric metal reductants. PMID:27472556

  19. Germanium accumulation-mode charge-injection-device process

    NASA Technical Reports Server (NTRS)

    Moore, T. G.

    1981-01-01

    Gallium doped germanium is suitable for applications in the detection of far infrared radiation. Measurements were made on experimental photoconductors (PCs), accumulation mode charge injection devices (AMCIDs), and the SSPC (a switched, sampled PC alternative to the AMCID). The results indicate that the SSPC, which had a responsivity near 1.5 amp/watt, is desirable for use in two dimensional detector arrays.

  20. Dark Matter Physics with SUB-keV Germanium Detectors

    NASA Astrophysics Data System (ADS)

    Wong, Henry T.

    2015-03-01

    Germanium detectors with sub-keV sensitivities open a window to study neutrino physics to search for light WIMP dark matter. We summarize the recent results on spin-independent couplings of light WIMPs from the TEXONO experiment at the Kuo-Sheng Reactor Neutrino Laboratory.

  1. Strained-layer epitaxy of germanium-silicon alloys.

    PubMed

    Bean, J C

    1985-10-11

    Despite the dominant position of silicon in semiconductor electronics, its use is ultimately limited by its incompatibility with other semiconducting materials. Strained-layer epitaxy overcomes problems of crystallographic compatibility and produces high-quality heterostructures of germanium-silicon layers on silicon. This opens the door to a range of electronic and photonic devices that are based on bandstructure physics. PMID:17842673

  2. Discovery of gallium, germanium, lutetium, and hafnium isotopes

    SciTech Connect

    Gross, J.L.; Thoennessen, M.

    2012-09-15

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  3. Solution-processable white-light-emitting germanium nanocrystals

    SciTech Connect

    Shirahata, Naoto

    2014-06-01

    This paper describes an efficient chemical route for the synthesis of visible light emitting nanocrystals of germanium (ncGe). The synthesis started by heating Ge(II) iodide at 300 °C in argon atmosphere. Spectroscopic characterizations confirmed the formation of diamond cubic lattice structures of ncGe. By grafting hydrophobic chains on the ncGe surface, the dispersions in nonpolar solvents of the ncGe became very stable. The as-synthesized ncGe showed the bluish white photoluminescence (PL) feature, but it was found that the PL spectrum is composed of many different emission spectra. Therefore, the color-tuning of white light emission is demonstrated through the witting removal of extra ncGe with unfavorable emission feature by making full use of column chromatographic techniques. - Highlights: • Visible light emitting nanocrystals of germanium was synthesized by chemical reduction of germanium iodide. • White light emission was achieved by control over size distribution of germanium nanocrystals. • Tuning the color of white light was achieved by separation of nanocrystals by emission.

  4. Active noise canceling system for mechanically cooled germanium radiation detectors

    SciTech Connect

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

    A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

  5. Enhanced life ion source for germanium and carbon ion implantation

    SciTech Connect

    Hsieh, Tseh-Jen; Colvin, Neil; Kondratenko, Serguei

    2012-11-06

    Germanium and carbon ions represent a significant portion of total ion implantation steps in the process flow. Very often ion source materials that used to produce ions are chemically aggressive, especially at higher temperatures, and result in fast ion source performance degradation and a very limited lifetime [B.S. Freer, et. al., 2002 14th Intl. Conf. on Ion Implantation Technology Proc, IEEE Conf. Proc., p. 420 (2003)]. GeF{sub 4} and CO{sub 2} are commonly used to generate germanium and carbon beams. In the case of GeF{sub 4} controlling the tungsten deposition due to the de-composition of WF{sub 6} (halogen cycle) is critical to ion source life. With CO{sub 2}, the materials oxidation and carbon deposition must be controlled as both will affect cathode thermionic emission and anti-cathode (repeller) efficiencies due to the formation of volatile metal oxides. The improved ion source design Extended Life Source 3 (Eterna ELS3) together with its proprietary co-gas material implementation has demonstrated >300 hours of stable continuous operation when using carbon and germanium ion beams. Optimizing cogas chemistries retard the cathode erosion rate for germanium and carbon minimizes the adverse effects of oxygen when reducing gas is introduced for carbon. The proprietary combination of hardware and co-gas has improved source stability and the results of the hardware and co-gas development are discussed.

  6. Modified matrix volatilization setup for characterization of high purity germanium.

    PubMed

    Meruva, Adisesha Reddy; Raparthi, Shekhar; Kumar, Sunil Jai

    2016-01-01

    Modified matrix volatilization (MV) method has been described to characterize high purity germanium material of 7 N (99.99999%) purity. Transport of both, the chlorine gas generated in-situ in this method and the argon gas (carrier) is fine controlled by means of a mass flow controller. This enabled both uniform reaction of chlorine gas with the germanium matrix and smooth removal of germanium matrix as its chloride. This resulted in improvement in the reproducibility of the analytical results. The use of quartz reaction vessel has lead to the reduction in the process blank levels. The combined effect of these modifications in the MV setup has resulted in very consistent and low process blanks and hence improved detection limits of this method. Applicability of the method has been expanded to rare earth elements and other elements after examining their recoveries. The quantification is done by using inductively coupled plasma quadrupole mass spectrometer (ICP-QMS) and continuum source graphite furnace atomic absorption spectrometry (CS-GFAAS). In the absence of certified reference materials for high pure germanium, the accuracy of the method is established by spike recovery tests. The precision of the method has been found to vary from 1 to 30% for concentrations between 1 and 30 ng g(-1). The limits of detection (LOD) for the target analytes are found to be between 18 and 0.033 ng g(-1). PMID:26695261

  7. The 100 micron detector development program. [gallium doped germanium photoconductors

    NASA Technical Reports Server (NTRS)

    Moore, W. J.

    1976-01-01

    An effort to optimize gallium-doped germanium photoconductors (Ge:Ga) for use in space for sensitive detection of far infrared radiation in the 100 micron region is described as well as the development of cryogenic apparatus capable of calibrating detectors under low background conditions.

  8. Novel approach for n-type doping of HVPE gallium nitride with germanium

    NASA Astrophysics Data System (ADS)

    Hofmann, Patrick; Krupinski, Martin; Habel, Frank; Leibiger, Gunnar; Weinert, Berndt; Eichler, Stefan; Mikolajick, Thomas

    2016-09-01

    We present a novel method for germanium doping of gallium nitride by in-situ chlorination of solid germanium during the hydride vapour phase epitaxy (HVPE) process. Solid germanium pieces were placed in the doping line with a hydrogen chloride flow directed over them. We deduce a chlorination reaction taking place at 800 ° C , which leads to germanium chloroform (GeHCl3) or germanium tetrachloride (GeCl4). The reactor shows a germanium rich residue after in-situ chlorination experiments, which can be removed by hydrogen chloride etching. All gallium nitride crystals exhibit n-type conductivity, which shows the validity of the in-situ chlorination of germanium for doping. A complex doping profile is found for each crystal, which was assigned to a combination of localised supply of the dopant and sample rotation during growth and switch-off effects of the HVPE reactor.

  9. Broad Band Antireflection Coatings for Silicon and Germanium Substrates.

    NASA Astrophysics Data System (ADS)

    Bezuidenhout, Dirk Francois

    Infrared antireflection coatings for silicon and germanium substrates and some of the associated problems are addressed in this thesis. One of the first problems identified and investigated was that of the adhesion of ZnS films to germanium substrates. The cleaning of the Ge discs was evaluated by means of Auger spectroscopy. The main contaminant species found were carbon, oxygen and in the case of germanium substrates sulphur. No sulphur was found on silicon substrates. A wash in a series of organic solutions followed by a bake inside the vacuum chamber lead to much improved though still not acceptable adhesion of ZnS films to germanium substrates. The influence of a contact layer between the substrate and ZnS was investigated. Firstly, metal contact layers (Ni, Cr, Cu) were tried to improve the adhesion of the ZnS films. These samples (germanium-metal-zinc sulphide) were annealed in air in order to transfer the germanium -metal film to a germanide region and thus high optical transmission at long wave-lengths. Slight absorption still results even after the annealing of these samples. A dielectric material, Y_2O_3 , was therefore tested replacing the metal films. The system Ge-Y_2O_3 -ZnS in conjunction with an organic wash and vacuum bake lead to excellent adhesion of the ZnS layers to the germanium substrates. The next problem area addressed was that of a low refractive index material replacement for ThF _4. Four materials were investigated, i.e. ZnS, PbF_2, Y_2O _3 and YF_3. The refractive indices found for these compounds in thin film form at a wavelength of 10 μm is 2,18 for ZnS, 1,7 for PbF_2, 1,42 for Y_2O_3 and 1,3 for YF_3. From these results YF_3 was chosen as low refractive index material in the coating designs. Multi-layer coatings incorporating ZnS, Ge and YF_3 films were designed and evaporated. Measured reflectance values below 0,2% were obtained from 9 μm to 11 mum. These systems were stable and robust. Finally, a silicon ball lens was

  10. Methyl Bromide Alternatives for Floriculture Production in a Problem Site

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Successful methyl bromide alternatives must manage a variety of pest problems in floriculture and vegetable production systems including weeds, plant-parasitic nematodes, and soil-borne diseases. Methods that may be successful in some situations may be challenged in sites with unusually heavy pest p...

  11. EFFECT OF BROMIDE ION ON FORMATION OF HAAS DURING CHLORINATION

    EPA Science Inventory

    loacetic acids (HAAs) during chlorination and he effects of independent variables, including pH, reaction time, and chlorine dosage. Almost all of the indpendent loaetic acids (HAAs) during chlorin...designed to statistically evaluate the influence of bromide ion on the formatio...

  12. Methyl bromide alternatives for postharvest insect disinfestation of California walnuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Before shipment, California inshell walnuts destined for the valuable export market must be disinfested of both field pests (codling moth and navel orangeworm) and common storage pests (Indianmeal moth and red flour beetle). Until recently fumigation with methyl bromide has been the most common dis...

  13. A COMPARISON OF BROMIDE AND NITRATE TRANSPORT IN SOILS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sandy soils (with sand content 95-98%) are used for agricultural production, which require careful management of water, chemicals, and nutrients to minimize leaching below the rooting zone. Bromide is used as an indicator of downward transport of soluble nutrients in soils. A leching column study ...

  14. HEALTH AND ENVIRONMENTAL EFFECTS PROFILE FOR METHYL BROMIDE

    EPA Science Inventory

    The Health and Environmental Effects Profile for Methyl Bromide was prepared to support listings of hazardous constituents of a wide range of waste streams under Section 3001 of the Resource Conservation and Recovery Act (RCRA) and to provide health-related limits for emergency a...

  15. Nickel-Catalyzed Reductive Amidation of Unactivated Alkyl Bromides.

    PubMed

    Serrano, Eloisa; Martin, Ruben

    2016-09-01

    A user-friendly, nickel-catalyzed reductive amidation of unactivated primary, secondary, and tertiary alkyl bromides with isocyanates is described. This catalytic strategy offers an efficient synthesis of a wide range of aliphatic amides under mild conditions and with an excellent chemoselectivity profile while avoiding the use of stoichiometric and sensitive organometallic reagents. PMID:27357076

  16. Reactive films for mitigating methyl bromide emissions from fumigated soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emissions of methyl bromide (MeBr) from agricultural fumigation can lead to depletion of the stratospheric ozone layer, and so its use is being phased out. However, as MeBr is still widely used under Critical Use Exemptions, strategies are still required to control such emissions. In this work, nove...

  17. Calla lily production with methyl bromide alternatives – Year 2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cut flower and ornamental bulb industries rely heavily on a methyl bromide/chloropicrin (MB/Pic) mixture as a key pest management tool. The loss of MB will seriously affect the cut flower and bulb industry, and, in the future, will require growers to use alternative fumigants. Past experiments have...

  18. Depleting methyl bromide residues in soil by reaction with bases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite generally being considered the most effective soil fumigant, methyl bromide (MeBr) use is being phased out because its emissions from soil can lead to stratospheric ozone depletion. However, a large amount is still currently used due to Critical Use Exemptions. As strategies for reducing the...

  19. Methyl bromide alternatives for postharvest insect disinfestation of California walnuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Before shipment, California inshell walnuts destined for the valuable export market must be disinfested of both field pests (codling moth and navel orangeworm) and common storage pests (Indianmeal moth and red flour beetle). Until recently fumigation with methyl bromide has been the most common disi...

  20. The Fate of Alternative Soil Funigants to Methyl Bromide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil fumigation is an important agricultural practice for the control of soil-borne pests. Since the phase–out of methyl bromide, due to its role in the depletion of stratospheric ozone, several alternatives such as 1,3-dichloropropene (1,3-D), chloropicrin (CP), and dimethyl disulfide (DMDS) are b...

  1. Status of Alternatives for Methyl Bromide in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide is a fumigant used for disinfestation of soils, commodities and structures. Listed as an ozone-depleting chemical international environmental protocols and the U.S. Clean Air Act require that its use be severely restricted. Although use of this fumigant has fallen considerably, the U....

  2. Weed Control with Methyl Bromide Alternatives: A Review.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide (MeBr) has been used for several decades for pre-plant soil fumigation in high value agricultural and horticultural crops because it can provide broad-spectrum control of insects, nematodes, pathogens, and weeds. However, MeBr has been identified as a powerful ozone-depleting chemica...

  3. Methyl bromide phase out could affect future reforestation efforts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide has long been an integral component in producing healthy tree seedlings in forest nurseries of California, Idaho, Montana, Oregon and Washington. The fumigant was supposed to be completely phased out of use in the United States of America by 2005, but many forest nurseries continue to...

  4. REVIEW OF CONTROL OPTIONS FOR METHYL BROMIDE IN COMMODITY TREATMENT

    EPA Science Inventory

    The report describes recent developments in the control of methyl bromide (MeBr) and discusses technical considerations and requirements for and economic feasibility of recovery. (NOTE: MeBr, fumigant for agricultural commodities, is an ozone depleting chemical. The U.S. EPA has ...

  5. Investigation of bromide's spectra by high resolution UV-laser

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Ma, Jian-guo

    2011-12-01

    Experimental investigation has been carried out for dissociation/ionisation of methyl bromide using time of flight mass spectrometer, then, the mass signals were assigned to H+, CHm+ (m= 0-3), iBr+ (i = 79, 81), and the main processes of multi-photon ionization and dissociation of CH3Br were given.

  6. PHYTOREMEDIATON POTENTIALS OF SELECTED TROPICAL PLANTS FOR ETHIDIUM BROMIDE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research and development has its own benefits and inconveniences. One of the inconveniences is the generation of enormous quantity of diverse toxic and hazardous wastes and its eventual contamination to soil and groundwater resources. Ethidium bromide (EtBr) is one of the commonly used substances i...

  7. Simultaneous determination of tin, germanium and molybdenum by diode array detection-flow injection analysis with partial least squares calibration model.

    PubMed

    Zou, Xiaoli; Li, Yuanqian; Li, Menglong; Zheng, Bo; Yang, Jingguo

    2004-03-10

    Simultaneous determination of tin, germanium and molybdenum in food samples has been established by flow injection-charge coupled detector (CCD) diode array detection spectrophotometry with partial least squares (PLS) algorithm. The method was based on the chromogenic reaction of metal ions and salicylflurone in the presence of cetyltrimethyl ammonium bromide. The overlapping spectra of these complexes are collected by CCD diode array detector and the multi-wavelength absorbance data are processed using partial least squares algorithm. The reaction conditions and analytical parameters of flow injection analysis have been investigated. The method was applied to directly determine Ge, Mo and Sn in several food samples after digestion with satisfactory results. The recoveries of spiked samples were 80.0-102.0% for tin, 86.3-92.0% for germanium and 83.2-95.2% for molybdenum, and the relative standard deviations for samples were 4.4-7.8%. Molybdenum in certified reference material of cattle liver was determined by the proposed method (n=8). The differential values between determined and guarantee values were within the given uncertain value ranges (t=1.687, P>0.05 for t-test). The samples of mung bean, kelp and pork liver were analyzed by the proposed method and inductively couple plasma-atomic emission spectroscopy (ICP-AES) method. The determination results of the two methods are in good agreement. The sampling rate is 30 samplesh(-1). PMID:18969354

  8. BROMIDE-OXIDANT INTERACTIONS AND THM (TRIHALOMETHANE) FORMATION: A LITERATURE REVIEW

    EPA Science Inventory

    The review focuses on the interactions, not only of bromide and chlorine, but also of bromide and two common oxidation alternatives to chlorine--chlorine dioxide and monochloramine. The data evaluations include discussions of reaction products, potentials for trihalomethane (THM)...

  9. T-type Ca2+ channel modulation by otilonium bromide

    PubMed Central

    Strege, Peter R.; Sha, Lei; Beyder, Arthur; Bernard, Cheryl E.; Perez-Reyes, Edward; Evangelista, Stefano; Gibbons, Simon J.; Szurszewski, Joseph H.

    2010-01-01

    Antispasmodics are used clinically to treat a variety of gastrointestinal disorders by inhibition of smooth muscle contraction. The main pathway for smooth muscle Ca2+ entry is through L-type channels; however, there is increasing evidence that T-type Ca2+ channels also play a role in regulating contractility. Otilonium bromide, an antispasmodic, has previously been shown to inhibit L-type Ca2+ channels and colonic contractile activity. The objective of this study was to determine whether otilonium bromide also inhibits T-type Ca2+ channels. Whole cell currents were recorded by patch-clamp technique from HEK293 cells transfected with cDNAs encoding the T-type Ca2+ channels, CaV3.1 (α1G), CaV3.2 (α1H), or CaV3.3 (α1I) alpha subunits. Extracellular solution was exchanged with otilonium bromide (10−8 to 10−5 M). Otilonium bromide reversibly blocked all T-type Ca2+ channels with a significantly greater affinity for CaV3.3 than CaV3.1 or CaV3.2. Additionally, the drug slowed inactivation in CaV3.1 and CaV3.3. Inhibition of T-type Ca2+ channels may contribute to inhibition of contractility by otilonium bromide. This may represent a new mechanism of action for antispasmodics and may contribute to the observed increased clinical effectiveness of antispasmodics compared with selective L-type Ca2+ channel blockers. PMID:20203058

  10. Detached Bridgman Growth of Germanium and Germanium-Silicon Alloy Crystals

    NASA Technical Reports Server (NTRS)

    Szofran, F. R.; Volz, M. P.; Schweizer, M.; Kaiser, N.; Cobb, S. D.; Motakef, S.; Vujisic, L. J.; Croell, A.; Dold, P.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Earth based experiments on the science of detached crystal growth are being conducted on germanium and germanium-silicon alloys (2at% Si average composition) in preparation for a series of experiments aboard the International Space Station (ISS) to differentiate among proposed mechanisms contributing to detachment. Sessile drop measurements were first carried out for a large number of substrates made of potential ampoule materials to determine the contact angles and the surface tension as a function of temperature and composition. The process atmosphere and duration of the experiment (for some cases) were also found to have significant influence on the wetting angle. Growth experiments have used pyrolytic boron nitride (pBN) and fused silica ampoules with the majority of the detached results occurring predictably in the pBN. The contact angles were 173 deg (Ge) and 165 deg (GeSi) for pBN. For fused silica, the contact angle decreases to an equilibrium value with duration of measurement ranging from 150 to 117 deg (Ge), 129 to 100 deg (GeSi). Forming gas (Ar + 2% H2) and vacuum have been used in the growth ampoules. With gas in the ampoule, a variation of the temperature profile during growth has been used to control the pressure difference between the top of the melt and the volume below the melt caused by detachment of the growing crystal. The stability of detachment has been modeled and substantial insight has been gained into the reasons that detachment has most often been observed in reduced gravity but nonetheless has occurred randomly even there. An empirical model for the conditions necessary to achieve sufficient stability to maintain detached growth for extended periods has been developed and will be presented. Methods for determining the nature and extent of detachment include profilometry and optical and electron microscopy. This surface study is the subject of another presentation at this Congress. Results in this presentation will show that we have

  11. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  12. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  13. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  14. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  15. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  16. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  17. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  18. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  19. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  20. Improving Memory Characteristics of Hydrogenated Nanocrystalline Silicon Germanium Nonvolatile Memory Devices by Controlling Germanium Contents.

    PubMed

    Kim, Jiwoong; Jang, Kyungsoo; Phu, Nguyen Thi Cam; Trinh, Thanh Thuy; Raja, Jayapal; Kim, Taeyong; Cho, Jaehyun; Kim, Sangho; Park, Jinjoo; Jung, Junhee; Lee, Youn-Jung; Yi, Junsin

    2016-05-01

    Nonvolatile memory (NVM) with silicon dioxide/silicon nitride/silicon oxynitride (ONO(n)) charge trap structure is a promising flash memory technology duo that will fulfill process compatibility for system-on-panel displays, down-scaling cell size and low operation voltage. In this research, charge trap flash devices were fabricated with ONO(n) stack gate insulators and an active layer using hydrogenated nanocrystalline silicon germanium (nc-SiGe:H) films at a low temperature. In this study, the effect of the interface trap density on the performance of devices, including memory window and retention, was investigated. The electrical characteristics of NVM devices were studied controlling Ge content from 0% to 28% in the nc-SiGe:H channel layer. The optimal Ge content in the channel layer was found to be around 16%. For nc-SiGe:H NVM with 16% Ge content, the memory window was 3.13 V and the retention data exceeded 77% after 10 years under the programming condition of 15 V for 1 msec. This showed that the memory window increased by 42% and the retention increased by 12% compared to the nc-Si:H NVM that does not contain Ge. However, when the Ge content was more than 16%, the memory window and retention property decreased. Finally, this research showed that the Ge content has an effect on the interface trap density and this enabled us to determine the optimal Ge content. PMID:27483856

  1. An environmentally-friendly vacuum reduction metallurgical process to recover germanium from coal fly ash.

    PubMed

    Zhang, Lingen; Xu, Zhenming

    2016-07-15

    The demand for germanium in the field of semiconductor, electronics, and optical devices is growing rapidly; however, the resources of germanium are scarce worldwide. As a secondary material, coal fly ash could be further recycled to retrieve germanium. Up to now, the conventional processes to recover germanium have two problems as follows: on the one hand, it is difficult to be satisfactory for its economic and environmental effect; on the other hand, the recovery ratio of germanium is not all that could be desired. In this paper, an environmentally-friendly vacuum reduction metallurgical process (VRMP) was proposed to recover germanium from coal fly ash. The results of the laboratory scale experiments indicated that the appropriate parameters were 1173K and 10Pa with 10wt% coke addition for 40min, and recovery ratio germanium was 93.96%. On the basis of above condition, the pilot scale experiments were utilized to assess the actual effect of VRMP for recovery of germanium with parameter of 1473K, 1-10Pa and heating time 40min, the recovery ratio of germanium reached 94.64%. This process considerably enhances germanium recovery, meanwhile, eliminates much of the water usage and residue secondary pollution compared with other conventional processes. PMID:27015376

  2. Lithium bromide absorption chiller passes gas conditioning field test

    SciTech Connect

    Lane, M.J.; Huey, M.A.

    1995-07-31

    A lithium bromide absorption chiller has been successfully used to provide refrigeration for field conditioning of natural gas. The intent of the study was to identify a process that could provide a moderate level of refrigeration necessary to meet the quality restrictions required by natural-gas transmission companies, minimize the initial investment risk, and reduce operating expenses. The technology in the test proved comparatively less expensive to operate than a propane refrigeration plant. Volatile product prices and changes in natural-gas transmission requirements have created the need for an alternative to conventional methods of natural-gas processing. The paper describes the problems with the accumulation of condensed liquids in pipelines, gas conditioning, the lithium bromide absorption cycle, economics, performance, and operating and maintenance costs.

  3. Aluminium Electroplating on Steel from a Fused Bromide Electrolyte

    SciTech Connect

    Prabhat Tripathy; Laura Wurth; Eric Dufek; Toni Y. Gutknecht; Natalie Gese; Paula Hahn; Steven Frank; Guy Fredrickson; J Stephen Herring

    2014-08-01

    A quaternary bromide bath (LiBr-KBr-CsBr-AlBr3) was used to electro-coat aluminium on steel substrates. The electrolyte was prepared by the addition of AlBr3 into the eutectic LiBr-KBr-CsBr melt. A smooth, thick, adherent and shiny aluminium coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminium coverage. Both salt immersion and open circuit potential measurement suggest that the coatings did display good corrosion-resistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminium coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminium coating on both ferrous and non-ferrous metals, including complex surfaces/geometries.

  4. Aluminum electroplating on steel from a fused bromide electrolyte

    SciTech Connect

    Prabhat K. Tripathy; Laura A. Wurth; Eric J. Dufek; Toni Y. Gutknecht; Natalie J. Gese; Paula Hahn; Steven M. Frank; Guy L. Frederickson; J. Stephen Herring

    2014-08-01

    A quaternary bromide bath (LiBr–KBr–CsBr–AlBr3) was used to electro-coat aluminum on steel substrates. The electrolytewas prepared by the addition of AlBr3 into the eutectic LiBr–KBr–CsBr melt. A smooth, thick, adherent and shiny aluminum coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminum coverage. Both salt immersion and open circuit potential measurement suggested that the coatings did display a good corrosionresistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminum coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminumcoating on both ferrous and non-ferrous metals, including complex surfaces/geometries.

  5. A novel and robust conditioning lesion induced by ethidium bromide

    PubMed Central

    Hollis, Edmund R; Ishiko, Nao; Tolentino, Kristine; Doherty, Ernest; Rodriguez, Maria J.; Calcutt, Nigel A.; Zou, Yimin

    2015-01-01

    Molecular and cellular mechanisms underlying the peripheral conditioning lesion remain unsolved. We show here that injection of a chemical demyelinating agent, ethidium bromide, into the sciatic nerve induces a similar set of regeneration-associated genes and promotes a 2.7-fold greater extent of sensory axon regeneration in the spinal cord than sciatic nerve crush. We found that more severe peripheral demyelination correlates with more severe functional and electrophysiological deficits, but more robust central regeneration. Ethidium bromide injection does not activate macrophages at the demyelinated sciatic nerve site, as observed after nerve crush, but briefly activates macrophages in the dorsal root ganglion. This study provides a new method for investigating the underlying mechanisms of the conditioning response and suggests that loss of the peripheral myelin may be a major signal to change the intrinsic growth state of adult sensory neurons and promote regeneration. PMID:25541322

  6. Viscosity and density of some lower alkyl chlorides and bromides

    SciTech Connect

    Rutherford, W.M.

    1988-07-01

    A high-pressure capillary viscometer, used previously to measure the viscosity of methyl chloride was rebuilt to eliminate the first-order dependence of the measured viscosity on the value assumed for the density of the fluid being investigated. At the same time, the system was arranged so that part of the apparatus could be used to measure density by a volumetric displacement technique. Viscosity and density were measured for ethyl chloride, 1-chloropropane, 1-chlorobutane, methyl bromide, ethyl bromide, and 1-bromopropane. The temperature and pressure ranges of the experiments were 20-150 /sup 0/C and 0.27-6.99 MPa, respectively. The accuracy of the viscosity measurements was estimated to be +-1% and of the density measurements, +-0.2%.

  7. [The use of syntropium bromide as an antispasmodic].

    PubMed

    Galeone, M; Cacioli, D; Moise, G; Bossi, M; Benazzi, E; Monti, G

    1985-09-22

    The following trials were carried out to evaluate the antispasmodic effect of sintropium bromide in a group of 30 patients. The antispasmodic effect on the gastroduodenal system was observed endoscopically. The results were compared by means of double blind tests carried out using placebo and rociverine. The effect in a group of 10 patients was examined by X-ray of the digestive tract. The effect on another group of 20 patients suffering from abdominal colic was clinically evaluated. Sintropium bromide has a prompt anticholinergic action and for this reason may be used in the treatment of painful conditions of the bile, gastro-enteric and renal tracts, and also during the course of endoscopic examinations. PMID:3900811

  8. Gamma Ray Interactions in Planar Germanium Strip Detectors

    NASA Astrophysics Data System (ADS)

    Jackson, E. G.; Lakshmi, S.; Chowdhury, P.; Deo, A. Y.; Guess, C. J.; Hota, S.; Lister, C. J.

    2011-10-01

    The position resolution of the interaction point of a gamma ray within the volume of a planar germanium crystal is under investigation. A 16x16 planar double-sided strip detector of high-purity germanium, measuring 92×92×20 mm, with 16 horizontal strips on one face and 16 vertical strips on the other, is used. Comparing the strongest strip signal from each side of the detector allows for a X-Y pixelation of the gamma ray interaction in the crystal. Energy and efficiency calibrations are performed with standard 152Eu and 133Ba sources placed at fixed distances from the detector face. The measured efficiency of each pixel is compared to calculated geometric efficiencies. Next steps involve the analysis of two-pixel events which pick out Compton scatters within the planar crystal. Results and status report will be presented. Work supported by the U.S. Department of Energy.

  9. Characterization of the impurities in tungsten/silicon-germanium contacts

    SciTech Connect

    Gregg, H.A. Sr.

    1986-03-26

    Secondary ion mass spectrometry and Auger electron spectrometry depth profiling were used to determine impurity distributions in sputter deposited tungsten films over N-type and P-type 80/20 silicon-germanium elements of thermoelectric devices. These analyses showed that silicon, oxygen, sodium, boron, and phosphorous were present as impurities in the tungsten film. All these impurities except oxygen and sodium came from the substrate. Oxygen was gettered by the tungsten films, while sodium was possibly the result of sample handling. Further, the results from this study indicate that an oxide build-up, primarily at the tungsten/silicon-germanium interface of the N-type materials, is the major contributor to contact resistance in thermoelectric devices.

  10. Synthesis and photoluminescence of ultra-pure germanium nanoparticles

    NASA Astrophysics Data System (ADS)

    Chivas, R.; Yerci, S.; Li, R.; Dal Negro, L.; Morse, T. F.

    2011-09-01

    We have used aerosol deposition to synthesize defect and micro-strain free, ultra-pure germanium nanoparticles. Transmission electron microscopy images show a core-shell configuration with highly crystalline core material. Powder X-ray diffraction measurements verify the presence of highly pure, nano-scale germanium with average crystallite size of 30 nm and micro-strain of 0.058%. X-ray photoelectron spectroscopy demonstrates that GeO x ( x ⩽ 2) shells cover the surfaces of the nanoparticles. Under optical excitation, these nanoparticles exhibit two separate emission bands at room temperature: a visible emission at 500 nm with 0.5-1 ns decay times and an intense near-infrared emission at 1575 nm with up to ˜20 μs lifetime.

  11. High temperature material interactions of thermoelectric systems using silicon germanium.

    NASA Technical Reports Server (NTRS)

    Stapfer, G.; Truscello, V. C.

    1973-01-01

    The efficient use of silicon germanium thermoelectric material for radioisotope thermoelectric generators (RTG) is achieved by operation at relatively high temperatures. The insulation technique which is most appropriate for this application uses multiple layers of molybdenum foil and astroquartz. Even so, the long term operation of these materials at elevated temperatures can cause material interaction to occur within the system. To investigate these material interactions, the Jet Propulsion Laboratory is currently testing a number of thermoelectric modules which use four silicon germanium thermoelectric couples in conjunction with the multifoil thermal insulation. The paper discusses the results of the ongoing four-couple module test program and correlates test results with those of a basic material test program.

  12. Diffusion of n-type dopants in germanium

    SciTech Connect

    Chroneos, A.; Bracht, H.

    2014-03-15

    Germanium is being actively considered by the semiconductor community as a mainstream material for nanoelectronic applications. Germanium has advantageous materials properties; however, its dopant-defect interactions are less understood as compared to the mainstream material, silicon. The understanding of self- and dopant diffusion is essential to form well defined doped regions. Although p-type dopants such as boron exhibit limited diffusion, n-type dopants such as phosphorous, arsenic, and antimony diffuse quickly via vacancy-mediated diffusion mechanisms. In the present review, we mainly focus on the impact of intrinsic defects on the diffusion mechanisms of donor atoms and point defect engineering strategies to restrain donor atom diffusion and to enhance their electrical activation.

  13. Development of neutron-transmutation-doped germanium bolometer material

    SciTech Connect

    Palaio, N.P.

    1983-08-01

    The behavior of lattice defects generated as a result of the neutron-transmutation-doping of germanium was studied as a function of annealing conditions using deep level transient spectroscopy (DLTS) and mobility measurements. DLTS and variable temperature Hall effect were also used to measure the activation of dopant impurities formed during the transmutation process. In additioon, a semi-automated method of attaching wires on to small chips of germanium (< 1 mm/sup 3/) for the fabrication of infrared detecting bolometers was developed. Finally, several different types of junction field effect transistors were tested for noise at room and low temperature (approx. 80 K) in order to find the optimum device available for first stage electronics in the bolometer signal amplification circuit.

