WorldWideScience

Sample records for electron tunneling process

  1. Nonadiabaticity of electron-tunneling-ionization processes in elliptical strong laser fields

    Science.gov (United States)

    Cai, Jun; Chen, Yan-jun; Xia, Qin-zhi; Ye, Di-fa; Liu, Jie; Fu, Li-bin

    2017-09-01

    We theoretically investigate the electron-tunneling process for a helium atom irradiated by an elliptical strong laser field. The momentum distribution for an electron ionized during the cycle when the laser intensity reaches its maximum is captured, such that we can ignore the interference between the wave packets ionized in different laser cycles and precisely determine the center of the momentum distribution. The quantum mechanical prediction of the center position is further compared to the semiclassical single-trajectory simulation as well as the experimental data. We find that the electron momentums along the minor axis of the laser polarization show good agreement with the nonadiabatic semiclassical calculation for a wide range of laser intensities, indicating the existence of a nonzero lateral momentum when the electron exits the barrier. On the other hand, the offset angles obtained by our quantum mechanical approach for different laser intensities are larger than the nonadiabatic semiclassical results, indicating the importance of the quantum effects during the electron's under-the-barrier dynamics.

  2. Probing electronic interactions using electron tunneling

    Indian Academy of Sciences (India)

    pratap

    Tunneling In the particle language. The fraction of particle tunneling falls rapidly with the width and height of the barrier. Need to have available states at the ... Order-disorder transition of a vortex lattice. 2.0 2.5 3.0 3.5 4.0 4.5 5.0. 0. 5. 10. 15. 20. 25. 30. 35. H p. H c2. T (K). H (kO e). Ordered state. Disordered state. 0. 10. 20.

  3. Single electron tunneling based arithmetic computation

    NARCIS (Netherlands)

    Lageweg, C.R.

    2004-01-01

    In this dissertation we investigate the implementation of computer arithmetic operations with Single Electron Tunneling (SET) technology based circuits. In our research we focus on the effective utilization of the SET technologys specific characteristic, i.e., the ability to control the transport of

  4. Resonant electron tunnelling assisted by charged domain walls in multiferroic tunnel junctions

    Science.gov (United States)

    Sanchez-Santolino, Gabriel; Tornos, Javier; Hernandez-Martin, David; Beltran, Juan I.; Munuera, Carmen; Cabero, Mariona; Perez-Muñoz, Ana; Ricote, Jesus; Mompean, Federico; Garcia-Hernandez, Mar; Sefrioui, Zouhair; Leon, Carlos; Pennycook, Steve J.; Muñoz, Maria Carmen; Varela, Maria; Santamaria, Jacobo

    2017-07-01

    The peculiar features of domain walls observed in ferroelectrics make them promising active elements for next-generation non-volatile memories, logic gates and energy-harvesting devices. Although extensive research activity has been devoted recently to making full use of this technological potential, concrete realizations of working nanodevices exploiting these functional properties are yet to be demonstrated. Here, we fabricate a multiferroic tunnel junction based on ferromagnetic La0.7Sr0.3MnO3 electrodes separated by an ultrathin ferroelectric BaTiO3 tunnel barrier, where a head-to-head domain wall is constrained. An electron gas stabilized by oxygen vacancies is confined within the domain wall, displaying discrete quantum-well energy levels. These states assist resonant electron tunnelling processes across the barrier, leading to strong quantum oscillations of the electrical conductance.

  5. Electron Tunneling in Lithium Ammonia Solutions Probed by Frequency-Dependent Electron-Spin Relaxation Studies

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T.J.; Harmer, Jeffrey; Freed, Jack H.; Edwards, Peter P.

    2012-01-01

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T1) and spin-spin (T2) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multi-exponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1–10)×10−12 s over a temperature range 230–290K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a timescale of ca. 10−13 s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great potential

  6. Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies.

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey; Freed, Jack H; Edwards, Peter P

    2012-06-06

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T(1)) and spin-spin (T(2)) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multiexponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1-10) × 10(-12) s over a temperature range 230-290 K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a time scale of ∼10(-13) s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great

  7. Magnetic tunnel transistor with a silicon hot-electron emitter

    NARCIS (Netherlands)

    Le Minh, P.; Gökcan, H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    We report on a modified magnetic tunnel transistor having a silicon tunnel emitter. The device has the structure Si/Al2O3 /base/Si with a spin-valve metal base, a Schottky barrier collector, but a silicon emitter separated from the base by a thin tunnel oxide. The energy of the hot electrons

  8. Simulation of inelastic electronic tunneling spectra of adsorbates from first principles

    Science.gov (United States)

    Ren, Hao; Yang, Jinlong; Luo, Yi

    2009-04-01

    We present first-principles simulations for inelastic electron tunneling spectra of molecules adsorbed on metal surface as measured in scanning tunneling microscopy experiments. Both elastic and inelastic tunneling processes are modeled in terms of Tersoff-Hamann approximation with a full vibration analysis at density functional theory levels. The calculated spectra of carbon oxide and acetylene molecules adsorbed on Cu(100) surface have well reproduced their experimental counterparts. The inelastic electron tunneling images of the observable vibration modes have been provided. The performance of gradient-corrected density functional is compared with that of local density functional.

  9. Simulation of inelastic electronic tunneling spectra of adsorbates from first principles.

    Science.gov (United States)

    Ren, Hao; Yang, Jinlong; Luo, Yi

    2009-04-07

    We present first-principles simulations for inelastic electron tunneling spectra of molecules adsorbed on metal surface as measured in scanning tunneling microscopy experiments. Both elastic and inelastic tunneling processes are modeled in terms of Tersoff-Hamann approximation with a full vibration analysis at density functional theory levels. The calculated spectra of carbon oxide and acetylene molecules adsorbed on Cu(100) surface have well reproduced their experimental counterparts. The inelastic electron tunneling images of the observable vibration modes have been provided. The performance of gradient-corrected density functional is compared with that of local density functional.

  10. Giant tunnel-electron injection in nitrogen-doped graphene

    DEFF Research Database (Denmark)

    Lagoute, Jerome; Joucken, Frederic; Repain, Vincent

    2015-01-01

    Scanning tunneling microscopy experiments have been performed to measure the local electron injection in nitrogen-doped graphene on SiC(000) and were successfully compared to ab initio calculations. In graphene, a gaplike feature is measured around the Fermi level due to a phonon-mediated tunneling...... and at carbon sites. Nitrogen doping can therefore be proposed as a way to improve tunnel-electron injection in graphene....

  11. An electronic scanner of pressure for wind tunnel models

    Science.gov (United States)

    Kauffman, Ronald C.; Coe, Charles F.

    1986-01-01

    An electronic scanner of pressure (ESOP) has been developed by NASA Ames Research Center for installation in wind tunnel models. An ESOP system consists of up to 20 pressure modules (PMs), each with 48 pressure transducers and a heater, an analog-to-digital (A/D) converter module, a microprocessor, a data controller, a monitor unit, a control and processing unit, and a heater controller. The PMs and the A/D converter module are sized to be installed in the models tested in the Ames Aerodynamics Division wind tunnels. A unique feature of the pressure module is the lack of moving parts such as a pneumatic switch used in other systems for in situ calibrations. This paper describes the ESOP system and the results of the initial testing of the system. The initial results indicate the system meets the original design goal of 0.15 percent accuracy.

  12. Quantum tunneling and field electron emission theories

    CERN Document Server

    Liang, Shi-Dong

    2013-01-01

    Quantum tunneling is an essential issue in quantum physics. Especially, the rapid development of nanotechnology in recent years promises a lot of applications in condensed matter physics, surface science and nanodevices, which are growing interests in fundamental issues, computational techniques and potential applications of quantum tunneling. The book involves two relevant topics. One is quantum tunneling theory in condensed matter physics, including the basic concepts and methods, especially for recent developments in mesoscopic physics and computational formulation. The second part is the f

  13. Quantum tunneling recombination in a system of randomly distributed trapped electrons and positive ions.

    Science.gov (United States)

    Pagonis, Vasilis; Kulp, Christopher; Chaney, Charity-Grace; Tachiya, M

    2017-09-13

    During the past 10 years, quantum tunneling has been established as one of the dominant mechanisms for recombination in random distributions of electrons and positive ions, and in many dosimetric materials. Specifically quantum tunneling has been shown to be closely associated with two important effects in luminescence materials, namely long term afterglow luminescence and anomalous fading. Two of the common assumptions of quantum tunneling models based on random distributions of electrons and positive ions are: (a) An electron tunnels from a donor to the nearest acceptor, and (b) the concentration of electrons is much lower than that of positive ions at all times during the tunneling process. This paper presents theoretical studies for arbitrary relative concentrations of electrons and positive ions in the solid. Two new differential equations are derived which describe the loss of charge in the solid by tunneling, and they are solved analytically. The analytical solution compares well with the results of Monte Carlo simulations carried out in a random distribution of electrons and positive ions. Possible experimental implications of the model are discussed for tunneling phenomena in long term afterglow signals, and also for anomalous fading studies in feldspars and apatite samples.

  14. Scanning tunneling spectroscopy on electron-boson interactions in superconductors

    CERN Document Server

    Schackert, Michael Peter

    2015-01-01

    This work describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

  15. Tunneling of electrons through semiconductor superlattices

    Indian Academy of Sciences (India)

    Unknown

    The SSL we have considered is Ga0⋅7Al0⋅3As–GaAs which has been drawing considerable attention during the recent past on account of some typical features of its band structure. We have indicated how our results would help fabrication of ultra high speed devices. Keywords. Semiconductor superlattices; tunneling. 1.

  16. Electronic Single Molecule Identification of Carbohydrate Isomers by Recognition Tunneling

    CERN Document Server

    Im, JongOne; Liu, Hao; Zhao, Yanan; Sen, Suman; Biswas, Sudipta; Ashcroft, Brian; Borges, Chad; Wang, Xu; Lindsay, Stuart; Zhang, Peiming

    2016-01-01

    Glycans play a central role as mediators in most biological processes, but their structures are complicated by isomerism. Epimers and anomers, regioisomers, and branched sequences contribute to a structural variability that dwarfs those of nucleic acids and proteins, challenging even the most sophisticated analytical tools, such as NMR and mass spectrometry. Here, we introduce an electron tunneling technique that is label-free and can identify carbohydrates at the single-molecule level, offering significant benefits over existing technology. It is capable of analyzing sub-picomole quantities of sample, counting the number of individual molecules in each subset in a population of coexisting isomers, and is quantitative over more than four orders of magnitude of concentration. It resolves epimers not well separated by ion-mobility and can be implemented on a silicon chip. It also provides a readout mechanism for direct single-molecule sequencing of linear oligosaccharides.

  17. Efficient evaluation of atom tunneling combined with electronic structure calculations

    Science.gov (United States)

    Ásgeirsson, Vilhjálmur; Arnaldsson, Andri; Jónsson, Hannes

    2018-03-01

    Methodology for finding optimal tunneling paths and evaluating tunneling rates for atomic rearrangements is described. First, an optimal JWKB tunneling path for a system with fixed energy is obtained using a line integral extension of the nudged elastic band method. Then, a calculation of the dynamics along the path is used to determine the temperature at which it corresponds to an optimal Feynman path for thermally activated tunneling (instanton) and a harmonic approximation is used to estimate the transition rate. The method is illustrated with calculations for a modified two-dimensional Müller-Brown surface but is efficient enough to be used in combination with electronic structure calculations of the energy and atomic forces in systems containing many atoms. An example is presented where tunneling is the dominant mechanism well above room temperature as an H3BNH3 molecule dissociates to form H2. Also, a solid-state example is presented where density functional theory calculations of H atom tunneling in a Ta crystal give close agreement with experimental measurements on hydrogen diffusion over a wide range in temperature.

  18. Microwave-induced co-tunneling in single electron tunneling transistors

    DEFF Research Database (Denmark)

    Ejrnaes, M.; Savolainen, M.; Manscher, M.

    2002-01-01

    The influence of microwaves on the co-tunneling in single electron tunneling transistors has been investigated as function of frequency and power in the temperature range from 150 to 500 mK. All 20 low frequency connections and the RF line were filtered, and the whole cryostat was suspended...... fixed at maximum Coulomb blockade. With the microwave signal applied to one side of the transistor, we find that the conductance increases linearly with T-2 and microwave power. (C) 2002 Elsevier Science B.V. All rights reserved....

  19. Simulation of single-electron tunnelling circuits using SPICE

    NARCIS (Netherlands)

    Van de Haar, R.

    2004-01-01

    Single-electron tunnelling (SET) devices have very promising properties, like their extremely low power consumption, their extremely high switching speeds and their extremely small physical dimensions. Since the field of SET devices is far from being fully exploited, and their device properties seem

  20. First Principles Study of Electron Tunneling through Ice

    KAUST Repository

    Cucinotta, Clotilde S.

    2012-10-25

    With the aim of understanding electrochemical scanning tunnel microscopy experiments in an aqueous environment, we investigate electron transport through ice in the coherent limit. This is done by using the nonequilibrium Greens functions method, implemented within density functional theory, in the self-interaction corrected local density approximation. In particular, we explore different ice structures and different Au electrode surface orientations. By comparing the decay coefficient for different thicknesses to the ice complex band structure, we find that the electron transport occurs via tunneling with almost one-dimensional character. The slow decay of the current with the ice thickness is largely due to the small effective mass of the conduction electrons. Furthermore, we find that the calculated tunneling decay coefficients at the Fermi energy are not sensitive to the structural details of the junctions and are at the upper end of the experimental range for liquid water. This suggests that linear response transport measurements are not capable of distinguishing between different ordered ice structures. However, we also demonstrate that a finite bias measurement may be capable of sorting polar from nonpolar interfaces due to the asymmetry of the current-voltage curves for polar interfaces. © 2012 American Chemical Society.

  1. Electron Tunneling Pathway and Role of Adenine in Repair of Damaged DNA by Photolyase

    Science.gov (United States)

    Liu, Zheyun; Tan, Chuang; Guo, Xunmin; Kao, Ya-Ting; Li, Jiang; Wang, Lijuan; Zhong, Dongping

    2012-06-01

    Through electron tunneling, photolyase, a photoenzyme, restores damaged DNA into normal bases. Here, we report our systematic characterization and analyses of three electron transfer processes in thymine dimer restoration by following the entire dynamical evolution during enzymatic repair with femtosecond resolution. We observed the complete dynamics of the reactants, all intermediates and final products, and determined their reaction time scales. Using (deoxy)uracil and thymine as dimer substrates, we unambiguously determined the electron tunneling pathways for the forward electron transfer to initiate repairing and for the final electron return to restore the active cofactor and complete the repair photocycle. Significantly, we found that the adenine moiety of the unusual bent cofactor is essential to mediating all electron transfer dynamics through a super-exchange mechanism, leading to a delicate balance of time scales. The active-site structural integrity, unique electron tunneling pathways and the critical role of adenine assure these elementary dynamics in synergy in this complex photorepair machinery to achieve the maximum repair efficiency close to unity. Z. Liu, C. Tan, X. Guo, Y.-T. Kao, J. Li, L. Wang, A. Sancar, and D. Zhong, Proc. Natl. Acad. Sci. USA 108, 14831 (2011) J. Li, Z. Liu, C. Tan, X. Guo, L. Wang, A. Sancar, and D. Zhong, Nature 466, 887 (2010)

  2. Dynamics and pathway of electron tunneling in repair of damaged DNA by photolyase

    Science.gov (United States)

    Liu, Zheyun; Guo, Xunmin; Tan, Chuang; Li, Jiang; Kao, Ya-Ting; Wang, Lijuan; Sancar, Aziz; Zhong, Dongping

    2013-03-01

    Through electron tunneling, photolyase, a photoenzyme, restores damaged DNA into normal bases. Here, we report our systematic characterization and analyses of three electron transfer processes in thymine dimer restoration by following the entire dynamical evolution during enzymatic repair with femtosecond resolution. Using (deoxy)uracil and thymine as dimer substrates, we unambiguously determined the electron tunneling pathways for the forward electron transfer to initiate repairing and for the final electron return to restore the active cofactor and complete the repair photocycle. Significantly, we found that the adenine moiety of the unusual bent cofactor is essential to mediating all electron-transfer dynamics through a super-exchange mechanism, leading to a delicate balance of time scales. The active-site structural integrity, unique electron tunneling pathways and the critical role of adenine assure these elementary dynamics in synergy in this complex photorepair machinery to achieve the maximum repair efficiency close to unity. The authors thank Drs. Chaitanya Sexana, Yi Yang, and Chen Zang for the initial help with experiment, and Prof. Sherwin Singer and Dr. Ali Hassanali for discussion.

  3. Electron Transport and Tunneling Resistance between Carbon Nanotube Fibers

    Science.gov (United States)

    Zhang, Peng; Lau, Y. Y.; Luginsland, J. W.; Gilgenbach, R. M.

    2015-11-01

    The carbon nanotube (CNT) has exceptional intrinsic properties in its mechanical strength and stiffness, low density, and electrical and thermal conductivity. However, on a macroscopic level, these outstanding properties, especially the electrical conductivity, remain elusive. The CNT fibers contain a very large number of junctions and contacts. It is therefore important to understand the electron transport through the contact between individual CNTs as well as the contact between CNT and the substrate. Based on a simple transmission line model, we study the tunneling resistance for a parallel contact formed between two closely spaced CNTs. The localized contact resistance along the contact region is modeled by the tunneling resistance, which is calculated from a recent self-consistent model. The results give insights on the macroscopic electrical conductivity of CNT fibers. This work was supported by AFOSR Grant No. FA9550-14-1-0309.

  4. Measuring Electron Tunneling Times as a Means of Single Shot/Single Electron Spin Readout

    Science.gov (United States)

    Robinson, Hans D.; Szkopek, Thomas; Rao, Deepak S.; Yablonovitch, Eli

    2004-03-01

    In this talk, we present our strategy for measuring the spin of a single electron trapped in an gate-defined quantum dot in a single shot measurement. The electron is allowed to tunnel out of the electron into a spin dependent final state, or conversely, an external electron with a definite spin is allowed to tunnel onto the dot. The measurement of spin is thereby turned into a measurement of time. A necessary prerequisite is the ability to reliably and accurately measure the dwell time for single electrons on the quantum dot with microsecond accuracy. We report on our experimental progress in this area, where rather than using a relatively hard to fabricate SET for charge detection, we employ a quantum point contact FET that is cofabricated with the quantum dot.