  14. Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

    SciTech Connect

    Nathan Robert Classen

    2002-12-31

    The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methylenegermacyclobutane system exhibited kinetic instability, making the study of the system difficult. In any case the germanium system decomposed through a complex mechanism which may not include olefin to carbene isomerization. However, this work lead to the study of the gas phase thermochemistry of a series of dialkylgermylene precursors in order to better understand the mechanism of the thermal decomposition of dialkylgermylenes. The resulting dialkylgermylenes were found to undergo a reversible intramolecular {beta} C-H insertion mechanism.

  15. P-type Modified Electrode Germanium Detector Impurity Profiles

    NASA Astrophysics Data System (ADS)

    Kephart, Jeremy

    2008-04-01

    Germanium detectors with unprecedented capabilities are needed for detecting ultra-rare events in future neutrinoless double-beta decay experiments, searches for dark matter, environmental monitoring programs, national security applications, and potentially neutrino astrophysics. An ideal detector would combine ultra-low background capabilities, minimal electronic instrumentation, extremely low energy threshold, and the ability to perform event reconstruction to determine the interaction type or the spatial distribution of ionization following an interaction. A germanium detector with a special, very low capacitance, contact geometry and presumably a deliberately contrived impurity profile could provide all these capabilities. We present an analysis of the detector impurity concentration profiles and their impact on the depletion voltage, capacitance and charge collection times for such detectors.

  16. Factors influencing the formation of polybromide monoanions in solutions of ionic liquid bromide salts.

    PubMed

    Easton, Max E; Ward, Antony J; Chan, Bun; Radom, Leo; Masters, Anthony F; Maschmeyer, Thomas

    2016-03-01

    Six different bromide salts - tetraethylammonium bromide ([N2,2,2,2]Br, Br), 1-ethyl-1-methylpiperidinium bromide ([C2MPip]Br, Br), 1-ethyl-1-methylpyrrolidinium bromide ([C2MPyrr]Br, Br), 1-ethyl-3-methylimidazolium bromide ([C2MIm]Br, Br), 1-ethylpyridinium bromide ([C2Py]Br, Br), and 1-(2-hydroxyethyl)pyridinium bromide ([C2OHPy]Br, Br) - were studied in regards to their capacity to form polybromide monoanion products on addition of molecular bromine in acetonitrile solutions. Using complementary spectroscopic and computational methods for the examination of tribromide and pentabromide anion formation, key factors influencing polybromide sequestration were identified. Here, we present criteria for the targeted synthesis of highly efficient bromine sequestration agents. PMID:26890026

  17. Oceanic Uptake of Methyl Bromide: Implications for Oceanic Production

    NASA Astrophysics Data System (ADS)

    Yvon-Lewis, S. A.; Butler, J. H.; King, D. B.; Saltzman, E. S.; Tokarczyk, R.

    2002-12-01

    Methyl bromide (CH3Br) is a source of inorganic bromine (Br) in the stratosphere, where it contributes to the depletion of stratospheric ozone. Unlike the chlorofluorocarbons, which are entirely anthropogenic, methyl bromide has both natural and anthropogenic sources. At ~10 parts per trillion in the troposphere, methyl bromide is believed to be the single largest contributor of stratospheric Br. Once in the stratosphere, Br is approximately 50 times more effective in depleting stratospheric ozone than Cl. However, the budget for CH3Br remains largely unbalanced with known sinks outweighing sources by ~50%. With production and degradation occurring in the ocean, the ocean is both a source and a sink for CH3Br. The balance between production and degradation results in the net undersaturation of CH3Br that has been observed over much of the world's ocean with an estimated global net ocean sink ranging from -11 to -20 Gg/y [King et al., 2000 and references therein]. However, effects of climate change, such as changes in windspeed distribution or sea-surface temperature could alter this balance. Modeling the potential effect of such forcing on the net flux of this important trace gas requires an understanding of the factors controlling the distributions of production and degradation in the surface ocean. During three recent research cruises (North Atlantic, North Pacific, and Southern Ocean), CH3Br degradation rate constants were measured along with saturation anomalies. Here we incorporate these data into a gridded global box model to examine the distribution of oceanic production rates necessary to support the observations. King, D.B., J.H. Butler, S.A. Montzka, S.A. Yvon-Lewis, and J.W. Elkins, Implications of methyl bromide supersaturations in the temperate North Atlantic Ocean, J. of Geophys. Res., 105 (D15), 19763-19769, 2000.

  18. Problems with NIOSH method 2520 for methyl bromide

    SciTech Connect

    Tharr, D.

    1994-03-01

    The National Institute for Occupational Safety and Health (NIOSH) publishes the NIOSH Manual of Analytical Methods (NMAM), a collection of analytical methods for characterizing exposures to environmental chemicals. When an industrial hygienist selects a method to monitor worker exposure, it is important to remember that not all the methods in the NMAM have undergone the same level of evaluation, as the following case demonstrates. As part of an industrywide study of the health effects resulting from methyl bromide exposure in structural and agricultural applicators, NIOSH researchers conducted industrial hygiene monitoring for methyl bromide in Florida during July 1990. NIOSH method 2520 was used. This method recommends use of two charcoal tubes (400 mg/100 mg) in series, desorption with carbon disulfide, and analysis by gas chromatography with a flame ionization detector. Sampling results from these surveys indicated a capacity problem. A project was then initiated to determine the reason for the methyl bromide breakthrough that occurred during industrial hygiene monitoring. While conducting research to define and solve this problem, several other problems were identified: reduced adsorption capacity caused by high humidity, difficulty in preparing standard solutions, sample instability, change in recovery with loading, and insufficiently low quantitation limit. The addition of a drying tube to the sampling train, as well as changes to the analytical technique, to the desorption solvent, and to the time till analysis, resulted in an improved method for methyl bromide. This case study demonstrates the importance of noting the conditions under which a method was evaluated and the benefit of testing method performance under conditions likely to exist at a field site. 5 refs.

  19. Criticality in aqueous solutions of 3-methylpyridine and sodium bromide.

    PubMed

    Kostko, A F; Anisimov, M A; Sengers, J V

    2004-08-01

    We address a controversial issue regarding the nature of critical behavior in ternary electrolyte solutions of water, 3-methylpyridine, and sodium bromide. Earlier light-scattering studies showed an anomalous critical behavior in this system that was attributed to the formation of a microheterogeneous phase associated with ion-molecule clustering [M.A. Anisimov, J. Jacob, A. Kumar, V.A. Agayan, and J. V. Sengers, Phys. Rev. Lett. 85, 2336 (2000)

  20. Methyl Bromide Poisoning—A Bizarre Neurological Disorder

    PubMed Central

    Collins, Raymond P.

    1965-01-01

    Methyl bromide, a widely used fumigant, may cause burns of the skin, fatalities accompanied by coma and convulsions, or prolonged neurologic and psychiatric symptoms. Burns are more likely to occur where evaporation is prevented under protective clothing. Symptoms of serious illness may not develop for hours after exposure. Since action appears to be one of methylation, especially of SH groups, B.A.L. may be helpful if used promptly. PMID:14347974

  1. Environmental applications for an intrinsic germanium well detector

    SciTech Connect

    Stegnar, P.; Eldridge, J.S.; Teasley, N.A.; Oakes, T.W.

    1983-01-01

    The overall performance of an intrinsic germanium well detector for /sup 125/I measurements was investigated in a program of environmental surveillance. Concentrations of /sup 125/I and /sup 131/I were determined in thyroids of road-killed deer showing the highest activities of /sup 125/I in the animals from the near vicinity of Oak Ridge National Laboratory. This demonstrates the utility of road-killed deer as a bioindicator for radioiodine around nuclear facilities. 6 refs., 2 figs., 3 tabs.

  2. Electronic Structure of Germanium Nanocrystal Films Probed with Synchrotron Radiation

    SciTech Connect

    Bostedt, C

    2002-05-01

    The fundamental structure--property relationship of semiconductor quantum dots has been investigated. For deposited germanium nanocrystals strong quantum confinement effects have been determined with synchrotron radiation based x-ray absorption and photoemission techniques. The nanocrystals are condensed out of the gas phase with a narrow size distribution and subsequently deposited in situ onto various substrates. The particles are crystalline in the cubic phase with a structurally disordered surface shell and the resulting film morphology depends strongly on the substrate material and condition. The disordered surface region has an impact on the overall electronic structure of the particles. In a size-dependent study, the conduction and valence band edge of germanium nanocrystals have been measured for the first time and compared to the bulk crystal. The band edges move to higher energies as the particle size is decreased, consistent with quantum confinement theory. To obtain a more accurate analysis of confinement effects in the empty states, a novel analysis method utilizing an effective particle size for the x-ray absorption experiment, which allows a deconvolution of absorption edge broadening effects, has been introduced. Comparison of the present study to earlier studies on silicon reveals that germanium exhibits stronger quantum confinement effects than silicon. Below a critical particle size of 2.3 {+-} 0.7 nm, the band gap of germanium becomes larger than that of silicon--even if it is the opposite for bulk materials. This result agrees phenomenologically with effective mass and tight binding theories but contradicts the findings of recent pseudopotential calculations. The discrepancy between theory and experiments is attributed to the differences in the theoretical models and experimental systems. The experimentally observed structural disorder of the particle surface has to be included in the theoretical models.

  3. Fabrication techniques for reverse electrode coaxial germanium nuclear radiation detectors

    SciTech Connect

    Hansen, W.L.; Haller, E.E.

    1980-11-01

    Germanium detectors with reverse polarity coaxial electrodes have been shown to exhibit improved resistance to radiation damage as compared with conventional electrode devices. However, the production of reverse electrode devices involves the development of new handling and fabrication techniques which has limited their wider application. We have developed novel techniques which lead to a device which is simple to fabricate, environmentally passivated and surface state adjusted.

  4. Preparation and Characterization of Hydrogenated Amorphous Germanium and Hydrogenated Amorphous Germanium - Thin Films.

    NASA Astrophysics Data System (ADS)

    Wu, Hai-Sheng

    Hydrogenated amorphous germanium (a-Ge:H) and germanium carbide (a-Ge_{rm 1 -x}C_{rm x} :H) films were prepared by rf sputtering of a polycrystalline Ge target in a vacuum ~4 times 10^{-7} Torr at various rf power 50 <=q P <=q 600 W (0.27-3.3 W/cm ^2), target-substrate distance 1 <=q d <=q 7 ^{''}, varying partial pressures of Ar, H_2, and C_3H_8, and flow rates f. The vibrational and opto-electronic properties such as infrared (IR) absorption, optical gap, electron -spin-resonance (ESR) signals, and conductivities vary with deposition conditions. The photoconductivity sigma_{rm ph}, in particular, was carefully monitored as a function of the deposition conditions to optimize it. The concentration of Ge-H bonds and the optical gap (E_{rm g}), generally decrease as P is increased. E_ {rm g} of the a-Ge_ {rm 1-x}C_{ rm x}:H films range from 0.85-2.3 eV. The ESR results range from 2 times 10 ^{17} to 2 times 10^{19}^ins/cm ^3. Results of annealing showed the enhanced segregation effect of Ge-C bonds >=q300^circC. The evolution of bonded hydrogen with temperature is studied. Deposition rates (R_{rm d}) of a-Ge:H films are estimated and compared. The thermalization curve for a Ge target is constructed. R _{rm d} was found to decrease exponentially with increasing d, to decrease with increasing partial pressures of H_2 and C_3H_8 and increasing flow rates. R_{ rm d} is maximal at some P_ {rm Ar} and is relatively insensitive to the substrate temperature T_{rm s}, and rises linearly with the rf power. Hydrogen incorporation markedly increased sigma_{rm ph}. The dark conductivity sigma_{rm d} and sigma_{rm ph} increase with increasing d, up to an optimal value at d ~ 6^ {''}, increase at f < 1 sccm, and increase with P and T _{rm s}. Incorporation of significant amounts of carbon sharply reduces sigma_{rm ph}. However, a small amount has little effect on sigma _{rm ph}. Although all increases in sigma_{rm ph} are significant relative to those of previously reported rf

  5. Structural, vibrational and theoretical studies of L-histidine bromide

    NASA Astrophysics Data System (ADS)

    Ahmed, A. Ben; Feki, H.; Abid, Y.; Boughzala, H.; Mlayah, A.

    2008-10-01

    This paper presents the results of our calculations of the geometric parameters, vibrational spectra and hyperpolarizability of a non linear optical material, L-histidine bromide. Due to the lack of sufficiently precise information on the geometric structure available in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystals of L-histidine bromide have been grown by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro symmetric space group P2 12 12 1 of the orthorhombic system. Raman spectra have been recorded in the range [200-3500 cm -1]. All observed vibrational bands have been discussed and assigned to normal mode or to combinations and overtones on the basis of our calculations. The optimized geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP and BLYP) show good agreement with the experimental data. Comparison between the measured and the calculated vibrational frequencies indicate that B3LYP is superior to the scaled HF approach for molecular vibrational problems. To investigate microscopic second order non linear optical properties of L-histidine bromide, the electric dipole μ, the polarizability α and the hyperpolarizability β were computed using DFT//B3LYP/6-31G(d) method. According to our calculations, the title compound exhibits non-zero β value revealing microscopic second order NLO behaviour.

  6. The Thz Absorption of Methyl Bromide (CH_3BR)

    NASA Astrophysics Data System (ADS)

    Ramos, Marlon; Drouin, Brian J.

    2011-06-01

    The possibility of monitoring Methyl Bromide is of interest for both environmental and health concerns. It has an ozone depletion potential of 0.2% and falls under regulations of the Clean Air Act. Neurological effects from long term exposure may result from its major use as a pesticide. Recent improvements in microwave limb sounding at mm & submm wavelengths have resulted in retrievals of Methyl Chloride from atmospheric spectra. It is conceivable that Methyl Bromide would also be measurable by this technique. In an effort to extend and improve the previous work, the THz spectrum of Methyl Bromide has been measured at JPL. We used an isotopically enriched 13CH_3Br (90%) sample and recorded spectra from 750 - 1200 GHz. Our assignment covers the CH_379Br, CH_381Br, 13CH_379Br and 13CH_381Br isotopologues with J< 66 and K< 17 for the ground vibrational state. We plan to assign vibrational satellites and investigate possible perturbations near K =12 in the ground state.

  7. [Manometric effects of pinaverium bromide in irritable bowel syndrome].

    PubMed

    Soifer, L; Varela, E; Olmos, J

    1992-01-01

    The effects of pinaverium bromide on colonic motility were investigated in a controlled, controlled, cross-over study in 32 patients with irritable bowel syndrome. Constipation was clearly predominant in one group of 16 patients, and diarrhea in the other group of 16. Manometric measurements were taken of the colonic motor response generated by distention of a balloon inserted to the rectosigmoid junction. Measurements were taken before and one hour after ingestion of two tablets containing placebo or two tablets each containing 50 mg of pinaverium bromide. Following intake of placebo the motility index increased from the basal value in patients with constipation, and resistance to distention decreased in the diarrhea group. These changes were attributable to repetition of the mechanical stimulus within a relatively brief time lapse, or more probably to the ingestion of liquid which accompanied intake of tablets. Compared with placebo, pinaverium bromide induced inhibition of both effects. From the therapeutic point of view, the decrease in motility index seen in patients with irritable bowel syndrome and constipation is particularly interesting. PMID:1295286

  8. L-Tryptophan L-tryptophanium bromide: Anhydrous and monohydrate

    NASA Astrophysics Data System (ADS)

    Ghazaryan, V. V.; Giester, G.; Fleck, M.; Petrosyan, A. M.

    2015-12-01

    L-Tryptophan L-tryptophanium bromide (I) and L-tryptophan L-tryptophanium bromide monohydrate (II) are new salts with (A⋯A+) type dimeric cation. The salt (I) crystallizes in the monoclinic system (space group P21, Z = 2) and is isostructural with respective chloride (V.V. Ghazaryan et al., Spectrochim. Acta A 136(2015) 743-750), while the salt (II) was obtained previously (T. Takigawa et al., Bull. Chem. Soc. Jap. 39(1966) 2369-2378) and described as hemyhydrate without structure determination. The salt (II) crystallizes in orthorhombic system (space group P212121, Z = 4). The dimeric cations in (I) and (II) are formed by O-H⋯O hydrogen bonds with the O⋯O distances equal to 2.538(3) Å and 2.481(3) Å respectively. The infrared and Raman spectra of the crystals are studied and compared with the spectra of L-tryptophan L-tryptophanium chloride and L-tryptophanium bromide.

  9. Anomalous signal of solvent bromides used for phasing of lysozyme.

    PubMed

    Dauter, Z; Dauter, M

    1999-05-28

    The anomalous signal of bromide ions, present in the crystal structure of tetragonal hen egg-white lysozyme through the substitution of NaCl by NaBr in the crystallization medium, was used for phasing of X-ray data collected to 1.7 A resolution with a wavelength near the absorption edge of bromine. Phasing of a single wavelength data set, based purely on anomalous deltaf " contribution, led to easily interpretable electron density, equivalent to the complete multiwavelength anonalous dispersion phasing based on four-wavelength data. The classic small-structure direct methods program SHELXS run against all anomalous differences gave a successful solution of six highest peaks corresponding to six bromide ions in the structure with data limited up to a resolution of 3.5 A. Interpretable maps were obtained at a resolution up to 3.0 A using programs MLPHARE and DM. Bromide ions occupy well ordered positions at the protein surface. Phasing based on the single wavelength signal of anomalous scatterers introduced into the ordered solvent shell can be proposed as a tool for solving structures of well diffracting crystals. PMID:10339408

  10. Synthesis and characterization of silicon and germanium nanowires, silica nanotubes, and germanium telluride/tellurium nanostructures

    NASA Astrophysics Data System (ADS)

    Tuan, Hsing-Yu

    A supercritical fluid-liquid solid (SFLS) nanowire growth process using alkanethiol-coated Au nanoparticles to seed silicon nanowires was developed for synthesizing silicon nanowires in solution. The organic solvent was found to significantly influence the silicon precursor decomposition in solution. 46.8 mg of silicon nanowires with 63% yield of silicon nanowire synthesis were achieved while using benzene as a solvent. The most widely used metal for seeding Si and Ge nanowires is Au. However, Au forms deep trap in both Si and Ge and alternative metal seeds are more desirable for electronic applications. Different metal nanocrystals were studied for Si and Ge nanowire synthesis, including Co, Ni, CuS, Mn, Ir, MnPt 3, Fe2O3, and FePt. All eight metals have eutectic temperatures with Si and Ge that are well above the nanowire growth temperature. Unlike Au nanocrystals, which seed nanowire growth through the formation of a liquid Au:Si (Au:Ge) alloy, these other metals seed nanowires by forming solid silicide alloys, a process we have called "supercritical fluid-solid-solid" (SFSS) growth. Moreover, Co and Ni nanoparticles were found to catalyze the decomposition of various silane reactants that do not work well to make Si nanowires using Au seeds. In addition to seeding solid nanowires, CuS nanoparticles were found to seed silica nanotubes via a SFSS like mechanism. 5% of synthesized silica nanotubes were coiled. Heterostructured nanomaterials are interesting since they merge the properties of the individual materials and can be used in diverse applications. GeTe/Te heterostructures were synthesized by reacting diphenylgermane (DPG) and TOP-Te in the presence of organic surfactants. Aligned Te nanorods were grown on the surface facets of micrometer-size germanium telluride particles.

  11. 3D positioning germanium detectors for gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Coburn, Wayne; Amrose, Susan; Boggs, Steven E.; Lin, Robert P.; Amman, Mark S.; Burks, Morgan T.; Hull, Ethan L.; Luke, Paul N.; Madden, Norman W.

    2003-01-01

    We have developed germanium detector technologies for use in the Nuclear Compton Telescope (NCT) - a balloon-borne soft γ-ray (0.2-10 MeV) telescope to study astrophysical sources of nuclear line emission and polarization. The heart of NCT is an array of twelve large volume cross strip germanium detectors, designed to provide 3-D positions for each photon interaction with ~1mm resolution while maintaining the high spectral resolution of germanium. Here we discuss the detailed performance of our prototype 19x19 strip detector, including laboratory tests, calibrations, and numerical simulations. In addition to the x and y positions provided by the orthogonal strips, the interaction depth (z-position) in the detector is measured using the relative timing of the anode and cathode charge collection signals. We describe laboratory calibrations of the depth discrimination using collimated sources with different characteristic energies, and compare the measurements to detailed Monte Carlo simulations and charge collection routines tracing electron-hole pairs from the interaction site to the electrodes. We have also investigated the effects of charge sharing and loss between electrodes, and present these in comparison to charge collection simulations. Detailed analysis of strip-to-strip uniformity in both efficiency and spectral resolution are also presented.

  12. High-Purity Germanium Crystals Study for Underground Experiments

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Yang, Gang; Gavoni, Jayesh; Wang, Guojian; Mei, Hao; Mei, Dongming; Cubed Collaboration

    2013-10-01

    The main characterization is the measurement of electrical properties such as carrier concentration, carrier mobility, resistivity of germanium crystal, as well as to identify whether the crystal is n-type or p-type. Van der pauw Hall effect measurement is conducted at room temperature and 77 K separately for measuring electrical properties for shallow level impurities. The results show that the ionized impurity level of crystals grown in our lab has reached about 1010 /cm3. The accumulated data are applied with theoretical analysis. The study of mobility reveals the different scattering mechanisms involved with impurities and lattice vibrations of the crystal. Theoretical calculations have been performed with reasonable parameter assumption and then compared with experimental data. It is found that neutral impurity concentration constrains mobility at 77 K while ionized impurity is within the acceptable range (below 1012/cm3) in germanium crystals. Mobility can increase significantly when neutral impurity concentration is below 1014/cm3. Therefore, a large reduction of neutral impurity is a desirable approach for obtaining larger mobility, which would improve timing response of germanium detectors. Sponsored by Department of Energy- DE-FG02-10ER46709 and the State of South Dakota.

  13. Metastable phases in mechanically alloyed aluminum germanium powders

    SciTech Connect

    Yvon, P.J.; Schwarz, R.B.

    1993-03-01

    Aluminum and germanium form a simple eutectic system with no stable intermetallic phase, and limited mutual solubility. We report the formation of a metastable rhombohedral,{gamma}{sub 1} phase by mechanically alloying aluminum and germanium powders. This phase, which appears for compositions between 20 and 50 at. % germanium, has also been observed in rapidly quenched alloys, but there is disagreement as to its composition. By measuring the heat of crystallization as a function of composition, we determined the composition of the {gamma}{sub 1} phase to be Al{sub 70}Ge{sub 30}. We also produced Al{sub 70}Ge{sub 30} by arc melting the pure elements, followed by splat-quenching at a cooling rate in the range of 10{sup 8} K s{sup {minus}1}. This method produced two metastable phases, one of which was found to be the {gamma}{sub 1} phase obtained by mechanical alloying. The other was a monoclinic phase reported earlier in the literature as {gamma}{sub 2}.

  14. High purity germanium crystal growth at the University of South Dakota

    NASA Astrophysics Data System (ADS)

    Wang, Guojian; Mei, Hao; Mei, Dongming; Guan, Yutong; Yang, Gang

    2015-05-01

    High-purity germanium crystal growth is challenging work, requiring the control of individual crystal properties such as the impurity distribution, the dislocation density, and the crystalline structure. Currently, we grow high-purity germanium crystals by the Czochralski method in our laboratory in order to understand the details of the growing process, especially for large diameter crystals. In this paper, we report the progress of detector-grade germanium crystal growth at the University of South Dakota.

  15. 3D microoptical elements formed in a photostructurable germanium silicate by direct laser writing

    NASA Astrophysics Data System (ADS)

    Malinauskas, M.; Žukauskas, A.; Purlys, V.; Gaidukevičiu¯tė, A.; Balevičius, Z.; Piskarskas, A.; Fotakis, C.; Pissadakis, S.; Gray, D.; Gadonas, R.; Vamvakaki, M.; Farsari, M.

    2012-12-01

    We present our investigations into the fabrication of three-dimensional microoptical elements by the direct femtosecond laser writing of a germanium-silicon photosensitive hybrid material. Germanium glass composites are very interesting for optical applications as they are photosensitive, and maintain high optical transparency in the visible and near-infrared bands of the spectrum. Here, we have used a germanium containing hybrid material to make nanophotonic structures and microoptical elements such as photonic crystal templates, prisms and spatial polarization plates, both on flat surfaces and fiber tips. Our results show that this germanium silicate composite is an excellent material for microoptics fabrication.

  16. Tin-germanium alloys as anode materials for sodium-ion batteries.

    PubMed

    Abel, Paul R; Fields, Meredith G; Heller, Adam; Mullins, C Buddie

    2014-09-24

    The sodium electrochemistry of evaporatively deposited tin, germanium, and alloys of the two elements is reported. Limiting the sodium stripping voltage window to 0.75 V versus Na/Na+ improves the stability of the tin and tin-rich compositions on repeated sodiation/desodiation cycles, whereas the germanium and germanium-rich alloys were stable up to 1.5 V. The stability of the electrodes could be correlated to the surface mobility of the alloy species during deposition suggesting that tin must be effectively immobilized in order to be successfully utilized as a stable electrode. While the stability of the alloys is greatly increased by the presence of germanium, the specific Coulombic capacity of the alloy decreases with increasing germanium content due to the lower Coulombic capacity of germanium. Additionally, the presence of germanium in the alloy suppresses the formation of intermediate phases present in the electrochemical sodiation of tin. Four-point probe resistivity measurements of the different compositions show that electrical resistivity increases with germanium content. Pure germanium is the most resistive yet exhibited the best electrochemical performance at high current densities which indicates that electrical resistivity is not rate limiting for any of the tested compositions. PMID:25158125

  17. 40 CFR 180.123a - Inorganic bromide residues in peanut hay and peanut hulls; statement of policy.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... containing residues of inorganic bromides from the use of methyl bromide are unsuitable as an ingredient in... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Inorganic bromide residues in peanut... RESIDUES IN FOOD Specific Tolerances § 180.123a Inorganic bromide residues in peanut hay and peanut...

  18. 40 CFR 180.123a - Inorganic bromide residues in peanut hay and peanut hulls; statement of policy.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... containing residues of inorganic bromides from the use of methyl bromide are unsuitable as an ingredient in... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Inorganic bromide residues in peanut... RESIDUES IN FOOD Specific Tolerances § 180.123a Inorganic bromide residues in peanut hay and peanut...

  19. 40 CFR 180.123a - Inorganic bromide residues in peanut hay and peanut hulls; statement of policy.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... containing residues of inorganic bromides from the use of methyl bromide are unsuitable as an ingredient in... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Inorganic bromide residues in peanut... RESIDUES IN FOOD Specific Tolerances § 180.123a Inorganic bromide residues in peanut hay and peanut...

  20. Functionalization of Mechanochemically Passivated Germanium Nanoparticles via "Click" Chemistry

    NASA Astrophysics Data System (ADS)

    Purkait, Tapas Kumar

    Germanium nanoparticles (Ge NPs) may be fascinating for their electronic and optoelectronic properties, as the band gap of Ge NPs can be tuned from the infrared into the visible range of solar spectru. Further functionalization of those nanoparticles may potentially lead to numerous applications ranging from surface attachment, bioimaging, drug delivery and nanoparticles based devices. Blue luminescent germanium nanoparticles were synthesized from a novel top-down mechanochemical process using high energy ball milling (HEBM) of bulk germanium. Various reactive organic molecules (such as, alkynes, nitriles, azides) were used in this process to react with fresh surface and passivate the surface through Ge-C or Ge-N bond. Various purification process, such as gel permeation chromatography (GPC), Soxhlet dailysis etc. were introduced to purify nanoparticles from molecular impurities. A size separation technique was developed using GPC. The size separated Ge NPs were characterize by TEM, small angle X-ray scattering (SAXS), UV-vis absorption and photoluminescence (PL) emission spectroscopy to investigate their size selective properties. Germanium nanoparticles with alkyne termini group were prepared by HEBM of germanium with a mixture of n-alkynes and alpha, o-diynes. Additional functionalization of those nanoparticles was achieved by copper(I) catalyzed azide-alkyne "click" reaction. A variety of organic and organometallic azides including biologically important glucals have been reacted in this manner resulting in nanopartilces adorned with ferrocenyl, trimethylsilyl, and glucal groups. Additional functionalization of those nanoparticles was achieved by reactions with various azides via a Cu(I) catalyzed azide-alkyne "click" reaction. Various azides, including PEG derivatives and cylcodextrin moiety, were grafted to the initially formed surface. Globular nanoparticle arrays were formed through interparticle linking via "click" chemistry or "host-guest" chemistry

  1. EFFECT OF BROMIDE ION IN WATER TREATMENT. 2. A LITERATURE REVIEW OF OZONE AND BROMIDE ION INTERACTIONS AND THE FORMATION OF ORGANIC BROMINE COMPOUNDS

    EPA Science Inventory

    Where bromide ion is found in water used as a source of drinking water, and chlorination is used for disinfection, bromide ion is oxidized to bromine and can result in the formation of organic bromine compounds. There are presently no treatment techniques available for economic r...

  2. Spatial Variation Scales of Rainfall Characteristics and Bromide Leaching

    NASA Astrophysics Data System (ADS)

    Wendroth, O. O.; Vasquez, V.; Matocha, C.

    2010-12-01

    Amount and intensity of rainfall are known as important characteristics that affect the leaching of surface-applied agri-chemicals. Besides these, the effect of the time interval between a fertilizer, pesticide or tracer application and subsequent rainfall on solute leaching is not well understood. Moreover, little is known about the spatial representativity of the solute concentration based on a relatively small soil sample in field-scale transport studies. To know the spatial representativity of a solute concentration sample at a time is crucial for analyzing solute leaching behavior over time as well as over space. The objectives of this study were to identify the impact of rainfall intensity and amount as well as the application time delay on solute transport in a well-drained Maury silt loam soil. Moreover, an experimental design and protocol had to be developed that exhibited spatial variability structure and representativity of bromide concentration. For this purpose, the variation scale of each of the factors investigated was chosen differently to apply frequency domain statistics. The study was conducted in a Maury silt loam soil at the University of Kentucky, College of Agriculture Experimental Farm Spindletop. Along a 64-m transect, 32 plots each 2-m long and 4-m wide were established. The three different treatments were spatially laid out in sinusoidal patterns at three respective wavelengths. Two different rainfall amounts were applied in blocks of eight consecutive plots, hence a wavelength of 32 m. These two different rainfall amounts were applied at four rates, spatially distributed in two waves each of 16 m length. Individual plots received the irrigation at specific times after the tracer had been applied. Four application delay times were chosen, hence the wavelength for this treatment was 8 m. Bromide concentration was measured for soil samples that were taken with a percussion auger at every 50 cm distance along the 64-m-transect. Auger cores

  3. Comparison of Heat and Bromide as Ground Water Tracers Near Streams

    USGS Publications Warehouse

    Constantz, J.; Cox, M.H.; Su, G.W.

    2003-01-01

    Heat and bromide were compared as tracers for examining stream/ground water exchanges along the middle reaches of the Santa Clara River, California, during a 10-hour surface water sodium bromide injection test. Three cross sections that comprise six shallow (<1 m) piezometers were installed at the upper, middle, and lower sections of a 17 km long study reach, to monitor temperatures and bromide concentrations in the shallow ground water beneath the stream. A heat and ground water transport simulation model and a closely related solute and ground water transport simulation model were matched up for comparison of simulated and observed temperatures and bromide concentrations in the streambed. Vertical, one-dimensional simulations of sediment temperature were fitted to observed temperature results, to yield apparent streambed hydraulic conductivities in each cross section. The temperature-based hydraulic conductivities were assigned to a solute and ground water transport model to predict sediment bromide concentrations, during the sodium bromide injection test. Vertical, one-dimensional simulations of bromide concentrations in the sediments yielded a good match to the observed bromide concentrations, without adjustment of any model parameters except solute dispersivities. This indicates that, for the spatial and temporal scales examined on the Santa Clara River, the use of heat and bromide as tracers provide comparable information with respect to apparent hydraulic conductivities and fluxes for sediments near streams. In other settings, caution should be used due to differences in the nature of conservative (bromide) versus nonconservative (heat) tracers, particularly when preferential flowpaths are present.

  4. Synthesis of silicon and germanium nanowires and silicon/germanium nanowire heterostructures

    NASA Astrophysics Data System (ADS)

    Clement, Teresa J.

    2007-12-01

    The vapor-liquid-solid growth process for synthesis of group-IV semiconducting nanowires using silane, germane, disilane and digermane precursor gases has been investigated. The nanowire growth process combines in situ gold seed formation by vapor deposition on atomically clean silicon (111) surfaces, in situ growth from the gaseous precursor(s), and real-time monitoring of nanowire growth as a function of temperature and pressure by a novel optical reflectometry technique. A significant dependence on precursor pressure and growth temperature for the synthesis of silicon and germanium nanowires is observed, depending on the stability of the specific precursor used. Also, the presence of a nucleation time for the onset of nanowire growth has been found using our new in situ optical reflectometry technique. Thermal annealing of the deposited gold seeds prior to nanowire growth is shown to lead to ripening of the gold seeds and the formation of pillars several nanometers in height under the seeds. These pillars are demonstrated to result from the catalytic collection of surface Si adatoms and provide a method to obtain 100% vertical growth of nanowires on Si (111) substrates. The growth of nanowire heterostructures has also been investigated with specific attention paid to the strain induced within these structures. Strain in axial and core-shell Si/Ge nanowire heterostructures provides a unique opportunity for modifying bandstructures of specific nanoscale heterostructures. Specific precursor selection adds an additional control by which we are able to grow specific heterostructures---axial or core-shell. Axial heterowires form more easily by catalyzing silane at the Au eutectic seed, while core-shell heterowires grow more easily by stabilizing lateral growth using disilane or digermane. Strain mapping of nanowires based on geometric phase analysis of high-resolution transmission electron microscopy lattice imaging reveals large strains present in core-shell Si

  5. Automated determination of bromide in waters by ion chromatography with an amperometric detector

    USGS Publications Warehouse

    Pyen, G.S.; Erdmann, D.E.

    1983-01-01

    An automated ion chromatograph, including a program controller, an automatic sampler, an integrator, and an amperometric detector, was used to develop a procedure for the determination of bromide in rain water and many ground waters. Approximately 10 min is required to obtain a chromatogram. The detection limit for bromide is 0.01 mg l-1 and the relative standard deivation is <5% for bromide concentrations between 0.05 and 0.5 mg l-1. Chloride interferes if the chloride-to-bromide ratio is greater than 1 000:1 for a range of 0.01-0.1 mg l-1 bromide; similarly, chloride interferes in the 0.1-1.0 mg l-1 range if the ratio is greater than 5 000:1. In the latter case, a maximum of 2 000 mg l-1 of chloride can be tolerated. Recoveries of known concentrations of bromide added to several samples, ranged from 97 to 110%. ?? 1983.

  6. Interaction between gaseous ozone and crystalline potassium bromide

    NASA Astrophysics Data System (ADS)

    Levanov, A. V.; Maksimov, I. B.; Isaikina, O. Ya.; Antipenko, E. E.; Lunin, V. V.

    2016-07-01

    The formation of nonvolatile products of the oxidation of a bromide ion during the interaction between gaseous ozone and powdered crystalline KBr is studied. It is found that potassium bromate KBrO3 is the main product of the reaction. The influence of major experimental factors (the duration of ozonation, the concentration of ozone, the humidity of the initial gas, and the temperature) on the rate of formation of bromate is studied. The effective constants of the formation of bromate during the interaction between O3 and Br- in a heterogeneous gas-solid body system and in a homogeneous aqueous solution are compared.

  7. Photodissociation of methyl chloride and methyl bromide in the atmosphere

    NASA Technical Reports Server (NTRS)

    Robbins, D. E.

    1976-01-01

    Methyl chloride (CH3Cl) and methyl bromide (CH3Br) have been suggested to be significant sources of the stratospheric halogens. The breakup of these compounds in the stratosphere by photodissociation or reaction with OH releases halogen atoms which catalytically destroy ozone. Experimental results are presented for ultraviolet photoabsorption cross sections of CH3Cl and CH3Br. Calculations are presented of loss rates for the methyl halides due to photodissociation and reaction with OH and of mixing ratios of these species in the stratosphere.

  8. Variable-Temperature Cryostat For Radiation-Damage Testing Of Germanium Detectors

    NASA Technical Reports Server (NTRS)

    Floyd, Samuel R.; Puc, Bernard P.

    1992-01-01

    Variable-temperature cryostats developed to study radiation damage to, and annealing of, germanium gamma-ray detectors. Two styles: one accommodates large single detector and one accommodates two medium-sized detectors. New cryostats allow complete testing of large-volume germanium gamma-ray detectors without breaking cryostat vacuum and removing detectors for annealing.

  9. Naturally occurring vapor-liquid-solid (VLS) Whisker growth of germanium sulfide

    USGS Publications Warehouse

    Finkelman, R.B.; Larson, R.R.; Dwornik, E.J.

    1974-01-01

    The first naturally occurring terrestrial example of vapor-liquid-solid (VLS) growth has been observed in condensates from gases released by burning coal in culm banks. Scanning electron microscopy, X-ray diffraction, and energy dispersive analysis indicate that the crystals consist of elongated rods (??? 100 ??m) of germanium sulfide capped by bulbs depleted in germanium. ?? 1974.

  10. Oriented bottom-up growth of armchair graphene nanoribbons on germanium

    DOEpatents

    Arnold, Michael Scott; Jacobberger, Robert Michael

    2016-03-15

    Graphene nanoribbon arrays, methods of growing graphene nanoribbon arrays and electronic and photonic devices incorporating the graphene nanoribbon arrays are provided. The graphene nanoribbons in the arrays are formed using a scalable, bottom-up, chemical vapor deposition (CVD) technique in which the (001) facet of the germanium is used to orient the graphene nanoribbon crystals along the [110] directions of the germanium.

  11. Oligogermanes as molecular precursors for germanium(0) nanoparticles: Size control and size-dependent fluorescence

    SciTech Connect

    Schrick, Aaron C.; Weinert, Charles S.

    2013-10-15

    Graphical abstract: Catenated germanium compounds are employed as molecular precursors for germanium(0) nanoparticles. The size of the nanoparticles, and their fluorescence spectra, depend on the number of catenated germanium atoms present in the precursor. - Highlights: • We have used oligogermanes for the size-specific synthesis of germanium(0) nanoparticles. • The size of the nanomaterials obtained depends directly on the degree of catenation present in the oligogermane precursor. • The nanoparticles are shown to exhibit size-dependent fluorescence. • Oligogermanes will function as useful precursors for the synthesis of a variety of nanomaterials. - Abstract: Germanium nanoparticles were synthesized in solution from novel oligogermane molecular precursors. The size of the nanoparticles obtained is directly related to the number of catenated germanium atoms present in the oligogermane precursor and the nanoparticles exhibit size-dependent fluorescence. The germanium nanoparticles were also characterized by TEM, powder XRD, FTIR, EDS and XPS methods. This method appears to be a promising new route for the synthesis of germanium nanoparticles since the size of the materials obtained can be controlled by the choice of the oligogermane used as the precursor.

  12. Heterogeneity of indium antimonide doped with tellurium, germanium, cadmium, and silicon

    SciTech Connect

    Gromova T.I.; Fridshtand, E.S.; Kevorkov, M.N.; Popkov, A.N.; Yorova, E.S.

    1986-05-01

    This paper investigates the heterogeneity of crystals of n- and p-type conductivity with a carrier concentration above 1014 cm-/sup 3/ at 77 K, that are doped with tellurium, germanium, cadmium, and silicon. Cadmium is the weak acceptor, whereas germanium and silicon show amphoteric properties, being located mainly at the sublattice points of the Group V element.

  13. Effects of pinaverium bromide and verapamil on the motility of the rat isolated colon.

    PubMed

    Baumgartner, A; Drack, E; Halter, F; Scheurer, U

    1985-09-01

    Pinaverium bromide was 30 times less potent than verapamil in inhibiting intraluminal pressure responses of in vitro rat colonic segments to barium chloride, acetylcholine, FK 33-824 or field stimulation. The inhibitory effects of both verapamil and pinaverium bromide on the pressure responses to field stimulation were antagonized similarly by exogenous calcium administration. These results support the concept that pinaverium bromide acts on calcium channels in the smooth muscle cell membrane. PMID:4052731

  14. Effects of pinaverium bromide and verapamil on the motility of the rat isolated colon.

    PubMed Central

    Baumgartner, A.; Drack, E.; Halter, F.; Scheurer, U.

    1985-01-01

    Pinaverium bromide was 30 times less potent than verapamil in inhibiting intraluminal pressure responses of in vitro rat colonic segments to barium chloride, acetylcholine, FK 33-824 or field stimulation. The inhibitory effects of both verapamil and pinaverium bromide on the pressure responses to field stimulation were antagonized similarly by exogenous calcium administration. These results support the concept that pinaverium bromide acts on calcium channels in the smooth muscle cell membrane. PMID:4052731

  15. Germanium Lift-Off Masks for Thin Metal Film Patterning

    NASA Technical Reports Server (NTRS)

    Brown, Ari

    2012-01-01

    A technique has been developed for patterning thin metallic films that are, in turn, used to fabricate microelectronics circuitry and thin-film sensors. The technique uses germanium thin films as lift-off masks. This requires development of a technique to strip or undercut the germanium chemically without affecting the deposited metal. Unlike in the case of conventional polymeric lift-off masks, the substrate can be exposed to very high temperatures during processing (sputter deposition). The reason why polymeric liftoff masks cannot be exposed to very high temperatures (greater than 100 C) is because (a) they can become cross linked, making lift-off very difficult if not impossible, and (b) they can outgas nitrogen and oxygen, which then can react with the metal being deposited. Consequently, this innovation is expected to find use in the fabrication of transition edge sensors and microwave kinetic inductance detectors, which use thin superconducting films deposited at high temperature as their sensing elements. Transition edge sensors, microwave kinetic inductance detectors, and their circuitry are comprised of superconducting thin films, for example Nb and TiN. Reactive ion etching can be used to pattern these films; however, reactive ion etching also damages the underlying substrate, which is unwanted in many instances. Polymeric lift-off techniques permit thin-film patterning without any substrate damage, but they are difficult to remove and the polymer can outgas during thin-film deposition. The outgassed material can then react with the film with the consequence of altered and non-reproducible materials properties, which, in turn, is deleterious for sensors and their circuitry. The purpose of this innovation was to fabricate a germanium lift-off mask to be used for patterning thin metal films.

  16. Temperature-dependent Refractive Index of Silicon and Germanium

    NASA Technical Reports Server (NTRS)

    Frey, Bradley J.; Leviton, Douglas B.; Madison, Timothy J.

    2006-01-01

    Silicon and germanium are perhaps the two most well-understood semiconductor materials in the context of solid state device technologies and more recently micromachining and nanotechnology. Meanwhile, these two materials are also important in the field of infrared lens design. Optical instruments designed for the wavelength range where these two materials are transmissive achieve best performance when cooled to cryogenic temperatures to enhance signal from the scene over instrument background radiation. In order to enable high quality lens designs using silicon and germanium at cryogenic temperatures, we have measured the absolute refractive index of multiple prisms of these two materials using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, as a function of both wavelength and temperature. For silicon, we report absolute refractive index and thermo-optic coefficient (dn/dT) at temperatures ranging from 20 to 300 K at wavelengths from 1.1 to 5.6 pin, while for germanium, we cover temperatures ranging from 20 to 300 K and wavelengths from 1.9 to 5.5 microns. We compare our measurements with others in the literature and provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures. Citing the wide variety of values for the refractive indices of these two materials found in the literature, we reiterate the importance of measuring the refractive index of a sample from the same batch of raw material from which final optical components are cut when absolute accuracy greater than k5 x 10" is desired.

  17. Three holes bound to a double acceptor - Be(+) in germanium

    NASA Technical Reports Server (NTRS)

    Haller, E. E.; Mcmurray, R. E., Jr.; Falicov, L. M.; Haegel, N. M.; Hansen, W. L.

    1983-01-01

    A double acceptor binding three holes has been observed for the first time with photoconductive far-infrared spectroscopy in beryllium-doped germanium single crystals. This new center, Be(+), has a hole binding energy of about 5 meV and is only present when free holes are generated by ionization of either neutral shallow acceptors or neutral Be double acceptors. The Be(+) center thermally ionizes above 4 K. It disappears at a uniaxial stress higher than about a billion dyn/sq cm parallel to (111) as a result of the lifting of the valence-band degeneracy.

  18. Phonon Quasidiffusion in Cryogenic Dark Matter Search Large Germanium Detectors

    SciTech Connect

    Leman, S.W.; Cabrera, B.; McCarthy, K.A.; Pyle, M.; Resch, R.; Sadoulet, B.; Sundqvist, K.M.; Brink, P.L.; Cherry, M.; Do Couto E Silva, E.; Figueroa-Feliciano, E.; Mirabolfathi, N.; Serfass, B.; Tomada, A.; /Stanford U., Phys. Dept.

    2012-06-04

    We present results on quasidiffusion studies in large, 3 inch diameter, 1 inch thick [100] high purity germanium crystals, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed with 59.5 keV gamma-rays from an Am-241 calibration source. We compare data obtained in two different detector types, with different phonon sensor area coverage, with results from a Monte Carlo. The Monte Carlo includes phonon quasidiffusion and the generation of phonons created by charge carriers as they are drifted across the detector by ionization readout channels.

  19. Germanium nanowire growth controlled by surface diffusion effects

    SciTech Connect

    Schmidtbauer, Jan; Bansen, Roman; Heimburger, Robert; Teubner, Thomas; Boeck, Torsten; Fornari, Roberto

    2012-07-23

    Germanium nanowires (NWs) were grown onto Ge(111) substrates by the vapor-liquid-solid process using gold droplets. The growth was carried out in a molecular beam epitaxy chamber at substrate temperatures between 370 Degree-Sign C and 510 Degree-Sign C. The resulting nanowire growth rate turns out to be highly dependent on the substrate temperature exhibiting the maximum at T = 430 Degree-Sign C. The temperature dependence of growth rate can be attributed to surface diffusion both along the substrate and nanowire sidewalls. Analyzing the diffusive material transport yields a diffusion length of 126 nm at a substrate temperature of 430 Degree-Sign C.

  20. Diffusion of iron, cobalt, and nickel in liquid germanium

    SciTech Connect

    Denisov, V.M.; Beletskii, V.V.

    1988-03-01

    To improve the processes employed for preparing single crystals with fixed electrophysical properties it is necessary to have information about the coefficients of diffusion of the impurities present in the melts. In this paper data on the diffusion of Fe, Co, and Ni in liquid germanium, starting from its melting point up to 1380/degree/K, are presented. The coefficients of diffusion of Fe, Co, and Ni in liquid Ge were determined by the capillary method. It was established that the change in the structure of liquid helium as a function of the temperature is responsible for the characteristic features of diffusion in the systems studied.

  1. Ultra-low noise mechanically cooled germanium detector

    NASA Astrophysics Data System (ADS)

    Barton, P.; Amman, M.; Martin, R.; Vetter, K.

    2016-03-01

    Low capacitance, large volume, high purity germanium (HPGe) radiation detectors have been successfully employed in low-background physics experiments. However, some physical processes may not be detectable with existing detectors whose energy thresholds are limited by electronic noise. In this paper, methods are presented which can lower the electronic noise of these detectors. Through ultra-low vibration mechanical cooling and wire bonding of a CMOS charge sensitive preamplifier to a sub-pF p-type point contact HPGe detector, we demonstrate electronic noise levels below 40 eV-FWHM.

  2. Electric current induced modification of germanium nanowire NEM switch contact

    NASA Astrophysics Data System (ADS)

    Meija, R.; Kosmaca, J.; Jasulaneca, L.; Petersons, K.; Biswas, S.; Holmes, J. D.; Erts, D.

    2015-05-01

    We present an investigation of contact properties of a germanium (Ge) nanowire based nanoelectromechanical (NEM) switch in its ON state. The contact stiffness in the ON state was evaluated by detecting the nanowire’s resonance frequency. It was found that the resonance frequency increases when electric current flows through the nanowire/counter electrode contact area. The reason for modification in the contact area is referred to as electric-current-induced processes in the native oxide layer covering the nanowires. The presented resonance shift method is a simple way to indicate strengthening of the nanowire/counter electrode contact area without disassembling the contact.

  3. Electric current induced modification of germanium nanowire NEM switch contact.

    PubMed

    Meija, R; Kosmaca, J; Jasulaneca, L; Petersons, K; Biswas, S; Holmes, J D; Erts, D

    2015-05-15

    We present an investigation of contact properties of a germanium (Ge) nanowire based nanoelectromechanical (NEM) switch in its ON state. The contact stiffness in the ON state was evaluated by detecting the nanowire's resonance frequency. It was found that the resonance frequency increases when electric current flows through the nanowire/counter electrode contact area. The reason for modification in the contact area is referred to as electric-current-induced processes in the native oxide layer covering the nanowires. The presented resonance shift method is a simple way to indicate strengthening of the nanowire/counter electrode contact area without disassembling the contact. PMID:25902759

  4. Doping of germanium nanowires grown in presence of PH3

    NASA Astrophysics Data System (ADS)

    Tutuc, E.; Chu, J. O.; Ott, J. A.; Guha, S.

    2006-12-01

    The authors study the Au-catalyzed chemical vapor growth of germanium (Ge) nanowires in the presence of phosphine (PH3), used as a dopant precursor. The device characteristics of the ensuing nanowire field effect transistors (FETs) indicate n-type, highly doped nanowires. Using a combination of different nanowire growth sequences and their FET characteristics, the authors determine that phosphorus incorporates predominately via the conformal growth, which accompanies the acicular, nanowire growth. As such, the Ge nanowires grown in the presence of PH3 contain a phosphorus doped shell and an undoped core. The authors determine the doping level in the shell to be ≃(1-4)×1019cm-3.

  5. Germanium wrap-around photodetectors on Silicon photonics.

    PubMed

    Going, Ryan; Seok, Tae Joon; Loo, Jodi; Hsu, Kyle; Wu, Ming C

    2015-05-01

    We present a novel waveguide coupling scheme where a germanium diode grown via rapid melt growth is wrapped around a silicon waveguide. A 4 fF PIN photodiode is demonstrated with 0.95 A/W responsivity at 1550 nm, 6 nA dark current, and nearly 9 GHz bandwidth. Devices with shorter intrinsic region exhibit higher bandwidth (30 GHz) and slightly lower responsivity (0.7 A/W). An NPN phototransistor is also demonstrated using the same design with 14 GHz f(T). PMID:25969287

  6. Resonance-enhanced waveguide-coupled silicon-germanium detector

    NASA Astrophysics Data System (ADS)

    Alloatti, L.; Ram, R. J.

    2016-02-01

    A photodiode with 0.55 ± 0.1 A/W responsivity at a wavelength of 1176.9 nm has been fabricated in a 45 nm microelectronics silicon-on-insulator foundry process. The resonant waveguide photodetector exploits carrier generation in silicon-germanium within a microring which is compatible with high-performance electronics. A 3 dB bandwidth of 5 GHz at -4 V bias is obtained with a dark current of less than 20 pA.

  7. Effect of germanium dioxide on growth of Spirulina platensis

    NASA Astrophysics Data System (ADS)

    Cao, Ji-Xiang

    1996-12-01

    This study on the effect of different concentrations of germanium dioxide (GeO2) on the specific growth rate (SGR), pigment contents, protein content and amino acid composition of Spirulina platensis showed that Ge was not the essential element of this alga; that GeO2 could speed up growth and raise protein content of S. platensis, and could possibly influence the photosynthesis system. The concentration range of GeO2 beneficial to growth of S. platensis is from 5 100mg/l. GeO2 is proposed to be utilized to remove contamination by Chlorella spp. usually occurring in the cultivation of Spirulina.

  8. Preparation of freestanding germanium nanocrystals by ultrasonic aerosol pyrolysis

    NASA Astrophysics Data System (ADS)

    Stoldt, Conrad R.; Haag, Michael A.; Larsen, Brian A.

    2008-07-01

    This letter reports a synthetic route adaptable for the continuous, large-scale production of germanium (Ge) nanocrystals for emerging electronic and optoelectronic applications. Using an ultrasonic aerosol pyrolysis approach, diamond cubic Ge nanocrystals with dense, spherical morphologies and sizes ranging from 3to14nm are synthesized at 700°C from an ultrasonically generated aerosol of tetrapropylgermane (TPG) precursor and toluene solvent. The ultimate crystal size demonstrates a near linear relationship within the range of TPG concentrations investigated, while the shape of the measured size distributions predicts multiple particle formation mechanisms during aerosol decomposition and condensation.

  9. Reaction studies of hot silicon, germanium and carbon atoms

    SciTech Connect

    Gaspar, P.P.

    1989-02-01

    Research has been continued on hot silicon, germanium and carbon atoms. The results of experiments directed toward attaining the goals of this research program are briefly presented for the period September 1, 1987 to January 31, 1989 in sections entitled: (1) The mechanism of hydrogen acquisition by high energy silicon atoms. (2) The mechanism of disilene formation in the reactions of recoiling silicon atoms with silane. (3) The contribution of ionic processes to the primary reactions of recoiling silicon atoms. (4) The role of phosphine in hydrogen acquisition by recoiling silicon atoms. (5) Mechanism of reaction of recoiling carbon atoms with aromatic molecules.

  10. Giant negative piezoresistance effect in copper-doped germanium

    SciTech Connect

    Dubon, O.D.; Haller, E.E. |; Walukiewicz, W.; Beeman, J.W.

    1996-09-01

    We have observed a stress-induced decrease of over ten orders of magnitude in the low-temperature electrical resistivity of copper- doped germanium single crystals. The application of large uniaxial stresses in a <001> direction leas to a change in the copper ground- state wavefunction from the highly localized (1s){sup 3} to the much more extended (1s){sup 2}(2s){sup 1} configuration. We attribute the decrease in the resistivity to impurity band conduction by the 2s - holes of the high pressure configuration.

  11. Synthesis and Characterization of Functional Iron and Germanium Nanomaterials

    NASA Astrophysics Data System (ADS)

    Hoffman, Melanie

    Germanium nanomaterials have many potential applications based on their size-tunable optical and electronic properties, for example in photodetectors, photovoltaics and non-volatile memory. In this work, the synthesis of Ge nanoparticles by two different methods based on tailorability through the substituent chemistry of the Ge precursors is explored. In Chapter Two, the effect of the organic substituent upon thermal decomposition of organogermanium oxides (RGeO1.5)n to yield oxide-embedded germanium nanocrystals (Ge-NCs) is investigated. Substituents with stable radical formation or the presence of beta-hydrogen are found to facilitate NC formation at lower temperatures. Lower temperature limits germanium production to a pathway based on disproportionation only, and not -- as previously -- also on hydrogen reduction of germanium oxides. The organic substituent also introduces tailorability of organogermanium oxide properties, such as melting points. For R = n-butyl, benzyl, these are lowered below the disproportionation temperature, yielding melts containing Ge-NCs. The knowledge gained in the substituent study is applied to solution synthesis of Ge-NCs in Chapter Three. The n-butyl substituent, which formed Ge-NC from (nBuGeO1.5)n at 300 °C, can eliminate by radical and beta-hydride elimination pathways. In the molecular compounds nBuxGeH4-x (x = 1-4), reductive elimination also becomes possible. We propose this leads to the decrease in decomposition temperature of nBu xGeH4-x from x = 4 to x = 1. In the second section of this thesis, Chapter Four, the catalytic activity of metal-decorated iron/iron-oxide core-shell nanoparticles (M/Fe Fe xOy) in Heck and Suzuki couplings is investigated. Electroless deposition of noble metals on Fe FexOy generates the catalyst. The catalytic activity of Pd/Fe FexOy is improved over standard heterogeneous catalysts (e.g., Pd/C) in Heck coupling of styrene and bromobenzene. Leaching studies in Suzuki coupling of bromobenzene with

  12. Infrared absorption study of neutron-transmutation-doped germanium

    NASA Technical Reports Server (NTRS)

    Park, I. S.; Haller, E. E.

    1988-01-01

    Using high-resolution far-infrared Fourier transform absorption spectroscopy and Hall effect measurements, the evolution of the shallow acceptor and donor impurity levels in germanium during and after the neutron transmutation doping process was studied. The results show unambiguously that the gallium acceptor level concentration equals the concentration of transmutated Ge-70 atoms during the whole process indicating that neither recoil during transmutation nor gallium-defect complex formation play significant roles. The arsenic donor levels appear at full concentration only after annealing for 1 h at 450 C. It is shown that this is due to donor-radiation-defect complex formation. Again, recoil does not play a significant role.

  13. Germanium-on-SOI waveguides for mid-infrared wavelengths.

    PubMed

    Younis, Usman; Vanga, Sudheer K; Lim, Andy Eu-Jin; Lo, Patrick Guo-Qiang; Bettiol, Andrew A; Ang, Kah-Wee

    2016-05-30

    We report on the development of Germanium-on-SOI waveguides for mid-infrared wavelengths. The strip waveguides have been formed in 0.85 and 2 μm thick Ge grown on SOI substrate with 220 nm thick Si overlayer. The propagation loss for various waveguide widths has been measured using the Fabry-Perot method with temperature tuning. The minimum loss of ~8 dB/cm has been achieved for 0.85 μm thick Ge core using 3.682 μm laser excitation. The transparency of these waveguides has been measured up to at least 3.82 μm. PMID:27410120

  14. Effect of pressure on arsenic diffusion in germanium

    SciTech Connect

    Mitha, S.; Theiss, S.D.; Aziz, M.J.; Schiferl, D.; Poker, D.B.

    1994-01-01

    We report preliminary results of a study of the activation volume for diffusion of arsenic in germanium. High-temperature high-pressure anneals were performed in a liquid argon pressure medium in a diamond anvil cell capable of reaching 5 GPa and 750 C,l which is externally heated for uniform and repeatable temperature profiles. Broadening of an ion-implanted arsenic profile was measured by Secondary Ion Mass Spectrometry. Hydrostatic pressure retards the diffusivity at 575 C, characterized by an activation volume that is +15% of the atomic volume of Ge. Implications for diffusion mechanisms are discussed.

  15. Gallium-doped germanium, evaluation of photoconductors, part 1

    NASA Technical Reports Server (NTRS)

    Moore, W. J.

    1979-01-01

    Gallium-doped germanium far infrared detectors were evaluated at low temperatures and low background simulating the space environment. Signal and noise characteristics were determined for detector temperatures in the 2K to 4K range. Optimum performance occurs at about 2.5K for all devices tested. The minimum average NEP in the 40-130 micron region was found to be approximately 4 x 10 to the minus 17th power watt Hz(-1/2) at a frequency of 1 Hz.

  16. Transient neuromyopathy after bromide intoxication in a dog with idiopathic epilepsy

    PubMed Central

    2012-01-01

    A seven-year old Australian Shepherd, suffering from idiopathic epilepsy under treatment with phenobarbitone and potassium bromide, was presented with generalised lower motor neuron signs. Electrophysiology and muscle-nerve biopsies revealed a neuromyopathy. The serum bromide concentration was increased more than two-fold above the upper reference value. Clinical signs disappeared after applying diuretics and reducing the potassium bromide dose rate. This is the first case report describing electrophysiological and histopathological findings associated with bromide induced lower motor neuron dysfunction in a dog. PMID:23216950

  17. Suspended germanium cross-shaped microstructures for enhancing biaxial tensile strain

    NASA Astrophysics Data System (ADS)

    Ishida, Satomi; Kako, Satoshi; Oda, Katsuya; Ido, Tatemi; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2016-04-01

    We fabricate a suspended germanium cross-shaped microstructure to biaxially enhance residual tensile strain using a germanium epilayer directly grown on a silicon-on-insulator substrate. Such a suspended germanium system with enhanced biaxial tensile strain will be a promising platform for incorporating optical cavities toward the realization of germanium lasers. We demonstrate systematic control over biaxial tensile strain and photoluminescence peaks by changing structural geometry. The photoluminescence peaks corresponding to the direct recombination between the conduction Γ valley and two strain-induced separated valence bands have been clearly assigned. A maximum biaxial strain of 0.8% has been achieved, which is almost half of that required to transform germanium into a direct band-gap semiconductor.

  18. Direct Bandgap Light Emission from Strained Germanium Nanowires Coupled with High-Q Nanophotonic Cavities.

    PubMed

    Petykiewicz, Jan; Nam, Donguk; Sukhdeo, David S; Gupta, Shashank; Buckley, Sonia; Piggott, Alexander Y; Vučković, Jelena; Saraswat, Krishna C

    2016-04-13

    A silicon-compatible light source is the final missing piece for completing high-speed, low-power on-chip optical interconnects. In this paper, we present a germanium nanowire light emitter that encompasses all the aspects of potential low-threshold lasers: highly strained germanium gain medium, strain-induced pseudoheterostructure, and high-Q nanophotonic cavity. Our nanowire structure presents greatly enhanced photoluminescence into cavity modes with measured quality factors of up to 2000. By varying the dimensions of the germanium nanowire, we tune the emission wavelength over more than 400 nm with a single lithography step. We find reduced optical loss in optical cavities formed with germanium under high (>2.3%) tensile strain. Our compact, high-strain cavities open up new possibilities for low-threshold germanium-based lasers for on-chip optical interconnects. PMID:26907359

  19. Thin film germanium on silicon created via ion implantation and oxide trapping

    NASA Astrophysics Data System (ADS)

    Anthony, R.; Knights, A. P.

    2015-06-01

    We present a novel process for integrating germanium with silicon-on-insulator (SOI) wafers. Germanium is implanted into SOI which is then oxidized, trapping the germanium between the two oxide layers (the grown oxide and the buried oxide). With careful control of the implantation and oxidation conditions this process creates a thin layer (current experiments indicate up to 20-30nm) of almost pure germanium. The layer can be used potentially for fabrication of integrated photo-detectors sensitive to infrared wavelengths, or may serve as a seed for further germanium growth. Results are presented from electron microscopy and Rutherford back-scattering analysis, as well as preliminary modelling using an analytical description of the process.

  20. Investigation of alginate binding to germanium and polystyrene substrata conditioned with mussel adhesive protein

    SciTech Connect

    Suci, P.A.; Geesey, G.G.

    1995-06-15

    Binding of alginate from Macrocystis pyrifera (kelp) to germanium and polystyrene substrata conditioned with mussel adhesive protein (MAP) from Mytilis edulis, to germanium substrata conditioned with bovine serum albumin (BSA) and polylysine, and to germanium substrata coated with aminopropyltriethoxysilane (APS) was investigated using attenuated total reflection Fourier transform infrared spectrometry. Binding of alginate to MAP appears to be proportional to surface coverage for levels tested. Distinct spectral features appear in the region associated with pyranose ring vibrations upon binding of alginate to MAP, polylysine, and APS, indicating that lysine residues play a prominent role in promoting irreversible adsorption with perturbation of pyranose ring atoms. BSA does not appear to enhance alginate adsorption over that observed on clean germanium and no new spectral features appear as a result of binding. The level of irreversible binding of alginate to germanium and polystyrene substrata conditioned with MAP is similar.

  1. Mechanical stresses and crystallization of lithium phosphorous oxynitride-coated germanium electrodes during lithiation and delithiation

    NASA Astrophysics Data System (ADS)

    Al-Obeidi, Ahmed; Kramer, Dominik; Mönig, Reiner; Thompson, Carl V.

    2016-02-01

    The evolution of mechanical stresses during the cycling of lithium phosphorous oxynitride (LiPON) coated germanium thin film electrodes was monitored using substrate curvature measurements. By coating germanium thin films with LiPON, morphology evolution, e.g. crack and island formation, can be strongly suppressed. LiPON-coated germanium thin film electrodes can retain their planar form during cycling, resulting in a clear and reproducible stress response originating primarily from the electrochemical processes occurring during lithiation and delithiation. Together with the electrochemical data, stress measurements were used to infer mechanisms underlying the alloying of lithium with germanium. The stress signatures associated with individual phases, crystallization, and amorphization of lithium-germanium alloys are reported and discussed.

  2. Adhesion and friction behavior of group 4 elements germanium, silicon, tin, and lead

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1975-01-01

    Adhesion and friction studies were conducted with thin films of the group IV elements silicon, germanium, tin, and lead ion plated on the nickel (011) substrate. The mating surface was gold (111). Contacts were made for the elements in the clean state and with oxygen present. Adhesion and friction experiments were conducted at very light loads of 1 to 10 g. Sliding was at a speed of 0.7 mm/min. Friction results indicate that the more covalently bonded elements silicon and germanium exhibit lower adhesion and friction than the more metallic bonded tin and lead. The adhesion of gold to germanium was observed, and recrystallization of the transferred gold occurred. Plastic flow of germanium was seen with sliding. Oxygen reduced, but did not eliminate, the adhesion observed with germanium and silicon.