  5. Pair tunneling resonance in the single-electron transport regime.

    Science.gov (United States)

    Leijnse, M; Wegewijs, M R; Hettler, M H

    2009-10-09

    We predict a new electron pair tunneling (PT) resonance in nonlinear transport through quantum dots with positive charging energies exceeding the broadening due to thermal and quantum fluctuations. The PT resonance shows up in the single-electron transport (SET) regime as a peak in the derivative of the nonlinear conductance, d(2)I/dV(2), when the electrochemical potential of one electrode matches the average of two subsequent charge addition energies. For a single level quantum dot (Anderson model) we find the analytic peak shape and the dependence on temperature, magnetic field, and junction asymmetry and compare with the inelastic cotunneling peak which is of the same order of magnitude. In experimental transport spectroscopy the PT resonance may be mistaken for a weak SET resonance judging only by the voltage dependence of its position. Our results provide essential clues to avoid such erroneous interpretation.

  6. Thermoelectric effects in electron chiral tunneling in metallic carbon nanotubes

    Science.gov (United States)

    Parafilo, A. V.; Ilinskaya, O. A.; Krive, I. V.; Park, Y. W.

    2015-12-01

    Thermoelectric effects in a metallic single-wall carbon nanotube in the presence of long-range electrostatic and pseudomagnetic potentials (produced by strain) are considered. It is shown that for strong scattering potentials (chiral tunneling) a pronounced energy "gap" appears in the energy dependence of electron transmission coefficient. This results in strong violation of Wiedemann-Franz law and in a peak-like behavior of thermopower as a function of chemical potential. The electronic figure-of-merit (ZT) is calculated and shown to be sensitive at low temperatures to nanotube chirality. By tuning chemical potential, ZT can reach high values (ZT≃5) that makes specially engineered nanotube-based thermocouple to be a promising nano-device with a high thermoelectric performance.

  7. Electron Beam Materials Processing

    Science.gov (United States)

    Powers, Donald E.

    2012-06-01

    In electron beam processing, a well-defined beam of relatively energetic electrons produced by a high voltage acceleration gap is used to transmit thermal energy into a material in a precise manner. This controlled deposition of heat is employed in a wide variety of industrial applications for precision cutting, drilling, and welding of materials as well as annealing, glazing, and surface hardening. This chapter will describe the equipment used and the most prominent industrial applications for this process.

  8. Probing flexible conformations in molecular junctions by inelastic electron tunneling spectroscopy

    Directory of Open Access Journals (Sweden)

    Mingsen Deng

    2015-01-01

    Full Text Available The probe of flexible molecular conformation is crucial for the electric application of molecular systems. We have developed a theoretical procedure to analyze the couplings of molecular local vibrations with the electron transportation process, which enables us to evaluate the structural fingerprints of some vibrational modes in the inelastic electron tunneling spectroscopy (IETS. Based on a model molecule of Bis-(4-mercaptophenyl-ether with a flexible center angle, we have revealed and validated a simple mathematical relationship between IETS signals and molecular angles. Our results might open a route to quantitatively measure key geometrical parameters of molecular junctions, which helps to achieve precise control of molecular devices.

  9. Ultralarge area MOS tunnel devices for electron emission

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar; Nielsen, Gunver; Vendelbo, Søren Bastholm

    2007-01-01

    A comparative analysis of metal-oxide-semiconductor (MOS) capacitors by capacitance-voltage (C-V) and current-voltage (I-V) characteristics has been employed to characterize the thickness variations of the oxide on different length scales. Ultralarge area (1 cm(2)) ultrathin (similar to 5 nm oxide......) MOS capacitors have been fabricated to investigate their functionality and the variations in oxide thickness, with the use as future electron emission devices as the goal. I-V characteristics show very low leakage current and excellent agreement to the Fowler-Nordheim expression for the current...... density. Oxide thicknesses have been extracted by fitting a model based on Fermi-Dirac statistics to the C-V characteristics. By plotting I-V characteristics in a Fowler plot, a measure of the thickness of the oxide can be extracted from the tunnel current. These apparent thicknesses show a high degree...

  10. Low-frequency noise in single electron tunneling transistor

    DEFF Research Database (Denmark)

    Tavkhelidze, A.N.; Mygind, Jesper

    1998-01-01

    The noise in current biased aluminium single electron tunneling (SET) transistors has been investigated in the frequency range of 5 mHz electromagnetic radiation and especially high energy...... of order seconds. In some cases, the positive and negative slopes of the V(Vg) curve have different overlaid noise patterns. For fixed bias on both slopes, we measure the same noise spectrum, and believe that the asymmetric noise is due to dynamic charge trapping near or inside one of the junctions induced...... when ramping the junction voltage. Dynamic trapping may limit the high frequency applications of the SET transistor. Also reported on are the effects of rf irradiation and the dependence of the SET transistor noise on bias voltage. ©1998 American Institute of Physics....

  11. Plasmons and Electrons as Nanosecond-Fast Sensors for Scanning Tunneling Microscopy

    Science.gov (United States)

    Loth, Sebastian

    2014-03-01

    The ability to measure the fast dynamical evolution of atomic-scale systems often holds the key to their understanding. We combine fast pump-probe spectroscopy tools with low-temperature scanning tunneling microscopy to study atomically assembled arrays of magnetic atoms. The dynamical information quantifies spin lifetimes, magnetic stability and even allows identifying the cross-over between quantum spins and classical magnetism. The spin relaxation times of transition metal atoms can be measured by all-electronic pump probe spectroscopy in which nanosecond-fast voltage pulses excite the spins and probe the average time-dependent response by variations in the spin-polarized tunnel current. In addition, the fast evolution of the local electrostatic potential can be mapped by detecting plasmonic light emission from the STM tunnel junction with time correlating single photon counting. The combination of electrical stimulus and optical detection provides precise control of the excitation process of individual atoms enabling new experiments to probe charge and spin dynamics in the scanning tunneling microscope.

  12. Imaging of Endogenous Metabolites of Plant Leaves by Mass Spectrometry Based on Laser Activated Electron Tunneling.

    Science.gov (United States)

    Huang, Lulu; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Chen, Disong; Zhang, Juan; Zhong, Hongying

    2016-04-07

    A new mass spectrometric imaging approach based on laser activated electron tunneling (LAET) was described and applied to analysis of endogenous metabolites of plant leaves. LAET is an electron-directed soft ionization technique. Compressed thin films of semiconductor nanoparticles of bismuth cobalt zinc oxide were placed on the sample plate for proof-of-principle demonstration because they can not only absorb ultraviolet laser but also have high electron mobility. Upon laser irradiation, electrons are excited from valence bands to conduction bands. With appropriate kinetic energies, photoexcited electrons can tunnel away from the barrier and eventually be captured by charge deficient atoms present in neutral molecules. Resultant unpaired electron subsequently initiates specific chemical bond cleavage and generates ions that can be detected in negative ion mode of the mass spectrometer. LAET avoids the co-crystallization process of routinely used organic matrix materials with analyzes in MALDI (matrix assisted-laser desorption ionization) analysis. Thus uneven distribution of crystals with different sizes and shapes as well as background peaks in the low mass range resulting from matrix molecules is eliminated. Advantages of LAET imaging technique include not only improved spatial resolution but also photoelectron capture dissociation which produces predictable fragment ions.

  13. Temperature activated tunnelling processes in aSe/pSi heterojunction

    African Journals Online (AJOL)

    It is deducted that tunnel hopping of electrons is prevalent in the aSe side while barrier tunneling of holes occur in the pSi of the interface. Recombination of electron and hole becomes predominant at high negative bias due to whole injection into the interface coming from the pSi. Keywords: Temperature, Tunneling ...

  14. Electronic properties of core-shell nanowire resonant tunneling diodes

    Science.gov (United States)

    2014-01-01

    The electronic sub-band structure of InAs/InP/InAs/InP/InAs core-shell nanowire resonant tunneling diodes has been investigated in the effective mass approximation by varying the core radius and the thickness of the InP barriers and InAs shells. A top-hat, double-barrier potential profile and optimal energy configuration are obtained for core radii and surface shells >10 nm, InAs middle shells barriers. In this case, two sub-bands exist above the Fermi level in the InAs middle shell which belongs to the m = 0 and m = 1 ladder of states that have similar wave functions and energies. On the other hand, the lowest m = 0 sub-band in the core falls below the Fermi level but the m = 1 states do not contribute to the current transport since they reside energetically well above the Fermi level. We compare the case of GaAs/AlGaAs/GaAs/AlGaAs/GaAs which may conduct current with smaller applied voltages due to the larger effective mass of electrons in GaAs and discuss the need for doping. PMID:25288912

  15. Electron-bombarded 〈110〉-oriented tungsten tips for stable tunneling electron emission

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, T. K.; Abe, T.; Nazriq, N. M. K.; Irisawa, T. [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

    2016-03-15

    A clean tungsten (W) tip apex with a robust atomic plane is required for producing a stable tunneling electron emission under strong electric fields. Because a tip apex fabricated from a wire by aqueous chemical etching is covered by impurity layers, heating treatment in ultra-high vacuum is experimentally known to be necessary. However, strong heating frequently melts the tip apex and causes unstable electron emissions. We investigated quantitatively the tip apex and found a useful method to prepare a tip with stable tunneling electron emissions by controlling electron-bombardment heating power. Careful characterizations of the tip structures were performed with combinations of using field emission I–V curves, scanning electron microscopy, X-ray diffraction (transmitted Debye-Scherrer and Laue) with micro-parabola capillary, field ion microscopy, and field emission microscopy. Tips were chemically etched from (1) polycrystalline W wires (grain size ∼1000 nm) and (2) long-time heated W wires (grain size larger than 1 mm). Heating by 10-40 W (10 s) was found to be good enough to remove oxide layers and produced stable electron emission; however, around 60 W (10 s) heating was threshold power to increase the tip radius, typically +10 ± 5 nm (onset of melting). Further, the grain size of ∼1000 nm was necessary to obtain a conical shape tip apex.

  16. Line shapes in inelastic electron tunneling spectroscopy of single-molecule junctions

    Science.gov (United States)

    Meierott, S.; Néel, N.; Kröger, J.

    2017-11-01

    Spectroscopic line-shape analyses for single-C60 vibrational modes are presented for two kinds of scanning tunneling microscope experiments. Inelastic electron tunneling spectroscopy is performed for C60 molecules with different adsorption geometries on Pb(111). Depending on the C60 adsorption site and rotational orientation, the lowest unoccupied molecular orbital exhibits varying degrees of overlap with C60 vibrational energies. Concomitantly, the line shapes of vibrational modes are affected according to expectations for on-resonance inelastic electron tunneling. Inelastic electron transport is further studied for decreasing tip-C60 distances covering tunneling and contact ranges. Line-shape changes signaling a conductance increase rather than the expected decrease upon exciting vibrational quanta are observed. A phenomenological approach is suggested to understand the dissimilar behavior of the junction conductance in the different electron transport ranges.

  17. Enhancement of spin injection from ferromagnetic metal into a two-dimensional electron gas using a tunnel barrier

    NARCIS (Netherlands)

    Heersche, HB; Schapers, T; Nitta, J; Takayanagi, H

    2001-01-01

    Using free electron approximation, we calculated the spin dependent tunnel conductance of ballistic ferromagnet/tunnel barrier/two-dimensional electron gas (FM/I/2DEG) junctions and FM/I/2DEG/I/FM double junctions for different barrier strengths. We find that a tunnel barrier improves spin injection

  18. Tuning the tunneling probability between low-dimensional electron systems by momentum matching

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Daming; Beckel, Andreas; Geller, Martin; Lorke, Axel, E-mail: axel.lorke@uni-due.de [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, Lotharstraße 1, 47048 Duisburg (Germany); Ludwig, Arne; Wieck, Andreas D. [Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum (Germany)

    2015-06-15

    We demonstrate the possibility to tune the tunneling probability between an array of self- assembled quantum dots and a two-dimensional electron gas (2DEG) by changing the energy imbalance between the dot states and the 2DEG. Contrary to the expectation from Fowler-Nordheim tunneling, the tunneling rate decreases with increasing injection energy. This can be explained by an increasing momentum mismatch between the dot states and the Fermi-circle in the 2DEG. Our findings demonstrate momentum matching as a useful mechanism (in addition to energy conservation, density of states, and transmission probability) to electrically control the charge transfer between quantum dots and an electron reservoir.

  19. Single-molecule electronics: Cooling individual vibrational modes by the tunneling current.

    Science.gov (United States)

    Lykkebo, Jacob; Romano, Giuseppe; Gagliardi, Alessio; Pecchia, Alessandro; Solomon, Gemma C

    2016-03-21

    Electronic devices composed of single molecules constitute the ultimate limit in the continued downscaling of electronic components. A key challenge for single-molecule electronics is to control the temperature of these junctions. Controlling heating and cooling effects in individual vibrational modes can, in principle, be utilized to increase stability of single-molecule junctions under bias, to pump energy into particular vibrational modes to perform current-induced reactions, or to increase the resolution in inelastic electron tunneling spectroscopy by controlling the life-times of phonons in a molecule by suppressing absorption and external dissipation processes. Under bias the current and the molecule exchange energy, which typically results in heating of the molecule. However, the opposite process is also possible, where energy is extracted from the molecule by the tunneling current. Designing a molecular "heat sink" where a particular vibrational mode funnels heat out of the molecule and into the leads would be very desirable. It is even possible to imagine how the vibrational energy of the other vibrational modes could be funneled into the "cooling mode," given the right molecular design. Previous efforts to understand heating and cooling mechanisms in single molecule junctions have primarily been concerned with small models, where it is unclear which molecular systems they correspond to. In this paper, our focus is on suppressing heating and obtaining current-induced cooling in certain vibrational modes. Strategies for cooling vibrational modes in single-molecule junctions are presented, together with atomistic calculations based on those strategies. Cooling and reduced heating are observed for two different cooling schemes in calculations of atomistic single-molecule junctions.

  20. Simulation of Wind Speed in the Ventilation Tunnel for Surge Tanks in Transient Processes

    OpenAIRE

    Jiandong Yang; Huang Wang; Wencheng Guo; Weijia Yang; Wei Zeng

    2016-01-01

    Hydroelectric power plants' open-type surge tanks may be built in mountains subject to the provision of atmospheric air. Hence, a ventilation tunnel is indispensable. The air flow in the ventilation tunnel is associated with the fluctuation of water-level in the surge tank. There is a great relationship between the wind speed and the safe use and project investment of ventilation tunnels. To obtain the wind speed in a ventilation tunnel for a surge tank during transient processes, this articl...

  1. Application of hydrogenation to low-temperature cleaning of the Si(001) surface in the processes of molecular-beam epitaxy: Investigation by scanning tunneling microscopy, reflected high-energy electron diffraction, and high resolution transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arapkina, L. V.; Krylova, L. A.; Chizh, K. V.; Chapnin, V. A.; Uvarov, O. V.; Yuryev, V. A. [A. M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 (Russian Federation)

    2012-07-01

    Structural properties of the clean Si(001) surface obtained as a result of low-temperature (470-650 Degree-Sign C) pre-growth annealings of silicon wafers in a molecular-beam epitaxy chamber have been investigated. To decrease the cleaning temperature, a silicon surface was hydrogenated in the process of a preliminary chemical treatment in HF and NH{sub 4}F aqueous solutions. It has been shown that smooth surfaces composed of wide terraces separated by monoatomic steps can be obtained by dehydrogenation at the temperatures Greater-Than-Or-Equivalent-To 600 Degree-Sign C, whereas clean surfaces obtained at the temperatures <600 Degree-Sign C are rough. It has been found that there exists a dependence of structural properties of clean surfaces on the temperature of hydrogen thermal desorption and the process of the preliminary chemical treatment. The frequency of detachment/attachment of Si dimers from/to the steps and effect of the Ehrlich-Schwoebel barrier on ad-dimer migration across steps have been found to be the most probable factors determining a degree of the resultant surface roughness.

  2. Electronic processes in organic electronics bridging nanostructure, electronic states and device properties

    CERN Document Server

    Kudo, Kazuhiro; Nakayama, Takashi; Ueno, Nobuo

    2015-01-01

    The book covers a variety of studies of organic semiconductors, from fundamental electronic states to device applications, including theoretical studies. Furthermore, innovative experimental techniques, e.g., ultrahigh sensitivity photoelectron spectroscopy, photoelectron yield spectroscopy, spin-resolved scanning tunneling microscopy (STM), and a material processing method with optical-vortex and polarization-vortex lasers, are introduced. As this book is intended to serve as a textbook for a graduate level course or as reference material for researchers in organic electronics and nanoscience from electronic states, fundamental science that is necessary to understand the research is described. It does not duplicate the books already written on organic electronics, but focuses mainly on electronic properties that arise from the nature of organic semiconductors (molecular solids). The new experimental methods introduced in this book are applicable to various materials (e.g., metals, inorganic and organic mater...

  3. Precision Electron Density Measurements in the SSX MHD Wind Tunnel

    Science.gov (United States)

    Suen-Lewis, Emma M.; Barbano, Luke J.; Shrock, Jaron E.; Kaur, Manjit; Schaffner, David A.; Brown, Michael R.

    2017-10-01

    We characterize fluctuations of the line averaged electron density of Taylor states produced by the magnetized coaxial plasma gun of the SSX device using a 632.8 nm HeNe laser interferometer. The analysis method uses the electron density dependence of the refractive index of the plasma to determine the electron density of the Taylor states. Typical magnetic field and density values in the SSX device approach about B ≅ 0.3 T and n = 0 . 4 ×1016 cm-3 . Analysis is improved from previous density measurement methods by developing a post-processing method to remove relative phase error between interferometer outputs and to account for approximately linear phase drift due to low-frequency mechanical vibrations of the interferometer. Precision density measurements coupled with local measurements of the magnetic field will allow us to characterize the wave composition of SSX plasma via density vs. magnetic field correlation analysis, and compare the wave composition of SSX plasma with that of the solar wind. Preliminary results indicate that density and magnetic field appear negatively correlated. Work supported by DOE ARPA-E ALPHA program.