  3. IUPAC-NIST Solubility Data Series. 94. Rare Earth Metal Iodides and Bromides in Water and Aqueous Systems. Part 2. Bromides

    NASA Astrophysics Data System (ADS)

    Mioduski, Tomasz; Gumiński, Cezary; Zeng, Dewen; Voigt, Heidelore

    2013-03-01

    This work presents solubility data for rare earth metal bromides in water and in aqueous ternary systems. Compilations of all available experimental data are introduced for each rare earth metal bromide with a corresponding critical evaluation. Every such evaluation contains a collection of all solubility results in water, a selection of suggested solubility data and a brief discussion of the multicomponent systems. Because the ternary systems were almost never studied more than once, no critical evaluations of such data were possible. Only simple bromides (no complexes) are treated as the input substances in this work. The literature has been covered through the end of 2011.

  4. Bromoform formation in ozonated groundwater containing bromide and humic substances

    SciTech Connect

    Cooper, W.J.; Amy, G.L.; Moore, C.A.; Zika, R.G.

    1986-01-01

    The effect of bromide ion, organic carbon concentration (natural aquatic humic substances), pH, and solar irradiation on the formation of bromoform in ozonated groundwater has been studied. The studies were conducted on four unique samples of groundwater taken from different regions of the Biscayne Aquifer in southern Florida. All other conditions being equal, increases in bromide ion concentrations resulted in increases in CHBr/sub 3/ formation. In three of the four samples, CHBr/sub 3/ formation decreased as the pH level increased from 5 to 9. The fourth sample exhibited an opposite trend whereby the CHBr/sub 3/ concentration increased with increasing pH. Bromoform concentration increased with increased O/sub 3/ concentration over an ozone dosage range of 3.4 to 6.7 mg/L. Ozonated samples placed in sunlight immediately after ozone addition showed a decrease in the formation of CHBr/sub 3/ presumably due to the photodecomposition of HOBr/OBr.

  5. Crystal Growth of Germanium-Silicon Alloys on the ISS

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.; Croell, A.

    2015-01-01

    A series of Ge(1-x)Si(x) crystal growth experiments are planned to be conducted in the Low Gradient Furnace (LGF) onboard the International Space Station. The experiments are part of the investigation "Influence of Containment on the Growth of Silicon-Germanium" (ICESAGE). The primary objective of the research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon alloy crystals. A comparison will be made between crystals grown by the normal and "detached" Bridgman methods and the ground-based float zone technique. Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in crystals. "Detached" or "dewetted" Bridgman growth is similar to regular Bridgman growth in that most of the melt is in contact with the crucible wall, but the crystal is separated from the wall by a small gap, typically of the order of 10-100 microns. Long duration reduced gravity is essential to test the proposed theory of detached growth. Detached growth requires the establishment of a meniscus between the crystal and the ampoule wall. This meniscus can exist over a much larger range of processing parameters in microgravity and the meniscus is more stable under microgravity conditions. The plans for the flight experiments will be described.

  6. Intrinsic germanium detector used in borehole sonde for uranium exploration

    USGS Publications Warehouse

    Senftle, F.E.; Moxham, R.M.; Tanner, A.B.; Boynton, G.R.; Philbin, P.W.; Baicker, J.A.

    1976-01-01

    A borehole sonde (~1.7 m long; 7.3 cm diameter) using a 200 mm2 planar intrinsic germanium detector, mounted in a cryostat cooled by removable canisters of frozen propane, has been constructed and tested. The sonde is especially useful in measuring X- and low-energy gamma-ray spectra (40–400 keV). Laboratory tests in an artificial borehole facility indicate its potential for in-situ uranium analyses in boreholes irrespective of the state of equilibrium in the uranium series. Both natural gamma-ray and neutron-activation gamma-ray spectra have been measured with the sonde. Although the neutron-activation technique yields greater sensitivity, improvements being made in the resolution and efficiency of intrinsic germanium detectors suggest that it will soon be possible to use a similar sonde in the passive mode for measurement of uranium in a borehole down to about 0.1% with acceptable accuracy. Using a similar detector and neutron activation, the sonde can be used to measure uranium down to 0.01%.

  7. Electrical properties of neutron-transmutation-doped germanium

    SciTech Connect

    Rodder, M.

    1982-08-01

    Electrical properties of neutron-transmutation-doped germanium (NTD Ge) and nearly uncompensated gallium-doped germanium have been measured as functions of net-impurity concentration (2 x 10/sup 15/cm/sup -3/ less than or equal to N/sub A/ - N/sub D/ less than or equal to 5 x 10/sup 16/cm/sup -3/) and temperature (0.3 K less than or equal to T less than or equal to 300 K). The method of impurity conduction as a function of carrier concentration and compensation was investigated in the low temperature hopping regime. For nearest neighbor hopping, the resistivity is expected to vary as rho = rho/sub 0/exp(..delta../T) while Mott's theory of variable range hopping predicts that rho = rho/sub 0/exp(..delta../T)/sup 1/4/ in the low temperature limit. In contrast, our results show that the resistivity can best be approximated by rho = rho/sub 0/exp(..delta../T)/sup 1/2/ in the hopping regime down to 0.3 K.

  8. Materials and Fabrication Issues for Large Machined Germanium Immersion Gratings

    SciTech Connect

    Kuzmenko, P J; Davis, P J; Little, S L; Hale, L C

    2006-05-22

    LLNL has successfully fabricated small (1.5 cm{sup 2} area) germanium immersion gratings. We studied the feasibility of producing a large germanium immersion grating by means of single point diamond flycutting. Our baseline design is a 63.4o blaze echelle with a 6 cm beam diameter. Birefringence and refractive index inhomogeneity due to stresses produced by the crystal growth process are of concern. Careful selection of the grating blank and possibly additional annealing to relieve stress will be required. The Large Optics Diamond Turning Machine (LODTM) at LLNL is a good choice for the fabrication. It can handle parts up to 1.5 meter in diameter and 0.5 meter in length and is capable of a surface figure accuracy of better than 28 nm rms. We will describe the machine modifications and the machining process for a large grating. A next generation machine, the Precision Optical Grinder and Lathe (POGAL), currently under development has tighter specifications and could produce large gratings with higher precision.

  9. Materials and fabrication issues for large machined germanium immersion gratings

    NASA Astrophysics Data System (ADS)

    Kuzmenko, Paul J.; Davis, Pete J.; Little, Steve L.; Hale, Layton C.

    2006-06-01

    LLNL has successfully fabricated small (1.5 cm2 area) germanium immersion gratings. We studied the feasibility of producing a large germanium immersion grating by means of single point diamond flycutting. Our baseline design is a 63.4° blaze echelle with a 6 cm beam diameter. Birefringence and refractive index inhomogeneity due to stresses produced by the crystal growth process are of concern. Careful selection of the grating blank and possibly additional annealing to relieve stress will be required. The Large Optics Diamond Turning Machine (LODTM) at LLNL is a good choice for the fabrication. It can handle parts up to 1.5 meter in diameter and 0.5 meter in length and is capable of a surface figure accuracy of better than 28 nm rms. We will describe the machine modifications and the machining process for a large grating. A next generation machine, the Precision Optical Grinder and Lathe (POGAL), currently under development has tighter specifications and could produce large gratings with higher precision.

  10. Evaluating a new segmented germanium detector contact technology

    NASA Astrophysics Data System (ADS)

    Jackson, E. G.; Lister, C. J.; Chowdhury, P.; Hull, E.; Pehl, R.

    2012-10-01

    New technologies for making gamma ray detectors position sensitive have many applications in space science, medical imaging, homeland security, and in nuclear structure research. One promising approach uses high-purity germanium wafers with the planar surfaces segmented into orthogonal strip patterns forming a Double-Sided Strip Detector (DSSD). The combination of data from adjoining strips, or pixels, is physics-rich for Compton image formation and polarization studies. However, sensitivity to charge loss and various kinds of cross-talk [1] have limited the usefulness of first generation devices. We are investigating new contact technologies, developed by PhDs Co [2], based on amorphous-germanium and yttrium contacts RF sputter deposited to a thickness of ˜ 1000 å. New techniques allow both physical and photolithographic segmentation of the contacts with inter-strip gap widths of 0.25 mm. These modifications should improve all aspects of charge collection. The new detector technology employs the same material and fabrication technique for both the n- and p- contacts, thus removing artificial asymmetry in the data. Results from tests of cross-talk, charge collection, and scattering asymmetry will be presented and compared with older technologies. This mechanically cooled counter, NP-7, seems to represent a breakthrough.[4pt] [1] S. Gros et al., Nucl. Inst. Meth. A 602, 467 (2009).[0pt] [2] E. Hull et al Nucl Inst Meth A 626, 39 (2011)

  11. Background Reduction For Germanium Double Beta Decay Experiments

    SciTech Connect

    Gomez, H.; Cebrian, S.; Morales, J.; Villar, J. A.

    2007-03-28

    The new generation experiments to search for the neutrinoless double beta decay of 76Ge (Q{beta}{beta}=2039keV) using enriched germanium detectors, need to reach a background level of {approx}10-3 c keV-1 kg-1 y-1 in the Region of Interest (RoI: 2-2.1 MeV) that would have, for 70 kg of germanium enriched to 86% in 76Ge, 3 keV of FWHM and 5 years of measuring time, a sensitivity on the effective neutrino mass of {<=} 40 meV. To reduce the background level close to the value needed, we have to combine several techniques. Three of the most important points to study are: segmentation and granularity of the crystal and spatial resolution of the detector directly correlated with an offline Pulse Shape Analysis (PSA). Preliminary studies about these strategies for background reduction were developed during last months, obtaining some promising results.

  12. Initial Component Testing for a Germanium Array Cryostat

    SciTech Connect

    Keillor, Martin E.; Aalseth, Craig E.; Day, Anthony R.; Fast, James E.; Hoppe, Eric W.; Hyronimus, Brian J.; Hossbach, Todd W.; Seifert, Allen

    2009-06-01

    This report describes progress on the construction of two ultra-low-background cryostats that are part of the NA-22 funded “Radionuclide Laboratories” (RN Labs) project. Each cryostat will house seven high-purity germanium crystals (HPGe). These cryostats are being built from a limited set of materials that are known to have very low levels of radioactive impurities. The RN Labs instrument is designed to take advantage of low background performance, high detection efficiency, and γ-γ coincidence signatures to provide unprecedented gamma spectroscopy sensitivity. The project is focused on improving gamma analysis capabilities for nuclear detonation detection (NDD) applications. The instrument also has the potential for basic nuclear physics research. Section 1 provides the background for the project. Section 2 discusses germanium crystal acceptance testing. Design problems were found after the first delivery of new detectors from the vendor, Canberra Semiconductors. The first four crystals were returned for repair, resulting in a delay in crystal procurement. Section 3 provides an update on copper electroforming. In general, electroforming parts for RN Labs has proceeded smoothly, but there have been recent problems in electroforming three large copper parts necessary for the project. Section 4 describes the first round of testing for the instrument: anti-cosmic scintillator testing, electronics testing, and initial vacuum testing. Section 5 concludes with an overall description of the state of the project and challenges that remain.

  13. Monte Carlo of Cryogenic Dark Matter Search large germanium detectors

    NASA Astrophysics Data System (ADS)

    Leman, Steven; McCarty, Kevin; Cabrera, Blas; Pyle, Matthew; Sundqvist, Kyle; Sadoulet, Bernard

    2010-02-01

    A description of the Cryogenic Dark Matter Search (CDMS) detector Monte Carlo (MC) is given along with a comparison to calibration data obtained in 3" diameter, 1" thick [100] germanium crystals. Prompt phonons are generated from electron-recoil interactions along with Luke phonons created by charges as they drift through the crystal via our ionization channels' electric field. The MC phonon transport is described by quasidiffusion, which includes anisotropic propagation, isotope scattering and anharmonic decay, until the phonons are absorbed in either the Transition Edge Sensor based phonon channels or lost in surface interactions. Charge creation is a powerful discriminator for electron-recoil and nuclear-recoil events and also surface interaction rejection. Unlike holes, electrons transports obliquely to the electric field in our detectors due to the germanium [100] crystal orientation and the indirect semiconductor band structure. We are improving the agreement between MC and calibration data in different detector designs, which provides a powerful consistency test of our phonon and charge models. )

  14. Reduction of phosphorus diffusion in germanium by fluorine implantation

    SciTech Connect

    El Mubarek, H. A. W.

    2013-12-14

    The control of phosphorus (P) diffusion in germanium (Ge) is essential for the realisation of ultrashallow n-type junctions in Ge. This work reports a detailed study of the effect of fluorine (F) co-implantation on P diffusion in Ge. P and F profiles were characterized by secondary ion mass spectroscopy. The ion implantation damage was investigated using cross sectional transmission electron microscopy. It is shown that F co-implantation reduces the implanted P profile width and reduces both intrinsic and extrinsic P diffusion in Ge. A defect mediated mechanism for the strong influence of F co-implantation on P diffusion in Ge is proposed and invokes the formation of F{sub n}V{sub m} clusters in the F-amorphized Ge layer. A fraction of these F{sub n}V{sub m} clusters decorate the interstitial type end-of-range defects in the re-grown Ge layer and the rest react during re-growth with interstitial germanium atoms diffusing back from the amorphous crystalline interface. The Ge vacancies are then annihilated and mobile interstitial F is released and out diffuses from the surface. This results in a re-grown Ge layer which has a low vacancy concentration and in which the P diffusion rate is reduced. These results open the way to the realization of enhanced Ge n-type devices.

  15. The distribution of bromide in water in the Floridan aquifer system, Duval County, northeastern Florida

    USGS Publications Warehouse

    German, E.R.; Taylor, G.F.

    1995-01-01

    Although Duval County, Florida, has ample ground-water resources for public supply, the potential exists for a problem with excessive disinfectant by-products. These disinfectant by-products result from the treatment of raw water containing low concentrations of bromide and naturally occurring organic compounds. Because of this potential problem, the relation of bromide concentrations to aquifer tapped, well location and depth, and chemical characteristics of water in the Floridan aquifer system underlying Duval County were studied to determine if these relations could be applied to delineate water with low-bromide concentrations for future supplies. In 1992, water samples from 106 wells that tap the Floridan aquifer system were analyzed for bromide and major dissolved constituents. A comparison of bromide concentrations from the 1992 sampling with data from earlier studies (1979-80) indicates that higher bromide concentrations were detected during the earlier studies. The difference between the old and new data is probably because of a change in analytical methodology in the analysis of samples. Bromide concentrations exceeded the detection limit (0.10 milligrams per liter) in water from 28 of the 106 wells (26 percent) sampled in 1992. The maximum concentration was 0.56 milligrams per liter. There were no relations between bromide and major dissolved constituents, well depth, or aquifer tapped that would be useful for determining bromide concentrations. Areal patterns of bromide occurrence are not clearly defined, but areas with relatively high bromide concentrations tend to be located in a triangular area near the community of Sunbeam, Florida, and along the St. Johns River throughout Duval County.

  16. Validation of an automated fluorescein method for determining bromide in water

    USGS Publications Warehouse

    Fishman, M. J.; Schroder, L.J.; Friedman, L.C.

    1985-01-01

    Surface, atmospheric precipitation and deionized water samples were spiked with ??g l-1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0.015 to 0.5 mg l-1 of bromide. The correlation coefficient for the same sets of paired data is 0.9987. Recovery data, except for the surface water samples to which 0.005 mg l-1 of bromide was added, range from 89 to 112%. There appears to be no loss of bromide from solution in either type of container.Surface, atmospheric precipitation and deionized water samples were spiked with mu g l** minus **1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0. 015 to 0. 5 mg l** minus **1 of bromide. The correlation coefficient for the same sets of paired data is 0. 9987. Recovery data, except for the surface water samples to which 0. 005 mg l** minus **1 of bromide was added, range from 89 to 112%. Refs.

  17. Germanium Isotopic Fractionation in Iron Meteorites : Comparison with Experimental Data

    NASA Astrophysics Data System (ADS)

    Luais, B.; Toplis, M.; Tissandier, L.; Roskosz, M.

    2009-05-01

    Magmatic and non-magmatic iron meteorites are thought to be formed respectively by processes of metal- silicate segregation, and complex impacts on undifferentiated parent bodies. These processes are inferred from variations of siderophile element concentrations, such as Ge, Ni, Ir. Germanium is moderately siderophile, with metal-silicate partition coefficients which depend on oxygen fugacity. Germanium is also moderately volatile, and fractionation would be expected during high temperature processes. In order to investigate the extent of elemental and isotopic fractionation of germanium during metal-silicate equilibria and impact processes, we use a double approach including (1) Ge isotopic measurements of iron meteorites from non-magmatic and magmatic groups [1], and (2) experimental investigations of the isotopic fractionation associated with germanium transfer from an oxidized silicate liquid to a metallic phase under various fO2 conditions. Experiments were performed in a 1 atm vertical drop quench furnace, with starting materials corresponding to a glass of 1 bar An-Di euctectic composition doped with ˜ 4,000 ppm reference Ge standard, and pure Ni capsules as the metal phase. The assembly was heated at 1355°C for t =2 to 60 hrs over a range of fO2 from 4 log units below, to 2.5 log units above, the IW buffer. Metal and silicate phases were then mechanically separated. For isotopic measurements, the metal phase of these experiments and the selected iron meteorites were dissolved in high-purity dilute nitric acid. Chemical purification of Ge, and isotopic measurements using the Isoprobe MC-ICPMS follow Luais (2007). Germanium isotopic measurements of Fe-meteorites show that δ74Ge of magmatic irons are constant (δ74Ge=+1.77±0.22‰, 2σ), but heavier than non-magmatic irons (IAB : +1.15±0.2‰; IIE : -0.27 to +1.40±0.2‰). Time series experiments at the IW buffer show that there is a clear continuous increase in δ 74Ge in the metal as a function of time

  18. Removal of bromide by aluminium chloride coagulant in the presence of humic acid.

    PubMed

    Ge, Fei; Shu, Haimin; Dai, Youzhi

    2007-08-17

    Bromide can form disinfection by-products (DBPs) in drinking water disinfection process, which have adverse effects on human health. Using aluminium chloride as a model coagulant, removal of bromide by coagulation was investigated in the absence or presence of humic acid (HA) in synthetic water and then was conducted in raw water. Results demonstrated that in synthetic water, 93.3-99.2% removal efficiency of bromide was achieved in the absence of HA with 3-15 mg/L coagulant, while 78.4-98.4% removal efficiency of bromide was obtained in the presence of HA with the same coagulant dosage and 86.8-98.8% HA was removed simultaneously. Bromide in raw water was removed 87.0% with 15 mg/L coagulant. HA apparently reduced the removal of bromide with low coagulant dosage or at high pH, while minor influence on removal of bromide was observed with high coagulant dosage or at low pH. Thus, bromide could be reduced effectively by enhanced coagulation in drinking water treatment. PMID:17289257

  19. Solid phase microextraction for active or passive sampling of methyl bromide during fumigations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The high diffusivity and volatility of methyl bromide make it an ideal compound for Solid Phase Micro Extraction (SPME)-based sampling of air prior to gas-chromatographic quantifications. SPME fibers can be used as active methyl bromide samplers, with high capacities and an equilibrium time of 1-2 m...

  20. Enthalpies of complex formation of boron and aluminum bromides with organic bases of high donor power

    SciTech Connect

    Grigor-ev, A.A.; Kondrat'ev, Y.V.; Suvorov, A.V.

    1986-11-20

    By the calorimetric method enthalpies of complex formation were determined for boron and aluminum bromides with piperidine and hexamethylphosphoric triamide in benzene solutions and for boron bromide with pyridine in dichloroethane, and also enthalpies of solution were determined for BBr/sub 3/ and the adducts AlBr/sub 3/ x PPy and BBr/sub 2/ x Py in benzene and pyridine.

  1. Destruction of methyl bromide sorbed to activated carbon by thiosulfate and electrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide is widely used as a fumigant for post-harvest and quarantine uses at port facilities due to the low treatment times required, but it is vented to the atmosphere after its use. Due to the potential contributions of methyl bromide to stratospheric ozone depletion, technologies for the c...

  2. Palladium-Catalyzed Selective α-Alkenylation of Pyridylmethyl Ethers with Vinyl Bromides.

    PubMed

    Yang, Xiaodong; Kim, Byeong-Seon; Li, Minyan; Walsh, Patrick J

    2016-05-20

    An efficient palladium-catalyzed α-alkenylation of pyridylmethyl ethers with vinyl bromides is presented. A Pd/NIXANTPHOS-based catalyst system enables a mild and chemoselective coupling between a variety of pyridylmethyl ethers and vinyl bromides in good to excellent yields. Under the mild conditions, β,γ-unsaturated products are obtained without isomerization or Heck byproducts observed. PMID:27160421

  3. 77 FR 48153 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-13

    ...On May 17, 2012, the EPA published a notice in the Federal Register requesting applications for the Critical Use Exemption from the phaseout of methyl bromide for 2015. On August 3, 2012, EPA received a letter from methyl bromide stakeholders requesting an extension to the August 15, 2012 deadline for submitting Critical Use Exemption applications. The letter requested a deadline of August 29,......

  4. 76 FR 34700 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-14

    ... AGENCY Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications... exemption from the phaseout of methyl bromide for 2014. Critical use exemptions last only one year. All... interested parties to provide EPA with new data on the technical and economic feasibility of methyl...

  5. 75 FR 41177 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-15

    ... AGENCY Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications... exemption from the phaseout of methyl bromide for 2013. Critical use exemptions last only one year. All... interested parties to provide EPA with new data on the technical and economic feasibility of methyl...

  6. In vivo and in vitro bromide equilibration time course in adults and sample handling effect

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extracellular water is a major component of body weight and an indicator of nutritional status. Bromide dilution has been used to estimate this compartment. Recent evidence, however, indicates that the bromide equilibration time is longer than the 4 hr assumed in many studies. The aim of this stud...

  7. Methyl bromide fumigation of packed table grapes: Effect of shipping box on gas concentrations and phytotoxicity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current methyl bromide schedules for table grapes to control mealybugs are approved for fruit packed in Toyon Kraft Veneer (TKV) boxes. The question arose concerning equivalence of exposure to methyl bromide if an Extruded Polystyrene (EPS) box was used in lieu of the TKV box for table grapes being ...

  8. Performance of soil solarization and methyl bromide in sites infested with root-knot nematodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil fumigation with methyl bromide has been the principal means of managing soil-borne pest problems on ornamental crops in the United States for many years. Interest in effective alternatives increased during the phase-out of methyl bromide, and will become more acute as existing stocks are deple...

  9. Germanium ion implantation to Improve Crystallinity during Solid Phase Epitaxy and the effect of AMU Contamination

    SciTech Connect

    Lee, K. S.; Yoo, D. H.; Son, G. H.; Lee, C. H.; Noh, J. H.; Han, J. J.; Yu, Y. S.; Hyung, Y. W.; Kim, Y. K.; Lee, S. C.; Lee, H. D.; Moon, J. T.; Yang, J. K.; Song, D. G.; Lim, T. J.

    2006-11-13

    Germanium ion implantation was investigated for crystallinity enhancement during solid phase epitaxial regrowth (SPE) using high current implantation equipment. Electron back-scatter diffraction(EBSD) measurement showed numerical increase of 19 percent of <100> signal, which might be due to pre-amorphization effect on silicon layer deposited by LPCVD process with germanium ion implantation. On the other hand, electrical property such as off-leakage current of NMOS transistor degraded in specific regions of wafers, which implied non-uniform distribution of donor-type impurities into channel area. It was confirmed that arsenic atoms were incorporated into silicon layer during germanium ion implantation. Since the equipment for germanium pre-amorphization implantation(PAI) was using several source gases such as BF3 and AsH3, atomic mass unit(AMU) contamination during PAI of germanium with AMU 74 caused the incorporation of arsenic with AMU 75 which resided in arc-chamber and other parts of the equipment. It was effective to use germanium isotope of AMU 72 to suppress AMU contamination, however it led serious reduction of productivity because of decrease in beam current by 30 percent as known to be difference in isotope abundance. It was effective to use enriched germanium source gas with AMU 72 in order to improve productivity. Spatial distribution of arsenic impurities in wafers was closely related to hardware configuration of ion implantation equipment.

  10. Formation of germanium oxide microcrystals on the surface of Te-implanted Ge

    NASA Astrophysics Data System (ADS)

    Perrin Toinin, J.; Rudzevich, Y.; Hoummada, K.; Texier, M.; Bernardini, S.; Portavoce, A.; Chow, L.

    2015-12-01

    The formation of voids on the surface of heavily implanted germanium has been known for more than 30 years. Recently there is a renewed interest in germanium due to its potential application in the complementary metal oxide semiconductor (CMOS) devices. Here we report the observation of germanium oxide microcrystals formed on the surface of tellurium implanted into a germanium substrate. The Ge target used was a (1 0 0) polished single crystalline germanium wafer and the implantation was carried out at room temperature with Te ions at 180 keV and a fluence of 3.6 × 1015 at/cm2. Under scanning electron microscope (SEM), the surface of the Ge substrate is evenly covered by microcrystals with a diameter about 1-2 μm and a coverage density of ∼107 particles/cm2. The initially smooth surface of the polished germanium substrate becomes very rough and mostly consists of voids with an average diameter of 40-60 nm, which is consistent with reports of heavily implanted germanium. The composition of the microcrystals was studied using energy dispersive X-ray analysis (EDX) and atom probe tomography (APT) and will be presented. Preliminary results indicate that tellurium is not detected in the microcrystals. The origin of the microcrystals will be discussed.

  11. Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring

    SciTech Connect

    Hull, Ethan L.; Pehl, Richard H.; Lathrop, James R.; Martin, Gregory N.; Mashburn, R. B.; Miley, Harry S.; Aalseth, Craig E.; Hossbach, Todd W.; Bowyer, Ted W.

    2006-09-21

    Compact maintenance free mechanical cooling systems are being developed to operate large volume (~570 cm3, ~3 kg, 140% or larger) germanium detectors for field applications. We are using a new generation of Stirling-cycle mechanical coolers for operating the very largest volume germanium detectors with absolutely no maintenance or liquid nitrogen requirements. The user will be able to leave these systems unplugged on the shelf until needed. The flip of a switch will bring a system to life in ~1 hour for measurements. The maintenance-free operating lifetime of these detector systems will exceed five years. These features are necessary for remote long-duration liquid-nitrogen free deployment of large-volume germanium gamma-ray detector systems for Nuclear Explosion Monitoring (NEM). The Radionuclide Aerosol Sampler/Analyzer (RASA) will greatly benefit from the availability of such detectors by eliminating the need for liquid nitrogen at RASA sites while still allowing the very largest available germanium detectors to be utilized. These mechanically cooled germanium detector systems being developed here will provide the largest, most sensitive detectors possible for use with the RASA. To provide such systems, the appropriate technical fundamentals are being researched. Mechanical cooling of germanium detectors has historically been a difficult endeavor. The success or failure of mechanically cooled germanium detectors stems from three main technical issues: temperature, vacuum, and vibration. These factors affect one another. There is a particularly crucial relationship between vacuum and temperature. These factors will be experimentally studied both separately and together to insure a solid understanding of the physical limitations each factor places on a practical mechanically cooled germanium detector system for field use. Using this knowledge, a series of mechanically cooled germanium detector prototype systems are being designed and fabricated. Our collaborators

  12. Classifying the Basic Parameters of Ultraviolet Copper Bromide Laser

    NASA Astrophysics Data System (ADS)

    Gocheva-Ilieva, S. G.; Iliev, I. P.; Temelkov, K. A.; Vuchkov, N. K.; Sabotinov, N. V.

    2009-10-01

    The performance of deep ultraviolet copper bromide lasers is of great importance because of their applications in medicine, microbiology, high-precision processing of new materials, high-resolution laser lithography in microelectronics, high-density optical recording of information, laser-induced fluorescence in plasma and wide-gap semiconductors and more. In this paper we present a statistical study on the classification of 12 basic lasing parameters, by using different agglomerative methods of cluster analysis. The results are based on a big amount of experimental data for UV Cu+ Ne-CuBr laser with wavelengths 248.6 nm, 252.9 nm, 260.0 nm and 270.3 nm, obtained in Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences. The relevant influence of parameters on laser generation is also evaluated. The results are applicable in computer modeling and planning the experiments and further laser development with improved output characteristics.

  13. Unveiling Residual Molecular Binding in Triply Charged Hydrogen Bromide

    SciTech Connect

    Penent, F.; Lablanquie, P.; Palaudoux, J.; Gamblin, G.; Carniato, S.; Andric, L.; Hikosaka, Y.; Ito, K.

    2011-03-11

    We present an experimental and theoretical study of triply charged hydrogen bromide ions formed by photoionization of the inner 3d shell of Br. The experimental results, obtained by detecting the 3d photoelectron in coincidence with the two subsequent Auger electrons, are analyzed using calculated potential energy curves of HBr{sup 3+}. The competition between the short-range chemical binding potential and the Coulomb repulsion in the dissociative process is shown. Two different mechanisms are observed for double Auger decay: one, a direct process with simultaneous ejection of two Auger electrons to final HBr{sup 3+} ionic states and the other, a cascade process involving double Auger decay characterized by the autoionization of Br*{sup +} ion subsequent to the HBr{sup 2+} fragmentation.

  14. Thermal parameters of carbon nanotubes and potassium bromide composites

    NASA Astrophysics Data System (ADS)

    Depriester, Michael; Hus, Philippe; Sahraoui, Abdelhak Hadj; Roussel, Frédérick

    2011-04-01

    Photothermal radiometry is employed to investigate the thermal parameters (diffusivity, effusivity, conductivity, and heat capacity) of carbon nanotubes [single-walled (SWNT) or multiple-walled (MWNT)] and potassium bromide (KBr) pressed pellets as a function of SWNT or MWNT mass fraction. A significant enhancement of the thermal conductivity for carbon nanotubes (CNTs) contents up to 2 wt. % was observed. Above 3 wt. % CNT, a morphological transition from a compacted to an unconsolidated granular media occurs leading to a sharp decrease of the thermal conductivity (k) caused by the presence of air interfaces. A geometrical model based on interpenetrating continua is applied to describe the unusual evolution of the thermal conductivity. The behavior of k is also discussed in regard to the latest theoretical reports.

  15. Timing resolution measurements of a 3 in. lanthanum bromide detector

    NASA Astrophysics Data System (ADS)

    Galli, L.; De Gerone, M.; Dussoni, S.; Nicolò, D.; Papa, A.; Tenchini, F.; Signorelli, G.

    2013-08-01

    Cerium-doped lanthanum bromide (LaBr3:Ce) is a scintillator that presents very good energy and timing resolutions and it is a perfect candidate for photon detector in future experiments to search for lepton flavor violation as in μ → eγ or μ → e conversion. While energy resolution was thoroughly investigated, timing resolution at several MeV presents some experimental challenge. We measured the timing resolution of a 3 in.×3 in. cylindrical LaBr3(Ce) crystal versus few reference detectors by means of a nuclear reaction from a Cockcroft-Walton accelerator that produces coincident γ-rays in the 4.4-11.6 MeV range. Preliminary results allow us to extrapolate the properties of a segmented γ-ray detector in the 50-100 MeV range.