  4. Dynamic tunneling force microscopy for characterizing electronic trap states in non-conductive surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R.; Williams, C. C., E-mail: clayton@physics.utah.edu [Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112 (United States)

    2015-09-15

    Dynamic tunneling force microscopy (DTFM) is a scanning probe technique for real space mapping and characterization of individual electronic trap states in non-conductive films with atomic scale spatial resolution. The method is based upon the quantum mechanical tunneling of a single electron back and forth between a metallic atomic force microscopy tip and individual trap states in completely non-conducting surface. This single electron shuttling is measured by detecting the electrostatic force induced on the probe tip at the shuttling frequency. In this paper, the physical basis for the DTFM method is unfolded through a physical model and a derivation of the dynamic tunneling signal as a function of several experimental parameters is shown. Experimental data are compared with the theoretical simulations, showing quantitative consistency and verifying the physical model used. The experimental system is described and representative imaging results are shown.

  5. Tunneling Current of Electron in Armchair Graphene Nanoribbon Bipolar Transistor Model Using Transfer Matrix Method

    Science.gov (United States)

    Fahmi, A. K.; Hasanah, L.; Rusdiana, D.; Aminudin, A.; Suhendi, E.

    2017-03-01

    The tunneling current of n-p-n bipolar junction transistor AGNR-based is modeled with semi-numerical method. The exponential solution from Schrödinger equation is used and solved analytically. The potential profile of n-p-n BJT divided into several segments in the numerical method. Then, the solved analytical result is used in the numerical method to compute the electron transmittance. Transfer Matrix Method (TMM) is the numerical method used to compute the electron transmittance. From the calculated transmittance the tunneling current can be computed by using Landauer formula with aid of Gauss-Legendre Quadrature (GLQ). Next, the tunneling current is computed with several change of variables which are base-emitter voltage (VBE), base-collector voltage (VBC), temperature and the AGNR’s width. The computed tunneling current shows that the larger value of applied voltage for both VBE and VBC results in larger value of tunneling current. At the lower temperature, the current is larger. The computed tunneling current shows that at wider width of AGNR, the current is also larger. This is due to the decreased band-gap energy (Eg) because of the wider width of AGNR.

  6. Theory of quantum-circuit refrigeration by photon-assisted electron tunneling

    Science.gov (United States)

    Silveri, Matti; Grabert, Hermann; Masuda, Shumpei; Tan, Kuan Yen; Möttönen, Mikko

    2017-09-01

    We focus on a recently experimentally realized scenario of normal-metal-insulator-superconductor tunnel junctions coupled to a superconducting resonator. We develop a first-principles theory to describe the effect of photon-assisted electron tunneling on the quantum state of the resonator. Our results are in very good quantitative agreement with the previous experiments on refrigeration and heating of the resonator using the photon-assisted tunneling, thus providing a stringent verification of the developed theory. Importantly, our results provide simple analytical estimates of the voltage-tunable coupling strength and temperature of the thermal reservoir formed by the photon-assisted tunneling. Consequently, they are used to introduce optimization principles for initialization of quantum devices using such a quantum-circuit refrigerator. Thanks to the first-principles nature of our approach, extension of the theory to the full spectrum of quantum electric devices seems plausible.

  7. Zero-Time Tunneling - Revisited

    Science.gov (United States)

    Nimtz, Günter; Aichmann, Horst

    2017-08-01

    Since 1931, the nonclassical process of tunneling was conjectured to have a zero-time delay in the barrier. These theories have been rejected and denied. However, photonic and recent electronic tunneling experiments have proven the zero-time prediction. Tunneling is due to virtual wave packets in electromagnetic, elastic, and Schrödinger wave fields up to the macroscopic level. In this article we cite theoretical and experimental studies on zero-time tunneling, which have proven this striking behavior.

  8. Intermolecular interaction effect on the inelastic electron tunneling spectroscopy of bi-octane-monothiol junctions

    Science.gov (United States)

    Leng, Jiancai; Zhao, Liyun; Zhang, Yujin; Ma, Hong

    2017-01-01

    The inelastic electron tunneling spectroscopy (IETS) of bi-octane-monothiol junctions is theoretically studied based on first-principles calculations. The results reveal that IETS is very sensitive to the vertical and lateral distance of the two molecules in the bimolecular junctions owing to the changes of interaction between the two molecules. It is further demonstrated that the transverse vibrational modes ν(C-H) around 0.38 V will be triggered when the two molecules are close to each other and open a new path for electron tunneling. Our theoretical results provide new insight into understanding the origin of the IETS peaks around 0.38 V.

  9. Probing the longitudinal momentum spread of the electron wave packet at the tunnel exit

    DEFF Research Database (Denmark)

    N. Pfeiffer, Adrian; Cirelli, Claudio; S. Landsman, Alexandra

    2012-01-01

    We present an ellipticity resolved study of momentum distributions arising from strong-field ionization of Helium at constant intensity. The influence of the ion potential on the departing electron is considered within a semi-classical model consisting of an initial tunneling step and subsequent ...... classical propagation. We find that the momentum distribution can be explained by the presence of a longitudinal momentum spread of the electron at the exit from the tunnel. Our combined experimental and theoretical study provides an estimate of this momentum spread....

  10. Band electron spectrum and thermodynamic properties of the pseudospin-electron model with tunneling splitting of levels

    Directory of Open Access Journals (Sweden)

    O.Ya.Farenyuk

    2006-01-01

    Full Text Available The pseudospin-electron model with tunneling splitting of levels is considered. Generalization of dynamic mean-field method for systems with correlated hopping was applied to the investigation of the model. Electron spectra, electron concentrations, average values of pseudospins and grand canonical potential were calculated within the alloy-analogy approximation. Electron spectrum and dependencies of the electron concentrations on chemical potential were obtained. It was shown that in the alloy-analogy approximation, the model possesses the first order phase transition to ferromagnetic state with the change of chemical potential and the second order phase transition with the change of temperature.

  11. Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

    NARCIS (Netherlands)

    Frisenda, R.; Perrin, M.L.; Van der Zant, H.S.J.

    2015-01-01

    We study single-molecule oligo(phenylene ethynylene)dithiol junctions by means of inelastic electron tunneling spectroscopy (IETS). The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from

  12. Local electronic structure of Fe(001) surfaces studied by scanning tunneling spectroscopy

    NARCIS (Netherlands)

    Bischoff, M.M.J.; Yamada, T.K.; Fang, C.M.; Groot, R.A. de; Kempen, H. van

    2003-01-01

    Scanning tunneling spectroscopy is used to study the local electronic structure of Fe(001) whiskers. The influence of a voltage dependent background on the apparent peak energies in the dI/dV curves is discussed. A relation between this background and the apparent barrier height is established. The

  13. A new electronic scanner of pressure designed for installation in wind-tunnel models

    Science.gov (United States)

    Coe, C. T.; Parra, G. T.; Kauffman, R. C.

    1981-01-01

    A new electronic scanner of pressure (ESOP) has been developed by NASA Ames Research Center for installation in wind-tunnel models. An ESOP system includes up to 20 pressure modules, each with 48 pressure transducers, an A/D converter, a microprocessor, a data controller, a monitor unit, and a heater controller. The system is sized so that the pressure modules and A/D converter module can be installed within an average-size model tested in the Ames Aerodynamics Division wind tunnels. This paper describes the ESOP system, emphasizing the main element of the system - the pressure module. The measured performance of the overall system is also presented.

  14. The Effect of the Electron Tunneling on the Photoelectric Hot Electrons Generation in Metallic-Semiconductor Nanostructures

    Science.gov (United States)

    Elsharif, Asma M.

    2018-01-01

    Semiconductor photonic crystals (MSPhC) were used to convert solar energy into hot electrons. An experimental model was designed by using metallic semiconductor photonic crystals (MSPhC). The designed MSPhC is based on TiO2/Au schottky contact. The model has similar nanocavity structure for broad gold absorption, but the materials on top of the cavity were changed to a metal and a semiconductor in order to collect the hot electrons. Detailed design steps and characterization have shown a broadband sub-bandgap photoresponse at a wavelength of 590 nm. This is due to the surface plasmon absorption by the wafer-scale Au/TiO2 metallic-semiconductor photonic crystal. Analytical calculation of the hot electron transport from the Au thin layer to the TiO2 conduction band is discussed. This theoretical study is based on the quantum tunneling effect. The photo generation of the hot electrons was undertaken at different wavelengths in Au absorber followed by tunneling through a schottky barrier into a TiO2 collector. The presence of a tunnel current from the absorber to the collector under illumination, offers a method to extract carriers from a hot-electron distribution at few bias voltages is presented in this study. The effects of doping different concentrations of the semiconductor on the evolution of the current characteristics were also investigated and discussed. The electrical characteristics were found to be sensitive to any change in the thickness of the barrier.

  15. Shifts and Dips in Inelastic Electron Tunneling Spectra Due to the Tunnel Junction Environment.

    Science.gov (United States)

    1981-05-27

    electrode. Peak shifts have La ’ en typically less than the line width of the peaks and peak __ intensities have been comparable to infrared and Raman...biochemistry,7𔄂 9 10 1water polution , electron beam irradiation, UV irradiation 12and lubrication 2 . Particularly promising applications have...equivalent to a lA -thick continuous layer. To obtain spectra without large background struccure 35 36 and zero-bias anamolies, we kept the particle size

  16. Probing Nanoscale Electronic and Magnetic Interaction with Scanning Tunneling Spectroscopy

    DEFF Research Database (Denmark)

    Bork, Jakob

    This thesis is concerned with fundamental research into electronic and magnetic interaction on the nanoscale. From small metallic and magnetic islands and layers to single atoms. The research revolves around magnetic interaction probed through the spectroscopic capabilities of the scanning....... This is related to research in correlated electron materials such as studies of phase transitions in heavy fermion compounds and magnetic interaction in spintronic research. The capping of cobalt islands on Cu(111) with silver is investigated with STM and photoemission spectroscopy. It is shown that at low...... coverage the silver preferably nucleates on top of the bilayer high cobalt islands compared to directly on the Cu(111) substrate. Furthermore, the silver forms a combination of a reconstruction and a Moire pattern which is investigated with low-energy electron diraction and spectroscopic STM mapping at 6...

  17. Klein tunnelling and electron trapping in nanometre-scale graphene quantum dots

    Science.gov (United States)

    Gutiérrez, Christopher; Brown, Lola; Kim, Cheol-Joo; Park, Jiwoong; Pasupathy, Abhay N.

    2016-11-01

    Relativistic fermions that are incident on a high potential barrier can pass through unimpeded, a striking phenomenon termed the `Klein paradox’ in quantum electrodynamics. Electrostatic potential barriers in graphene provide a solid-state analogue to realize this phenomenon. Here, we use scanning tunnelling microscopy to directly probe the transmission of electrons through sharp circular potential wells in graphene created by substrate engineering. We find that electrons in this geometry display quasi-bound states where the electron is trapped for a finite time before escaping via Klein tunnelling. We show that the continuum Dirac equation can be successfully used to model the energies and wavefunctions of these quasi-bound states down to atomic dimensions. We demonstrate that by tuning the geometry of the barrier it is possible to trap particular energies and angular momentum states with increased efficiency, showing that atomic-scale electrostatic potentials can be used to engineer quantum transport through graphene.

  18. METHOD OF ELECTRON BEAM PROCESSING

    DEFF Research Database (Denmark)

    2003-01-01

    As a rule, electron beam welding takes place in a vacuum. However, this means that the workpieces in question have to be placed in a vacuum chamber and have to be removed therefrom after welding. This is time−consuming and a serious limitation of a process the greatest advantage of which is the o......As a rule, electron beam welding takes place in a vacuum. However, this means that the workpieces in question have to be placed in a vacuum chamber and have to be removed therefrom after welding. This is time−consuming and a serious limitation of a process the greatest advantage of which...... exploiting the potential of electron beam processing to a greater degree than previously possible, for example by means of electron beam welding...

  19. Advanced electron microscopy of novel ferromagnetic materials and ferromagnet/oxide interfaces in magnetic tunnel junctions

    Science.gov (United States)

    Shi, Fengyuan

    We have studied novel ferromagnetic (FM) materials and FM electrode/tunnel barrier interfaces in magnetic tunnel junctions (MTJs) by advanced electron microscopy including scanning transmission electron microscopy (HRSTEM) and electron energy loss spectroscopy (EELS). MTJs are one of the prototypical spintronic devices, with applications in magnetic random access memory, sensors and read heads. The performance of MTJs depends on several factors, including the FM electrodes and the FM/tunnel barrier interfaces. Therefore, to realize the high performance of MTJs, we first need high quality ferromagnetic electrodes with high spin polarization. High-quality Fe3O4 and Fe4N electrodes with theoretically predicted -100% spin polarization were fabricated by various methods and investigated by HRSTEM and STEM EELS. The Fe3O4 and Fe4N thin films have low defect density and good crystallinity, but when integrated as electrodes in a MTJ, problems emerged. In a Fe4N/AlOx/Fe MTJ, the magnetoresistance was negative, but relatively small, due to a defective Fe 3O4 reaction layer formed at the Fe4N/tunnel barrier interface revealed by HRSTEM and EELS. The interfacial reaction layer was thin and discontinuous which made direct imaging difficult. Therefore, STEM EELS was used to map out the reaction layer. A Fe3O4 reaction layer was also found in a nominally symmetric CoFe/AlOx/CoFe MTJs after annealing, which also exhibited inverse TMR and a non-symmetric bias dependence. We also investigated the MTJs with the Heusler alloy Co2MnSi as one or both electrode and crystalline MgO as the tunnel barrier, which exhibit quite high TMR due to coherent tunneling. We showed that the Co2MnSi/MgO interface in these junctions is dominated by a configuration of a pure Mn plane bonded across the interface to O. This was the first observation of that interface termination. HRSTEM images also show that the fraction of MnMn/O interface termination increases with increasing Mn concentration in the CMS

  20. Shimmed electron beam welding process

    Science.gov (United States)

    Feng, Ganjiang; Nowak, Daniel Anthony; Murphy, John Thomas

    2002-01-01

    A modified electron beam welding process effects welding of joints between superalloy materials by inserting a weldable shim in the joint and heating the superalloy materials with an electron beam. The process insures a full penetration of joints with a consistent percentage of filler material and thereby improves fatigue life of the joint by three to four times as compared with the prior art. The process also allows variable shim thickness and joint fit-up gaps to provide increased flexibility for manufacturing when joining complex airfoil structures and the like.

  1. Electronic tunneling through a fullerene-like molecular bridge

    Science.gov (United States)

    Vanaie, H.; Yaghobi, M.

    2017-11-01

    This study was conducted to consider the electronic transport properties of the N_{36} B_{36} molecule, using the Green's function method based on the GW model. The number, width, height and position of density of state peaks are dramatically dependent on the correlation effect, the contact type and symmetric properties of the molecule. Also, negative differential resistance behavior was observed for all modes in voltages 4.4 V (- 4.5 V) to 4.7 V (- 4.7 V). The N_{36} B_{36} molecule behaves as an insulator where the total current becomes zero for the same values of the gate voltages but acts as a metal at other values. Therefore, the physical picture of electron conduction may change in N_{36} B_{36} —based molecular devices and it could behave as a semiconductor.

  2. Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Govind Mallick

    2017-08-01

    Full Text Available Due to their unique chemical, thermal, electronic and photonic properties, low -dimensional transition metal oxides, especially NiO, have attracted great deal of attention for potential applications in a wide range of technologies, such as, sensors, electrochromic coatings and self-healing materials. However, their synthesis involves multi-step complex procedures that in addition to being expensive, further introduce impurities. Here we present a low cost facile approach to synthesize uniform size NiO nanoparticles (NPs from hydrothermally grown Ni(OH2. Detailed transmission electron microscopic analysis reveal the average size of NiO NPs to be around 29 nm. The dimension of NiO NP is also corroborated by the small area scanning tunneling microscope (STM measurements. Further, we investigate electron transport characteristics of newly synthesized Ni(OH2 and NiO nanoparticles on p-type Si substrate using scanning tunneling microscopy. The conductivity of Ni(OH2 and NiO are determined to be 1.46x10-3 S/cm and 2.37x10-5 S/cm, respectively. The NiO NPs exhibit a lower voltage window (∼0.7 V electron tunneling than the parent Ni(OH2.

  3. Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

    Science.gov (United States)

    Mallick, Govind; Labh, Jyotsna; Giri, Lily; Pandey, Avinash C.; Karna, Shashi P.

    2017-08-01

    Due to their unique chemical, thermal, electronic and photonic properties, low -dimensional transition metal oxides, especially NiO, have attracted great deal of attention for potential applications in a wide range of technologies, such as, sensors, electrochromic coatings and self-healing materials. However, their synthesis involves multi-step complex procedures that in addition to being expensive, further introduce impurities. Here we present a low cost facile approach to synthesize uniform size NiO nanoparticles (NPs) from hydrothermally grown Ni(OH)2. Detailed transmission electron microscopic analysis reveal the average size of NiO NPs to be around 29 nm. The dimension of NiO NP is also corroborated by the small area scanning tunneling microscope (STM) measurements. Further, we investigate electron transport characteristics of newly synthesized Ni(OH)2 and NiO nanoparticles on p-type Si substrate using scanning tunneling microscopy. The conductivity of Ni(OH)2 and NiO are determined to be 1.46x10-3 S/cm and 2.37x10-5 S/cm, respectively. The NiO NPs exhibit a lower voltage window (˜0.7 V) electron tunneling than the parent Ni(OH)2.

  4. Combined action of the bound-electron nonlinearity and the tunnel-ionization current in low-order harmonic generation in noble gases.

    Science.gov (United States)

    Sapaev, Usman; Husakou, Anton; Herrmann, Joachim

    2013-10-21

    We study numerically low-order harmonic generation in noble gases pumped by intense femtosecond laser pulses in the tunneling ionization regime. We analyze the influence of the phase-mismatching on this process, caused by the generated plasma, and study in dependence on the pump intensity the origin of harmonic generation arising either from the bound-electron nonlinearity or the tunnel-ionization current. It is shown that in argon the optimum pump intensity of about 100 TW/cm² leads to the maximum efficiency, where the main contribution to low-order harmonics originates from the bound-electron third and fifth order susceptibilities, while for intensities higher than 300 TW/cm² the tunnel-ionization current plays the dominant role. Besides, we predict that VUV pulses at 133 nm can be generated with relatively high efficiency of about 1.5 × 10⁻³ by 400 nm pump pulses.

  5. Irreversibility on the Level of Single-Electron Tunneling

    Directory of Open Access Journals (Sweden)

    B. Küng

    2012-01-01

    Full Text Available We present a low-temperature experimental test of the fluctuation theorem for electron transport through a double quantum dot. The rare entropy-consuming system trajectories are detected in the form of single charges flowing against the source-drain bias by using time-resolved charge detection with a quantum point contact. We find that these trajectories appear with a frequency that agrees with the theoretical predictions even under strong nonequilibrium conditions, when the finite bandwidth of the charge detection is taken into account.

  6. Atomic structure and electronic properties of MgO grain boundaries in tunnelling magnetoresistive devices

    Science.gov (United States)

    Bean, Jonathan J.; Saito, Mitsuhiro; Fukami, Shunsuke; Sato, Hideo; Ikeda, Shoji; Ohno, Hideo; Ikuhara, Yuichi; McKenna, Keith P.

    2017-04-01

    Polycrystalline metal oxides find diverse applications in areas such as nanoelectronics, photovoltaics and catalysis. Although grain boundary defects are ubiquitous their structure and electronic properties are very poorly understood since it is extremely challenging to probe the structure of buried interfaces directly. In this paper we combine novel plan-view high-resolution transmission electron microscopy and first principles calculations to provide atomic level understanding of the structure and properties of grain boundaries in the barrier layer of a magnetic tunnel junction. We show that the highly [001] textured MgO films contain numerous tilt grain boundaries. First principles calculations reveal how these grain boundaries are associated with locally reduced band gaps (by up to 3 eV). Using a simple model we show how shunting a proportion of the tunnelling current through grain boundaries imposes limits on the maximum magnetoresistance that can be achieved in devices.

  7. An advanced tunnel oxide layer process for 65 nm NOR floating-gate flash memories

    Science.gov (United States)

    Chiu, Shengfen; Xu, Yue; Ji, Xiaoli; Liao, Yiming; Wu, Fuwei; Yan, Feng

    2015-10-01

    An advanced tunnel oxide layer process for 65 nm NOR-type floating-gate flash memory is proposed to improve tunnel oxide quality by an additive sacrificial oxide layer growth. The sacrificial oxide layer process effectively controls the thickness variation of tunnel oxide and improves the flatness of the SiO2/Si interface across the active area. The interface traps’ generation during program/erase cycling of flash cells is found to be reduced, and the reliability property is significantly improved as compared to flash cells without the sacrificial oxide layer process. The technology is applicable to further scaled floating-gate flash memories.

  8. Vibrational Inelastic Electron Tunneling Spectroscopy of Surface Adsorbed Single Molecules at Sub-Kelvin Temperature

    OpenAIRE

    Jiang, Chi-Lun

    2015-01-01

    With a 600mk homebuilt UHV STM system, we studied molecular vibration at the solid surface with inelastic electron tunneling spectroscopy (IETS) of Acetylene single molecules adsorbed on Cu(100) surface and revealed five new vibrational modes that were previously inaccessible to STM-IETS at 8K temperature. The identification of vibrational IETS features with normalized conductance change (Δσ/σ) as low as 0.24% was demonstrated. Facilitated by the high energy resolution, we also revealed the a...

  9. Electron Tunneling and Hopping Possibilites in RuO2 Thick Films

    OpenAIRE

    Halder, N. C.

    1983-01-01

    It is proposed in this paper that the temperature coefficient of resistivity (TCR) in thick film resistors arises from (i) the usual particle-to-particle conduction, (ii) electron tunneling, and (iii) the phononassisted hopping. Equations for activation energies are derived for the temperature minimum of the resistance with and without hopping. New equations for TCR are suggested. Some extensive calculations of TCR and activation energy have been made for RuO2 thick film resistors, the result...

  10. Energy-Filtered Tunnel Transistor: A New Device Concept Toward Extremely-Low Energy Consumption Electronics

    Science.gov (United States)

    2015-12-17

    technical report 3. DATES COVERED {From - To) Apri 1 1, 2012 - September 30, 2015 4. TITLE AND SUBTITLE Energy-Filtered Tunnel Transistor : A...occurring at room temperature as well as its applications to practical devices such as room-temperature single-electron transistors and ultralow...energy consumption transistors . We have experimentally demonstrated, for the first time, that a quantum well energy level can filter out energetic

  11. Detecting element specific electrons from a single cobalt nanocluster with synchrotron x-ray scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kersell, Heath; Shirato, Nozomi; Cummings, Marvin; Chang, Hao; Miller, Dean; Rosenmann, Daniel; Hla, Saw-Wai; Rose, Volker

    2017-09-04

    We use a nanofabricated scanning tunneling microscope tip as a detector to investigate local X-ray induced tunneling and electron emission from a single cobalt nanocluster on a Au(111) surface. The tip-detector is positioned a few angstroms above the nanocluster, and ramping the incident X-ray energy across the Co photoabsorption K-edge enables the detection of element specific electrons. Atomic-scale spatial dependent changes in the X-ray absorption cross section are directly measured by taking the X-ray induced current as a function of X-ray energy. From the measured sample and tip currents, element specific X-ray induced current components can be separated and thereby the corresponding yields for the X-ray induced processes of the single cobalt nanocluster can be determined. The detection of element specific synchrotron X-ray induced electrons of a single nanocluster opens a new avenue for materials characterization on a one particle at-a-time basis.

  12. Long-range protein electron transfer observed at the single-molecule level: In situ mapping of redox-gated tunneling resonance

    DEFF Research Database (Denmark)

    Chi, Qijin; Farver, O; Ulstrup, Jens

    2005-01-01

    on the redox potential. Maximum resonance appears around the equilibrium redox potential of azurin with an on/off current ratio of approximate to 9. Simulation analyses, based on a two-step interfacial ET model for the scanning tunneling microscopy redox process, were performed and provide quantitative......A biomimetic long-range electron transfer (ET) system consisting of the blue copper protein azurin, a tunneling barrier bridge, and a gold single-crystal electrode was designed on the basis of molecular wiring self-assembly principles. This system is sufficiently stable and sensitive in a quasi...

  13. Measurement of laser activated electron tunneling from semiconductor zinc oxide to adsorbed organic molecules by a matrix assisted laser desorption ionization mass spectrometer.

    Science.gov (United States)

    Zhong, Hongying; Fu, Jieying; Wang, Xiaoli; Zheng, Shi

    2012-06-04

    Measurement of light induced heterogeneous electron transfer is important for understanding of fundamental processes involved in chemistry, physics and biology, which is still challenging by current techniques. Laser activated electron tunneling (LAET) from semiconductor metal oxides was observed and characterized by a MALDI (matrix assisted laser desorption ionization) mass spectrometer in this work. Nanoparticles of ZnO were placed on a MALDI sample plate. Free fatty acids and derivatives were used as models of organic compounds and directly deposited on the surface of ZnO nanoparticles. Irradiation of UV laser (λ=355 nm) with energy more than the band gap of ZnO produces ions that can be detected in negative mode. When TiO(2) nanoparticles with similar band gap but much lower electron mobility were used, these ions were not observed unless the voltage on the sample plate was increased. The experimental results indicate that laser induced electron tunneling is dependent on the electron mobility and the strength of the electric field. Capture of low energy electrons by charge-deficient atoms of adsorbed organic molecules causes unpaired electron-directed cleavages of chemical bonds in a nonergodic pathway. In positive detection mode, electron tunneling cannot be observed due to the reverse moving direction of electrons. It should be able to expect that laser desorption ionization mass spectrometry is a new technique capable of probing the dynamics of electron tunneling. LAET offers advantages as a new ionization dissociation method for mass spectrometry. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Conceptual design for an electron-beam heated hypersonic wind tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Lipinski, R.J.; Kensek, R.P.

    1997-07-01

    There is a need for hypersonic wind-tunnel testing at about mach 10 and above using natural air and simulating temperatures and pressures which are prototypic of flight at 50 km altitude or below. With traditional wind-tunnel techniques, gas cooling during expansion results in exit temperatures which are too low. Miles, et al., have proposed overcoming this difficulty by heating the air with a laser beam as it expands in the wind-tunnel nozzle. This report discusses an alternative option of using a high-power electron beam to heat the air as it expands. In the e-beam heating concept, the electron beam is injected into the wind-tunnel nozzle near the exit and then is guided upstream toward the nozzle throat by a strong axial magnetic field. The beam deposits most of its power in the dense air near the throat where the expansion rate is greatest. A conceptual design is presented for a large-scale system which achieves Mach 14 for 0.1 seconds with an exit diameter of 2.8 meters. It requires 450 MW of electron beam power (5 MeV at 90 A). The guiding field is 500 G for most of the transport length and increases to 100 kG near the throat to converge the beam to a 1.0-cm diameter. The beam generator is a DC accelerator using a Marx bank (of capacitors) and a diode stack with a hot cathode. 14 refs. 38 figs., 9 tabs.

  15. Simulation of Wind Speed in the Ventilation Tunnel for Surge Tanks in Transient Processes

    National Research Council Canada - National Science Library

    Yang, Jiandong; Wang, Huang; Guo, Wencheng; Yang, Weijia; Zeng, Wei

    2016-01-01

    .... To obtain the wind speed in a ventilation tunnel for a surge tank during transient processes, this article adopts the one-dimensional numerical simulation method and establishes a mathematical model...

  16. Simulation of Wind Speed in the Ventilation Tunnel for Surge Tanks in Transient Processes

    Directory of Open Access Journals (Sweden)

    Jiandong Yang

    2016-02-01

    Full Text Available Hydroelectric power plants’ open-type surge tanks may be built in mountains subject to the provision of atmospheric air. Hence, a ventilation tunnel is indispensable. The air flow in the ventilation tunnel is associated with the fluctuation of water-level in the surge tank. There is a great relationship between the wind speed and the safe use and project investment of ventilation tunnels. To obtain the wind speed in a ventilation tunnel for a surge tank during transient processes, this article adopts the one-dimensional numerical simulation method and establishes a mathematical model of a wind speed by assuming the boundary conditions of air discharge for a surge tank. Thereafter, the simulation of wind speed in a ventilation tunnel, for the case of a surge tank during transient processes, is successfully realized. Finally, the effective mechanism of water-level fluctuation in a surge tank and the shape of the ventilation tunnel (including length, sectional area and dip angle for the wind speed distribution and the change process are discovered. On the basis of comparison between the simulation results of 1D and 3D computational fluid dynamics (CFD, the results indicate that the one-dimensional simulation method as proposed in this article can be used to accurately simulate the wind speed in the ventilation tunnel of a surge tank during transient processes. The wind speed fluctuations can be superimposed by using the low frequency mass wave (i.e., fundamental wave and the high frequency elastic wave (i.e., harmonic wave. The water-level fluctuation in a surge tank and the sectional area of the ventilation tunnel mainly affect the amplitude of fundamental and harmonic waves. The period of a fundamental wave can be determined from the water-level fluctuations. The length of the ventilation tunnel has an effect on the period and amplitude of harmonic waves, whereas the dip angle influences the amplitude of harmonic waves.

  17. Submolecular Electronic Mapping of Single Cysteine Molecules by in Situ Scanning Tunneling Imaging

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Chi, Qijin; Nazmutdinov, R. R.

    2009-01-01

    based on a slab model for the metal surface. The ordered monolayer offers a platform for submolecular scale electronic mapping that is an issue of fundamental interest but remains a challenge in STM imaging science and surface chemistry. Single Cys molecules were mapped as three electronic subunits......We have used L-Cysteine (Cys) as a model system to study the surface electronic structures of single molecules at the submolecular level in aqueous buffer solution by a combination of electrochemical scanning tunneling microscopy (in situ STM), electrochemistry including voltammetry...... contributed mainly from three chemical moieties: thiol (-SH), carboxylic (-COOH), and amine (-NH2) groups. The contrasts of the three subunits depend on the environment (e.g., pH), which affects the electronic structure of adsorbed species. From the DFT computations focused on single molecules, rational...

  18. Electron Tunneling Counting Statistics of a GaAs Quantum Dot at Thermal Equilibrium

    Science.gov (United States)

    Zhang, Xinchang; Xiao, Ming; Yablonovitch, Eli; Jiang, Hongwen

    2008-03-01

    Full counting statistics (FCS) is an innovative way to investigate current fluctuations of mesoscopic conductors which can provide additional information beyond the conventional average current measurement [1]. Suppression of the 2nd moment and the 3rd moment were observed in a many-electron quantum dot(QD)under nonequilibrium conditions [1]. Here we studied the FCS of single electron tunneling of a GaAs QD in the few electron regime at thermal equilibrium in the in-plane magnetic fields. The device consists of a multiple-surface-gates defined GaAs QD integrated with a very sensitive, high bandwidth field effect transitor (FET) channel for the QD charge state read-out. Monitoring the FET current revealed two sequences of random telegraph signals which represent the electron tunneling onto and off the QD in real time. When the QD level is aligned with Fermi level of the reservoir, the statistics shows a maximum value of both mean () and standard deviation (sigma), but a minimum skewness in its distribution function. It was also found that an in-plane magnetic field suppresses both and sigma, but enhances the skewness. [1], S. Gustavsson et. al, PRL 96, 76695(2006). .

  19. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    When a molecule is subject to a strong laser field, there is a probability that an electron can escape, even though the electrons are bound by a large potential barrier. This is possible because electrons are quantum mechanical in nature, and they are therefore able to tunnel through potential...... barriers, an ability classical particles do not possess. Tunnelling is a fundamental quantum mechanical process, a process that is distinctly non-classical, so solving this tunnelling problem is not only relevant for molecular physics, but also for quantum theory in general. In this dissertation the theory...... of tunneling ionizaion of molecules is presented and the results of numerical calculations are shown. One perhaps surprising result is, that the frequently used Born-Oppenheimer approximation breaks down for weak fields when describing tunneling ionization. An analytic theory applicable in the weak-field limit...

  20. Wind Tunnel Model Design and Test Using Rapid Prototype Materials and Processes

    Science.gov (United States)

    2001-07-23

    UNCLASSIFIED WIND TUNNEL MODEL DESIGN AND TEST USING RAPID PROTOTYPE MATERIALS AND PROCESSES Richard R. Heisler and Clifford L. Ratliff The Johns Hopkins...deflection, and attach directly to the strongback with screws. A and tolerance deviations when the material was grown. schematic diagram of the RPM...constructed around the clay to contain the I. R. R. Heisler , "Final Test Report for the Wind pouring of silicon resin. Tunnel Test of the JHU/APL WTM-01 at

  1. Rotation of a Single Acetylene Molecule on Cu(001) by Tunneling Electrons in STM

    Science.gov (United States)

    Shchadilova, Yulia E.; Tikhodeev, Sergei G.; Paulsson, Magnus; Ueba, Hiromu

    2013-11-01

    We study the elementary processes behind one of the pioneering works on scanning tunneling microscope controlled reactions of single molecules [Stipe et al., Phys. Rev. Lett. 81, 1263 (1998)]. Using the Keldysh-Green function approach for the vibrational generation rate in combination with density functional theory calculations to obtain realistic parameters we reproduce the experimental rotation rate of an acetylene molecule on a Cu(100) surface as a function of bias voltage and tunneling current. This combined approach allows us to identify the reaction coordinate mode of the acetylene rotation and its anharmonic coupling with the C-H stretch mode. We show that three different elementary processes, the excitation of C-H stretch, the overtone ladder climbing of the hindered rotational mode, and the combination band excitation together explain the rotation of the acetylene molecule on Cu(100).

  2. Comparison of Experimental and Theoretical Inelastic Electron Tunneling Intensities for Thiourea and Urea.

    Science.gov (United States)

    Yang, Wen-Jung

    A comparison of experimental and calculated inelastic electron tunneling intensities for several modes of thiourea has been made. The measurements were made on aluminum -aluminum oxide-lead tunnel junctions doped with thiourea. The partial charge model of Kirtley, Scalapino, and Hansma was used to calculate the relative intensities of each mode. The best agreement between the two sets of intensities occurred when the C=S bond was oriented perpendicular to the oxide surface, the structure was non-planar, and the separation between the molecule and the image plane formed by the lead electrode was about 1.6 angstroms. The orientation was such that the sulfur was bonded to the aluminum oxide and the plane formed by the SCNN atoms was perpendicular to the surface. Tunneling spectra was also obtained for urea. Urea has a structure similar to that of thiourea. It was chosen with the intention of comparing results obtained for these two similar structures to determine whether the partial charge model gave reasonably consistent results for the two. There was evidence, however, in the urea spectra that the urea reacted with the oxide to form a much different molecular structure. Evidence was seen for the presence of C-O and Al-N stretch modes. The different structure observed for the adsorbed urea precluded doing the corresponding theoretical calculations.

  3. Preliminary design of CERN Future Circular Collider tunnel: first evaluation of the radiation environment in critical areas for electronics

    Directory of Open Access Journals (Sweden)

    Infantino Angelo

    2017-01-01

    Full Text Available As part of its post-LHC high energy physics program, CERN is conducting a study for a new proton-proton collider, called Future Circular Collider (FCC-hh, running at center-of-mass energies of up to 100 TeV in a new 100 km tunnel. The study includes a 90-350 GeV lepton collider (FCC-ee as well as a lepton-hadron option (FCC-he. In this work, FLUKA Monte Carlo simulation was extensively used to perform a first evaluation of the radiation environment in critical areas for electronics in the FCC-hh tunnel. The model of the tunnel was created based on the original civil engineering studies already performed and further integrated in the existing FLUKA models of the beam line. The radiation levels in critical areas, such as the racks for electronics and cables, power converters, service areas, local tunnel extensions was evaluated.

  4. Electron modes of plasma generated at tunnel ionization of atoms by a circularly polarized radiation

    Science.gov (United States)

    Vagin, K. Yu.; Uryupin, S. A.

    2017-10-01

    The collective modes of photoionized plasmas are studied using the model description of electron velocity distribution formed at tunnel ionization of atoms by circularly polarized radiation. The dispersion laws of transverse and approximately longitudinal high-frequency waves propagating at an arbitrary angle to the anisotropy axis of photoelectron distribution are obtained. The dispersion law of potential surface waves is derived. It is shown that the frequency of these waves may be greater than plasma frequency. The aperiodic instability of photoionized plasmas is described.