  16. Tiotropium Bromide in Chronic Obstructive Pulmonary Disease and Bronchial Asthma

    PubMed Central

    Alvarado-Gonzalez, Alcibey; Arce, Isabel

    2015-01-01

    Inhaled bronchodilators are the mainstay of pharmacological treatment for stable chronic obstructive pulmonary disease (COPD), including β2-agonists and muscarinic antagonists. Tiotropium bromide, a long-acting antimuscarinic bronchodilator (LAMA), is a treatment choice for moderate-to-severe COPD; its efficacy and safety have been demonstrated in recent trials. Studies also point to a beneficial role of tiotropium in the treatment of difficult-to-control asthma and a potential function in the asthma-COPD overlap syndrome (ACOS). Combination of different bronchodilator molecules and addition of inhaled corticosteroids are viable therapeutic alternatives. A condensation of the latest trials and the rationale behind these therapies will be presented in this article. PMID:26491494

  17. Simultaneous electrochemical determination of three sunscreens using cetyltrimethylammonium bromide.

    PubMed

    Cardoso, Juliano Carvalho; Armondes, Bruna Milca Lenzi; Ferreira, João Bosco Galindo Júnior e Valdir Souza

    2008-05-01

    This paper proposes a methodology based on electrochemical reduction for the simultaneous determination of three sunscreen agents, namely 4-methylbenzylidene camphor (MBC), benzophenone-3 (BENZO) and 2-ethylhexyl-4-methoxycinnamate (EHMC) by differential-pulse polarography (DPP). The highest peak currents and optimal separation of reduction peaks were obtained by using a supporting electrolyte consisted of Britton-Robinson buffer-methanol (8:2) solution at pH 4.0 and cationic surfactant 3.0 x 10(-4)mol L(-1) cetyltrimethylammonium bromide (CTAB). The methodology was validated using four commercial sunscreen preparation as a sample and the results showed high recovery rates. The efficiency of the proposed methodology was demonstrated by comparing the results obtained by DPP with those obtained by the high-performance liquid chromatography (HPLC) method. PMID:18093812

  18. Absorption of Water Vapor into Aqueous Solutions of Lithium Bromide

    NASA Astrophysics Data System (ADS)

    Takahara, Tsutomu; Hayashida, Atsushi; Yabase, Hajime; Hihara, Eiji; Saito, Takamoto

    Heat and mass transfer processes are experimentally investigated for the case of water absorption into aqueous solutions of lithium bromide flowing over a flat plate. Variables considered are inlet solution flow rate,concentration of an additive,and inclination angle of the plate. The use of 2-ethyl-1-hexanol as an additive results in about a four to five fold improvement in absorption rate. The occurrence of surface distrbances dose not has a direct connection with the solubility limit of the additive. The cause of the surface disturbances in the presence of additives is investigated through experiments for pool absorption By regulating the flow of water vapor,the form of the Marangoni convection can be controlled. A qualitative discussion of addictives in the role of inducing surface disturbances is presented.

  19. Location of Bromide Ions in Tetragonal Lysozyme Crystals

    NASA Technical Reports Server (NTRS)

    Lim, Kap; Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    Anions have been shown to play a dominant role in the crystallization of chicken egg white lysozyme from salt solutions. Previous studies employing X-ray crystallography had found one chloride ion binding site in the tetragonal crystal form of the protein and four nitrate ion binding sites in the monoclinic form. In this study the anion positions in the tetragonal form were determined from the difference Fourier map obtained from lysozyme crystal grown in bromide and chloride solutions. Five possible anion binding sites were found in this manner. Some of these sites were in pockets containing basic residues while others were near neutral, but polar, residues. The sole chloride ion binding site found in previous studies was confirmed, while four of these sites corresponded to four binding sites found for nitrate ions in monoclinic crystals. The study suggests that most of the anion binding sites in lysozyme remain unchanged, even when different anions and different crystal forms of lysozyme are employed.

  20. Detecting Arbitrary DNA Mutations Using Graphene Oxide and Ethidium Bromide.

    PubMed

    Huang, Jiahao; Wang, Zhenyu; Kim, Jang-Kyo; Su, Xuefen; Li, Zhigang

    2015-12-15

    We propose a simple and fast method for detecting arbitrary DNA mutations. Single-stranded DNA probes labeled with fluorescein amidite (FAM-ssDNA), ethidium bromide (EB), and graphene oxide (GO) are employed in the sensing system. The detection is achieved in two steps. In the first step, the sensing system contains FAM-ssDNA probes and EB molecules. It exhibits different fluorescence emissions in the presence of perfectly matched, mismatched, and random DNA sequences. With the addition of GO in the second step, the fluorescence signal for perfectly matched and random DNA does not vary greatly, which, however, experiences a significant change for mismatched DNA targets. The signal ratio before and after the addition of GO can clearly distinguish mutations from normal and random DNA sequences. The detection method works well regardless of the mutation positions and only requires "mix-and-detect" steps, which are completed within 15 min. PMID:26559174

  1. N-(2-Bromo­benz­yl)cinchoninium bromide

    PubMed Central

    Skórska-Stania, Agnieszka; Jezierska-Zięba, Magdalena; Kąkol, Barbara; Fedoryński, Michał; Oleksyn, Barbara J.

    2012-01-01

    The title compound {systematic name: 1-(2-bromo­benz­yl)-5-ethenyl-2-[hy­droxy(quinolin-4-yl)meth­yl]-1-aza­bicyclo­[2.2.2]octan-1-ium bromide}, C26H28BrN2O+·Br−, is a chiral quater­nary ammonium salt of one of the Cinchona alkaloids. The planes of the quinoline and of the bromo­benzyl substituent are inclined to one another by 9.11 (9)°. A weak intra­molecular C—H⋯O hydrogen bond occurs. The crystal structure features strong O—H⋯Br hydrogen bonds and weak C—H⋯Br inter­actions. PMID:22969676

  2. Error Evaluation of Methyl Bromide Aerodynamic Flux Measurements

    USGS Publications Warehouse

    Majewski, M.S.

    1997-01-01

    Methyl bromide volatilization fluxes were calculated for a tarped and a nontarped field using 2 and 4 hour sampling periods. These field measurements were averaged in 8, 12, and 24 hour increments to simulate longer sampling periods. The daily flux profiles were progressively smoothed and the cumulative volatility losses increased by 20 to 30% with each longer sampling period. Error associated with the original flux measurements was determined from linear regressions of measured wind speed and air concentration as a function of height, and averaged approximately 50%. The high errors resulted from long application times, which resulted in a nonuniform source strength; and variable tarp permeability, which is influenced by temperature, moisture, and thickness. The increase in cumulative volatilization losses that resulted from longer sampling periods were within the experimental error of the flux determination method.

  3. Rejection of Bromide and Bromate Ions by a Ceramic Membrane

    PubMed Central

    Moslemi, Mohammadreza; Davies, Simon H.; Masten, Susan J.

    2012-01-01

    Abstract Effects of pH and the addition of calcium chloride (CaCl2) on bromate (BrO3−) and bromide (Br−) rejection by a ceramic membrane were investigated. Rejection of both ions increased with pH. At pH 8, the rejection of BrO3− and Br− was 68% and 63%, respectively. Donnan exclusion appears to play an important role in determining rejection of BrO3− and Br−. In the presence of CaCl2, rejection of BrO3− and Br− ions was greatly reduced, confirming the importance of electrostatic interactions in determining rejection of BrO3− and Br−. The effect of Ca2+ is so pronounced that in most natural waters, rejection of both BrO3− and Br− by the membrane would be extremely small. PMID:23236251

  4. Action of pinaverium bromide, a calcium-antagonist, on gastrointestinal motility disorders.

    PubMed

    Christen, M O

    1990-01-01

    1. The evidence reviewed here indicates that pinaverium bromide (Dicetel) relaxes gastrointestinal (GI) structures primarily by inhibiting Ca2+ influx through potential-dependent channels of surface membranes of smooth muscle cells. 2. The in vivo selectivity of pinaverium bromide for the GI tract appears to be due mainly to its pharmacokinetic properties. Because of its low absorption (typical for quaternary ammonium compounds) and marked hepatobiliary excretion, most of the orally-administered dose of pinaverium bromide remains in the GI tract. 3. Orally-administered pinaverium bromide does not elicit adverse cardiovascular side-effects at doses that effectively relieve GI spasm, pain, transit disturbances and other symptoms related to motility disorders. 4. Pinaverium bromide is the only Ca2(+)-antagonist with known therapeutic efficacy in the treatment of irritable bowel syndrome and certain other functional intestinal disorders. PMID:2177709

  5. Comparative mobility of sulfonamides and bromide tracer in three soils

    USGS Publications Warehouse

    Kurwadkar, S.T.; Adams, C.D.; Meyer, M.T.; Kolpin, D.W.

    2011-01-01

    In animal agriculture, sulfonamides are one of the routinely used groups of antimicrobials for therapeutic and sub-therapeutic purposes. It is observed that, the animals when administered the antimicrobials, often do not completely metabolize them; and excrete the partially metabolized forms into the environment. Due to the continued use of antimicrobials and disposal of untreated waste, widespread occurrence of partially metabolized antimicrobials in aquatic and terrestrial environments has been reported in various scientific journals. In this research, the mobility of two sulfonamides - sulfamethazine (SMN), sulfathiazole (STZ) and a conservative bromide tracer was investigated in three soils collected from regions in the United States with large number of concentrated animal-feed operations. Results of a series of column studies indicate that the mobility of these two sulfonamides was dependent on pH, soil charge density, and contact time. At low pH and high charge density, substantial retention of sulfonamides was observed in all three soils investigated, due to the increased fraction of cationic and neutral forms of the sulfonamides. Conversely, enhanced mobility was observed at high pH, where the sulfonamides are predominantly in the anionic form. The results indicate that when both SMN and STZ are predominantly in anionic forms, their mobility approximates the mobility of a conservative bromide tracer. This observation is consistent for the mobility of both SMN and STZ individually, and also in the presence of several other antimicrobials in all three soils investigated. Higher contact time indicates lower mobility due to increased interaction with soil material. ?? 2011.

  6. Influence of Containment on the Growth of Silicon-Germanium: A Materials Science Flight Project

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.; Croell, A.

    2012-01-01

    This investigation involves the comparison of results achieved from three types of crystal growth of germanium and germanium-silicon alloys: (1) Float zone growth (2) Bridgman growth (3) Detached Bridgman growth crystal The fundamental goal of the proposed research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon (GeSi) crystals (silicon concentration in the solid up to 5 at%) for three different growth configurations in order to quantitatively assess the improvements of crystal quality possible by detached growth.

  7. Discrimination of nuclear and electronic recoil events using plasma effect in germanium detectors

    NASA Astrophysics Data System (ADS)

    Wei, W.-Z.; Liu, J.; Mei, D.-M.

    2016-07-01

    We report a new method of using the plasma time difference, which results from the plasma effect, between the nuclear and electronic recoil events in high-purity germanium detectors to distinguish these two types of events in the search for rare physics processes. The physics mechanism of the plasma effect is discussed in detail. A numerical model is developed to calculate the plasma time for nuclear and electronic recoils at various energies in germanium detectors. It can be shown that under certain conditions the plasma time difference is large enough to be observable. The experimental aspects in realizing such a discrimination in germanium detectors is discussed.

  8. Characterization of three planar germanium detectors fabricated with the crystals grown at USD

    NASA Astrophysics Data System (ADS)

    Nazir, Hossain; Huang, Mianliang; Khizar, Muhammad; Mei, Dongming; Wang, Guojian; Mei, Hao; Guan, Yutong; University of South Dakota Team

    2014-03-01

    We characterized the performance of planar germanium detectors developed in the University of South Dakota (USD). The planar detectors were made from high purity germanium crystals with amorphous germanium contacts. These detectors were developed possible for the neutrinoless double beta-decay measurements and dark matter search underground. They were tested in a temporary cryostat to investigate the depletion voltage, leakage current, efficiency and resolution using a 60Co γ ray source. This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota.

  9. Improving Thick Germanium Detectors: Cryogenic Dark Matter Search

    NASA Astrophysics Data System (ADS)

    Epstein, Paulette; Mahapatra, Rupak; CDMS at Texas A&M University Team

    2011-10-01

    Texas A&M University is working on improving the current production rate, quality, and reproducibility of fabricated detectors, specifically for the Cryogenic Dark Matter Search (CDMS) to detect particles called WIMPs (Weakly Interacting Massive Particles). An automated sputtering system is used to deposit amorphous silicon and high quality tungsten and aluminum thin-films on 3 inch by 1 inch germanium substrates to demonstrate repeatable depositions with desired properties, such as, accurate thickness, desirable critical temperature, and good sensitivity at low energy. These techniques can then be used in the future to improve detectors, not only for the search for Dark Matter, but for other areas of research in nuclear and particle physics. Funded by DOE and NSF-REU Program.

  10. Germanium-Vacancy Single Color Centers in Diamond

    PubMed Central

    Iwasaki, Takayuki; Ishibashi, Fumitaka; Miyamoto, Yoshiyuki; Doi, Yuki; Kobayashi, Satoshi; Miyazaki, Takehide; Tahara, Kosuke; Jahnke, Kay D.; Rogers, Lachlan J.; Naydenov, Boris; Jelezko, Fedor; Yamasaki, Satoshi; Nagamachi, Shinji; Inubushi, Toshiro; Mizuochi, Norikazu; Hatano, Mutsuko

    2015-01-01

    Atomic-sized fluorescent defects in diamond are widely recognized as a promising solid state platform for quantum cryptography and quantum information processing. For these applications, single photon sources with a high intensity and reproducible fabrication methods are required. In this study, we report a novel color center in diamond, composed of a germanium (Ge) and a vacancy (V) and named the GeV center, which has a sharp and strong photoluminescence band with a zero-phonon line at 602 nm at room temperature. We demonstrate this new color center works as a single photon source. Both ion implantation and chemical vapor deposition techniques enabled fabrication of GeV centers in diamond. A first-principles calculation revealed the atomic crystal structure and energy levels of the GeV center. PMID:26250337

  11. Portable electro-mechanically cooled high-resolution germanium detector

    NASA Astrophysics Data System (ADS)

    Neufeld, K. W.; Ruhter, W. D.

    1995-05-01

    We have integrated a small, highly-reliable, electro-mechanical cryo-cooler with a high-resolution germanium detector for portable/field applications. The system weighs 6.8 kg and requires 40 watts of power to operate once the detector is cooled to its operating temperature. The detector is a 500 mm(exp 2) by 20-mm thick low-energy configuration that gives a full-width at half maximum (FWHM) energy resolution of 523 eV at 122 keV, when cooled with liquid nitrogen. The energy resolution of the detector, when cooled with the electro-mechanical cooler, is 570 eV at 122 keV. We have field tested this system in measurements of plutonium and uranium for isotopic and enrichment information using the MGA and MGAU analysis programs without any noticeable effects on the results.

  12. Reliability assessment of germanium gate stacks with promising initial characteristics

    NASA Astrophysics Data System (ADS)

    Lu, Cimang; Lee, Choong Hyun; Nishimura, Tomonori; Nagashio, Kosuke; Toriumi, Akira

    2015-02-01

    This work reports on the reliability assessment of germanium (Ge) gate stacks with promising initial electrical properties, with focus on trap generation under a constant electric stress field (Estress). Initial Ge gate stack properties do not necessarily mean highly robust reliability when it is considered that traps are newly generated under high Estress. A small amount of yttrium- or scandium oxide-doped GeO2 (Y-GeO2 or Sc-GeO2, respectively) significantly reduces trap generation in Ge gate stacks without deterioration of the interface. This is explained by the increase in the average coordination number (Nav) of the modified GeO2 network that results from the doping.

  13. Band Anticrossing in Dilute Germanium Carbides Using Hybrid Density Functionals

    NASA Astrophysics Data System (ADS)

    Stephenson, Chad A.; O'brien, William A.; Qi, Meng; Penninger, Michael; Schneider, William F.; Wistey, Mark A.

    2016-04-01

    Dilute germanium carbides (Ge1- x C x ) offer a direct bandgap for compact silicon photonics, but widely varying properties have been reported. This work reports improved band structure calculations for Ge1- x C x using ab initio simulations that employ the HSE06 exchange-correlation density functional. Contrary to Vegard's law, the conduction band minimum at Γ is consistently found to decrease with increasing C content, while L and X valleys change much more slowly. The calculated Ge bandgap is within 11% of experimental values. A decrease in energy at the Γ conduction band valley of (170 meV ± 50)/%C is predicted, leading to a direct bandgap for x > 0.008. These results indicate a promising material for Group IV lasers.

  14. Characteristics of GRIFFIN high-purity germanium clover detectors

    NASA Astrophysics Data System (ADS)

    Rizwan, U.; Garnsworthy, A. B.; Andreoiu, C.; Ball, G. C.; Chester, A.; Domingo, T.; Dunlop, R.; Hackman, G.; Rand, E. T.; Smith, J. K.; Starosta, K.; Svensson, C. E.; Voss, P.; Williams, J.

    2016-06-01

    The Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new experimental facility for radioactive decay studies at the TRIUMF-ISAC laboratory. The performance of the 16 high-purity germanium (HPGe) clover detectors that will make up the GRIFFIN spectrometer is reported. The energy resolution, efficiency, timing resolution, crosstalk and preamplifier properties of each crystal were measured using a combination of analog and digital data acquisition techniques. The absolute efficiency and add-back factors are determined for the energy range of 80-3450 keV. The detectors show excellent performance with an average over all 64 crystals of a FWHM energy resolution of 1.89(6) keV and relative efficiency with respect to a 3 in . × 3 in . NaI detector of 41(1)% at 1.3 MeV.

  15. Giant pop-ins and amorphization in germanium during indentation

    NASA Astrophysics Data System (ADS)

    Oliver, David J.; Bradby, Jodie E.; Williams, Jim S.; Swain, Michael V.; Munroe, Paul

    2007-02-01

    Sudden excursions of unusually large magnitude (>1 μm), "giant pop-ins," have been observed in the force-displacement curve for high load indentation of crystalline germanium (Ge). A range of techniques including Raman microspectroscopy, focused ion-beam cross sectioning, and transmission electron microscopy, are applied to study this phenomenon. Amorphous material is observed in residual indents following the giant pop-in. The giant pop-in is shown to be a material removal event, triggered by the development of shallow lateral cracks adjacent to the indent. Enhanced depth recovery, or "elbowing," observed in the force-displacement curve following the giant pop-in is explained in terms of a compliant response of plates of material around the indent detached by lateral cracking. The possible causes of amorphization are discussed, and the implications in light of earlier indentation studies of Ge are considered.

  16. Properties of silicon-germanium thermoelectric alloys with additives

    NASA Technical Reports Server (NTRS)

    Mclane, George; Raag, Valvo; Danielson, Lee; Wood, Charles; Vandersande, Jan

    1986-01-01

    The paper reports the results of measurements (Seebeck and Hall coefficients, electrical resistivity, and thermal conductivity) on silicon-germanium (Si-20 at. pct Ge) alloy with boron phosphide, B(6.5)P) as an additive, prepared as described by McLane et al. (1986). The power factor (Seebeck coefficient squared divided by electrical resistivity) and the thermal conductivity of SeGe/B(6.5)P material were found to be lower than for the 'standard' SiGe (Si-22 at. pct Ge) material. However, no net improvement was achieved in the figure-of-merit of the sample tested. It is suggested that structural inhomogeneities, revealed by a SEM examination, might be responsible for this lack of improvement.

  17. Young’s modulus of [111] germanium nanowires

    DOE PAGESBeta

    Maksud, M.; Yoo, J.; Harris, C. T.; Palapati, N. K. R.; Subramanian, A.

    2015-11-02

    Our paper reports a diameter-independent Young’s modulus of 91.9 ± 8.2 GPa for [111] Germanium nanowires (Ge NWs). When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 ± 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ~75%. Furthermore, with increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior.

  18. Young’s modulus of [111] germanium nanowires

    SciTech Connect

    Maksud, M.; Palapati, N. K. R.; Subramanian, A.; Yoo, J.; Harris, C. T.

    2015-11-01

    This paper reports a diameter-independent Young’s modulus of 91.9 ± 8.2 GPa for [111] Germanium nanowires (Ge NWs). When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 ± 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ∼75%. With increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior.

  19. Tunable split-ring resonators using germanium telluride

    NASA Astrophysics Data System (ADS)

    Kodama, C. H.; Coutu, R. A.

    2016-06-01

    We demonstrate terahertz (THz) split-ring resonator (SRR) designs with incorporated germanium telluride (GeTe) thin films. GeTe is a chalcogenide that undergoes a nonvolatile phase change from the amorphous to crystalline state at approximately 200 °C, depending on the film thickness and stoichiometry. The phase change also causes a drop in the material's resistivity by six orders of magnitude. In this study, two GeTe-incorporated SRR designs were investigated. The first was an SRR made entirely out of GeTe and the second was a gold SRR structure with a GeTe film incorporated into the gap region of the split ring. These devices were characterized using THz time-domain spectroscopy and were heated in-situ to determine the change in the design operation with varying temperatures.

  20. Anomalous compression behavior of germanium during phase transformation

    SciTech Connect

    Yan, Xiaozhi; Tan, Dayong; Ren, Xiangting; Yang, Wenge E-mail: duanweihe@scu.edu.cn; He, Duanwei E-mail: duanweihe@scu.edu.cn; Mao, Ho-Kwang

    2015-04-27

    In this article, we present the abnormal compression and plastic behavior of germanium during the pressure-induced cubic diamond to β-tin structure transition. Between 8.6 GPa and 13.8 GPa, in which pressure range both phases are co-existing, first softening and followed by hardening for both phases were observed via synchrotron x-ray diffraction and Raman spectroscopy. These unusual behaviors can be interpreted as the volume misfit between different phases. Following Eshelby, the strain energy density reaches the maximum in the middle of the transition zone, where the switch happens from softening to hardening. Insight into these mechanical properties during phase transformation is relevant for the understanding of plasticity and compressibility of crystal materials when different phases coexist during a phase transition.

  1. Towards monolithic integration of germanium light sources on silicon chips

    NASA Astrophysics Data System (ADS)

    Saito, Shinichi; Zaher Al-Attili, Abdelrahman; Oda, Katsuya; Ishikawa, Yasuhiko

    2016-04-01

    Germanium (Ge) is a group-IV indirect band gap semiconductor, and therefore bulk Ge cannot emit light efficiently. However, the direct band gap energy is close to the indirect one, and significant engineering efforts are being made to convert Ge into an efficient gain material monolithically integrated on a Si chip. In this article, we will review the engineering challenges of developing Ge light sources fabricated using nano-fabrication technologies compatible with complementary metal-oxide-semiconductor processes. In particular, we review recent progress in applying high-tensile strain to Ge to reduce the direct band gap. Another important technique is doping Ge with donor impurities to fill the indirect band gap valleys in the conduction band. Realization of carrier confinement structures and suitable optical cavities will be discussed. Finally, we will discuss possible applications of Ge light sources in potential photonics-electronics convergent systems.

  2. Study on the Properties of High Purity Germanium Crystals

    NASA Astrophysics Data System (ADS)

    Yang, G.; Mei, H.; Guan, Y. T.; Wang, G. J.; Mei, D. M.; Irmscher, K.

    2015-05-01

    In the crystal growth lab of South Dakota University, we are growing high purity germanium (HPGe) crystals and using the grown crystals to make radiation detectors. As the detector grade HPGe crystals, they have to meet two critical requirements: an impurity level of ∼109 to 10 atoms /cm3 and a dislocation density in the range of ∼102 to 104 / cm3. In the present work, we have used the following four characterization techniques to investigate the properties of the grown crystals. First of all, an x-ray diffraction method was used to determine crystal orientation. Secondly, the van der Pauw Hall effect measurement was used to measure the electrical properties. Thirdly, a photo-thermal ionization spectroscopy (PTIS) was used to identify what the impurity atoms are in the crystal. Lastly, an optical microscope observation was used to measure dislocation density in the crystal. All of these characterization techniques have provided great helps to our crystal activities.

  3. Dislocation distribution in large high-purity germanium crystal

    NASA Astrophysics Data System (ADS)

    Mei, Hao; Wang, Guojian; Mei, Dongming; Huang, Mianliang; Yang, Gang; Guan, Yutong; Cubed Collaboration

    2014-03-01

    We investigated the impacts of growth rate, time-temperature profile, thermal gradient on the dislocation distribution in large high-purity germanium crystal (12 cm in diameter) grown via Czochralski along <100>orientation. The time-temperature profiles of the crystal grown at different input power were investigated using direct measurements and computational modeling. The effect of crystallization speed on dislocation density is discussed from the context of thermal gradient during growth. Several samples from the grown crystals were used for this investigation. We measured dislocation density across the entire cross-section of the grown crystal through the microscope. By measuring and calculating the dislocation density, we were able to identify the denseness and the type of dislocation, which allows us to study how the thermal stress impacts the dislocation generation and distribution across the large grown crystals. This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota.

  4. Submicron fabrication by local anodic oxidation of germanium thin films

    NASA Astrophysics Data System (ADS)

    Oliveira, A. B.; Medeiros-Ribeiro, G.; Azevedo, A.

    2009-08-01

    Here we describe a lithography scheme based on the local anodic oxidation of germanium film by a scanning atomic force microscope in a humidity-controlled atmosphere. The oxidation kinetics of the Ge film were investigated by a tapping mode, in which a pulsed bias voltage was synchronized and applied with the resonance frequency of the cantilever, and by a contact mode, in which a continuous voltage was applied. In the tapping mode we clearly identified two regimes of oxidation as a function of the applied voltage: the trench width increased linearly during the vertical growth and increased exponentially during the lateral growth. Both regimes of growth were interpreted taking into consideration the Cabrera-Mott mechanism of oxidation applied to the oxide/Ge interface. We also show the feasibility of the bottom-up fabrication process presented in this work by showing a Cu nanowire fabricated on top of a silicon substrate.

  5. Isotopically enriched germanium detectors for astrophysical gamma-ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    1990-01-01

    A study is presented of the instrumental background in astrophysical gamma-ray spectrometers using isotopically enriched germanium detectors. Calculations show that the beta-decay background, which is the largest component between approximately 0.1 and 1.0 MeV in balloonborne and satellite spectrometers, is dominated by the activation of Ge-74. This component can be reduced by an order of magnitude using detectors enriched to more than 80 percent in (Ge-70). The predicted reduction in the total background for current balloonborne instruments is more than a factor of 1.7 between 0.2 and 1.0 MeV. For future satellite instruments, the reduction in this energy range is by more than a factor of 5.

  6. Germanium-Vacancy Single Color Centers in Diamond.

    PubMed

    Iwasaki, Takayuki; Ishibashi, Fumitaka; Miyamoto, Yoshiyuki; Doi, Yuki; Kobayashi, Satoshi; Miyazaki, Takehide; Tahara, Kosuke; Jahnke, Kay D; Rogers, Lachlan J; Naydenov, Boris; Jelezko, Fedor; Yamasaki, Satoshi; Nagamachi, Shinji; Inubushi, Toshiro; Mizuochi, Norikazu; Hatano, Mutsuko

    2015-01-01

    Atomic-sized fluorescent defects in diamond are widely recognized as a promising solid state platform for quantum cryptography and quantum information processing. For these applications, single photon sources with a high intensity and reproducible fabrication methods are required. In this study, we report a novel color center in diamond, composed of a germanium (Ge) and a vacancy (V) and named the GeV center, which has a sharp and strong photoluminescence band with a zero-phonon line at 602 nm at room temperature. We demonstrate this new color center works as a single photon source. Both ion implantation and chemical vapor deposition techniques enabled fabrication of GeV centers in diamond. A first-principles calculation revealed the atomic crystal structure and energy levels of the GeV center. PMID:26250337

  7. Electron temperature and density measurements of laser induced germanium plasma

    NASA Astrophysics Data System (ADS)

    Shakeel, Hira; Arshad, Saboohi; Haq, S. U.; Nadeem, Ali

    2016-05-01

    The germanium plasma produced by the fundamental harmonics (1064 nm) of Nd:YAG laser in single and double pulse configurations have been studied spectroscopically. The plasma is characterized by measuring the electron temperature using the Boltzmann plot method for neutral and ionized species and electron number density as a function of laser irradiance, ambient pressure, and distance from the target surface. It is observed that the plasma parameters have an increasing trend with laser irradiance (9-33 GW/cm2) and with ambient pressure (8-250 mbar). However, a decreasing trend is observed along the plume length up to 4.5 mm. The electron temperature and electron number density are also determined using a double pulse configuration, and their behavior at fixed energy ratio and different interpulse delays is discussed.

  8. Bridgman Growth of Germanium Crystals in a Rotating Magnetic Field

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Szofran, F. R.; Cobb, S. D.; Schweizer, M.; Walker, J. S.

    2005-01-01

    A series of (100)-oriented gallium-doped germanium crystals has been grown by the vertical Bridgman method and under the influence of a rotating magnetic field (RMF). Time-dependent flow instabilities occur when the critical magnetic Taylor number (Tm(sup c)) is exceeded, and this can be observed by noting the appearance of striations in the grown crystals. Tm(sup c) decreases as the aspect ratio of the melt increases, and approaches the theoretical limit expected for an infinite cylinder. Intentional interface demarcations are introduced by pulsing the RMF on and off The RMF has a marked affect on the interface shape, changing it from concave to nearly flat as the RMF strength is increased.

  9. Comparison of Germanium Telluride (GeTe) Crystals

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Comparison of Germanium Telluride (GeTe) Crystals grown on Earth (left) and in space (right) during the Skylab SL-3 mission. These crystals were grown using a vapor transport crystal growth method in the Multipurpose Electric Furnace System (MEFS). Crystals grown on earth are needles and platelettes with distorted surfaces and hollow growth habits. The length of the ground-based needle is approximately 2 mm and the average lenth of the platelets is 1 mm. The dull appearance of the Skylab crystals resulted from condensation of the transport agent during the long cooling period dictated by the Skylab furnace. In a dedicated process, this would be prevented by removing the ampoule from the furnace and quenching the vapor source.

  10. Noise performance of high-efficiency germanium quantum dot photodetectors

    NASA Astrophysics Data System (ADS)

    Siontas, Stylianos; Liu, Pei; Zaslavsky, Alexander; Pacifici, Domenico

    2016-08-01

    We report on the noise analysis of high performance germanium quantum dot (Ge QD) photodetectors with responsivity up to ˜2 A/W and internal quantum efficiency up to ˜400%, over the 400-1100 nm wavelength range and at a reverse bias of -10 V. Photolithography was performed to define variable active-area devices that show suppressed dark current, leading to a higher signal-to-noise ratio, up to 105, and specific detectivity D * ≃ 6 × 10 12 cm Hz 1 / 2 W-1. These figures of merit suggest Ge QDs as a promising alternative material for high-performance photodetectors working in the visible to near-infrared spectral range.

  11. Bridgman Growth of Germanium Crystals in a Rotating Magnetic Field

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Schweizer, M.; Cobb, S. D.; Walker, J. S.; Szofran, F. R.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    A series of (100)-oriented gallium-doped germanium crystals have been grown by the Bridgman method and under the influence of a rotating magnetic field (RMF). The RMF has a marked affect on the interface shape, changing it from concave to nearly flat. The onset of time-dependent flow instabilities occurs when the critical magnetic Taylor number is exceeded, and this can be observed by noting the appearance of striations in the grown crystals. The critical magnetic Taylor number is a sensitive function of the aspect ratio and, as the crystal grows under a constant applied magnetic field, the induced striations change from nonperiodic to periodic, undergo a period-doubling transition, and then cease to exist. Also, by pulsing the RMF on and off, it is shown that intentional interface demarcations can be introduced.

  12. A pseudo-single-crystalline germanium film for flexible electronics

    SciTech Connect

    Higashi, H.; Yamada, S.; Kanashima, T.; Hamaya, K.; Kasahara, K.; Park, J.-H.; Miyao, M.; Kudo, K.; Okamoto, H.; Moto, K.; Tsunoda, I.

    2015-01-26

    We demonstrate large-area (∼600 μm), (111)-oriented, and high-crystallinity, i.e., pseudo-single-crystalline, germanium (Ge) films at 275 °C, where the temperature is lower than the softening temperature of a flexible substrate. A modulated gold-induced layer exchange crystallization method with an atomic-layer deposited Al{sub 2}O{sub 3} barrier and amorphous-Ge/Au multilayers is established. From the Raman measurements, we can judge that the crystallinity of the obtained Ge films is higher than those grown by aluminum-induced-crystallization methods. Even on a flexible substrate, the pseudo-single-crystalline Ge films for the circuit with thin-film transistor arrays can be achieved, leading to high-performance flexible electronics based on an inorganic-semiconductor channel.

  13. Bridgman Growth of Germanium Crystals in a Rotating Magnetic Field

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Walker, J. S.; Schweizer, M.; Cobb, S. D.; Szofran, F. R.

    2004-01-01

    A series of (100)-oriented gallium-doped germanium crystals have been grown by the Bridgman method and under the influence of a rotating magnetic field (RMF). Time-dependent flow instabilities occur when the critical magnetic Taylor number (Tm(sup c) is exceeded, and this can be observed by noting the appearance of striations in the grown crystals. The experimental data indicate that Tm(sup c) increases as the aspect ratio of the melt decreases. Modeling calculations predicting Tm(sup c) as a function of aspect ratio are in reasonable agreement with the experimental data. The RMF has a marked affect on the interface shape, changing it from concave to nearly flat as the RMF strength is increased. Also, by pulsing the RMF on and off, it is shown that intentional interface demarcations can be introduced.