  5. Electronic properties of (Zn,CoO systems probed by scanning tunnelling spectroscopy

    Directory of Open Access Journals (Sweden)

    L. Moldovan

    2008-05-01

    Full Text Available The aim of this paper is to gain insight into theelectronic properties of (Zn,CoO system - a widebandgap Diluted Magnetic Semiconductors (DMSshowing room temperature (RT ferromagnetism undern-type doping conditions. On the experimental side, ultrahigh-vacuum scanning tunnelling microscopy andspectroscopy (STM and STS at variable temperature (Tare used to probe the local electronic structure of thesystem. It is presented the map of the local density ofstates (LDOS of polar ZnO surfaces. Then, it is possibleto decorate (incorporate Co atoms onto (into thesemiconductor.

  6. Electronic Handbooks Simplify Process Management

    Science.gov (United States)

    2012-01-01

    Getting a multitude of people to work together to manage processes across many organizations for example, flight projects, research, technologies, or data centers and others is not an easy task. Just ask Dr. Barry E. Jacobs, a research computer scientist at Goddard Space Flight Center. He helped NASA develop a process management solution that provided documenting tools for process developers and participants to help them quickly learn, adapt, test, and teach their views. Some of these tools included editable files for subprocess descriptions, document descriptions, role guidelines, manager worksheets, and references. First utilized for NASA's Headquarters Directives Management process, the approach led to the invention of a concept called the Electronic Handbook (EHB). This EHB concept was successfully applied to NASA's Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs, among other NASA programs. Several Federal agencies showed interest in the concept, so Jacobs and his team visited these agencies to show them how their specific processes could be managed by the methodology, as well as to create mockup versions of the EHBs.

  7. Coulomb Repulsion Effect in Two-electron Non-adiabatic Tunneling through a One-level redox Molecule

    DEFF Research Database (Denmark)

    Medvedev, Igor M.; Kuznetsov, Alexander M.; Ulstrup, Jens

    2009-01-01

    We investigated Coulomb repulsion effects in nonadiabatic (diabatic) two-electron tunneling through a redox molecule with a single electronic level in a symmetric electrochemical contact under ambient conditions, i.e., room temperature and condensed matter environment. The electrochemical contact...

  8. Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons

    Directory of Open Access Journals (Sweden)

    Kai Braun

    2015-05-01

    Full Text Available Here, we demonstrate a bias-driven superluminescent point light-source based on an optically pumped molecular junction (gold substrate/self-assembled molecular monolayer/gold tip of a scanning tunneling microscope, operating at ambient conditions and providing almost three orders of magnitude higher electron-to-photon conversion efficiency than electroluminescence induced by inelastic tunneling without optical pumping. A positive, steadily increasing bias voltage induces a step-like rise of the Stokes shifted optical signal emitted from the junction. This emission is strongly attenuated by reversing the applied bias voltage. At high bias voltage, the emission intensity depends non-linearly on the optical pump power. The enhanced emission can be modelled by rate equations taking into account hole injection from the tip (anode into the highest occupied orbital of the closest substrate-bound molecule (lower level and radiative recombination with an electron from above the Fermi level (upper level, hence feeding photons back by stimulated emission resonant with the gap mode. The system reflects many essential features of a superluminescent light emitting diode.

  9. Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons.

    Science.gov (United States)

    Braun, Kai; Wang, Xiao; Kern, Andreas M; Adler, Hilmar; Peisert, Heiko; Chassé, Thomas; Zhang, Dai; Meixner, Alfred J

    2015-01-01

    Here, we demonstrate a bias-driven superluminescent point light-source based on an optically pumped molecular junction (gold substrate/self-assembled molecular monolayer/gold tip) of a scanning tunneling microscope, operating at ambient conditions and providing almost three orders of magnitude higher electron-to-photon conversion efficiency than electroluminescence induced by inelastic tunneling without optical pumping. A positive, steadily increasing bias voltage induces a step-like rise of the Stokes shifted optical signal emitted from the junction. This emission is strongly attenuated by reversing the applied bias voltage. At high bias voltage, the emission intensity depends non-linearly on the optical pump power. The enhanced emission can be modelled by rate equations taking into account hole injection from the tip (anode) into the highest occupied orbital of the closest substrate-bound molecule (lower level) and radiative recombination with an electron from above the Fermi level (upper level), hence feeding photons back by stimulated emission resonant with the gap mode. The system reflects many essential features of a superluminescent light emitting diode.

  10. Direct exchange between silicon nanocrystals and tunnel oxide traps under illumination on single electron photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Chatbouri, S., E-mail: Samir.chatbouri@yahoo.com; Troudi, M.; Sghaier, N.; Kalboussi, A. [Avenue de I’environnement, Université de Monastir, Laboratoire de Micro électronique et Instrumentation (LR13ES12), Faculté des Sciences de Monastir (Tunisia); Aimez, V. [Université de Sherbrooke, Laboratoire Nanotechnologies et Nanosystémes (UMI-LN2 3463), Université de Sherbrooke—CNRS—INSA de Lyon-ECL-UJF-CPE Lyon, Institut Interdisciplinaire d’Innovation Technologique (Canada); Drouin, D. [Avenue de I’environnement, Université de Monastir, Laboratoire de Micro électronique et Instrumentation (LR13ES12), Faculté des Sciences de Monastir (Tunisia); Souifi, A. [Institut des Nanotechnologies de Lyon—site INSA de Lyon, UMR CNRS 5270 (France)

    2016-09-15

    In this paper we present the trapping of photogenerated charge carriers for 300 s resulted by their direct exchange under illumination between a few silicon nanocrystals (ncs-Si) embedded in an oxide tunnel layer (SiO{sub x} = 1.5) and the tunnel oxide traps levels for a single electron photodetector (photo-SET or nanopixel). At first place, the presence of a photocurrent limited in the inversion zone under illumination in the I–V curves confirms the creation of a pair electron/hole (e–h) at high energy. This photogenerated charge carriers can be trapped in the oxide. Using the capacitance-voltage under illumination (the photo-CV measurements) we show a hysteresis chargement limited in the inversion area, indicating that the photo-generated charge carriers are stored at traps levels at the interface and within ncs-Si. The direct exchange of the photogenerated charge carriers between the interface traps levels and the ncs-Si contributed on the photomemory effect for 300 s for our nanopixel at room temperature.

  11. Electronic structure of carbon nanotube systems measured with scanning tunneling microscopy

    Science.gov (United States)

    Hornbaker, Daniel Jay

    Carbon fullerenes are unusually structured molecules with robust mechanical and electronic properties. Their versatility is astounding; envisioned applications range from field emission displays to impregnated metal composites, battery storage media, and nanoelectronic devices. The combination of simple constituency, diverse behavior, and ease of fabrication makes these materials a cornerstone topic in current research. This thesis details scanning tunneling microscopy (STM) experiments investigating how carbon nanotube fullerenes interact with and couple to their local environment. Scanning tunneling microscopy continues to be a key method for characterizing fullerenes, particularly in regards to their electronic properties. The atomic scale nature of this technique makes it uniquely suited for observing individual molecules and determining correlations between locally measured electronic properties and the particular environment of the molecule. The primary subject of this study is single-wall carbon nanotubes (SWNTs), which were observed under various perturbative influences resulting in measurable changes in the electronic structure. Additionally, fullerene heterostructures formed by the encapsulation of C60 molecules within the hollow interiors of SWNTs were characterized for the first time with STM. These novel macromolecules (dubbed "peapods") demonstrate the potential for custom engineering the properties of fullerene materials. Measurements indicate that the properties of individual nanotubes depend sensitively on local interactions. In particular, pronounced changes in electronic behavior are observed in nanotubes exhibiting mechanical distortion, interacting with extrinsic materials (including other nanotubes), and possessing intrinsic defects in the atomic lattice. In fullerene peapods, while no discernable change in the atomic ordering of the encapsulating nanotubes was evident, the presence of interior C60 molecules has a dramatic effect on the

  12. An experimental estimate of the electron-tunneling distance for some outer-sphere electrochemical reactions

    Science.gov (United States)

    Hupp, J. T.; Weaver, M. J.

    1983-11-01

    Estimates of the reaction zone thickness over which electron tunneling can effectively occur for the outer-sphere electrochemical reduction of some Cr(III) complexes are obtained by comparing the observed work-corrected rate constants with unimolecular rate constants for the electroreduction of structurally similar surface-bound Cr(III) reactants. Effective reaction zone thicknesses of ca. 0.1-0.3 A and ca. 5 A are obtained for outer-sphere electron transfer with Cr(III) reactants containing predominantly aquo or ammine ligands, respectively. This indicates that the former reactions are marginally nonadiabatic whereas the latter are decidedly adiabatic at their respective places of closest approach. These findings are compatible with the greater reactant-electrode separation distances previously noted for Cr(III) aquo relative to ammine complexes resulting from the more extensive hydration sheath surrounding the former reactants.

  13. Inelastic electron tunneling spectroscopy of difurylethene-based photochromic single-molecule junctions.

    Science.gov (United States)

    Kim, Youngsang; Bahoosh, Safa G; Sysoiev, Dmytro; Huhn, Thomas; Pauly, Fabian; Scheer, Elke

    2017-01-01

    Diarylethene-derived molecules alter their electronic structure upon transformation between the open and closed forms of the diarylethene core, when exposed to ultraviolet (UV) or visible light. This transformation results in a significant variation of electrical conductance and vibrational properties of corresponding molecular junctions. We report here a combined experimental and theoretical analysis of charge transport through diarylethene-derived single-molecule devices, which are created using the mechanically controlled break-junction technique. Inelastic electron tunneling (IET) spectroscopy measurements performed at 4.2 K are compared with first-principles calculations in the two distinct forms of diarylethenes connected to gold electrodes. The combined approach clearly demonstrates that the IET spectra of single-molecule junctions show specific vibrational features that can be used to identify different isomeric molecular states by transport experiments.

  14. Time-dependent tunneling of spin-polarized electrons in coupled quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, H; Luis, D [Departamento de Fisica Basica, Universidad de La Laguna, 38204 La Laguna, Tenerife (Spain)], E-mail: hcruz@ull.es

    2008-02-15

    We have solved the in-plane momentum-dependent effective-mass nonlinear Schroedinger equation for a spin-polarized electron wave packet in a InAs double quantum well system with an interlayer voltage. Considering a time-dependent Hartree potential, we have calculated the spin-polarized nonlinear electron dynamics between both quantum wells at different in-plane momentum values and applied bias. The spin-splitting caused by the Rashba effect is combined with the level matching between the spin dependent resonant tunneling levels making possible the observed local spin density oscillations which depend on the applied bias value. The filtering efficiency has been studied using time-dependent calculations.

  15. Influence of spin-orbit interaction within the insulating barrier on the electron transport in magnetic tunnel junctions

    Science.gov (United States)

    Vedyayev, A.; Ryzhanova, N.; Strelkov, N.; Titova, M.; Chshiev, M.; Rodmacq, B.; Auffret, S.; Cuchet, L.; Nistor, L.; Dieny, B.

    2017-02-01

    We present a theory of the anisotropy of tunneling magnetoresistance (ATMR) phenomenon in magnetic tunnel junctions (MTJs) attributed to Rashba spin-orbit interaction in the insulating barrier. ATMR represents the difference of tunnel magnetoresistance (TMR) amplitude measured with in-plane and out-of-plane magnetic configurations. It is demonstrated that within the spin-polarized free-electron model the change of conductance associated with the ATMR is exactly twice the change of conductance measured at full saturation (i.e., in parallel configuration of magnetizations) between in-plane and out-of-plane configuration, i.e., the tunneling anisotropic magnetoresistance (TAMR). Both ATMR and TAMR are closely related to the TMR amplitude and spin-orbit constant. The predicted ATMR phenomenon is confirmed experimentally, showing a few percent value in the case of the widely studied CoFeB/MgO/CoFeB based MTJ.

  16. Modelling of tunnelling processes and rock cutting tool wear with the particle finite element method

    Science.gov (United States)

    Carbonell, Josep Maria; Oñate, Eugenio; Suárez, Benjamín

    2013-09-01

    Underground construction involves all sort of challenges in analysis, design, project and execution phases. The dimension of tunnels and their structural requirements are growing, and so safety and security demands do. New engineering tools are needed to perform a safer planning and design. This work presents the advances in the particle finite element method (PFEM) for the modelling and the analysis of tunneling processes including the wear of the cutting tools. The PFEM has its foundation on the Lagrangian description of the motion of a continuum built from a set of particles with known physical properties. The method uses a remeshing process combined with the alpha-shape technique to detect the contacting surfaces and a finite element method for the mechanical computations. A contact procedure has been developed for the PFEM which is combined with a constitutive model for predicting the excavation front and the wear of cutting tools. The material parameters govern the coupling of frictional contact and wear between the interacting domains at the excavation front. The PFEM allows predicting several parameters which are relevant for estimating the performance of a tunnelling boring machine such as wear in the cutting tools, the pressure distribution on the face of the boring machine and the vibrations produced in the machinery and the adjacent soil/rock. The final aim is to help in the design of the excavating tools and in the planning of the tunnelling operations. The applications presented show that the PFEM is a promising technique for the analysis of tunnelling problems.

  17. Freezing and thawing of processed meat in an industrial freezing tunnel

    OpenAIRE

    Glaucio Antonio Marini; Eduarda Molardi Bainy; Marcelo Kaminski Lenzi; Marcos Lúcio Corazza

    2014-01-01

    Freezing is a commonly used preservation method in the meat industry. The understanding of the product behavior during the freezing process can assist in a better process management and quality control. This work reports the study of freezing and thawing of three types of processed meat in order to determine process parameters in an industrial forced‑air freezing tunnel at ‑30oC. Chicken sausages (frankfurter type), mortadela (bologna type) and mechanically deboned chicken meat (MDCM) were st...

  18. Chemical imaging of latent fingerprints by mass spectrometry based on laser activated electron tunneling.

    Science.gov (United States)

    Tang, Xuemei; Huang, Lulu; Zhang, Wenyang; Zhong, Hongying

    2015-03-03

    Identification of endogenous and exogenous chemicals contained in latent fingerprints is important for forensic science in order to acquire evidence of criminal identities and contacts with specific chemicals. Mass spectrometry has emerged as a powerful technique for such applications without any derivatization or fluorescent tags. Among these techniques, MALDI (Matrix Assisted Laser Desorption Ionization) provides small beam size but has interferences with MALDI matrix materials, which cause ion suppressions as well as limited spatial resolution resulting from uneven distribution of MALDI matrix crystals with different sizes. LAET (Laser Activated Electron Tunneling) described in this work offers capabilities for chemical imaging through electron-directed soft ionization. A special film of semiconductors has been designed for collection of fingerprints. Nanoparticles of bismuth cobalt zinc oxide were compressed on a conductive metal substrate (Al or Cu sticky tape) under 10 MPa pressure. Resultant uniform thin films provide tight and shining surfaces on which fingers are impressed. Irradiation of ultraviolet laser pulses (355 nm) on the thin film instantly generates photoelectrons that can be captured by adsorbed organic molecules and subsequently cause electron-directed ionization and fragmentation. Imaging of latent fingerprints is achieved by visualization of the spatial distribution of these molecular ions and structural information-rich fragment ions. Atomic electron emission together with finely tuned laser beam size improve spatial resolution. With the LAET technique, imaging analysis not only can identify physical shapes but also reveal endogenous metabolites present in females and males, detect contacts with prohibited substances, and resolve overlapped latent fingerprints.

  19. Equilibrium and non-equilibrium electron tunneling via discrete quantum states

    OpenAIRE

    Deshmukh, Mandar M.; Bonet, Edgar; Pasupathy, A. N.; Ralph, D. C.

    2001-01-01

    Tunneling is measured via the quantum levels of a metal nanoparticle. We analyze quantitatively the resonance energies, widths, and amplitudes, both in the regime where only one state is accessible for tunneling and in the non-equilibrium regime when additional states are made accessible one-by-one. For tunneling through one state, our results agree with expectations for sequential tunneling, but in the non-equilibrium regime the resonances are broadened and shifted in ways that require takin...

  20. Vibrational Inelastic Electron Tunneling Spectroscopy of Single Acetylene Molecules Adsorbed on Copper (100) Surface

    OpenAIRE

    Jiang, Chi-Lun

    2015-01-01

    With a 600mk homebuilt UHV STM system, we studied molecular vibration at the solid surface with inelastic electron tunneling spectroscopy (IETS) of Acetylene single molecules adsorbed on Cu(100) surface. The identification of vibrational IETS features with normalized conductance change (Δσ/σ) as low as 0.24% in dI2/d2V spectra was demonstrated. Five vibrational modes with energy level at 117.70meV (Δσ/σ =0.42%), 84.07meV (Δσ/σ =0.24%), 58.46meV (Δσ/σ =1.18%), 34.80meV (Δσ/σ =0.65% ) and 22.1...

  1. Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

    Directory of Open Access Journals (Sweden)

    Riccardo Frisenda

    2015-12-01

    Full Text Available We study single-molecule oligo(phenylene ethynylenedithiol junctions by means of inelastic electron tunneling spectroscopy (IETS. The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from direct current measurements, both as a function of time and electrode separation. We find that for fixed electrode separation the molecule switches between various configurations, which are characterized by different IETS spectra. Similar variations in the IETS signal are observed during atomic rearrangements upon stretching of the molecular junction. Using quantum chemistry calculations, we identity some of the vibrational modes which constitute a chemical fingerprint of the molecule. In addition, changes can be attributed to rearrangements of the local molecular environment, in particular at the molecule–electrode interface. This study shows the importance of taking into account the interaction with the electrodes when describing inelastic contributions to transport through single-molecule junctions.

  2. Effects of tunnelling and asymmetry for system-bath models of electron transfer

    Science.gov (United States)

    Mattiat, Johann; Richardson, Jeremy O.

    2018-03-01

    We apply the newly derived nonadiabatic golden-rule instanton theory to asymmetric models describing electron-transfer in solution. The models go beyond the usual spin-boson description and have anharmonic free-energy surfaces with different values for the reactant and product reorganization energies. The instanton method gives an excellent description of the behaviour of the rate constant with respect to asymmetry for the whole range studied. We derive a general formula for an asymmetric version of the Marcus theory based on the classical limit of the instanton and find that this gives significant corrections to the standard Marcus theory. A scheme is given to compute this rate based only on equilibrium simulations. We also compare the rate constants obtained by the instanton method with its classical limit to study the effect of tunnelling and other quantum nuclear effects. These quantum effects can increase the rate constant by orders of magnitude.

  3. Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy.

    Science.gov (United States)

    Frisenda, Riccardo; Perrin, Mickael L; van der Zant, Herre S J

    2015-01-01

    We study single-molecule oligo(phenylene ethynylene)dithiol junctions by means of inelastic electron tunneling spectroscopy (IETS). The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from direct current measurements, both as a function of time and electrode separation. We find that for fixed electrode separation the molecule switches between various configurations, which are characterized by different IETS spectra. Similar variations in the IETS signal are observed during atomic rearrangements upon stretching of the molecular junction. Using quantum chemistry calculations, we identity some of the vibrational modes which constitute a chemical fingerprint of the molecule. In addition, changes can be attributed to rearrangements of the local molecular environment, in particular at the molecule-electrode interface. This study shows the importance of taking into account the interaction with the electrodes when describing inelastic contributions to transport through single-molecule junctions.

  4. A New XOR Structure Based on Resonant-Tunneling High Electron Mobility Transistor

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Sharifi

    2009-01-01

    Full Text Available A new structure for an exclusive-OR (XOR gate based on the resonant-tunneling high electron mobility transistor (RTHEMT is introduced which comprises only an RTHEMT and two FETs. Calculations are done by utilizing a new subcircuit model for simulating the RTHEMT in the SPICE simulator. Details of the design, input, and output values and margins, delay of each transition, maximum operating frequency, static and dynamic power dissipations of the new structure are discussed and calculated and the performance is compared with other XOR gates which confirm that the presented structure has a high performance. Furthermore, to the best of authors' knowledge, it has the least component count in comparison to the existing structures.

  5. Study of optical techniques for the Ames unitary wind tunnel: Digital image processing, part 6

    Science.gov (United States)

    Lee, George

    1993-01-01

    A survey of digital image processing techniques and processing systems for aerodynamic images has been conducted. These images covered many types of flows and were generated by many types of flow diagnostics. These include laser vapor screens, infrared cameras, laser holographic interferometry, Schlieren, and luminescent paints. Some general digital image processing systems, imaging networks, optical sensors, and image computing chips were briefly reviewed. Possible digital imaging network systems for the Ames Unitary Wind Tunnel were explored.

  6. Electron-tunneling modulation in percolating network of graphene quantum dots: fabrication, phenomenological understanding, and humidity/pressure sensing applications.

    Science.gov (United States)

    Sreeprasad, T S; Rodriguez, Alfredo Alexander; Colston, Jonathan; Graham, Augustus; Shishkin, Evgeniy; Pallem, Vasanta; Berry, Vikas

    2013-04-10

    The two-dimensional (2D) electron cloud, flexible carbon-carbon bonds, chemical modifiability, and size-dependent quantum-confinement and capacitance makes graphene nanostructures (GN) a widely tunable material for electronics. Here we report the oxidation-led edge-roughening and cleavage of long graphene nanoribbons (GNRs) (150 nm wide) synthesized via nanotomy (nanoscale cutting) of graphite (with 2 nm edged diamond knife) to produce graphene quantum dots (GQD). These GQDs (~100-200 nm) selectively interfaced with polyelectrolyte microfiber (diameter = 2-20 μm) form an electrically percolating-network exhibiting a characteristic Coulomb blockade signature with a dry tunneling distance of 0.58 nm and conduction activation energy of 3 meV. We implement this construct to demonstrate the functioning of humidity and pressure sensors and outline their governing model. Here, a 0.36 nm decrease in the average tunneling-barrier-width between GQDs (tunneling barrier = 5.11 eV) increases the conductivity of the device by 43-fold. These devices leverage the modulation in electron tunneling distances caused by pressure and humidity induced water transport across the hygroscopic polymer microfiber (Henry's constant = 0.215 Torr(-1)). This is the foremost example of GQD-based electronic sensors. We envision that this polymer-interfaced GQD percolating network will evolve a new class of sensors leveraging the low mass, low capacitance, high conductivity, and high sensitivity of GQD and the interfacial or dielectric properties of the polymer fiber.

  7. Electron heating by photon-assisted tunneling in niobium terahertz mixers with integrated niobium titanium nitride striplines

    NARCIS (Netherlands)

    Leone, B; Gao, [No Value; Klapwijk, TM; Jackson, BD; Laauwen, WM; de Lange, G

    2001-01-01

    We describe the gap voltage depression and current-voltage (I-V) characteristics in pumped niobium superconductor-insulator-superconductor junction with niobium titanium nitride tuning stripline by introducing an electron heating power contribution resulting from the photon-assisted tunneling

  8. Properties of thermoluminescence glow curves from tunneling recombination processes in random distributions of defects

    Energy Technology Data Exchange (ETDEWEB)

    Kitis, George [Nuclear Physics Laboratory, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Pagonis, Vasilis, E-mail: vpagonis@mcdaniel.edu [Physics Department, McDaniel College, Westminster, MD 21157 (United States)

    2014-09-15

    Localized electronic recombination processes in donor–acceptor pairs of luminescent materials have been recently modeled using a new kinetic model based on tunneling. Within this model, recombination is assumed to take place via the excited state of the donor, and nearest-neighbor recombinations take place within a random distribution of centers. An approximate semi-analytical version of the model has been shown to simulate successfully thermally and optically stimulated luminescence (TL and OSL), linearly modulated OSL (LM-OSL) and isothermal TL processes. This paper presents a detailed analysis of the geometrical properties of the TL glow curves obtained within three different published versions of the model. The dependence of the shape of the TL glow curves on the kinetic parameters of the model is examined by allowing simultaneous random variations of the parameters, within wide ranges of physically reasonable values covering several orders of magnitude. It is found that the TL glow curves can be characterized according to their shape factors μ{sub g}, as commonly done in TL theory of delocalized transitions. The values of the shape factor are found to depend rather weakly on the activation energy E and the frequency factor s, but they have a strong dependence on the parameter ρ′ which characterizes the concentration of acceptors in the model. It is also shown by simulation that both the variable heating rate and initial rise methods are applicable in this type of model and can yield the correct value of the activation energy E. However, the initial rise method of analysis for the semianalytical version of the model fails to yield the correct E value, since it underestimates the low temperature part of the TL glow curves. Two analytical expressions are given for the TL intensity, which can be used on an empirical basis for computerized glow curve deconvolution analysis (CGCD). - Highlights: • Detailed study of TL glow curves in a tunneling model for

  9. InAs nanowire with epitaxial aluminium as a single-electron transistor with fixed tunnel barriers

    DEFF Research Database (Denmark)

    Taupin, M.; Mannila, E.; Krogstrup, P.

    2016-01-01

    We report on fabrication of single-electron transistors using InAs nanowires with epitaxial aluminium with fixed tunnel barriers made of aluminium oxide. The devices exhibit a hard superconducting gap induced by the proximized aluminium cover shell and they behave as metallic single-electron tran......We report on fabrication of single-electron transistors using InAs nanowires with epitaxial aluminium with fixed tunnel barriers made of aluminium oxide. The devices exhibit a hard superconducting gap induced by the proximized aluminium cover shell and they behave as metallic single......-electron transistors. In contrast to the typical few channel contacts in semiconducting devices, our approach forms opaque multichannel contacts to a semiconducting wire and thus provides a complementary way to study them. In addition, we confirm that unwanted extra quantum dots can appear at the surface...

  10. 78 FR 14233 - Electronic Retirement Processing

    Science.gov (United States)

    2013-03-05

    ... OF PERSONNEL MANAGEMENT 5 CFR Part 850 RIN 3206-AM45 Electronic Retirement Processing AGENCY: Office... part so that it better serves OPM's ongoing modernization of the processing of benefits under the Civil... electronic recordkeeping and automated retirement processing improvements being deployed by OPM, agencies...

  11. Electronic processes in organic systems

    Science.gov (United States)

    Valkunas, Leonas

    2012-08-01

    Organic materials are particularly promising in optoelectronics as demonstrated by recent development of organic light emitting diodes, organic lasers and organic solar cells. Some of these products are already on the level of commercialization. Molecular electronics is also stimulated by a common believe that the devices based on organic materials should be easily recyclable, cheaper and more flexible than the silicon-based electronics dominating in industrial applications. Medical and biological applications correspond to another rapidly developing field, where "smart" organic sensors and tracers gain their positions.

  12. Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopy

    Science.gov (United States)

    Battisti, I.; Fedoseev, V.; Bastiaans, K. M.; de la Torre, A.; Perry, R. S.; Baumberger, F.; Allan, M. P.

    2017-06-01

    The effective Mott gap measured by scanning tunneling microscopy (STM) in the lightly doped Mott insulator (Sr1-xLax) 2IrO4 differs greatly from values reported by photoemission and optical experiments. Here we show that this is a consequence of the poor electronic screening of the tip-induced electric field in this material. Such effects are well known from STM experiments on semiconductors and go under the name of tip-induced band bending (TIBB). We show that this phenomenon also exists in the lightly doped Mott insulator (Sr1-xLax) 2IrO4 and that, at doping concentrations of x ≤4 % , it causes the measured energy gap in the sample density of states to be bigger than the one measured with other techniques. We develop a model able to retrieve the intrinsic energy gap leading to a value which is in rough agreement with other experiments, bridging the apparent contradiction. At doping x ≈5 % we further observe circular features in the conductance layers that point to the emergence of a significant density of free carriers in this doping range and to the presence of a small concentration of donor atoms. We illustrate the importance of considering the presence of TIBB when doing STM experiments on correlated-electron systems and discuss the similarities and differences between STM measurements on semiconductors and lightly doped Mott insulators.

  13. Characterizing low-coordinated atoms at the periphery of MgO-supported Au islands using scanning tunneling microscopy and electronic structure calculations

    Science.gov (United States)

    Lin, Xiao; Nilius, Niklas; Sterrer, Martin; Koskinen, Pekka; Häkkinen, Hannu; Freund, Hans-Joachim

    2010-04-01

    The perimeter of oxide-supported metal particles is suggested to be of pivotal importance for various catalytic processes. To elucidate the underlying effects, the electronic properties of edge and corner atoms of planar Au clusters on MgO/Ag(001) thin films have been analyzed with scanning tunneling microscopy and electronic structure calculations. The low-coordinated perimeter atoms are characterized by a high density of s -derived states at the Fermi level. Those states accommodate transfer electrons from the MgO/Ag substrate, which render the perimeter atoms negatively charged. In contrast, the inner atoms of the island are not affected by the charge transfer and remain neutral. This combination of charge accumulation and high state-density explains the specific relevance of the cluster perimeter in adsorption and reaction processes.

  14. Non-perturbation theory of electronic dynamic conductivity for two-barrier resonance tunnel nano-structure

    Directory of Open Access Journals (Sweden)

    O.M. Voitsekhivska

    2011-12-01

    Full Text Available The non-perturbation theory of electronic dynamic conductivity for open two-barrier resonance tunnel structure is established for the first time within the model of rectangular potentials and different effective masses of electrons in the elements of nano-structure and the wave function linear over the intensity of electromagnetic field. It is proven that the results of the theory of dynamic conductivity, developed earlier in weak signal approximation within the perturbation method, qualitatively and quantitatively correlate with the obtained results. The advantage of non-perturbation theory is that it can be extended to the case of electronic currents interacting with strong electromagnetic fields in open multi-shell resonance tunnel nano-structures, as active elements of quantum cascade lasers and detectors.

  15. Process Design Model for a Single-Zone Tunnel Dryer.

    Science.gov (United States)

    1987-12-01

    34’ " " ’ " * =" €: CHAPTER 1 INTRODUCTION Many products such as foods , paper, lumber, pharmaceuticals and chemicals must be dried in their manufacture. Beyond... psychrometric property is the adiabatic saturation temperature. Consider the process shown in Figure 2-3 in which humid air cnters an adiabatic control...the air water system used for analysis of air conditioning equipment, such as psychrometric charts, use the adiabatic saturation temperature as a

  16. Fundamentals of electronic image processing

    CERN Document Server

    Weeks, Arthur R

    1996-01-01

    This book is directed to practicing engineers and scientists who need to understand the fundamentals of image processing theory and algorithms to perform their technical tasks. It is intended to fill the gap between existing high-level texts dedicated to specialists in the field and the need for a more practical, fundamental text on image processing. A variety of example images are used to enhance reader understanding of how particular image processing algorithms work.

  17. Indirect processes in electron-ion scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bottcher, C.; Griffin, D.C.; Pindzola, M.S.; Phaneuf, R.A.

    1983-10-01

    A summary is given of an informal workshop held at Oak Ridge National Laboratory on June 22-23, 1983, in which the current status of theoretical calculations of indirect processes in electron-ion scattering was reviewed. Processes of particular interest in astrophysical and fusion plasmas were emphasized. Topics discussed include atomic structure effects, electron-impact ionization, and dielectronic recombination.

  18. Slip-cast zirconia dental roots with tunnels drilled by laser process.

    Science.gov (United States)

    Minamizato, T

    1990-06-01

    Zirconia was used in this study for implant dental roots because of its superior properties over other materials used as dental roots in mechanical strength, toughness, workability, and biocompatibility. Zirconia blades were formed by the slip casting method and tunnels were drilled in the laser processing. The results indicate that (1) the slip casting method has made it possible to form a complicated artificial dental root with an accurate shape and size; (2) the zirconia blade has adequate strength in occlusion; (3) the neodymium: yttrium-aluminum-garnet (Nd:YAG) laser machine can drill many tunnels of the same size in diameter by using it repeatedly under the same conditions of power, pulse width, and focus; (4) zirconia is a recommended material for laser processing from the standpoint of toughness and less heat conductivity; and (5) the opacity of zirconia to x-ray penetration presents better observation during and after implantation than other ceramics.

  19. Discretization of electronic states in large InAsP/InP multilevel quantum dots probed by scanning tunneling spectroscopy.

    Science.gov (United States)

    Fain, B; Robert-Philip, I; Beveratos, A; David, C; Wang, Z Z; Sagnes, I; Girard, J C

    2012-03-23

    The topography and the electronic structure of InAsP/InP quantum dots are probed by cross-sectional scanning tunneling microscopy and spectroscopy. The study of the local density of states in such large quantum dots confirms the discrete nature of the electronic levels whose wave functions are measured by differential conductivity mapping. Because of their large dimensions, the energy separation between the discrete electronic levels is low, allowing for quantization in both the lateral and growth directions as well as the observation of the harmonicity of the dot lateral potential.

  20. The weak π − π interaction originated resonant tunneling and fast switching in the carbon based electronic devices

    Directory of Open Access Journals (Sweden)

    Jun He

    2012-03-01

    Full Text Available By means of the nonequilibrium Green's functions and the density functional theory, we have investigated the electronic transport properties of C60 based electronic device with different intermolecular interactions. It is found that the electronic transport properties vary with the types of the interaction between two C60 molecules. A fast electrical switching behavior based on negative differential resistance has been found when two molecules are coupled by the weak π − π interaction. Compared to the solid bonding, the weak interaction is found to induce resonant tunneling, which is responsible for the fast response to the applied electric field and hence the velocity of switching.

  1. Combustion Processes in Model SCRAM Jet Combustor Using Detonation Driven Shock Tunnel

    OpenAIRE

    小原, 哲郎; 伊藤, 豪明; 大八木, 重治; 金, 泰煥; 坪井, 伸幸

    2006-01-01

    Experiments were conducted in order to investigate mixing and combustion processes in a model SCRAM (Supersonic Combustion RAM) jet combustor equipped with a backward-facing step. A detonation-driven shock tunnel was used to generate high-enthalpy flow of Mach number three. Firstly, an influence of installing a sidewall on the combustor model was investigated. Secondly, flow-fields around the step were visualized using high-speed video camera with an aid of schlieren technique. A hydrogen fue...

  2. Quantum tunneling injection of hot electrons in Au/TiO2 plasmonic photocatalysts.

    Science.gov (United States)

    Shiraishi, Yasuhiro; Yasumoto, Naoki; Imai, Jun; Sakamoto, Hirokatsu; Tanaka, Shunsuke; Ichikawa, Satoshi; Ohtani, Bunsho; Hirai, Takayuki

    2017-06-22

    Visible light absorption of plasmonic Au nanoparticles supported on semiconductor TiO2 leads to injection of their photoactivated "hot electrons (ehot-)" into the TiO2 conduction band. This charge separation facilitates several oxidation and reduction reactions. These plasmonic systems, however, suffer from low quantum yields because the Schottky barrier created at the Au-TiO2 interface suppresses ehot- injection. Here we report that Au nanoparticles supported on the anatase particles isolated from Degussa (Evonik) P25 TiO2 promote ehot- injection with much higher efficiency than those supported on other commercially-available TiO2 and catalyze aerobic oxidation with very high quantum yield (7.7% at 550 nm). Photoelectrochemical and spectroscopic analysis revealed that the number of Ti4+ atoms located at the Au-TiO2 interface is the crucial factor. These Ti4+ atoms neutralize the negative charge of the Au particles and create a Schottky barrier with narrower depletion layer. This facilitates efficient ehot- injection by "quantum tunneling" through the Schottky barrier without overbarrier energy. The ehot- injection depends on several factors, and loading of 2 wt% Au particles with 3.5-4 nm diameters at around room temperature exhibits the highest activity of plasmonic photocatalysis.