  14. Buried Porous Silicon-Germanium Layers in Monocrystalline Silicon Lattices

    NASA Technical Reports Server (NTRS)

    Fathauer, Robert W. (Inventor); George, Thomas (Inventor); Jones, Eric W. (Inventor)

    1998-01-01

    Monocrystalline semiconductor lattices with a buried porous semiconductor layer having different chemical composition is discussed and monocrystalline semiconductor superlattices with a buried porous semiconductor layers having different chemical composition than that of its monocrystalline semiconductor superlattice are discussed. Lattices of alternating layers of monocrystalline silicon and porous silicon-germanium have been produced. These single crystal lattices have been fabricated by epitaxial growth of Si and Si-Ge layers followed by patterning into mesa structures. The mesa structures are strain etched resulting in porosification of the Si-Ge layers with a minor amount of porosification of the monocrystalline Si layers. Thicker Si-Ge layers produced in a similar manner emitted visible light at room temperature.

  15. Method of manufacturing a niobium-aluminum-germanium superconductive material

    DOEpatents

    Wang, John L.; Pickus, Milton R.; Douglas, Kent E.

    1980-01-01

    A method for manufacturing flexible Nb.sub.3 (Al,Ge) multifilamentary superconductive material in which a sintered porous niobium compact is infiltrated with an aluminum-germanium alloy and thereafter deformed and heat treated in a series of steps at different successively higher temperatures preferably below 1000.degree. C. to produce filaments composed of Nb.sub.3 (Al,G3) within the compact. By avoiding temperatures in excess of 1000.degree. C. during the heat treatment, cladding material such as copper can be applied to facilitate a deformation step preceding the heat treatment and can remain in place through the heat treatment to also serve as a temperature stabilizer for supeconductive material produced. Further, these lower heat treatment temperatures favor formation of filaments with reduced grain size and, hence with more grain boundaries which in turn increase the current-carrying capacity of the superconductive material.

  16. Development of silicon-germanium visible-near infrared arrays

    NASA Astrophysics Data System (ADS)

    Zeller, John W.; Rouse, Caitlin; Efstathiadis, Harry; Haldar, Pradeep; Lewis, Jay S.; Dhar, Nibir K.; Wijewarnasuriya, Priyalal; Puri, Yash R.; Sood, Ashok K.

    2016-05-01

    Photodetectors based on germanium which do not require cooling and can provide good near-infrared (NIR) detection performance offer a low-cost alternative to conventional infrared sensors based on material systems such as InGaAs, InSb, and HgCdTe. As a result of the significant difference in thermal expansion coefficients between germanium and silicon, tensile strain incorporated into Ge epitaxial layers deposited on Si utilizing specialized growth processes can extend the operational range of detection to 1600 nm and longer wavelengths. We have fabricated Ge based PIN photodetectors on 300 mm diameter Si wafers to take advantage of high throughput, large-area complementary metal-oxide semiconductor (CMOS) technology. This device fabrication process involves low temperature epitaxial deposition of Ge to form a thin p+ (boron) Ge seed/buffer layer, and subsequent higher temperature deposition of a thicker Ge intrinsic layer. This is followed by selective ion implantation of phosphorus of various concentrations to form n+ Ge regions, deposition of a passivating oxide cap, and then top copper contacts to complete the PIN detector devices. Various techniques including transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) have been employed to characterize the material and structural properties of the epitaxially grown layers and fabricated detector devices, and these results are presented. The I-V response of the photodetector devices with and without illumination was also measured, for which the Ge based photodetectors consistently exhibited low dark currents of around ~1 nA at -1 V bias.

  17. The time and temperature dependence of the thermoelectric properties of silicon-germanium alloy

    NASA Technical Reports Server (NTRS)

    Raag, V.

    1975-01-01

    Experimental data on the electrical resistivity and Seebeck coefficient of n-type and p-type silicon-germanium alloys are analyzed in terms of a solid-state dopant precipitation model proposed by Lifshitz and Slyozov (1961). Experimental findings on the time and temperature dependence of the thermal conductivity of these two types of alloy indicate that the thermal conductivity of silicon-germanium alloys changes with time, contrary to previous hypothesis. A preliminary model is presented which stipulates that the observed thermal conductivity decrease in silicon-germanium alloys is due partly to dopant precipitation underlying the electrical property changes and partly to enhanced alloying of the material. It is significant that all three properties asymptotically approach equilibrium values with time. Total characterization of these properties will enable the time change to be fully compensated in the design of a thermoelectric device employing silicon-germanium alloys.

  18. Self-assembled asymmetric membrane containing micron-size germanium for high capacity lithium ion batteries

    DOE PAGESBeta

    Byrd, Ian; Chen, Hao; Webber, Theron; Li, Jianlin; Wu, Ji

    2015-10-23

    We report the formation of novel asymmetric membrane electrode containing micron-size (~5 μm) germanium powders through a self-assembly phase inversion method for high capacity lithium ion battery anode. 850 mA h g-1 capacity (70%) can be retained at a current density of 600 mA g-1 after 100 cycles with excellent rate performance. Such a high retention rate has rarely been seen for pristine micron-size germanium anodes. Moreover, scanning electron microscope studies reveal that germanium powders are uniformly embedded in a networking porous structure consisting of both nanopores and macropores. It is believed that such a unique porous structure can efficientlymore » accommodate the ~260% volume change during germanium alloying and de-alloying process, resulting in an enhanced cycling performance. Finally, these porous membrane electrodes can be manufactured in large scale using a roll-to-roll processing method.« less

  19. IR absorption and Raman spectra of single crystals of stable germanium isotopes

    NASA Astrophysics Data System (ADS)

    Gavva, V. A.; Kotereva, T. V.; Lipskiy, V. A.; Nezhdanov, A. V.

    2016-02-01

    The Raman and IR absorption spectra of single crystals of germanium isotopes 72Ge, 73Ge, 74Ge, and 76Ge in the region of phonon absorption and interband electronic transitions are studied at room temperature. The dependence of the Raman peak position on the atomic mass has the form ν ~ M -1/2. The shifts of the phonon absorption peaks of individual isotopes with respect to germanium of natural isotopic composition natGe are determined. With increasing average atomic mass of germanium, these peaks shift to longer wavelengths. In the region of interband electronic transitions, the intrinsic absorption edge of 76Ge is observed to shift by 1 meV to higher energies with respect to Ge of natural isotopic composition. For isotopes with atomic masses close to that of natural germanium (72Ge,73Ge, 74Ge), we found no significant difference in the band gap width at room temperature.

  20. Impurity distribution in high purity germanium crystal and its impact on the detector performance

    NASA Astrophysics Data System (ADS)

    Wang, Guojian; Amman, Mark; Mei, Hao; Mei, Dongming; Irmscher, Klaus; Guan, Yutong; Yang, Gang

    High-purity germanium crystals were grown in a hydrogen atmosphere using the Czochralski method. The axial and radial distributions of impurities in the crystals were measured by Hall effect and Photo-thermal ionization spectroscopy (PTIS). Amorphous semiconductor contacts were deposited on the germanium crystals to make detectors. Three planar detectors were fabricated from three crystals with different net carrier concentrations (1.7, 7.9 and 10x1010 cm-3). We evaluated the electrical and spectral performance of three detectors. Measurements of gamma-ray spectra from 137Cs, 241Am and 60Co sources demonstrate that the detectors have excellent energy resolution. The relationship between the impurities and detector's energy resolution was analyzed. Keywords: High-purity germanium crystal, High-purity germanium detector This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota..

  1. Jet thinning of germanium for TEM using automatic termination of polishing

    SciTech Connect

    Kestel, B.J.

    1993-01-01

    This report describes an automated jet electropolishing technique, using modified commercial equipment, for the production of germanium TEM specimens. This technique allows rapid and reliable thinning of large areas and results in clean surfaces.

  2. Electronic and magnetic properties of Fe and Mn doped two dimensional hexagonal germanium sheets

    SciTech Connect

    Soni, Himadri R. Jha, Prafulla K.

    2014-04-24

    Using first principles density functional theory calculations, the present paper reports systematic total energy calculations of the electronic properties such as density of states and magnetic moment of pristine and iron and manganese doped two dimensional hexagonal germanium sheets.

  3. Induced Radioactivity Measured in a Germanium Detector After a Long Duration Balloon Flight

    NASA Technical Reports Server (NTRS)

    Starr, R.; Evans, L. G.; Floyed, S. R.; Drake, D. M.; Feldman, W. C.; Squyres, S. W.; Rester, A. C.

    1997-01-01

    A 13-day long duration balloon flight carrying a germanium detector was flown from Williams Field, Antartica in December 1992. After recovery of the payload the activity induced in the detector was measured.

  4. Self-assembled asymmetric membrane containing micron-size germanium for high capacity lithium ion batteries

    SciTech Connect

    Byrd, Ian; Chen, Hao; Webber, Theron; Li, Jianlin; Wu, Ji

    2015-10-23

    We report the formation of novel asymmetric membrane electrode containing micron-size (~5 μm) germanium powders through a self-assembly phase inversion method for high capacity lithium ion battery anode. 850 mA h g-1 capacity (70%) can be retained at a current density of 600 mA g-1 after 100 cycles with excellent rate performance. Such a high retention rate has rarely been seen for pristine micron-size germanium anodes. Moreover, scanning electron microscope studies reveal that germanium powders are uniformly embedded in a networking porous structure consisting of both nanopores and macropores. It is believed that such a unique porous structure can efficiently accommodate the ~260% volume change during germanium alloying and de-alloying process, resulting in an enhanced cycling performance. Finally, these porous membrane electrodes can be manufactured in large scale using a roll-to-roll processing method.

  5. Mechanically Cooled Large-Volume Germanium Detector Systems for Neclear Explosion Monitoring DOENA27323-2

    SciTech Connect

    Hull, E.L.

    2006-10-30

    Compact maintenance free mechanical cooling systems are being developed to operate large volume high-resolution gamma-ray detectors for field applications. To accomplish this we are utilizing a newly available generation of Stirling-cycle mechanical coolers to operate the very largest volume germanium detectors with no maintenance. The user will be able to leave these systems unplugged on the shelf until needed. The maintenance-free operating lifetime of these detector systems will exceed 5 years. Three important factors affect the operation of mechanically cooled germanium detectors: temperature, vacuum, and vibration. These factors will be studied in the laboratory at the most fundamental levels to insure a solid understanding of the physical limitations each factor places on a practical mechanically cooled germanium detector system. Using this knowledge, mechanically cooled germanium detector prototype systems will be designed and fabricated.

  6. Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring DOENA27323-1

    SciTech Connect

    Hull, E.L.

    2006-07-28

    Compact maintenance free mechanical cooling systems are being developed to operate large volume germanium detectors for field applications. To accomplish this we are utilizing a newly available generation of Stirling-cycle mechanical coolers to operate the very largest volume germanium detectors with no maintenance. The user will be able to leave these systems unplugged on the shelf until needed. The flip of a switch will bring a system to life in ~ 1 hour for measurements. The maintenance-free operating lifetime of these detector systems will exceed 5 years. These features are necessary for remote long-duration liquid-nitrogen free deployment of large-volume germanium gamma-ray detector systems for Nuclear Explosion Monitoring. The Radionuclide Aerosol Sampler/Analyzer (RASA) will greatly benefit from the availability of such detectors by eliminating the need for liquid nitrogen at RASA sites while still allowing the very largest available germanium detectors to be reliably utilized.

  7. Direct band gap electroluminescence from bulk germanium at room temperature using an asymmetric fin type metal/germanium/metal structure

    SciTech Connect

    Wang, Dong Maekura, Takayuki; Kamezawa, Sho; Yamamoto, Keisuke; Nakashima, Hiroshi

    2015-02-16

    We demonstrated direct band gap (DBG) electroluminescence (EL) at room temperature from n-type bulk germanium (Ge) using a fin type asymmetric lateral metal/Ge/metal structure with TiN/Ge and HfGe/Ge contacts, which was fabricated using a low temperature (<400 °C) process. Small electron and hole barrier heights were obtained for TiN/Ge and HfGe/Ge contacts, respectively. DBG EL spectrum peaked at 1.55 μm was clearly observed even at a small current density of 2.2 μA/μm. Superlinear increase in EL intensity was also observed with increasing current density, due to superlinear increase in population of elections in direct conduction band. The efficiency of hole injection was also clarified.

  8. The reactivity of phenancyl bromide under β-cyclodextrin as supramolecular catalyst: a computational survey.

    PubMed

    Wan, Yali; Wang, Xueye; Liu, Na

    2015-05-01

    Phenacyl bromide as one starting material in multicomponent reactions (MCRs) with β-cyclodextrin (β-CD) as catalyst can get an excellent yield in short reaction times. The interaction of β-CD with phenacyl bromide plays an important role in this process. This paper studies the complex of β-CD with phenacyl bromide using density functional theory (DFT) method. Energy is investigated to find out the lowest energy of two possible complexation models. Hydrogen bonds are researched on the basis of natural bonding orbital (NBO) analysis. The relative position between phenacyl bromide and β-CD is confirmed by (1)H nuclear magnetic resonance ((1)HNMR). The results of frontier molecular orbitals and charge distribution reveal that β-CD catalyst improves the reactivity and electrophilicity of phenacyl bromide, meanwhile, the carbonyl group of phenacyl bromide more easily gives a carbocationic intermediate in the presence of β-CD as catalyst. The reactivity of phenancyl bromide under β-CD as supramolecular catalysis is improved. PMID:25929992

  9. HEROICA: A fast screening facility for the characterization of germanium detectors

    SciTech Connect

    Andreotti, Erica; Collaboration: GERDA Collaboration

    2013-08-08

    In the course of 2012, a facility for the fast screening of germanium detectors called HEROICA (Hades Experimental Research Of Intrinsic Crystal Appliances) has been installed at the HADES underground laboratory in the premises of the Belgian Nuclear Research Centre SCK•CEN, in Mol (Belgium). The facility allows performing a complete characterization of the critical germanium detectors' operational parameters with a rate of about two detectors per week.

  10. Methyl bromide emissions from a covered field: I. Experimental conditions and degradation in soil

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.

    1996-01-01

    An experiment is described to investigate the environmental fate and transport of methyl bromide in agricultural systems. The experiment was designed to determine the dynamics of methyl bromide movement through soil, degradation, and total emissions to the atmosphere. This is of particular interest because it will allow an assessment of the environmental impacts (i.e., stratospheric ozone depletion) resulting from the agricultural use of methyl bromide. Methyl bromide was applied at a rate of 843 kg in a 3.5-ha (i.e., 240 kg/ha) field at a depth of 0.25 m and covered with a sheet of 1-mil polyethylene plastic. The maximum methyl bromide concentration in the atmosphere occurred at night between 0200 and 0600 h. During the first 3 d of the experiment, the maximum daily concentrations at 0.2 m above the soil surface were 30, 5, and 1 mg/(m{sup 3} of air), respectively. The trend of reduced emissions with time continued until the plastic was removed, when a momentary increase in the methyl bromide emissions occurred. The maximum soil gas concentration 24 h after injection was 30 g/m{sup 3} located at a 0.25-m depth. When the plastic was removed from the field (at 5.6 d), the maximum soil gas concentration was approximately 2 g/m{sup 3} at a 0.5-m depth. A mass-difference method for estimating the total methyl bromide emissions from the soil, based on degradation of methyl bromide to Br{sup -}, indicates that approximately 39% or 325 kg ({+-} 164 kg) of the applied methyl bromide was converted to Br{sup -} and, therefore, 61% or 518 kg ({+-} 164 kg) was lost via volatilization. 16 refs., 11 figs., 2 tabs.

  11. Design of a Prototype Cryogenic Chamber and Characterization of a High Purity Germanium Detector

    NASA Astrophysics Data System (ADS)

    Hossain, Abu Hena Muhammad Nazir

    Germanium detectors are the best choice for gamma ray spectrometry because of their good energy resolution and high efficiency compared to any other gamma rays spectrometers. Due to their high sensitivity and good energy resolution, these kinds of detector have a range of application. There is a significant number of particles detection experiments going on which used germanium detectors all around the world. These also have applications in non-proliferation and medical diagnosis. Thus, germanium detectors have a wide range of applications both research and industry. The Center for Ultra-Low Background Experiment in the Dakotas (CUBED) at the University of South Dakota is developing the facilities to fabricate germanium detectors. It is requires to characterize the germanium detector properties, especially electrical properties. In this project I design and developed a cryogenic chamber for the CUBED group which is able to rest any type of radiation detectors of different sizes and shapes. The cryostat chamber is able to provide low pressure and low temperature for the testing of the germanium detector sample. Leakage current measurements have been done for several detector samples by using this cryostat chamber. Several kinds of electrical properties such as depletion voltage, breakdown voltage, electronics noise, impurity concentration etc. can be derived from these experiments in the future.

  12. The Primary and Secondary Production of Germanium: A Life-Cycle Assessment of Different Process Alternatives

    NASA Astrophysics Data System (ADS)

    Robertz, Benedicte; Verhelle, Jensen; Schurmans, Maarten

    2015-02-01

    Germanium is a semiconducting metalloid element used in optical fibers, catalysis, infrared optics, solar cells, and light-emitting diodes. The need for Ge in these markets is considered to increase by a steady ~1% on a yearly basis. Its economic importance, coupled with the identified supply risks, has led to the classification of germanium as a critical raw material within Europe. Since the early 1950s, Umicore Electro-Optic Materials has supplied germanium-based materials solutions to its markets around the world. Umicore extracts germanium from a wide range of refining and recycling feeds. The main objectives of this study were to quantify the potential environmental impacts of the production of germanium from production scraps from the photovoltaic industry and to compare them with the potential impacts of the primary production of germanium from coal. The data related to the secondary production are Umicore-specific data. Environmental impact scores have been calculated for the impact categories recommended by the International reference life cycle data system. The comparison of the primary and secondary production highlights the benefit linked to the recycling of metals.

  13. Palladium-Catalyzed Alkoxycarbonylation of Unactivated Secondary Alkyl Bromides at Low Pressure.

    PubMed

    Sargent, Brendon T; Alexanian, Erik J

    2016-06-22

    Catalytic carbonylations of organohalides are important C-C bond formations in chemical synthesis. Carbonylations of unactivated alkyl halides remain a challenge and currently require the use of alkyl iodides under harsh conditions and high pressures of CO. Herein we report a palladium-catalyzed alkoxycarbonylation of secondary alkyl bromides that proceeds at low pressure (2 atm CO) under mild conditions. Preliminary mechanistic studies are consistent with a hybrid organometallic-radical process. These reactions efficiently deliver esters from unactivated alkyl bromides across a diverse range of substrates and represent the first catalytic carbonylations of alkyl bromides with carbon monoxide. PMID:27267421

  14. The action of structural analogues of ethidium bromide on the mitochondrial genome of yeast.

    PubMed

    Hall, R M; Mattick, J S; Nagley, P; Cobon, G S; Eastwood, F W; Linnane, A W

    1977-12-01

    We have studied the effects on the yeast mitochondrial genome of four analogues of ethidium bromide, in which the phenyl moieyt has been replaced by linear alkyl chains of lengths varying from seven to fifteen carbon atoms. These analogues are more efficient than ethidium bromide in inducing petite mutants in Saccharomyces cervisiae. The drugs also cause a loss of mtDNA from the cells in vivo; however these analogues are in fact less effective inhibitors of mitochondrial DNA replication per se, as shown by direct in vitro studies. It is concluded that these analogues are more efficient than ethidium bromide in causing the fragmentation of mitochondrial DNA in S. cervisiae. PMID:339057

  15. Evaluation of alkali bromide salts for potential pyrochemical applications

    SciTech Connect

    Tripathy, P.K.; Gutknecht, T.Y.; Herrmann, S.D.; Fredrickson, G.L.; Lister, T.E.

    2013-07-01

    Transient techniques were employed to study the electrochemical behavior, reduction mechanism and transport properties of REBr{sub 3} (RE - La, Nd and Gd) in pure LiBr, LiBr-KBr (eutectic) and LiBr-KBr-CsBr (eutectic) melts. Gd(III) showed a reversible single step soluble-insoluble exchange phenomenon in LiBr melt at 973 K. Although La (III), Nd(III) and Gd(III) ions showed reversible behavior in eutectic LiBr-KBr melts, these ions showed a combination of temperature dependent reversible and pseudo-reversible behavior. While both La(III) and Gd(III) showed one step reduction, the reduction of Nd(III) was observed to be a two step process. La metal could be electrodeposited from the ternary electrolyte at a temperature of 673 K. Various electrochemical measurements suggest that both binary and ternary bromide melts can potentially be used to electro-deposit high purity RE metals at comparatively lower operating temperatures. (authors)

  16. Water-lithium bromide double-effect absorption cooling analysis

    NASA Astrophysics Data System (ADS)

    Vliet, G. C.; Lawson, M. B.; Lithgow, R. A.

    1980-12-01

    A numerical model was developed for the transient simulation of the double-effect, water-lithium bromide absorption cooling machine and was used to determine the effect of the various design and input variables on the absorption unit performance. The performance parameters considered were coefficient of performance and cooling capacity. The variables considered include source hot water, cooling water, and chilled water temperatures; source hot water, cooling water, and chilled water flow rates; solution circulation rate; heat exchanger areas; pressure drop between evaporator and absorber; solution pump characteristics; and refrigerant flow control methods. The performance sensitivity study indicates that the distribution of heat exchanger area among the various (seven) heat exchange components is a very important design consideration. Moreover, it indicated that the method of flow control of the first effect refrigerant vapor through the second effect is a critical design feature when absorption units operate over a significant range of cooling capacity. The model was used to predict the performance of the Trane absorption unit with fairly good accuracy.

  17. [Treatment of cetyltrimethyl ammonium bromide wastewater by potassium ferrate].

    PubMed

    Yang, Wei-hua; Wang, Hong-hui; Zeng, Xiao-xu; Huang, Ting-ting

    2009-08-15

    A novel oxidant potassium ferrate (K2FeO4) was used to remove cetyltrimethyl ammonium bromide (CTAB) at room temperature. The effects of various conditions on the removal ratio, such as reaction time, dosing quantity of K2FeO4 and initial pH, were investigated. The experiments results show that the removal ratio reaches 79.4% when the reaction time is 30 min, the dosing quantity of K2FeO4 to CTAB is 1:1, the initial pH of the solution is 7. In the reaction progress, the oxidation of K2FeO4 and the flocculation of the reduction product have synergistic effect on the removal of CTAB. In addition, infrared spectra of CTAB before and after being treated with K2FeO4 were further studied. The results indicate that the degradation process involves the interruption of chain and the subsequent mineralization to inorganic molecules. Furthermore, the reaction of K2FeO4 and CTAB follows second order kinetics law. PMID:19799287

  18. Structural and electronic properties of Diisopropylammonium bromide molecular ferroelectric crystal

    NASA Astrophysics Data System (ADS)

    Alsaad, A.; Qattan, I. A.; Ahmad, A. A.; Al-Aqtash, N.; Sabirianov, R. F.

    2015-10-01

    We report the results of ab-initio calculations based on Generalized Gradient Approximation (GGA) and hybrid functional (HSE06) of electronic band structure, density of states and partial density of states to get a deep insight into structural and electronic properties of P21 ferroelectric phase of Diisopropylammonium Bromide molecular crystal (DIPAB). We found that the optical band gap of the polar phase of DIPAB is ∼ 5 eV confirming it as a good dielectric. Examination of the density of states and partial density of states reveal that the valence band maximum is mainly composed of bromine 4p orbitals and the conduction band minimum is dominated by carbon 2p, carbon 2s, and nitrogen 2s orbitals. A unique aspect of P21 ferroelectric phase is the permanent dipole within the material. We found that P21 DIPAB has a spontaneous polarization of 22.64 consistent with recent findings which make it good candidate for the creation of ferroelectric tunneling junctions (FTJs) which have the potential to be used as memory devices.

  19. 4-Bromophenacyl Bromide Specifically Inhibits Rhoptry Secretion during Toxoplasma Invasion

    PubMed Central

    Ravindran, Sandeep; Lodoen, Melissa B.; Verhelst, Steven H. L.; Bogyo, Matthew; Boothroyd, John C.

    2009-01-01

    Toxoplasma gondii is a eukaryotic parasite of the phylum Apicomplexa that is able to infect a wide variety of host cells. During its active invasion process it secretes proteins from discrete secretory organelles: the micronemes, rhoptries and dense granules. Although a number of rhoptry proteins have been shown to be involved in important interactions with the host cell, very little is known about the mechanism of secretion of any Toxoplasma protein into the host cell. We used a chemical inhibitor of phospholipase A2s, 4-bromophenacyl bromide (4-BPB), to look at the role of such lipases in the secretion of Toxoplasma proteins. We found that 4-BPB was a potent inhibitor of rhoptry secretion in Toxoplasma invasion. This drug specifically blocked rhoptry secretion but not microneme secretion, thus effectively showing that the two processes can be de-coupled. It affected parasite motility and invasion, but not attachment or egress. Using propargyl- or azido-derivatives of the drug (so-called click chemistry derivatives) and a series of 4-BPB-resistant mutants, we found that the drug has a very large number of target proteins in the parasite that are involved in at least two key steps: invasion and intracellular growth. This potent compound, the modified “click-chemistry” forms of it, and the resistant mutants should serve as useful tools to further study the processes of Toxoplasma early invasion, in general, and rhoptry secretion, in particular. PMID:19956582

  20. 4-Bromophenacyl bromide specifically inhibits rhoptry secretion during Toxoplasma invasion.

    PubMed

    Ravindran, Sandeep; Lodoen, Melissa B; Verhelst, Steven H L; Bogyo, Matthew; Boothroyd, John C

    2009-01-01

    Toxoplasma gondii is a eukaryotic parasite of the phylum Apicomplexa that is able to infect a wide variety of host cells. During its active invasion process it secretes proteins from discrete secretory organelles: the micronemes, rhoptries and dense granules. Although a number of rhoptry proteins have been shown to be involved in important interactions with the host cell, very little is known about the mechanism of secretion of any Toxoplasma protein into the host cell. We used a chemical inhibitor of phospholipase A2s, 4-bromophenacyl bromide (4-BPB), to look at the role of such lipases in the secretion of Toxoplasma proteins. We found that 4-BPB was a potent inhibitor of rhoptry secretion in Toxoplasma invasion. This drug specifically blocked rhoptry secretion but not microneme secretion, thus effectively showing that the two processes can be de-coupled. It affected parasite motility and invasion, but not attachment or egress. Using propargyl- or azido-derivatives of the drug (so-called click chemistry derivatives) and a series of 4-BPB-resistant mutants, we found that the drug has a very large number of target proteins in the parasite that are involved in at least two key steps: invasion and intracellular growth. This potent compound, the modified "click-chemistry" forms of it, and the resistant mutants should serve as useful tools to further study the processes of Toxoplasma early invasion, in general, and rhoptry secretion, in particular. PMID:19956582

  1. Associated anisotropy decays of ethidium bromide interacting with DNA

    NASA Astrophysics Data System (ADS)

    Chib, Rahul; Raut, Sangram; Sabnis, Sarika; Singhal, Preeti; Gryczynski, Zygmunt; Gryczynski, Ignacy

    2014-03-01

    Ethidium Bromide (EB) is a commonly used dye in a deoxyribonucleic acid (DNA) study. Upon an intercalation, this dye significantly increases its brightness and fluorescence lifetime. In this report we have studied the time resolved fluorescence properties of EB existing simultaneously in free and DNA-bound forms in the solution. Fluorescence intensity decays were fitted globally to a double exponential model with lifetimes corresponding to free (1.6 ns) and bound (22 ns) forms, and molar fractions were determined for all used solutions. Anisotropy decays displayed characteristic time dependence with an initial rapid decline followed by recovery and slow decay. The short-lived fraction associated with free EB molecules decreases faster than long-lived fraction associated with EB bound to DNA. Consequently, contribution from fast rotation leads to initial rapid decay in anisotropy. On the other hand bound fraction, due to slow rotation helps recover anisotropy in time. This effect of associated anisotropy decays in systems such as EB free/EB-DNA is clearly visible in a wide range of concentrations, and should be taken into account in polarization assays and biomolecule dynamics studies.

  2. Fabrication of double-sided thallium bromide strip detectors

    NASA Astrophysics Data System (ADS)

    Hitomi, Keitaro; Nagano, Nobumichi; Onodera, Toshiyuki; Kim, Seong-Yun; Ito, Tatsuya; Ishii, Keizo

    2016-07-01

    Double-sided strip detectors were fabricated from thallium bromide (TlBr) crystals grown by the traveling-molten zone method using zone-purified materials. The detectors had three 3.4-mm-long strips with 1-mm widths and a surrounding electrode placed orthogonally on opposite surfaces of the crystals at approximately 6.5×6.5 mm2 in area and 5 mm in thickness. Excellent charge transport properties for both electrons and holes were observed from the TlBr crystals. The mobility-lifetime products for electrons and holes in the detector were measured to be ~3×10-3 cm2/V and ~1×10-3 cm2/V, respectively. The 137Cs spectra corresponding to the gamma-ray interaction position were obtained from the detector. An energy resolution of 3.4% of full width at half maximum for 662-keV gamma rays was obtained from one "pixel" (an intersection of the strips) of the detector at room temperature.

  3. Locations of Bromide Ions in Tetragonal Lysozyme Crystals

    NASA Technical Reports Server (NTRS)

    Lim, Kap; Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    Anions have been shown to play a dominant role in the crystallization of chicken egg-white lysozyme from salt solutions. Previous studies employing X-ray crystallography have found one chloride ion binding site in the tetragonal crystal form of the protein and four nitrate ion binding sites in the monoclinic form. In this study the anion positions in the tetragonal form were determined from the difference Fourier map obtained from lysozyme crystals grown in bromide and chloride solutions. Five possible anion-binding sites were found in this manner. Some of these sites were in pockets containing basic residues while others were near neutral, but polar, residues. The sole chloride ion binding site found in previous studies was confirmed, while four further sites were found which corresponded to the four binding sites found for nitrate ions in monoclinic crystals. The study suggests that most of the anion-binding sites in lysozyme remain unchanged even when different anions and different crystal forms of lysozyme are employed.

  4. Fluorometric Determination of Deoxyribonucleic Acid in Bacteria with Ethidium Bromide

    PubMed Central

    Donkersloot, J. A.; Robrish, S. A.; Krichevsky, M. I.

    1972-01-01

    A simple, sensitive, and rapid method is presented for the determination of deoxyribonucleic acid (DNA) in both gram-positive and gram-negative bacteria. It is based upon the fluorometric determination of DNA with ethidium bromide after alkaline digestion of the bacteria to hydrolyze the interfering ribonucleic acid. The assay takes less than 2 hr. Its sensitivity is at least 0.2 μg of DNA in a final solution of 4 ml and it uses commonly available filter or double monochromator fluorometers. Judicious choice of light source and filters allows an additional 10-fold increase in sensitivity with a filter fluorometer. Turbidity caused by bacteria or insoluble polysaccharides does not interfere with the fluorescence measurements. There was no significant difference between the results obtained with this method and those obtained with the indole and diphenylamine methods when these assays were applied to Escherichia coli and sucrose- or glucose-grown Streptococcus mutans. The method was also tested by determining the specific growth rate of E. coli. This new procedure should be especially useful for the determination of bacterial DNA in dilute suspensions and for the estimation of bacterial growth or DNA replication where more conventional methods are not applicable or sensitive enough. PMID:4561101

  5. Chloride, bromide and iodide scintillators with europium doping

    DOEpatents

    Zhuravleva, Mariya; Yang, Kan

    2014-08-26

    A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.

  6. Bacterial oxidation of methyl bromide in Mono Lake, California

    USGS Publications Warehouse

    Connell, T.L.; Joye, S.B.; Miller, L.G.; Oremland, R.S.

    1997-01-01

    The oxidation of methyl bromide (MeBr) in the water column of Mono Lake, CA, was studied by measuring the formation of H14CO3 from [14C]MeBr. Potential oxidation was detected throughout the water column, with highest rates occurring in the epilimnion (5-12 m depth). The oxidation of MeBr was eliminated by filter-sterilization, thereby demonstrating the involvement of bacteria. Vertical profiles of MeBr activity differed from those obtained for nitrification and methane oxidation, indicating that MeBr oxidation is not simply a co-oxidation process by either nitrifiers or methanotrophs. Furthermore, specific inhibitors of methane oxidation and/or nitrification (e.g., methyl fluoride, acetylene, allyl sulfide) had no effect upon the rate of MeBr oxidation in live samples. Of a variety of potential electron donors added to Mono Lake water, only trimethylamine resulted in the stimulation of MeBr oxidation. Cumulatively, these results suggest that the oxidation of MeBr in Mono Lake waters is attributable to trimethylamine-degrading methylotrophs. Neither methyl chloride nor methanol inhibited the oxidation of [14C]MeBr in live samples, indicating that these bacteria directly oxidized MeBr rather than the products of MeBr nucleophilic substitution reactions.