  3. Hydrogeochemical processes and isotopes analysis. Study case: "La Línea Tunnel", Colombia

    Science.gov (United States)

    Piña, Adriana; Donado, Leonardo; Cramer, Thomas

    2017-04-01

    Hydrogeochemical and stable isotopes analyses have been widely used to identify recharge and discharge zones, flowpaths, type, origin and age of water, chemical processes between minerals and groundwater as well as effects caused by anthropogenic or natural pollution. In this paper we analyze the interactions between groundwater and surface water using as laboratory the tunnels located at the La Línea Massif in the Cordillera Central of the Colombian Andes. The massif is formed by two igneous-metamorphic fractured complexes (Cajamarca and Quebradagrande group) plus andesithic porphyry rocks from the tertiary period. There, eight main fault zones related to surface creeks were identified and main inflows inside the tunnels were reported. 60 water samples were collected in surface and inside the tunnel in fault zones in two different years, 2010 and 2015. To classify water samples, a multivariate statistical analysis combining Factor Analysis (FA) with Hierarchical Cluster Analysis (HCA) was performed. Then, analyses of the major chemical elements and water isotopes (18O, 2H and 3H) were used to define the origin of dissolved components and to analyse the evolution in time. Most samples were classified as bicarbonate calcite water or bicarbonate magnesium water type. Isotopic analyses show a characteristic behavior for east and west watershed and each geologic group. According to the FA and HCA, obtained factors and clusters are first related to the location of the samples (surface or tunnel samples) followed by the geology. Surface samples behave according to the Colombian meteoric line as inflows related to permeable faults while less permeable faults show hydrothermal processes. Finally, water evolution in time shows a decrease of pH, conductivity and Mg2+ related to silicate weathering or precipitation/dissolution processes that affect the spacing in fractures and consequently, the hydraulic properties.

  4. Liquid-induced damping of mechanical feedback effects in single electron tunneling through a suspended carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, D. R.; Stiller, P. L.; Strunk, Ch.; Hüttel, A. K., E-mail: andreas.huettel@ur.de [Institute for Experimental and Applied Physics, University of Regensburg, Universitätsstr. 31, 93053 Regensburg (Germany)

    2015-09-21

    In single electron tunneling through clean, suspended carbon nanotube devices at low temperature, distinct switching phenomena have regularly been observed. These can be explained via strong interaction of single electron tunneling and vibrational motion of the nanotube. We present measurements on a highly stable nanotube device, subsequently recorded in the vacuum chamber of a dilution refrigerator and immersed in the {sup 3}He/ {sup 4}He mixture of a second dilution refrigerator. The switching phenomena are absent when the sample is kept in the viscous liquid, additionally supporting the interpretation of dc-driven vibration. Transport measurements in liquid helium can thus be used for finite bias spectroscopy where otherwise the mechanical effects would dominate the current.

  5. Electronic “Edge” State on Molybdenite Basal Plane Observed by Ultrahigh-Vacuum Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Komiyama, Masaharu; Tomita, Hiroyuki; Yoda, Eisuke

    2007-09-01

    An electronic state heretofore unreported has been found on a cleaved basal plane of a natural molybdenite (MoS2) single crystal by ultrahigh-vacuum scanning tunneling microscopy (UHV-STM), and examined in detail both by STM and scanning tunneling spectroscopy (STS). The new electronic state resides on the edge of the upper terrace of MoS2(0001), manifesting itself in the form of bright ridges with a width of ca. 4 nm along the step edges in negatively sample-biased STM images. This ridge structure is nonexistent in STM images taken with positive sample biases. STS showed that the local density of states (LDOS) on such ridge structures is much higher than that on the terraces in the range of 0.2-1.2 eV below the Fermi edge. The nature and origin of this high LDOS at the step edges are discussed.

  6. Final Scientific/Technical Report: Electronics for Large Superconducting Tunnel Junction Detector Arrays for Synchrotron Soft X-ray Research

    Energy Technology Data Exchange (ETDEWEB)

    Warburton, William K

    2009-03-06

    Superconducting tunnel junction (STJ) detectors offer a an approach to detecting soft x-rays with energy resolutions 4-5 times better and at rates 10 faster than traditions semiconductor detectors. To make such detectors feasible, however, then need to be deployed in large arrays of order 1000 detectors, which in turn implies that their processing electronics must be compact, fully computer controlled, and low cost per channel while still delivering ultra-low noise performance so as to not degrade the STJ's performance. We report on our progress in designing a compact, low cost preamplifier intended for this application. In particular, we were able to produce a prototype preamplifier of 2 sq-cm area and a parts cost of less than $30 that matched the energy resolution of the best conventional system to date and demonstrated its ability to acquire an STJ I-V curve under computer control, the critical step for determining and setting the detectors' operating points under software control.

  7. Atom Tunneling in the Hydroxylation Process of Taurine/α-Ketoglutarate Dioxygenase Identified by Quantum Mechanics/Molecular Mechanics Simulations.

    Science.gov (United States)

    Álvarez-Barcia, Sonia; Kästner, Johannes

    2017-06-01

    Taurine/α-ketoglutarate dioxygenase is one of the most studied α-ketoglutarate-dependent dioxygenases (αKGDs), involved in several biotechnological applications. We investigated the key step in the catalytic cycle of the αKGDs, the hydrogen transfer process, by a quantum mechanics/molecular mechanics approach (B3LYP/CHARMM22). Analysis of the charge and spin densities during the reaction demonstrates that a concerted mechanism takes place, where the H atom transfer happens simultaneously with the electron transfer from taurine to the Fe═O cofactor. We found the quantum tunneling of the hydrogen atom to increase the rate constant by a factor of 40 at 5 °C. As a consequence, a quite high kinetic isotope effect close to 60 is obtained, which is consistent with the experimental value.

  8. Infinite dwell time and group delay in resonant electron tunneling through double complex potential barrier

    Science.gov (United States)

    Opacak, Nikola; Milanović, Vitomir; Radovanović, Jelena

    2017-12-01

    Tunneling times in complex potentials are investigated. Analytical expressions for dwell time, self-interference time and group delay are obtained for the case of complex double delta potentials. It is shown that we can always find a set of parameters of the potential so that the tunneling times achieve very large values and even approach infinity for the case of resonance. The phenomenon of infinite tunneling times occurs for only one particular positive value of the imaginary part of the potential, if all other parameters are given.

  9. Is spin transport through molecules really occurring in organic spin valves? A combined magnetoresistance and inelastic electron tunnelling spectroscopy study

    Science.gov (United States)

    Galbiati, Marta; Tatay, Sergio; Delprat, Sophie; Khanh, Hung Le; Servet, Bernard; Deranlot, Cyrile; Collin, Sophie; Seneor, Pierre; Mattana, Richard; Petroff, Frédéric

    2015-02-01

    Molecular and organic spintronics is an emerging research field which combines the versatility of chemistry with the non-volatility of spintronics. Organic materials have already proved their potential as tunnel barriers (TBs) or spacers in spintronics devices showing sizable spin valve like magnetoresistance effects. In the last years, a large effort has been focused on the optimization of these organic spintronics devices. Insertion of a thin inorganic tunnel barrier (Al2O3 or MgO) at the bottom ferromagnetic metal (FM)/organic interface seems to improve the spin transport efficiency. However, during the top FM electrode deposition, metal atoms are prone to diffuse through the organic layer and potentially short-circuit it. This may lead to the formation of a working but undesired FM/TB/FM magnetic tunnel junction where the organic plays no role. Indeed, establishing a protocol to demonstrate the effective spin dependent transport through the organic layer remains a key issue. Here, we focus on Co/Al2O3/Alq3/Co junctions and show that combining magnetoresistance and inelastic electron tunnelling spectroscopy measurements one can sort out working "organic" and short-circuited junctions fabricated on the same wafer.

  10. Is spin transport through molecules really occurring in organic spin valves? A combined magnetoresistance and inelastic electron tunnelling spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Galbiati, Marta; Tatay, Sergio; Delprat, Sophie; Khanh, Hung Le; Deranlot, Cyrile; Collin, Sophie; Seneor, Pierre, E-mail: pierre.seneor@thalesgroup.com; Mattana, Richard, E-mail: richard.mattana@thalesgroup.com; Petroff, Frédéric [Unité Mixte de Physique CNRS/Thales, 1 Av. A. Fresnel, 91767 Palaiseau, France and Université Paris-Sud, 91405 Orsay (France); Servet, Bernard [Thales Research and Technology, 1 Av. A. Fresnel, 91767 Palaiseau (France)

    2015-02-23

    Molecular and organic spintronics is an emerging research field which combines the versatility of chemistry with the non-volatility of spintronics. Organic materials have already proved their potential as tunnel barriers (TBs) or spacers in spintronics devices showing sizable spin valve like magnetoresistance effects. In the last years, a large effort has been focused on the optimization of these organic spintronics devices. Insertion of a thin inorganic tunnel barrier (Al{sub 2}O{sub 3} or MgO) at the bottom ferromagnetic metal (FM)/organic interface seems to improve the spin transport efficiency. However, during the top FM electrode deposition, metal atoms are prone to diffuse through the organic layer and potentially short-circuit it. This may lead to the formation of a working but undesired FM/TB/FM magnetic tunnel junction where the organic plays no role. Indeed, establishing a protocol to demonstrate the effective spin dependent transport through the organic layer remains a key issue. Here, we focus on Co/Al{sub 2}O{sub 3}/Alq{sub 3}/Co junctions and show that combining magnetoresistance and inelastic electron tunnelling spectroscopy measurements one can sort out working “organic” and short-circuited junctions fabricated on the same wafer.

  11. Electron-induced processes in hydroxyl cations

    Science.gov (United States)

    Cristian Stroe, Marius; Fifirig, Magda

    2018-01-01

    Competing processes (namely, dissociative recombination, vibrational excitation and vibrational de-excitation) taking place in the collisions between slow electrons and hydroxyl cations have been investigated for electron energies below 1 eV in the framework of the multichannel quantum defect theory. Rydberg states converging to the lowest excited ionic core have been included in some computations reported here.

  12. Tunneling time, exit time and exit momentum in strong field tunnel ionization

    Energy Technology Data Exchange (ETDEWEB)

    Teeny, Nicolas

    2016-10-18

    Tunnel ionization belongs to the fundamental processes of atomic physics. It is still an open question when does the electron tunnel ionize and how long is the duration of tunneling. In this work we solve the time-dependent Schroedinger equation in one and two dimensions and use ab initio quantum calculations in order to answer these questions. Additionally, we determine the exit momentum of the tunnel ionized electron from first principles. We find out results that are different from the assumptions of the commonly employed two-step model, which assumes that the electron ionizes at the instant of electric field maximum with a zero momentum. After determining the quantum final momentum distribution of tunnel ionized electrons we show that the two-step model fails to predict the correct final momentum. Accordingly we suggest how to correct the two-step model. Furthermore, we determine the instant at which tunnel ionization starts, which turns out to be different from the instant usually assumed. From determining the instant at which it is most probable for the electron to enter the tunneling barrier and the instant at which it exits we determine the most probable time spent under the barrier. Moreover, we apply a quantum clock approach in order to determine the duration of tunnel ionization. From the quantum clock we determine an average tunneling time which is different in magnitude and origin with respect to the most probable tunneling time. By defining a probability distribution of tunneling times using virtual detectors we relate both methods and explain the apparent discrepancy. The results found have in general an effect on the interpretation of experiments that measure the spectra of tunnel ionized electrons, and specifically on the calibration of the so called attoclock experiments, because models with imprecise assumptions are usually employed in order to interpret experimental results.

  13. Extracellular Electron Transport Coupling Biogeochemical Processes Centimeters

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Fossing, Henrik; Christensen, Peter Bondo

    2010-01-01

    Recent observations in marine sediment have revealed  conductive networks transmitting electrons from oxidation processes in the anoxic zone to oxygen reduction in the oxiczone [1]. The electrochemical processes and conductors seem to be biologically controlled and may account for more than half...... of the oxygen uptake in laboratory incubations of initially homogenized and stabilized sediment. Using microsensors and process rate measurements we further investigated the effect of the electric currents on sediment biogeochemistry. Dissolved sulfide readily donated electrons to the networks and could...... confirmed the depth range of the electric communication and indicated donation of electrons directly from organotrophic bacteria. The separation of oxidation and reduction processes created steep pH gradients eventually causing carbonate precipitation at the surface. The results indicate that electron...

  14. Single-molecule electron tunnelling through multiple redox levels with environmental relaxation

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2004-01-01

    We present an analytical theory for electron flow through a molecule with several redox levels, enclosed between a pair of metallic electrodes. The levels can be electronic or electronic-vibrational levels. Vibrational energy spacing characterises the latter sets. The levels are further coupled...... relations at fixed electrochemical overpotential or gate voltage, and current-overpotential or current-gate voltage relations at fixed bias voltage are equivalent in the two systems. Due to the activation-less nature of the processes, electron flow between the electrodes through the molecular redox levels...... can be only achieved when the latter are located between the Fermi levels of the substrate and tip or source and drain electrodes. The redox levels can be brought into this "energy window", either by the overpotential or bias and gate voltages, or by vibrational relaxation of (a) given (set of) redox...

  15. Ion beam processing of advanced electronic materials

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, N.W.; Marwick, A.D.; Roberto, J.B. (eds.) (California Univ., Berkeley, CA (USA); International Business Machines Corp., Yorktown Heights, NY (USA). Thomas J. Watson Research Center; Oak Ridge National Lab., TN (USA))

    1989-01-01

    This report contains research programs discussed at the materials research society symposia on ion beam processing of advanced electronic materials. Major topics include: shallow implantation and solid-phase epitaxy; damage effects; focused ion beams; MeV implantation; high-dose implantation; implantation in III-V materials and multilayers; and implantation in electronic materials. Individual projects are processed separately for the data bases. (CBS)

  16. Improvement Of Search Process In Electronic Catalogues

    Directory of Open Access Journals (Sweden)

    Titas Savickas

    2014-05-01

    Full Text Available The paper presents investigation on search in electronic catalogues. The chosen problem domain is the search system in the electronic catalogue of Lithuanian Academic Libraries. The catalogue uses ALEPH system with MARC21 bibliographic format. The article presents analysis of problems pertaining to the current search engine and user expectations related to the search system of the electronic catalogue of academic libraries. Subsequent to analysis, the research paper presents the architecture for a semantic search system in the electronic catalogue that uses search process designed to improve search results for users.

  17. Survey on electron beam processing technologies

    Science.gov (United States)

    Yasui, S.; Sunabe, K.; Inaba, T.

    1990-06-01

    The developing situation is studied of electron beam processing technologies and the future problems are shown when these are utilized for electric power utilities. When an electron beam is used as a heating source by focussing, the electron beam has features of high focusability, high controllability and high energy density, so that the electron beam is used for parts requiring high quality processing from micro machining, case hardening, and welding to melting furnaces of metals of high melting point. Presently is necessary to hold ultra high voltage for acceleration and high vacuum because of lower current. Since the processing capability with high energy density is high and the energy consumption efficiency is also high for the chemical field using the high energy density of the electron beam, the application are researched in the field from sterilization of medical instruments, sterilization of sludge, through food processing, improvement of thermal resistance of insulated wires to flue gas irradiation to desulfurize and denitrify. But a practical use is not yet realized because of small current of electron beam. Therefore, the largest technological problem may be the development of high current electron gun and the beam control systems.

  18. Infrared catastrophe and tunneling into strongly correlated electron systems: Exact x-ray edge limit for the one-dimensional electron gas and two-dimensional Hall fluid

    Science.gov (United States)

    Patton, Kelly R.; Geller, Michael R.

    2006-06-01

    In previous work [K. R. Patton and M. R. Geller, Phys. Rev. B 72, 125108 (2005)] we have proposed that the non-Fermi-liquid spectral properties in a variety of low-dimensional and strongly correlated electron systems are caused by the infrared catastrophe, and we used an exact functional integral representation for the interacting Green’s function to map the tunneling problem onto the x-ray edge problem, plus corrections. The corrections are caused by the recoil of the tunneling particle, and, in systems where the method is applicable, are not expected to change the qualitative form of the tunneling density of states (DOS). Qualitatively correct results were obtained for the DOS of the one-dimensional electron gas and two-dimensional Hall fluid when the corrections to the x-ray edge limit were neglected and when the corresponding Nozières-De Dominicis integral equations were solved by resummation of a divergent perturbation series. Here we reexamine the x-ray edge limit for these two models by solving these integral equations exactly, finding the expected modifications of the DOS exponent in the one-dimensional case but finding no changes in the DOS of the two-dimensional Hall fluid with short-range interaction. Our analysis provides an exact solution of the Nozières-De Dominicis equation for the two-dimensional electron gas in the lowest Landau level.

  19. Electronic devices for analog signal processing

    CERN Document Server

    Rybin, Yu K

    2012-01-01

    Electronic Devices for Analog Signal Processing is intended for engineers and post graduates and considers electronic devices applied to process analog signals in instrument making, automation, measurements, and other branches of technology. They perform various transformations of electrical signals: scaling, integration, logarithming, etc. The need in their deeper study is caused, on the one hand, by the extension of the forms of the input signal and increasing accuracy and performance of such devices, and on the other hand, new devices constantly emerge and are already widely used in practice, but no information about them are written in books on electronics. The basic approach of presenting the material in Electronic Devices for Analog Signal Processing can be formulated as follows: the study with help from self-education. While divided into seven chapters, each chapter contains theoretical material, examples of practical problems, questions and tests. The most difficult questions are marked by a diamon...

  20. The effect of interface phonons on operating electron states in three-barrier resonant tunneling structure as an active region of quantum cascade detector

    Directory of Open Access Journals (Sweden)

    M.V. Tkach

    2014-06-01

    Full Text Available The Hamiltonian of electrons interacting with interface phonons in three-barrier resonant tunneling structure is established using the first principles within the models of effective mass and polarization continuum. Using the Green's functions method, the temperature shifts and decay rates of operating electron states are calculated depending on geometric design of three-barrier nano-structure GaAs/AlxGa1-xAs which is an active region of quantum cascade detector. It is established that independently of the temperature, the energy of quantum transition during the process of electromagnetic field absorption is a nonlinear weakly varying function of the position of the inner barrier with respect to the outer barriers of the structure.

  1. Simulation and analysis of natural rain in a wind tunnel via digital image processing techniques

    Science.gov (United States)

    Aaron, K. M.; Hernan, M.; Parikh, P.; Sarohia, V.; Gharib, M.

    1986-01-01

    It is desired to simulate natural rain in a wind tunnel in order to investigate its influence on the aerodynamic characteristics of aircraft. Rain simulation nozzles have been developed and tested at JPL. Pulsed laser sheet illumination is used to photograph the droplets in the moving airstream. Digital image processing techniques are applied to these photographs for calculation of rain statistics to evaluate the performance of the nozzles. It is found that fixed hypodermic type nozzles inject too much water to simulate natural rain conditions. A modification uses two aerodynamic spinners to flex a tube in a pseudo-random fashion to distribute the water over a larger area.

  2. Process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction

    Science.gov (United States)

    Toet, Daniel; Sigmon, Thomas W.