  7. Bioreactors for removing methyl bromide following contained fumigations

    USGS Publications Warehouse

    Miller, L.G.; Baesman, S.M.; Oremland, R.S.

    2003-01-01

    Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (> 110 ??mol L-1) from recirculating air. Strain IMB-1 grew slowly to high cell densities in the bioreactor using MeBr as its sole carbon and energy source. Bacterial oxidation of MeBr produced CO2 and hydrobromic acid (HBr), which required continuous neutralization with NaOH for the system to operate effectively. Strain IMB-1 was capable of sustained oxidation of large amounts of MeBr (170 mmol in 46 d). In an open-system bioreactor (10-L fermenter), strain IMB-1 oxidized a continuous supply of MeBr (220 ??mol L-1 in air). Growth was continuous, and 0.5 mol of MeBr was removed from the air supply in 14 d. The specific rate of MeBr oxidation was 7 ?? 10-16 mol cell-1 h-1. Bioreactors such as these can therefore be used to remove large quantities of contaminant MeBr, which opens the possibility of biodegradation as a practical means for its disposal.

  8. Atmospheric methyl bromide: Trends and global mass balance

    SciTech Connect

    Khalil, M.A.K.; Rasmussen, R.A.; Gunawardena, R. )

    1993-02-20

    Atmospheric methyl bromide is of considerable environmental importance as the largest reservoir of gaseous bromine in the atmosphere. Bromine gases can catalytically destroy stratospheric ozone. Since agricultural activities, automobiles, biomass burning, and other human activities produce CH[sub 3]Br, it is of interest to know its global mass balance and particularly the specific sources and sinks. In this paper the authors provide a decadal time series of global CH[sub 3]Br concentrations in the Earth's atmosphere. The data show that average concentrations are about 10 pptv and during the last 4 years may be increasing at 0.3 [plus minus] 0.1 pptv/yr (3%/yr [plus minus] 1%/yr). They estimate that the atmospheric lifetime of CH[sub 3]Br that is due to reaction with OH, is about 2 years, resulting in a calculated global emission rate of about 100 Gy/yr. Ocean supersaturations of 140-180% are observed, and atmospheric concentrations over the open oceans are higher than at comparably located coastal sites. The ocean source is estimated to be about 35 Gg/yr. The remaining emissions must come from other natural sources and anthropogenic activities. The results are based on some 2,200 samples obtained over more than a decade. Mass balance calculations explain most aspects of the present data but other implications are not easily reconciled, leaving open the possibility of undiscovered sources and sinks. 20 refs., 5 figs., 4 tabs.

  9. Polarization effects in thallium bromide x-ray detectors

    SciTech Connect

    Kozorezov, A.; Wigmore, J. K.; Gostilo, V.; Shorohov, M.; Owens, A.; Quarati, F.; Webb, M. A.

    2010-09-15

    We present the results of a detailed experimental study of polarization effects in thallium bromide planar x-ray detectors. Measurements were carried out in the range 10-100 keV by scanning a highly focused x-ray beam, 50 {mu}m in diameter, from a synchrotron source across the detector. Above a certain radiation threshold the detector response showed a systematic degradation of its spectroscopic characteristics, peak channel position, peak height, and energy resolution. Using a pump-and-probe technique, we studied the dynamics of spectral degradation, the spatial extent and relaxation of the polarized region, and the dependence of the detector response on bias voltage and temperature. For comparison, we modeled polarization effects induced by the charging of traps by both electrons and holes using a model based on recent theoretical work of Bale and Szeles. We calculated the charge collection efficiency and spectral line shapes as functions of exposure time, beam position, count rate, and photon energy, and obtained credible agreement with experimental results.

  10. Nanocapsules of perfluorooctyl bromide for theranostics: from formulation to targeting

    NASA Astrophysics Data System (ADS)

    Diou, O.; Fattal, E.; Payen, T.; Bridal, S. L.; Valette, J.; Tsapis, N.

    2014-03-01

    The need to detect cancer at its early stages, as well as, to deliver chemotherapy to targeted site motivates many researchers to build theranostic platforms which combine diagnostic and therapy. Among imaging modalities, ultrasonography and Magnetic Resonance Imaging (MRI) are widely available, non invasive and complement each other. Both techniques often require the use of contrast agents. We have developed nanocapsules of perfluorooctyl bromide as dual contrast agent for both imaging modalities. The soft, amorphous polymer shell provides echogenicity, while the high-density perfluorinated liquid core allows detection by 19F MRI. We have used a shell of poly(lactide-co-glycolide) (PLGA) since this polymer is biodegradable, biocompatible and can be loaded with drugs. These capsules were shown to be efficient in vitro as contrast agents for both 19F MRI and ultrasonography. In addition, for in vivo applications a poly(ethyleneglycol) (PEG) coating promotes stability and prolonged circulation. Being stealth, nanocapsule can accumulate passively into implanted tumors by the EPR effect. We will present nanocapsule formulation and characterization, and will show promising in vivo results obtained for both ultrasonography and 19F MRI.

  11. Improved spectrometric characteristics of thallium bromide nuclear radiation detectors

    NASA Astrophysics Data System (ADS)

    Hitomi, K.; Murayama, T.; Shoji, T.; Suehiro, T.; Hiratate, Y.

    1999-06-01

    Thallium bromide (TlBr) is a compound semiconductor with a high atomic number and wide band gap. In this study, nuclear radiation detectors have been fabricated from the TlBr crystals. The TlBr crystals were grown by the horizontal travelling molten zone (TMZ) method using the materials purified by many pass zone refining. The crystals were characterized by measuring the resistivity, the mobility-lifetime ( μτ) product and the energy required to create an electron-hole pair (the ɛ value). Improved energy resolution has been obtained by the TlBr radiation detectors. At room temperature the full-width at half-maximum (FWHM) for the 59.5, 122 and 662 keV γ-ray photo peak obtained from the detectors were 3.3, 8.8 and 29.5 keV, respectively. By comparing the saturated peak position of the TlBr detector with that of the CdTe detector, the ɛ value has been estimated to be about 5.85 eV for the TlBr crystal.

  12. Evaluation of Alkali Bromide Salts for Potential Pyrochemical Applications

    SciTech Connect

    Prabhat K. Tripathy; Steven D. Herrmann; Guy L. Fredrickson; Tedd E. Lister; Toni Y. Gutknecht

    2013-10-01

    Transient techniques were employed to study the electrochemical behavior, reduction mechanism and transport properties of REBr3 (RE - La, Nd and Gd) in pure LiBr, LiBr-KBr (eutectic) and LiBr-KBr-CsBr (eutectic) melts. Gd(III) showed a reversible single step soluble-insoluble exchange phenomenon in LiBr melt at 973K. Although La (III), Nd(III) and Gd(III) ions showed reversible behavior in eutectic LiBr-KBr melts, these ions showed a combination of temperature dependent reversible and pseudo-reversible behavior. While both La(III) and Gd(III) showed one step reduction, the reduction of Nd(III) was observed to be a two step process. La metal could be electrodeposited from the ternary electrolyte at a temperature of 673K. Various electrochemical measurements suggest that both binary and ternary bromide melts can potentially be used to electrodeposit high purity RE metals at comparatively lower operating temperatures.

  13. Reduced effect of bromide on the genotoxicity in secondary effluent of a municipal wastewater treatment plant during chlorination.

    PubMed

    Wu, Qian-Yuan; Li, Yi; Hu, Hong-Ying; Sun, Ying-Xue; Zhao, Feng-Yun

    2010-07-01

    Chlorination of wastewater can form genotoxic, mutagenic, and/or carcinogenic disinfection byproduct (DBPs). In this study, the effect of bromide on genotoxicity in secondary effluent of a municipal wastewater treatment plant during chlorination was evaluated by the SOS/umu test. The presence of bromide notably decreased the genotoxicity in secondary effluent during chlorination, especially under conditions of high ammonia concentration. Bromide significantly decreased the concentration of ofloxacin, a genotoxic chemical in secondary effluent, during chlorination with high concentration of ammonia, while genotoxic DBPs formation of humic acid and aromatic amino acids associated with bromide limitedly contributed to the changes of genotoxicity in secondary effluent under the conditions of this study. By fractionating dissolved organic matter (DOM) in the secondary effluent into different fractions, the fractions containing hydrophilic substances (HIS) and hydrophobic acids (HOA) contributed to the decrease in genotoxicity induced by bromide. Chlorination of HOA without bromide increased genotoxicity, while the addition of bromide decreased genotoxicity. PMID:20521844

  14. Maximizing Tensile Strain in Germanium Nanomembranes for Enhanced Optoelectronic Properties

    NASA Astrophysics Data System (ADS)

    Sanchez Perez, Jose Roberto

    Silicon, germanium, and their alloys, which provide the leading materials platform of microelectronics, are extremely inefficient light emitters because of their indirect fundamental energy band gap. This basic materials property has so far hindered the development of group-IV photonic-active devices, including light emitters and diode lasers, thereby significantly limiting our ability to integrate electronic and photonic functionalities at the chip level. Theoretical studies have predicted that tensile strain in Ge lowers the direct energy band gap relative to the indirect one, and that, with sufficient strain, Ge becomes direct-band gap, thus enabling facile interband light emission and the fabrication of Group IV lasers. It has, however, not been possible to impart sufficient strain to Ge to reach the direct-band gap goal, because bulk Ge fractures at much lower strains. Here it is shown that very thin sheets of Ge(001), called nanomembranes (NMs), can be used to overcome this materials limitation. Germanium nanomembranes (NMs) in the range of thicknesses from 20nm to 100nm were fabricated and then transferred and mounted to a flexible substrate [a polyimide (PI) sheet]. An apparatus was developed to stress the PI/NM combination and provide for in-situ Raman measurements of the strain as a function of applied stress. This arrangement allowed for the introduction of sufficient biaxial tensile strain (>1.7%) to transform Ge to a direct-band gap material, as determined by photoluminescence (PL) measurements and theory. Appropriate shifts in the emission spectrum and increases in PL intensities were observed. The advance in this work was nanomembrane fabrication technology; i.e., making thin enough Ge sheets to accept sufficiently high levels of strain without fracture. It was of interest to determine if the strain at which fracture ultimately does occur can be raised, by evaluating factors that initiate fracture. Attempts to assess the effect of free edges (enchant

  15. BROMIDE'S EFFECT ON DBP FORMATION, SPECIATION, AND CONTROL: PART 1, OZONATION

    EPA Science Inventory

    The effect of variable ozone dosage and bromide concentration on the formation of organic disinfection byproducts (DBPs) and bromate were evaluated. Low ozone dosages resulted in oxidation of organic precursors, yielding decreases in the formation potential for total trihalometha...

  16. Palladium-catalyzed direct α-arylation of methyl sulfones with aryl bromides.

    PubMed

    Zheng, Bing; Jia, Tiezheng; Walsh, Patrick J

    2013-04-01

    A direct and efficient approach for palladium-catalyzed arylation of aryl and alkyl methyl sulfones with aryl bromides has been developed. The catalytic system affords arylated sulfones in good to excellent yields (73-90%). PMID:23517309

  17. Electrochemical removal of bromide and reduction of THM formation potential in drinking water.

    PubMed

    Kimbrough, David Eugene; Suffet, I H

    2002-11-01

    Trihalomethanes (THMs), a by-product of the chlorination of natural waters containing dissolved organic carbon and bromide, are the focus of considerable public health concern and regulation due to their potential as a carcinogen by ingestion. This paper presents a promising new water treatment process that lowers the concentration of bromide in drinking water and thus, lowers the THM formation potential. Bromide is oxidized by electrolysis to bromine and then the bromine apparently volatilized. The electrolyzed water, when chlorinated, produces measurably lower amounts of THMs and proportionately fewer brominated THMs, which are of greater public health concern than the chlorinated THMs. Removing bromide should also reduce the formation of other disinfection by-products such as bromate and haloacetic acids. PMID:12448534

  18. Factors affecting performance of methyl bromide alternatives - a South Atlantic perspective

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumigant application methods and equipment were identified as a source of variability in the performance of methyl bromide alternatives during several field demonstration trials conducted in 2007. Shank injection systems incorrectly modified to accommodate reduced fumigant flow rates through deliv...

  19. CHLORPYRIFOS TRANSFORMATION BY AQUEOUS CHLORINE IN THE PRESENCE OF BROMIDE AND NATURAL ORGANIC MATTER

    EPA Science Inventory

    The aqueous chlorination of chlorpyrifos (CP) was investigated in the presence of bromide and natural organic matter (NOM), which were identified as naturally occurring aqueous constituents that could impact CP transformation rates to the toxic product chlorpyrifos oxon (CPO). Br...

  20. Uptake and excretion of ( UC)methyl bromide as influenced by exposure concentration

    SciTech Connect

    Medinsky, M.A.; Dutcher, J.S.; Bond, J.A.; Henderson, R.F.; Mauderly, J.L.; Snipes, M.B.; Mewhinney, J.A.; Cheng, Y.S.; Birnbaum, L.S.

    1985-01-01

    Uptake of methyl bromide and pathways for excretion of UC were investigated in male Fischer-344 rats after nose-only inhalation of 50, 300, 5700, or 10,400 nmol (1.6 to 310 ppm) of ( UC)methyl bromide/liter of air for 6 hr. Fractional uptake of methyl bromide decreased at the highest concentrations, 5700 and 10,400 nmol/liter, with 37 and 27% of the inhaled methyl bromide absorbed, respectively, compared to 48% at the lower levels. Total methyl bromide absorbed was 9 or 40 mol/kg body wt after exposure to 50 or 300 nmol/liter, respectively. Elimination of UC was linearly related to the amount of methyl bromide absorbed as determined from urine, feces, expired CO2, and parent compound collected for 66 hr after the end of exposure. Exhaled UCO2 was the dominant route of excretion, with from 1.2 to 110 mol (50% of amount absorbed) exhaled, and was described by a two-component negative exponential function; 85% was exhaled with t1/2 of 4 hr, and the remaining 15% was exhaled with a t1/2 of 17 hr. The rate of exhalation of UCO2 was not affected by the amount of ( UC)methyl bromide absorbed. From 0.4 to 54 mol was excreted in urine (20% of amount absorbed). The half-time for excretion of UC in urine was approximately 10 hr, and the rate of excretion was not dependent on the amount of ( UC)methyl bromide absorbed. Little UC was exhaled as methyl bromide (<4% of the dose) or excreted in feces (<2%). At the end of 66 hr, 25% of the UC absorbed remained in the rats. Liver, kidneys, adrenals, lungs, thymus, and turbinates (maxilloturbinates, ethmoturbinates, and nasal epithelial membrane) contained the highest concentrations of UC. Results indicated that uptake of inhaled methyl bromide could be saturated. Any ( UC)methyl bromide equivalents absorbed, however, would be excreted by concentration-independent mechanisms. 20 references, 5 figures, 4 tables.

  1. Bromide transport in a sandy and a silty soil - a comparative lysimeter study

    NASA Astrophysics Data System (ADS)

    Schober, L.; Iden, S. C.; Durner, W.

    2009-04-01

    The aim of this study was a comparison of bromide leaching through a silty and a sandy soil and the characterization of systematic differences in solute transport in these undisturbed soils of differing texture. The amount of seepage water and bromide concentrations in the water were measured in 5 lysimeters for each soil type for a period of 460 days. Additionally, meteorological data were measured next to the lysimeter station for this period. The water transport regime of the lysimeters was simulated by means of a numerical solution of the Richards equation using the software package HYDRUS 1D. The observed bromide transport was simulated by steady-state approximation, applying the simulation tool CXTFIT, which is implemented in the software package STANMOD, version 2.0. Analysis of the measured data showed that a correct reproduction of the water balance was possible, but required the adaptation of soil-dependent crop coefficients for the potential transpiration of Phacelia and Winter Rape. The mean bromide transport through the sandy soil could be approximately reproduced assuming a bromide uptake by plants. Observed double peaks of some of the individual breakthrough curves, however, indicated that the actual transport regime in the lysimeters was subject to local heterogeneity which cannot be covered by the effective one-dimensional transport model. Bromide transport through the silty soil showed an unexplained mass deficit of nearly 90 % of the applied bromide and the detection of a mean distinct bromide peak in seepage water after percolation of only 0.5 pore volumes. It was not possible to simulate this behaviour with an effective 1D equilibrium or nonequilibrium convection-dispersion model.

  2. Stabilized thallium bromide radiation detectors and methods of making the same

    SciTech Connect

    Leao, Cedric Rocha; Lordi, Vincenzo

    2015-11-24

    According to one embodiment, a crystal includes thallium bromide (TlBr), one or more positively charged dopants, and one or more negatively charged dopants. According to another embodiment, a system includes a monolithic crystal including thallium bromide (TlBr), one or more positively charged dopants, and one or more negatively charged dopants; and a detector configured to detect a signal response of the crystal.

  3. The effect of pinaverium bromide (LA 1717) on the lower oesophageal sphincter.

    PubMed

    Wöltje, M; Huchzermeyer, H

    1982-01-01

    An acute, double-blind study was carried out in 8 healthy male volunteers to investigate any effect of a new antispasmodic, pinaverium bromide, compared with placebo on the lower oesophageal sphincter. Manometric measurements showed no significant differences in resting pressures either after placebo or a therapeutic dose (200 mg) of pinaverium bromide, suggesting that the active drug does not cause any impairment of function of the lower oesophageal sphincter. PMID:7128186

  4. Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region

    NASA Astrophysics Data System (ADS)

    Furukawa, Masahiro; Kaji, Masao; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

    To improve the thermal performance of high temperature generator of absorption chiller/heater, heat transfer characteristics of flow boiling of lithium bromide aqueous solution in the subcooled region were experimentally investigated. Experiments were made for water and lithium bromide aqueous solution flowing in a rectangular channel (5 mm × 20 mm cross section) with one side wall heated. Boiling onset quality of lithium bromide aqueous solution is greater than that of water. The heat transfer coefficient of lithium bromide aqueous solution is about a half of that of water under the same experimental conditions of inlet velocity and heat flux. The experimental data of heat transfer coefficient for water are compared with the empirical correlation of Thom et al.11) and a fairly good agreement is obtained. The predictive calculations by the method of Sekoguchi et al.12) are compared with the data for water and lithium bromide aqueous solution. Agreement between them is good for water, while the results for lithium bromide aqueous solution are not satisfactory.

  5. Methyl bromide intoxication in four field-workers during removal of soil fumigation sheets.

    PubMed

    Herzstein, J; Cullen, M R

    1990-01-01

    Methyl bromide is a highly toxic and penetrating compound used extensively as an insecticide for dry foodstuffs and as a soil fumigant (in greenhouses and fields) for the control of nematodes, fungi, and weeds. More than 300 cases of systemic poisoning and 60 fatalities attributable to methyl bromide have been reported [Alexeeff and Kilgore, 1983], resulting in substantial regulations concerning its handling, storage, application, and disposal. A recent exposure incident at a Connecticut nursery represents to our knowledge the first report of toxicity stemming from exposures in the field during removal of plastic sheets days after injection of methyl bromide into soil. Following removal of polyethylene sheets covering soil fumigated with methyl bromide, four field-workers developed fatigue and light-headedness and 3 workers noted progressive respiratory, gastrointestinal (GI), and neurologic symptoms. The acute systemic symptoms improved over several days, but later-onset neuropsychiatric symptoms persisted for several weeks. This incident stresses the need for improved worker education and strict adherence to safety precautions during all stages of methyl bromide fumigation and raises the possibility of an increased risk of toxicity associated with methyl bromide fumigation during a cool season. PMID:2305812

  6. HEROICA: an underground facility for the fast screening of germanium detectors

    NASA Astrophysics Data System (ADS)

    Andreotti, E.; Garfagnini, A.; Maneschg, W.; Barros, N.; Benato, G.; Brugnera, R.; Costa, F.; Falkenstein, R.; Guthikonda, K. K.; Hegai, A.; Hemmer, S.; Hult, M.; Jänner, K.; Kihm, T.; Lehnert, B.; Liao, H.; Lubashevskiy, A.; Lutter, G.; Marissens, G.; Modenese, L.; Pandola, L.; Reissfelder, M.; Sada, C.; Salathe, M.; Schmitt, C.; Schulz, O.; Schwingenheuer, B.; Turcato, M.; Ur, C.; von Sturm, K.; Wagner, V.; Westermann, J.

    2013-06-01

    HEROICA (Hades Experimental Research Of Intrinsic Crystal Appliances) is an infrastructure to characterize germanium detectors and has been designed and constructed at the HADES Underground Research Laboratory, located in Mol (Belgium). Thanks to the 223 m overburden of clay and sand, the muon flux is lowered by four orders of magnitude. This natural shield minimizes the exposure of radio-pure germanium material to cosmic radiation resulting in a significant suppression of cosmogenic activation in the germanium detectors. The project has been strongly motivated by a special production of germanium detectors for the GERDA experiment. GERDA, currently collecting data at the Laboratori Nazionali del Gran Sasso of INFN, is searching for the neutrinoless double beta decay of 76Ge. In the near future, GERDA will increase its mass and sensitivity by adding new Broad Energy Germanium (BEGe) detectors. The production of the BEGe detectors is done at Canberra in Olen (Belgium), located about 30 km from the underground test site. Therefore, HADES is used both for storage of the crystals over night, during diode production, and for the characterization measurements. A full quality control chain has been setup and tested on the first seven prototype detectors delivered by the manufacturer at the beginning of 2012. The screening capabilities demonstrate that the installed setup fulfills a fast and complete set of measurements on the diodes and it can be seen as a general test facility for the fast screening of high purity germanium detectors. The results are of major importance for a future massive production and characterization chain of germanium diodes foreseen for a possible next generation 1-tonne double beta decay experiment with 76Ge.

  7. Development of a new type of germanium detector for dark matter searches

    NASA Astrophysics Data System (ADS)

    Wei, Wenzhao

    Monte Carlo simulation is an important tool used to develop a better understanding of important physical processes. This thesis describes three Monte Carlo simulations used to understand germanium detector response to low energy nuclear recoils and radiogenic backgrounds for direct dark matter searches. The first simulation is the verification of Barker-Mei model, a theoretical model for calculating the ionization efficiency for germanium detector for the energy range of 1 - 100 keV. Utilizing the shape analysis, a bin-to-bin comparison between simulation and experimental data was performed for verifying the accuracy of the Barker-Mei model. A percentage difference within 4% was achieved between data and simulation, which showed the validity of the Barker-Mei model. The second simulation is the study of a new type of germanium detector for n/gamma discrimination at 77 K with plasma time difference in pulse shape. Due to the poor time resolution, conventional P-type Point Contact (PPC) and coaxial germanium detectors are not capable of discriminating nuclear recoils from electron recoils. In this thesis, a new idea of using great detector granularity and plasma time difference in pulse shape to discriminate nuclear recoils from electron recoils with planar germanium detectors in strings was discussed. The anticipated sensitivity of this new detector array is shown for detecting dark matter. The last simulation is a study of a new type of germanium-detector array serving as a PMT screening facility for ultra-low background dark matter experiments using noble liquid xenon as detector material such LUX/LZ and XENON100/XENON1T. A well-shaped germanium detector array and a PMT were simulated to study the detector response to the signal and background for a better understanding of the radiogenic gamma rays from PMTs. The detector efficiency and other detector performance were presented in this work.

  8. Point defect states in Sb-doped germanium

    SciTech Connect

    Patel, Neil S. Monmeyran, Corentin; Agarwal, Anuradha; Kimerling, Lionel C.

    2015-10-21

    Defect states in n-type Sb-doped germanium were investigated by deep-level transient spectroscopy. Cobalt-60 gamma rays were used to generate isolated vacancies and interstitials which diffuse and react with impurities in the material to form four defect states (E{sub 37}, E{sub 30}, E{sub 22}, and E{sub 21}) in the upper half of the bandgap. Irradiations at 77 K and 300 K as well as isothermal anneals were performed to characterize the relationships between the four observable defects. E{sub 37} is assigned to the Sb donor-vacancy associate (E-center) and is the only vacancy containing defect giving an estimate of 2 × 10{sup 11 }cm{sup −3} Mrad{sup −1} for the uncorrelated vacancy-interstitial pair introduction rate. The remaining three defect states are interstitial associates and transform among one another. Conversion ratios between E{sub 22}, E{sub 21}, and E{sub 30} indicate that E{sub 22} likely contains two interstitials.

  9. Etching of germanium-tin using ammonia peroxide mixture

    SciTech Connect

    Dong, Yuan; Ong, Bin Leong; Wang, Wei; Gong, Xiao; Liang, Gengchiau; Yeo, Yee-Chia; Zhang, Zheng; Pan, Jisheng; Tok, Eng-Soon

    2015-12-28

    The wet etching of germanium-tin (Ge{sub 1-x}Sn{sub x}) alloys (4.2% < x < 16.0%) in ammonia peroxide mixture (APM) is investigated. Empirical fitting of the data points indicates that the etch depth of Ge{sub 1-x}Sn{sub x} is proportional to the square root of the etch time t and decreases exponentially with increasing x for a given t. In addition, X-ray photoelectron spectroscopy results show that increasing t increases the intensity of the Sn oxide peak, whereas no obvious change is observed for the Ge oxide peak. This indicates that an accumulation of Sn oxide on the Ge{sub 1-x}Sn{sub x} surface decreases the amount of Ge atoms exposed to the etchant, which accounts for the decrease in etch rate with increasing etch time. Atomic force microscopy was used to examine the surface morphologies of the Ge{sub 0.918}Sn{sub 0.082} samples. Both root-mean-square roughness and undulation periods of the Ge{sub 1-x}Sn{sub x} surface were observed to increase with increasing t. This work provides further understanding of the wet etching of Ge{sub 1-x}Sn{sub x} using APM and may be used for the fabrication of Ge{sub 1-x}Sn{sub x}-based electronic and photonic devices.

  10. Characterization of germanium stripe x-ray lasers

    SciTech Connect

    Wan, A.S.; Moreno, J.C.; MacGowan, B.J.

    1993-07-01

    One method of improving the transverse spatial coherence of x-ray lasers (XRLS) is by adaptive spatial filtering of XRL apertures using geometric shaping in the form of bowtie or wedge XRLS. However, we must maintain the desired geometric shapes in exploding foil or slab configurations during the lasing period. As a first step toward understanding Lasing in such geometries we study the behavior of simple stripe XRLs. Past experience with stripe XRLs deposited on thick plastic substrates resulted in significantly weaker laser intensities as compared to line-focused slab XRLs. Possible reasons for this intensity reduction of stripe XRLs could include mixing at the laser boundary, and changes in plasma, kinetics, and hydrodynamic properties which affect laser gains and propagation. We will present experimental and theoretical characterizations of germanium line-focused and stripe XRLs. Key experimental parameters we will study include images of emission profiles of the laser blow-off, angular divergences, XRL output intensities, and ionization balances as we vary XRL designs. We will compare the experimental results with two-dimensional (2-D) laser deposition and hydrodynamics simulations using LASNEX, and study the changes in ionization balances and level populations from post-processing LASNEX results.

  11. An Ab Initio Study on Silicon and Germanium Nanotubes

    NASA Astrophysics Data System (ADS)

    Pradhan, Prachi

    2005-03-01

    First principles calculations using hybrid density functional theory have been performed to examine the electronic and geometric structure properties of single-walled silicon (SWSiNT) and germanium (SWGeNT) nanotubes. Finite clusters XmHn^ (X = Si or Ge) are used to model the nanotubes (e.g. the smallest SWSiNT is modeled as Si60H12). Hydrogen termination is done to simulate the effect of longer tubes as well as to take care of end effects. A pseudopotential basis set has been used for the silicon atoms^1 and complete geometry optimizations of the structures has been carried out using the Gaussian 03 suite of programs.^2 Computer simulations predict that the existence and stability of the nanotubes are highly dependent on the ratio of the sp^2 to sp^3 hybridization. Results will be presented on cohesive energies, HOMO- LUMO gaps, and other electronic structure properties and their dependence on the tube diameter. We will discuss the density of states (DOS) to explain the possible metallic or semi-conducting character of the tubes. Detailed comparisons with published data in the literature will also be presented. * Work supported, in part, by the Welch Foundation, Houston, Texas (Grant No. Y-1525). ^1 P. J. Hay and W. R. Wadt, J. Chem. Phys. 82, 270 (1985). ^2 Gaussian03, Revision A.1, M. J. Frisch et al., Gaussian Inc., Pittsburgh, PA , 2003.

  12. Atomic layer deposition of hafnium oxide on germanium substrates

    NASA Astrophysics Data System (ADS)

    Delabie, Annelies; Puurunen, Riikka L.; Brijs, Bert; Caymax, Matty; Conard, Thierry; Onsia, Bart; Richard, Olivier; Vandervorst, Wilfried; Zhao, Chao; Heyns, Marc M.; Meuris, Marc; Viitanen, Minna M.; Brongersma, Hidde H.; de Ridder, Marco; Goncharova, Lyudmila V.; Garfunkel, Eric; Gustafsson, Torgny; Tsai, Wilman

    2005-03-01

    Germanium combined with high-κ dielectrics has recently been put forth by the semiconductor industry as potential replacement for planar silicon transistors, which are unlikely to accommodate the severe scaling requirements for sub-45-nm generations. Therefore, we have studied the atomic layer deposition (ALD) of HfO2 high-κ dielectric layers on HF-cleaned Ge substrates. In this contribution, we describe the HfO2 growth characteristics, HfO2 bulk properties, and Ge interface. Substrate-enhanced HfO2 growth occurs: the growth per cycle is larger in the first reaction cycles than the steady growth per cycle of 0.04nm. The enhanced growth goes together with island growth, indicating that more than a monolayer coverage of HfO2 is required for a closed film. A closed HfO2 layer is achieved after depositing 4-5HfO2 monolayers, corresponding to about 25 ALD reaction cycles. Cross-sectional transmission electron microscopy images show that HfO2 layers thinner than 3nm are amorphous as deposited, while local epitaxial crystallization has occurred in thicker HfO2 films. Other HfO2 bulk properties are similar for Ge and Si substrates. According to this physical characterization study, HfO2 can be used in Ge-based devices as a gate oxide with physical thickness scaled down to 1.6nm.

  13. Proton-induced radiation damage in germanium detectors

    NASA Technical Reports Server (NTRS)

    Brueckner, J.; Koerfer, M.; Waenke, H.; Schroeder, A. N. F.; Filges, D.; Dragovitsch, P.; Englert, P. A. J.; Starr, R.; Trombka, J. I.

    1991-01-01

    High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process, several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10 to the 8th protons/sq cm (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific and engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation, all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage, the detectors were stepwise-annealed at temperatures below 110 C, while kept in their specially designed cryostats. This study shows that n-type HPGe detectors can be used in charged-particle environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.

  14. Radiation damage of the HEAO C-1 germanium detectors

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Ling, J. C.; Jacobson, A. S.

    1981-01-01

    The effects of radiation damage from proton bombardment of the four HEAO C-1 high purity germanium detectors have been measured and compared to predictions. Because of the presence of numerous gamma-ray lines in the detector background spectra and because of the relatively long exposure time of the HEAO 3 satellite to cosmic-ray and trapped protons, it has been possible to measure both the energy and time dependence of radiation damage. After 100 d in orbit, each of the four detectors has been exposed to approximately 3 x 10 to the 7th protons/sq cm, and the average energy resolution at 1460 keV had degraded from 3.2 keV fwhm to 8.6 keV fwhm. The lines were all broadened to the low energy side although the line profile was different for each of the four detectors. The damage-related contribution to the degradation in energy resolution was found to be linear in energy and proton influence.

  15. Spatial resolution attainable in germanium detectors by pulse shape analysis

    SciTech Connect

    Blair, J., Bechtel, NV; Beckedahl, D.; Kammeraad, J.; Schmid, G., LLNL

    1998-05-01

    There are several applications for which it is desirable to calculate the locations and energies of individual gamma-ray interactions within a high purity germanium (HPGe) detector. These include gamma-ray imaging and Compton suppression. With a segmented detector this can be accomplished by analyzing the pulse shapes of the signals from the various segments. We examine the fundamental limits to the spatial resolution attainable with this approach. The primary source of error is the series noise of the field effect transistors (FETs) at the inputs of the charge amplifiers. We show how to calculate the noise spectral density at the output of the charge amplifiers due to an optimally selected FET. This calculation is based only on the detector capacitance and a noise constant for the FET technology. We show how to use this spectral density to calculate the uncertainties in parameters, such as interaction locations and energies, that are derived from pulse shape analysis using maximum likelihood estimation (MLE) applied to filtered and digitized recordings of the charge signals. Example calculations are given to illustrate our approach. Experimental results are given that demonstrate that one can construct complete systems, from detector through data analysis, that come near the theoretical limits.

  16. X-ray microcalorimeters with germanium resistance thermometers

    SciTech Connect

    Labov, S.; Silver, E.; Pfafman, T.; Wai, Y. ); Beeman, J.; Goulding, F.; Landis, D.; Madden, N.; Haller, E. )

    1990-08-13

    We report on the current of our work on x-ray microcalorimeters for use as high resolution x-ray spectrometers. To maximize the x-ray collecting area and the signal to noise ratio, the total heat capacity of the device must be minimized. This is best achieved if the calorimeter is divided into two components, a thermal sensor and an x-ray absorber. The thermal sensor is a neutron transmutation doped (NTD) germanium resistor made as small as possible to minimize the heat capacity of the calorimeter. The thermistor can be attached to a thin x-ray absorber with large area and low heat capacity fabricated from superconducting materials such as niobium. We discuss results from our most recent studies of such superconducting absorbers and present the x-ray spectra obtained with these composite microcalorimeters at a temperature of 0.1 K. An energy resolution of 19 eV FWHM has been measured. 14 refs., 3 figs.

  17. Bending-induced Symmetry Breaking of Lithiation in Germanium Nanowires

    SciTech Connect

    Gu, Meng; Yang, Hui; Perea, Daniel E.; Zhang, Jiguang; Zhang, Sulin; Wang, Chong M.

    2014-08-01

    From signal transduction of living cells to oxidation and corrosion of metals, mechanical stress intimately couples with chemical reactions, regulating these biological and physiochemical processes. The coupled effect is particularly evident in electrochemical lithiation/delithiation cycling of high-capacity electrodes, such as silicon (Si), where on one hand lithiation-generated stress mediates lithiation kinetics, and on the other electrochemical reaction rate regulates stress generation and mechanical failure of the electrodes. Here we report for the first time the evidence on the controlled lithiation in germanium nanowires (GeNWs) through external bending. Contrary to the symmetric core-shell lithiation in free-standing GeNWs, we show bending GeNWs breaks the lithiation symmetry, speeding up lithaition at the tensile side while slowing down at the compressive side of the GeNWs. The bending-induced symmetry breaking of lithiation in GeNWs is further corroborated by chemomechanical modeling. In the light of the coupled effect between lithiation kinetics and mechanical stress in the electrochemical cycling, our findings shed light on strain/stress engineering of durable high-rate electrodes and energy harvesting through mechanical motion.

  18. Ductile-regime turning of germanium and silicon

    NASA Technical Reports Server (NTRS)

    Blake, Peter N.; Scattergood, Ronald O.

    1989-01-01

    Single-point diamond turning of silicon and germanium was investigated in order to clarify the role of cutting depth in coaxing a ductile chip formation in normally brittle substances. Experiments based on the rapid withdrawal of the tool from the workpiece have shown that microfracture damage is a function of the effective depth of cut (as opposed to the nominal cutting depth). In essence, damage created by the leading edge of the tool is removed several revolutions later by lower sections of the tool edge, where the effective cutting depth is less. It appears that a truly ductile cutting response can be achieved only when the effective cutting depth, or critical chip thickness, is less than about 20 nm. Factors such as tool rake angle are significant in that they will affect the actual value of the critical chip thickness for transition from brittle to ductile response. It is concluded that the critical chip thickness is an excellent parameter for measuring the effects of machining conditions on the ductility of the cut and for designing tool-workpiece geometry in both turning and grinding.

  19. Spin Qubits in Germanium Structures with Phononic Gap

    NASA Technical Reports Server (NTRS)

    Smelyanskiy, V. N.; Vasko, F. T.; Hafiychuk, V. V.; Dykman, M. I.; Petukhov, A. G.

    2014-01-01

    We propose qubits based on shallow donor electron spins in germanium structures with phononic gap. We consider a phononic crystal formed by periodic holes in Ge plate or a rigid cover / Ge layer / rigid substrate structure with gaps approximately a few GHz. The spin relaxation is suppressed dramatically, if the Zeeman frequency omegaZ is in the phononic gap, but an effective coupling between the spins of remote donors via exchange of virtual phonons remains essential. If omegaZ approaches to a gap edge in these structures, a long-range (limited by detuning of omegaZ) resonant exchange interaction takes place. We estimate that ratio of the exchange integral to the longitudinal relaxation rate exceeds 10(exp 5) and lateral scale of resonant exchange 0.1 mm. The exchange contribution can be verified under microwave pumping through oscillations of spin echo signal or through the differential absorption measurements. Efficient manipulation of spins due to the Rabi oscillations opens a new way for quantum information applications.

  20. Proton-induced radiation damage in germanium detectors

    SciTech Connect

    Bruckner, J.; Korfer, M.; Wanke, H. , Mainz ); Schroeder, A.N.F. ); Figes, D.; Dragovitsch, P. ); Englert, P.A.J. ); Starr, R.; Trombka, J.I. . Goddard Space Flight Center); Taylor, I. ); Drake, D.M.; Shunk, E.R. )

    1991-04-01

    High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10{sub 8} protons cm{sup {minus}2} (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific as well as engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage the detectors were stepwise annealed at temperatures T {le} 110{degrees}C while staying specially designed cryostats. This paper shows that n-type HPGe detectors can be used in charged particles environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.

  1. Comparison of CDMS [100] and [111] Oriented Germanium Detectors

    SciTech Connect

    Leman, S.W.; Hertel, S.A.; Kim, P.; Cabrera, B.; Do Couto E.Silva, E.; Figueroa-Feliciano, E.; McCarthy, K.A.; Resch, R.; Sadoulet, B.; Sundqvist, K.M.; /UC, Berkeley

    2012-09-14

    The Cryogenic Dark Matter Search (CDMS) utilizes large mass, 3-inch diameter x 1-inch thick target masses as particle detectors. The target is instrumented with both phonon and ionization sensors and comparison of energy in each channel provides event-by-event classification of electron and nuclear recoils. Fiducial volume is determined by the ability to obtain good phonon and ionization signal at a particular location. Due to electronic band structure in germanium, electron mass is described by an anisotropic tensor with heavy mass aligned along the symmetry axis defined by the [111] Miller index (L valley), resulting in large lateral component to the transport. The spatial distribution of electrons varies significantly for detectors which have their longitudinal axis orientations described by either the [100] or [111] Miller indices. Electric fields with large fringing component at high detector radius also affect the spatial distribution of electrons and holes. Both effects are studied in a 3 dimensional Monte Carlo and the impact on fiducial volume is discussed.

  2. Germanium Detector Crystal Axis Orientation for the MAJORANA Demonstrator

    NASA Astrophysics Data System (ADS)

    Letourneau, Hannah

    2013-10-01

    The MAJORANA Demonstrator, currently being constructed at Sanford Underground Research Facility in Lead, South Dakota, is an array of germanium detectors which will be used to search for neutrinoless double beta decay, which would demonstrate that neutrinos have a Majorana mass term and lepton number is not conserved. An important characteristic of semiconductor detectors is the crystal axis orientation, because the propagation of electromagnetic signals is attenuated by the location of the interaction relative to the axis of the crystal. Conventionally, a goniometer is used to position a collimated low energy gamma source in many small increments around the detector to measure the rise time at each position. However, due to physical constraints from the casing of the Demonstrator, a different method must be developed. At the University of Washington this summer, I worked with a 76 Ge point-contact detector. I found the crystal axis orientation first with Americium 241, a lower energy gamma source. Then, I used a higher energy source, Thorium 232, in conjunction with the only a few angular reference points to also calculate rise time. Also, I wrote code to process the data. The success of this method will be evaluated and discussed. NSF

  3. Spin pumping and inverse spin Hall effect in germanium

    NASA Astrophysics Data System (ADS)

    Rojas Sanchez, Juan-Carlos; Vergnaud, C.; Vila, L.; Attane, J.-P.; Marty, A.; Jaffres, Henri; Jamet, Matthieu; George, Jean-Marie

    2014-03-01

    We have measured the inverse spin Hall effect (ISHE) in n-Ge at room temperature. The spin current in germanium was generated by spin pumping from a CoFeB/MgO magnetic tunnel junction in order to prevent the impedance mismatch issue. A clear electromotive force was measured in Ge at the ferromagnetic resonance of CFB. The same study was then carried out on several test samples, in particular, we have investigated the influence of the MgO tunnel barrier and sample annealing on the ISHE signal. The reference CFB/MgO bilayer grown on SiO2 exhibits a clear electromotive force due to anisotropic magnetoresistance and anomalous Hall effect, which is dominated by an asymmetric contribution with respect to the resonance field. We also found that the MgO tunnel barrier is essential to observe ISHE in Ge and that sample annealing systematically leads to an increase of the signal. We propose a theoretical model based on the presence of localized states at the interface to account for these observations. Finally, all of our results are fully consistent with the observation of ISHE in heavily doped n-Ge with a spin Hall angle around 0.001. JCRS acknowledges the Eurotalent CEA program.

  4. Isotopic germanium targets for high beam current applications at GAMMASPHERE.

    SciTech Connect

    Greene, J. P.; Lauritsen, T.

    2000-11-29

    The creation of a specific heavy ion residue via heavy ion fusion can usually be achieved through a number of beam and target combinations. Sometimes it is necessary to choose combinations with rare beams and/or difficult targets in order to achieve the physics goals of an experiment. A case in point was a recent experiment to produce {sup 152}Dy at very high spins and low excitation energy with detection of the residue in a recoil mass analyzer. Both to create the nucleus cold and with a small recoil-cone so that the efficiency of the mass analyzer would be high, it was necessary to use the {sup 80}Se on {sup 76}Ge reaction rather than the standard {sup 48}Ca on {sup 108}Pd reaction. Because the recoil velocity of the {sup 152}Dy residues was very high using this symmetric reaction (5% v/c), it was furthermore necessary to use a stack of two thin targets to reduce the Doppler broadening. Germanium targets are fragile and do not withstand high beam currents, therefore the {sup 76}Ge target stacks were mounted on a rotating target wheel. A description of the {sup 76}Ge target stack preparation will be presented and the target performance described.

  5. Measurement of Compton scattering in phantoms by germanium detectors

    SciTech Connect

    Zasadny, K.R.; Koral, K.F. . Medical Center); Floyd, C.E. Jr.; Jaszczak, R.J. . Dept. of Radiology)

    1990-04-01

    Quantitative Anger-camera tomography requires correction for Compton scattering. The Anger camera spectral-fitting technique can measure scatter fractions at designated positions in an image allowing for correction. To permit verification of those measurements for {sup 131}I, the authors have determined scatter fractions with a high-purity germanium (HPGe) detector and various phantom configurations. The scatter fraction values for {sup 99m}Tc were also measured and are compared to results from Monte Carlo simulation. The phantom consisted of a 22.2 cm diameter {times} 18.6 cm high cylinder filled with water and a 6 cm diameter water-filled sphere placed at various locations inside the cylinder. Radioisotope is added to either the sphere or the cylinder. The source is collimated by an Anger camera collimator and the active area of the HPGe detector is defined by a 0.6 cm diameter hole in a lead shielding mask. Corrections include accounting for the HPGe detector efficiency as a function of gamma-ray energy, the finite energy resolution of detector and the HPGe detector energy resolution compared to that for a NaI(Tl) Anger camera.

  6. Environmental Radioactivity: Gamma Ray Spectroscopy with Germanium detector

    NASA Astrophysics Data System (ADS)

    Vyas, Gargi; Beausang, Cornelius; Hughes, Richard; Tarlow, Thomas; Gell, Kristen; University of Richmond Physics Team

    2013-10-01

    A CF-1000BRL series portable Air Particle Sampler with filter paper as filter media was placed in one indoor and one outdoor location at 100 LPM flow rate on six dates under alternating rainy and warm weather conditions over the course of sixteen days in May 2013. The machine running times spanned between 6 to 69 hours. Each filter paper was then put in a germanium gamma ray detector, and the counts ranged from 93000 to 250000 seconds. The spectra obtained were analyzed by the CANBERRA Genie 2000 software, corrected using a background spectrum, and calibrated using a 20.27 kBq activity multi-nuclide source. We graphed the corrected counts (from detector analysis time)/second (from air sampler running time)/liter (from the air sampler's flow rate) of sharp, significantly big peaks corresponding to a nuclide in every sample against the sample number along with error bars. The graphs were then used to compare the samples and they showed a similar trend. The slight differences were usually due to the different running times of the air sampler. The graphs of about 22 nuclides were analyzed. We also tried to recognize the nuclei to which several gamma rays belonged that were displayed but not recognized by the Genie 2000 software.

  7. What is the thermal conductivity limit of silicon germanium alloys?

    PubMed

    Lee, Yongjin; Pak, Alexander J; Hwang, Gyeong S

    2016-07-20

    The lowest possible thermal conductivity of silicon-germanium (SiGe) bulk alloys achievable through alloy scattering, or the so-called alloy limit, is important to identify for thermoelectric applications. However, this limit remains a subject of contention as both experimentally-reported and theoretically-predicted values tend to be widely scattered and inconclusive. In this work, we present a possible explanation for these discrepancies by demonstrating that the thermal conductivity can vary significantly depending on the degree of randomness in the spatial arrangement of the constituent atoms. Our study suggests that the available experimental data, obtained from alloy samples synthesized using ball-milling techniques, and previous first-principles calculations, restricted by small supercell sizes, may not have accessed the alloy limit. We find that low-frequency anharmonic phonon modes can persist unless the spatial distribution of Si and Ge atoms is completely random at the atomic scale, in which case the lowest possible thermal conductivity may be achieved. Our theoretical analysis predicts that the alloy limit of SiGe could be around 1-2 W m(-1) K(-1) with an optimal composition around 25 at% Ge, which is substantially lower than previously reported values from experiments and first-principles calculations. PMID:27398924

  8. Defect Density Characterization of Detached-Grown Germanium Crystals

    NASA Technical Reports Server (NTRS)

    Schweizer, M.; Cobb, S. D.; Volz, M. P.; Szoke, J.; Szofran, F. R.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Several (111)-oriented, Ga-doped germanium crystals were grown in pyrolytic boron nitride (pBN) containers by the Bridgman and the detached Bridgman growth techniques. Growth experiments in closed-bottom pBN containers resulted in nearly completely detached-grown crystals, because the gas pressure below the melt can build up to a higher pressure than above the melt. With open-bottom tubes the gas pressure above and below the melt is balanced during the experiment, and thus no additional force supports the detachment. In this case the crystals grew attached to the wall. Etch pit density (EPD) measurements along the axial growth direction indicated a strong improvement of the crystal quality of the detached-grown samples compared to the attached samples. Starting in the seed with an EPD of 6-8 x 10(exp 3)/square cm it decreased in the detached-grown crystals continuously to about 200-500/square cm . No significant radial difference between the EPD on the edge and the middle of the crystal exists. In the attached grown samples the EPD increases up to a value of about 2-4 x 10(exp 4)/square cm (near the edge) and up to 1 x 10(exp 4)/square cm in the middle of the sample. Thus the difference between the detached- and the attached-grown crystals with respect to the EPD is approximately two orders of magnitude.

  9. X-ray Characterization of Detached-Grown Germanium Crystals

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Schweizer, M.; Raghothamachar, B.; Dudley, M.; Szoke, J.; Cobb, S. D.; Szofran, F. R.

    2005-01-01

    Germanium (111)-oriented crystals have been grown by the vertical Bridgman technique, in both detached and attached configurations. Microstructural characterization of these crystals has been performed using synchrotron white beam x-ray topography (SWBXT) and double axis x-ray diffraction. Dislocation densities were measured from x-ray topographs obtained using the reflection geometry. For detached-grown crystals, the dislocation density is 4-6 x 10(exp 4) per square centimeter in the seed region, and decreases in the direction of growth to less than 10(exp 3) per square centimeter, and in some crystals reaches less than 10(exp 2) per square centimeter. For crystals grown in the attached configuration, dislocation densities were on the order of 10(exp 4) per square centimeter in the middle of the crystals, increasing to greater than 10(exp 5) per square centimeter near the edge. The measured dislocation densities are in excellent agreement with etch pit density results. The rocking curve linewidths were relatively insensitive to the dislocation densities. However, broadening and splitting of the rocking curves were observed in the vicinity of subgrain boundaries identified by x-ray topography in some of the attached-grown crystals.

  10. Predicting bromide incorporation in a chlorinated indoor swimming pool.

    PubMed

    Chowdhury, Shakhawat; Mazumder, Abu Jafar; Husain, Tahir

    2016-06-01

    The water in and air above swimming pools often contain high levels of disinfection byproducts (DBPs) due to chemical reactions between chlorine- or bromine-based disinfectants and organic/inorganic matter in the source water and released from swimmers. Exposure to these DBPs, though inevitable, can pose health threats to humans. In this study, DBPs in tap water (S1), and water from a chlorinated indoor swimming pool before (S2) and after swimming (S3) were measured. The brominated species constituted the majority of DBPs formed in S1, S2, and S3. Trihalomethanes (THMs) in S3 was 6.9 (range 2.9-11.1) and 1.4 (range 0.52-2.9) times those in S1 and S2, respectively; and the haloacetic acids (HAAs) in S3 was 4.2 (range 2.5-7.5) and 1.2 (range 0.6-2.6) times those in S1 and S2, respectively. The mean THMs in air above the swimming pool before (S2-A) and after swimming (S3-A) were 72.2 and 93.0 μg/m(3), respectively, and their ranges were 36.3-105.8 and 44.1-133.6 μg/m(3), respectively. The average percentages of bromide incorporation (BI) into THMs in S1, S2, and S3 were 3.0, 9.3, and 10.6 %, respectively; and the BI into HAAs in S1, S2, and S3 were 6.6, 12.0, and 12.2 %, respectively. Several models were trained for predicting the BI into THMs and HAAs. The results indicate that additional information is required to develop predictive models for BI in swimming pools. PMID:26971516

  11. Bacterial oxidation of methyl bromide in fumigated agricultural soils

    USGS Publications Warehouse

    Miller, L.G.; Connell, T.L.; Guidetti, J.R.; Oremland, R.S.

    1997-01-01

    The oxidation of [14C]methyl bromide ([14C]MeBr) to 14CO2 was measured in field experiments with soils collected from two strawberry plots fumigated with mixtures of MeBr and chloropicrin (CCI3NO2). Although these fumigants are considered potent biocides, we found that the highest rates of MeBr oxidation occurred 1 to 2 days after injection when the fields were tarped, rather than before or several days after injection. No oxidation of MeBr occurred in heat-killed soils, indicating that microbes were the causative agents of the oxidation. Degradation of MeBr by chemical and/or biological processes accounted for 20 to 50% of the loss of MeBr during fumigation, with evasion to the atmosphere inferred to comprise the remainder. In laboratory incubations, complete removal of [14C]MeBr occurred within a few days, with 47 to 67% of the added MeBr oxidized to 14CO2 and the remainder of counts associated with the solid phase. Chloropicrin inhibited the oxidation of MeBr, implying that use of this substance constrains the extent of microbial degradation of MeBr during fumigation. Oxidation was by direct bacterial attack of MeBr and not of methanol, a product of the chemical hydrolysis of MeBr. Neither nitrifying nor methane-oxidizing bacteria were sufficiently active in these soils to account for the observed oxidation of MeBr, nor could the microbial degradation of MeBr be linked to cooxidation with exogenously supplied electron donors. However, repeated addition of MeBr to live soils resulted in higher rates of its removal, suggesting that soil bacteria used MeBr as an electron donor for growth. To support this interpretation, we isolated a gram-negative, aerobic bacterium from these soils which grew with MeBr as a sole source of carbon and energy.

  12. Carbon isotope fractionation of methyl bromide during agricultural soil fumigations

    USGS Publications Warehouse

    Bill, M.; Miller, L.G.; Goldstein, Allen H.

    2002-01-01

    The isotopic composition of methyl bromide (CH3Br) has been suggested to be a potentially useful tracer for constraining the global CH3Br budget. In order to determine the carbon isotopic composition of CH3Br emitted from the most significant anthropogenic application (pre-plant fumigation) we directly measured the ??13C of CH3Br released during commercial fumigation. We also measured the isotopic fractionation associated with degradation in agricultural soil under typical field fumigation conditions. The isotopic composition of CH3Br collected in soil several hours after injection of the fumigant was -44.5??? and this value increased to -20.7??? over the following three days. The mean kinetic isotope effect (KIE) associated with degradation of CH3Br in agricultural soil (12???) was smaller than the reported value for methylotrophic bacterial strain IMB-1, isolated from previously fumigated agricultural soil, but was similar to methylotrophic bacterial strain CC495, isolated from a pristine forest litter zone. Using this fractionation associated with the degradation of CH3Br in agricultural soil and the mean ??13C of the industrially manufactured CH3Br (-54.4???), we calculate that the agricultural soil fumigation source has a carbon isotope signature that ranges from -52.8??? to -42.0???. Roughly 65% of industrially manufactured CH3Br is used for field fumigations. The remaining 35% is used for structural and post-harvest fumigations with a minor amount used during industrial chemical manufacturing. Assuming that the structural and post-harvest fumigation sources of CH3Br are emitted without substantial fractionation, we calculate that the ??13C of anthropogenically emitted CH3Br ranges from -53.2??? to -47.5???.

  13. Dicationic Alkylammonium Bromide Gemini Surfactants. Membrane Perturbation and Skin Irritation

    PubMed Central

    Almeida, João A. S.; Faneca, Henrique; Carvalho, Rui A.; Marques, Eduardo F.; Pais, Alberto A. C. C.

    2011-01-01

    Dicationic alkylammonium bromide gemini surfactants represent a class of amphiphiles potentially effective as skin permeation enhancers. However, only a limited number of studies has been dedicated to the evaluation of the respective cytotoxicity, and none directed to skin irritation endpoints. Supported on a cell viability study, the cytotoxicity of gemini surfactants of variable tail and spacer length was assessed. For this purpose, keratinocyte cells from human skin (NCTC 2544 cell line), frequently used as a model for skin irritation, were employed. The impact of the different gemini surfactants on the permeability and morphology of model vesicles was additionally investigated by measuring the leakage of calcein fluorescent dye and analyzing the NMR spectra of 31P, respectively. Detail on the interaction of gemini molecules with model membranes was also provided by a systematic differential scanning calorimetry (DSC) and molecular dynamics (MD) simulation. An irreversible impact on the viability of the NCTC 2544 cell line was observed for gemini concentrations higher than 25 mM, while no cytotoxicity was found for any of the surfactants in a concentration range up to 10 mM. A higher cytotoxicity was also found for gemini surfactants presenting longer spacer and shorter tails. The same trend was obtained in the calorimetric and permeability studies, with the gemini of longest spacer promoting the highest degree of membrane destabilization. Additional structural and dynamical characterization of the various systems, obtained by 31P NMR and MD, provide some insight on the relationship between the architecture of gemini surfactants and the respective perturbation mechanism. PMID:22102870

  14. Clinical potential of aclidinium bromide in chronic obstructive pulmonary disease

    PubMed Central

    Jones, Paul W

    2015-01-01

    Three long-acting muscarinic antagonists (LAMAs) are now available in Europe, providing clinicians and patients with a choice of interventions, which is important in COPD, which is clinically a heterogeneous disease. The first LAMA, tiotropium, has been widely used over the last decade as a once-daily maintenance therapy in stable COPD to improve patients’ health-related quality of life and to reduce the risk of exacerbations. Administered via the HandiHaler® device, it is safe and well tolerated. Another new once-daily LAMA, glycopyrronium, has also been shown to improve health status and reduce exacerbations, and is well tolerated. The subject of this review is a third LAMA, aclidinium bromide, which was approved as a twice-daily maintenance bronchodilator treatment. In the pivotal Phase III clinical trials, patients receiving aclidinium achieved significantly greater improvements in lung function, reductions in breathlessness, and improvements in health status compared with placebo, for up to 24 weeks. In continuation studies, these improvements were sustained for up to 52 weeks. Pooled data showed exacerbation frequency was significantly reduced with aclidinium versus placebo. Preclinical and pharmacological studies demonstrating low systemic bioavailability and a low propensity to induce cardiac arrhythmias were translated into a favorable tolerability profile in the clinical trial program – the adverse event profile of aclidinium was similar to placebo, with a low incidence of anticholinergic and cardiac adverse events. While additional studies are needed to evaluate its full clinical potential, aclidinium is an important part of this recent expansion of LAMA therapeutic options, providing clinicians and patients with an effective and well-tolerated COPD treatment. PMID:25848244

  15. Increasing sp3 hybridized carbon atoms in germanium carbide films by increasing the argon ion energy and germanium content

    NASA Astrophysics Data System (ADS)

    Hu, C. Q.; Zheng, B.; Zhu, J. Q.; Han, J. C.; Zheng, W. T.; Guo, L. F.

    2010-04-01

    We have prepared germanium carbide (Ge1-xCx) films on Si(0 0 1) by radio frequency (RF) reactive sputtering a pure Ge(1 1 1) target in a CH4/Ar mixture discharge, and found that the sp3 hybridized carbon atoms in the Ge1-xCx film can be significantly increased in two ways. One is by increasing the Ge content via increasing the RF power during the film deposition, which can lead to a transition from sp2 C-C to sp3 C-Ge bonding in the film. Another is by increasing the Ar ion energy in a discharge Ar/CH4 gas by applying the negative bias voltage, which plays an important role in inducing the compressive stress in film. We find that when the compressive stress increases above a critical value of 2.2 GPa, an abrupt transition from sp2 C-C to sp3 C-C bonding occurs in the Ge1-xCx film, which is a consequence of energy minimization.

  16. Germanium anode with excellent lithium storage performance in a germanium/lithium-cobalt oxide lithium-ion battery.

    PubMed

    Li, Xiuwan; Yang, Zhibo; Fu, Yujun; Qiao, Li; Li, Dan; Yue, Hongwei; He, Deyan

    2015-02-24

    Germanium is a highly promising anode material for lithium-ion batteries as a consequence of its large theoretical specific capacity, good electrical conductivity, and fast lithium ion diffusivity. In this work, Co3O4 nanowire array fabricated on nickel foam was designed as a nanostructured current collector for Ge anode. By limiting the voltage cutoff window in an appropriate range, the obtained Ge anode exhibits excellent lithium storage performance in half- and full-cells, which can be mainly attributed to the designed nanostructured current collector with good conductivity, enough buffering space for the volume change, and shortened ionic transport length. More importantly, the assembled Ge/LiCoO2 full-cell shows a high energy density of 475 Wh/kg and a high power density of 6587 W/kg. A high capacity of 1184 mA h g(-1) for Ge anode was maintained at a current density of 5000 mA g(-1) after 150 cycles. PMID:25629917

  17. Analysis of optical gain threshold in n-doped and tensile-strained germanium heterostructure diodes

    NASA Astrophysics Data System (ADS)

    Prost, M.; El Kurdi, M.; Aniel, F.; Zerounian, N.; Sauvage, S.; Checoury, X.; BÅ`uf, F.; Boucaud, P.

    2015-09-01

    The optical emission of germanium-based luminescent and/or laser devices can be enhanced by tensile strain and n-type doping. In this work, we study by simulation the interplay between electrical transport and optical gain in highly n-doped and intrinsic germanium p-n heterostructure diodes under tensile strain. The effects of strain and doping on carrier mobilities and energy distribution are taken into account. Whereas the n-doping of Ge enhances the filling of the indirect L and Brillouin zone-center conduction band states, the n-doping also reduces the carrier injection efficiency, which is detrimental for the achievement of optical gain at reduced current densities. For applied biaxial strains larger than 1.25%, i.e., far before reaching the cross-over from indirect to direct band gap regime, undoped germanium exhibits a lower optical gain threshold as compared to doped germanium. We also show that the threshold current needed to reach transparency in germanium heterostructures has been significantly underestimated in the previous works.

  18. Integrated analysis and design optimization of germanium purification process using zone-refining technique

    NASA Astrophysics Data System (ADS)

    Wang, Sen; Fang, H. S.; Jin, Z. L.; Zhao, C. J.; Zheng, L. L.

    2014-12-01

    Germanium (Ge) is a preferred material in the fabrication of high-performance gamma radiation detector for spectroscopy in nuclear physics. To maintain an intrinsic region in which electrons and holes reach the contacts to produce a spectroscopic signal, germanium crystals are usually doped with lithium (Li) ions. Consequently, hyperpure germanium (HPGe) should be prepared before the doping process to eliminate the interference of unexpected impurities in the Li dopant. Zone-refining technique, widely used in purification of ultra-pure materials, is chosen as one of the purification steps during detector-grade germanium production. In the paper, numerical analysis has been conducted to analyze heat transfer, melt flow and impurity segregation during a multi-pass zone-refining process of germanium in a Cyberstar mirror furnace. By modifying the effective redistribution coefficients, axial segregations of various impurities are investigated. Marangoni convection is found dominant in the melt. It affects the purification process through modifying the boundary layer thickness. Impurity distributions along the ingot are obtained with different conditions, such as pass number, zone travel rate, initial impurity concentration, segregation coefficient, and hot-zone length. Based on the analysis, optimization of the purification process design is proposed.

  19. Biallelic and Genome Wide Association Mapping of Germanium Tolerant Loci in Rice (Oryza sativa L.)

    PubMed Central

    Talukdar, Partha; Douglas, Alex; Price, Adam H.; Norton, Gareth J.

    2015-01-01

    Rice plants accumulate high concentrations of silicon. Silicon has been shown to be involved in plant growth, high yield, and mitigating biotic and abiotic stresses. However, it has been demonstrated that inorganic arsenic is taken up by rice through silicon transporters under anaerobic conditions, thus the ability to efficiently take up silicon may be considered either a positive or a negative trait in rice. Germanium is an analogue of silicon that produces brown lesions in shoots and leaves, and germanium toxicity has been used to identify mutants in silicon and arsenic transport. In this study, two different genetic mapping methods were performed to determine the loci involved in germanium sensitivity in rice. Genetic mapping in the biparental cross of Bala × Azucena (an F6 population) and a genome wide association (GWA) study with 350 accessions from the Rice Diversity Panel 1 were conducted using 15 μM of germanic acid. This identified a number of germanium sensitive loci: some co-localised with previously identified quantitative trait loci (QTL) for tissue silicon or arsenic concentration, none co-localised with Lsi1 or Lsi6, while one single nucleotide polymorphism (SNP) was detected within 200 kb of Lsi2 (these are genes known to transport silicon, whose identity was discovered using germanium toxicity). However, examining candidate genes that are within the genomic region of the loci detected above reveals genes homologous to both Lsi1 and Lsi2, as well as a number of other candidate genes, which are discussed. PMID:26356220

  20. Hydrometallurgical recovery of germanium from coal gasification fly ash: pilot plant scale evaluation

    SciTech Connect

    Arroyo, F.; Fernandez-Pereira, C.; Olivares, J.; Coca, P.

    2009-04-15

    In this article, a hydrometallurgical method for the selective recovery of germanium from fly ash (FA) has been tested at pilot plant scale. The pilot plant flowsheet comprised a first stage of water leaching of FA, and a subsequent selective recovery of the germanium from the leachate by solvent extraction method. The solvent extraction method was based on Ge complexation with catechol in an aqueous solution followed by the extraction of the Ge-catechol complex (Ge(C{sub 6}H{sub 4}O{sub 2}){sub 3}{sup 2-}) with an extracting organic reagent (trioctylamine) diluted in an organic solvent (kerosene), followed by the subsequent stripping of the organic extract. The process has been tested on a FA generated in an integrated gasification with combined cycle (IGCC) process. The paper describes the designed 5 kg/h pilot plant and the tests performed on it. Under the operational conditions tested, approximately 50% of germanium could be recovered from FA after a water extraction at room temperature. Regarding the solvent extraction method, the best operational conditions for obtaining a concentrated germanium-bearing solution practically free of impurities were as follows: extraction time equal to 20 min; aqueous phase/organic phase volumetric ratio equal to 5; stripping with 1 M NaOH, stripping time equal to 30 min, and stripping phase/organic phase volumetric ratio equal to 5. 95% of germanium were recovered from water leachates using those conditions.