    2003-01-01

    A process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction for use in advanced magnetic random access memory (MRAM) cells for high performance, non-volatile memory arrays. The process is based on pulsed laser processing for the fabrication of vertical polycrystalline silicon electronic device structures, in particular p-n junction diodes, on films of metals deposited onto low temperature-substrates such as ceramics, dielectrics, glass, or polymers. The process preserves underlayers and structures onto which the devices are typically deposited, such as silicon integrated circuits. The process involves the low temperature deposition of at least one layer of silicon, either in an amorphous or a polycrystalline phase on a metal layer. Dopants may be introduced in the silicon film during or after deposition. The film is then irradiated with short pulse laser energy that is efficiently absorbed in the silicon, which results in the crystallization of the film and simultaneously in the activation of the dopants via ultrafast melting and solidification. The silicon film can be patterned either before or after crystallization.

  3. Double deuterated acetylacetone in neon matrices: infrared spectroscopy, photoreactivity and the tunneling process.

    Science.gov (United States)

    Gutiérrez-Quintanilla, Alejandro; Chevalier, Michèle; Crépin, Claudine

    2016-07-27

    The effect of deuteration of acetylacetone (C5O2H8) is explored by means of IR spectroscopy of its single and double deuterated isotopologues trapped in neon matrices. The whole vibrational spectra of chelated enols are very sensitive to the H-D exchange of the hydrogen atom involved in the internal hydrogen bond. UV excitation of double deuterated acetylacetone isolated in neon matrices induces the formation of four open enol isomers which can be divided into two groups of two conformers, depending on their formation kinetics. Within each group, one conformer is more stable than the other: slow conformer interconversion due to a tunneling process is observed in the dark at low temperature. Moreover, IR laser irradiation at the OD stretching overtone frequency is used to induce interconversion either from the most stable to the less stable conformer or the opposite, depending on the excitation wavelength. The interconversion process is of great help to assign conformers which are definitively identified by comparison between experimental and calculated IR spectra. Kinetic constants of the tunneling process at play are theoretically estimated and agree perfectly with experiments, including previous experiments with the totally hydrogenated acetylacetone [Lozada García et al., Phys. Chem. Chem. Phys., 2012, 14, 3450].

  4. Experimental evidence for Wigner's tunneling time

    CERN Document Server

    Camus, Nicolas; Fechner, Lutz; Klaiber, Michael; Laux, Martin; Mi, Yonghao; Hatsagortsyan, Karen Z; Pfeifer, Thomas; Keitel, Christoph H; Moshammer, Robert

    2016-01-01

    Tunneling of a particle through a potential barrier remains one of the most remarkable quantum phenomena. Owing to advances in laser technology, electric fields comparable to those electrons experience in atoms are readily generated and open opportunities to dynamically investigate the process of electron tunneling through the potential barrier formed by the superposition of both laser and atomic fields. Attosecond-time and angstrom-space resolution of the strong laser-field technique allow to address fundamental questions related to tunneling, which are still open and debated: Which time is spent under the barrier and what momentum is picked up by the particle in the meantime? In this combined experimental and theoretical study we demonstrate that for strong-field ionization the leading quantum mechanical Wigner treatment for the time resolved description of tunneling is valid. We achieve a high sensitivity on the tunneling barrier and unambiguously isolate its effects by performing a differential study of t...

  5. Process variation in electron beam sterilization

    Science.gov (United States)

    Beck, Jeffrey A.

    2012-08-01

    The qualification and control of electron beam sterilization can be improved by the application of proven statistical analysis techniques such as Analysis of Variance (ANOVA) and Statistical Tolerance Limits. These statistical techniques can be useful tools in: Locating and quantifying the minimum and maximum absorbed dose in a product. Estimating the expected process maximum dose, given a minimum sterilizing dose. Setting a process minimum dose target, based on an allowance for random measurement and process variation. Determining the dose relationship between a reference dosimeter and process minimum and maximum doses. This study investigates and demonstrates the application of these tools in qualifying electron beam sterilization, and compares the conclusions obtained with those obtained using practices recommended in Association for the Advancement of Medical Instrumentation (AAMI) TIR 29 (2002) Guide for Process Control in Radiation Sterilization. The study supports the following conclusions for electron beam processes: ANOVA is a more effective tool for evaluating the equivalency of absorbed doses than methods suggested in AAMI TIR29 (2002). Process limits computed using statistical tolerance limits more accurately reflect actual process variability than the AAMI method, which applies +/-2 sample standard deviations (s) regardless of sample size. The use of reference dose ratios lends itself to qualification using statistical tolerance limits. The current AAMI recommended approach may result in an overly optimistic estimate of the reference dose adjustment factor, as it is based on application of +/-2(s) tolerances regardless of sample size.

  6. Quantum dots and tunnel barriers in InAs/InP nanowire heterostructures: Electronic and optical properties

    Science.gov (United States)

    Niquet, Yann-Michel; Mojica, Dulce Camacho

    2008-03-01

    We compute the structural and electronic properties of ⟨111⟩-oriented InAs/InP nanowire heterostructures using Keating’s valence force field and a tight-binding model. We focus on the optical properties (exciton energies and polarization) of InAs quantum dots embedded in InP nanowires and on the height of InP and InAsP tunnel barriers embedded in InAs nanowires. We show that InAs quantum dots exhibit bright optical transitions, at variance with the highly mismatched InAs/GaAs nanowire heterostructures. The polarization of the photons is perpendicular to the nanowire for thin InAs layers but rotates parallel to the nanowire for thick enough ones, as a result of the increasing light-hole character of the exciton. As for tunnel barriers, we show that the residual strains can significantly reduce the conduction band discontinuity in thin InAsP layers. This must be taken into account in the design of nanowire tunneling devices.

  7. Hard rock tunnel boring machine penetration test as an indicator of chipping process efficiency

    Directory of Open Access Journals (Sweden)

    M.C. Villeneuve

    2017-08-01

    Full Text Available The transition from grinding to chipping can be observed in tunnel boring machine (TBM penetration test data by plotting the penetration rate (distance/revolution against the net cutter thrust (force per cutter over the full range of penetration rates in the test. Correlating penetration test data to the geological and geomechanical characteristics of rock masses through which a penetration test is conducted provides the ability to reveal the efficiency of the chipping process in response to changing geological conditions. Penetration test data can also be used to identify stress-induced tunnel face instability. This research shows that the strength of the rock is an important parameter for controlling how much net cutter thrust is required to transition from grinding to chipping. It also shows that the geological characteristics of a rock will determine how efficient chipping occurs once it has begun. In particular, geological characteristics that lead to efficient fracture propagation, such as fabric and mica contents, will lead to efficient chipping. These findings will enable a better correlation between TBM performance and geological conditions for use in TBM design, as a basis for contractual payments where penetration rate dominates the excavation cycle and in further academic investigations into the TBM excavation process.

  8. Conceptual Design of a 50--100 MW Electron Beam Accelerator System for the National Hypersonic Wind Tunnel Program

    Energy Technology Data Exchange (ETDEWEB)

    SCHNEIDER,LARRY X.

    2000-06-01

    The National Hypersonic Wind Tunnel program requires an unprecedented electron beam source capable of 1--2 MeV at a beam power level of 50--100 MW. Direct-current electron accelerator technology can readily generate high average power beams to approximately 5 MeV at output efficiencies greater than 90%. However, due to the nature of research and industrial applications, there has never been a requirement for a single module with an output power exceeding approximately 500 kW. Although a 50--100 MW module is a two-order extrapolation from demonstrated power levels, the scaling of accelerator components appears reasonable. This paper presents an evaluation of component and system issues involved in the design of a 50--100 MW electron beam accelerator system with precision beam transport into a high pressure flowing air environment.

  9. APPLICATIONS OF LASERS AND OTHER TOPICS IN LASER PHYSICS AND TECHNOLOGY: Emission of surface electromagnetic waves in the case of resonance tunneling of electrons

    Science.gov (United States)

    Belenov, É. M.; Luskinovich, P. N.; Romanenko, V. I.; Sobolev, A. G.; Uskov, A. V.

    1987-10-01

    A calculation is made of the spectral density of the intensity of surface electromagnetic waves excited by the passage of a current across metal-barrier-metal tunnel structures when there are quantum potential wells inside the barrier. It is shown that quasilevels in these quantum wells give rise to narrow peaks in the spectrum of the excited surface electromagnetic waves and that the quantum efficiency of the excitation of such waves by tunneling electrons can reach unity. The peak positions can be controlled by altering the voltage across a tunnel structure.

  10. Electron beam flue gas treatment process. Review

    Energy Technology Data Exchange (ETDEWEB)

    Honkonen, V.A. [Kuopio Univ. (Finland). Dept. of Physics; Chmielewski, A.G. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

    1996-12-31

    The basis of the process for electron beam flue gas treatment are presented in the report. In tabular form the history of the research is reviewed. Main dependences of SO{sub 2} and NO{sub x} removal efficiencies on different physico-chemical parameters are discussed. Trends concerning industrial process implementation are presented in the paper,finally. (author). 74 refs, 11 figs, 1 tab.

  11. A 3-d laser scanning system and scan data processing method for the monitoring of tunnel deformations

    Science.gov (United States)

    Chmelina, Klaus; Jansa, Josef; Hesina, Gerd; Traxler, Christoph

    2012-11-01

    The paper presents the mobile multi-sensor system Orthos Plus for the monitoring and mapping of tunnel walls, a scan data processing method for the evaluation of 3-d tunnel wall displacements from subsequent wall scans and, finally, a virtual reality tool supporting the interpretation of data. The measuring system consists of a 3-d laser scanner, a motorised total station and a digital camera that are integrated on a light metal frame that is installed on a mobile platform. It has been designed to perform tunnel measurements most efficiently and to meet the special requirements of tunnels under construction. The evaluation of 3-d displacements is based on a 3-d matching algorithm that takes advantage of the particular conditions of tunnel (shotcrete) surfaces. The virtual reality tool allows viewing of data in a 3-d virtual reality tunnel model and their animation in time and space in order supports understanding in an optimal way. The measuring system Orthos Plus has been developed in the course of a national research project, the 3-d matching method in the frame of the Austrian Christian Doppler Laboratory Spatial Data from Laser Scanning and Remote Sensing and the VR tool in the Austrian COMET K1 Competence Center VRVis Center (www.vrvis.at).

  12. Cryogenic Quenching Process for Electronic Part Screening

    Science.gov (United States)

    Sheldon, Douglas J.; Cressler, John

    2011-01-01

    The use of electronic parts at cryogenic temperatures (less than 100 C) for extreme environments is not well controlled or developed from a product quality and reliability point of view. This is in contrast to the very rigorous and well-documented procedures to qualify electronic parts for mission use in the 55 to 125 C temperature range. A similarly rigorous methodology for screening and evaluating electronic parts needs to be developed so that mission planners can expect the same level of high reliability performance for parts operated at cryogenic temperatures. A formal methodology for screening and qualifying electronic parts at cryogenic temperatures has been proposed. The methodology focuses on the base physics of failure of the devices at cryogenic temperatures. All electronic part reliability is based on the bathtub curve, high amounts of initial failures (infant mortals), a long period of normal use (random failures), and then an increasing number of failures (end of life). Unique to this is the development of custom screening procedures to eliminate early failures at cold temperatures. The ability to screen out defects will specifically impact reliability at cold temperatures. Cryogenic reliability is limited by electron trap creation in the oxide and defect sites at conductor interfaces. Non-uniform conduction processes due to process marginalities will be magnified at cryogenic temperatures. Carrier mobilities change by orders of magnitude at cryogenic temperatures, significantly enhancing the effects of electric field. Marginal contacts, impurities in oxides, and defects in conductor/conductor interfaces can all be magnified at low temperatures. The novelty is the use of an ultra-low temperature, short-duration quenching process for defect screening. The quenching process is designed to identify those defects that will precisely (and negatively) affect long-term, cryogenic part operation. This quenching process occurs at a temperature that is at least

  13. Electronic band alignment and electron transport in Cr/BaTiO{sub 3}/Pt ferroelectric tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zenkevich, A. [NRNU ' Moscow Engineering Physics Institute,' 115409 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region (Russian Federation); Minnekaev, M.; Matveyev, Yu.; Lebedinskii, Yu. [NRNU ' Moscow Engineering Physics Institute,' 115409 Moscow (Russian Federation); Bulakh, K.; Chouprik, A.; Baturin, A. [Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region (Russian Federation); Maksimova, K. [Immanuel Kant Baltic Federal University, 236041 Kaliningrad (Russian Federation); Thiess, S.; Drube, W. [Deutsches Elektronen-Synchrotron DESY, D-22603 Hamburg (Germany)

    2013-02-11

    Electroresistance in ferroelectric tunnel junctions is controlled by changes in the electrostatic potential profile across the junction upon polarization reversal of the ultrathin ferroelectric barrier layer. Here, hard X-ray photoemission spectroscopy is used to reconstruct the electric potential barrier profile in as-grown Cr/BaTiO{sub 3}(001)/Pt(001) heterostructures. Transport properties of Cr/BaTiO{sub 3}/Pt junctions with a sub-{mu}m Cr top electrode are interpreted in terms of tunneling electroresistance with resistance changes of a factor of {approx}30 upon polarization reversal. By fitting the I-V characteristics with the model employing an experimentally determined electric potential barrier we derive the step height changes at the BaTiO{sub 3}/Pt (Cr/BaTiO{sub 3}) interface +0.42(-0.03) eV following downward to upward polarization reversal.

  14. Time Dependent Tunneling in Laser Irradiated Scanning Tunneling Microscope Junction

    Science.gov (United States)

    Park, Sookyung Hur

    A principal motivation for the studies reported in this thesis was to obtain a theoretical explanation for the experimental results obtained by Nguyen et al. (1989) to determine the traversal time of an electron tunneling through a quantum mechanical barrier in a laser irradiated STM junction. The work therefore focused on the calculation of tunneling in a time-dependent oscillating barrier, and more specifically on the inelastic contributions to the tunneling current. To do so the kinetic formalism for tunneling was modified and extended to calculate inelastic processes in an irradiated tunneling junction. Furthermore, there is significant absorption of power from the laser beam in the junction electrodes resulting in thermal effects which can influence the tunneling. Extensive analysis of the spatial and temporal temperature distributions was first done for a realistic model of the diode emitter and anode using the Green function method. Specifically we considered (i) thermal effects due to surface heating of the absorbed laser radiation, (ii) the thermoelectric emf produced in the junction due to differential heating, and (iii) resistive and Thomson heat produced in the junction by laser induced currents. Using first-order time-dependent perturbation theory we also (iv) calculated the inelastic tunneling current due to a time dependent oscillating barrier produced by the antenna geometry of the STM junction. Lastly, we (v) formulated photo-assisted tunneling due to the electron -photon interaction in the junction using the second-quantization formalism. Although quite significant results were obtained for the tunneling current density as a function of frequency, gap distance and other junction parameters which gave insights into important features of the Nguyen et al. experiment (and tunneling characteristics of an irradiated STM in general), no single expression was derived or calculated results obtained which explains or fits all their observed data, or

  15. Neural-Net Processing of Characteristic Patterns From Electronic Holograms of Vibrating Blades

    Science.gov (United States)

    Decker, Arthur J.

    1999-01-01

    Finite-element-model-trained artificial neural networks can be used to process efficiently the characteristic patterns or mode shapes from electronic holograms of vibrating blades. The models used for routine design may not yet be sufficiently accurate for this application. This document discusses the creation of characteristic patterns; compares model generated and experimental characteristic patterns; and discusses the neural networks that transform the characteristic patterns into strain or damage information. The current potential to adapt electronic holography to spin rigs, wind tunnels and engines provides an incentive to have accurate finite element models lor training neural networks.

  16. Quantum interference effect in electron tunneling through a quantum-dot-ring spin valve

    Directory of Open Access Journals (Sweden)

    Ma Jing-Min

    2011-01-01

    Full Text Available Abstract Spin-dependent transport through a quantum-dot (QD ring coupled to ferromagnetic leads with noncollinear magnetizations is studied theoretically. Tunneling current, current spin polarization and tunnel magnetoresistance (TMR as functions of the bias voltage and the direct coupling strength between the two leads are analyzed by the nonequilibrium Green's function technique. It is shown that the magnitudes of these quantities are sensitive to the relative angle between the leads' magnetic moments and the quantum interference effect originated from the inter-lead coupling. We pay particular attention on the Coulomb blockade regime and find the relative current magnitudes of different magnetization angles can be reversed by tuning the inter-lead coupling strength, resulting in sign change of the TMR. For large enough inter-lead coupling strength, the current spin polarizations for parallel and antiparallel magnetic configurations will approach to unit and zero, respectively. PACS numbers:

  17. Non-equilibrium quantum transport of spin-polarized electrons and back action on molecular magnet tunnel-junction

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    2016-11-01

    Full Text Available We investigate the non-equilibrium quantum transport through a single-molecule magnet embedded in a tunnel junction with ferromagnetic electrodes, which generate spin-polarized electrons. The lead magnetization direction is non-collinear with the uniaxial anisotropy easy-axis of molecule-magnet. Based on the Pauli rate-equation approach we demonstrate the magnetization reversion of molecule-magnet induced by the back action of spin-polarized current in the sequential tunnel regime. The asymptotic magnetization of molecular magnet and spin-polarization of transport current are obtained as functions of time by means of time-dependent solution of the rate equation. It is found that the antiparallel configuration of the ferromagnetic electrodes and molecular anisotropy easy-axis is an effective structure to reverse both the magnetization of molecule-magnet and spin-polarization of the transport current. Particularly the non-collinear angle dependence provides useful knowledge for the quantum manipulation of molecule-magnet and spin polarized electron-transport.

  18. Non-equilibrium quantum transport of spin-polarized electrons and back action on molecular magnet tunnel-junction

    Science.gov (United States)

    Zhang, Chao; Yao, Hui; Nie, Yi-Hang; Liang, J.-Q.

    2016-11-01

    We investigate the non-equilibrium quantum transport through a single-molecule magnet embedded in a tunnel junction with ferromagnetic electrodes, which generate spin-polarized electrons. The lead magnetization direction is non-collinear with the uniaxial anisotropy easy-axis of molecule-magnet. Based on the Pauli rate-equation approach we demonstrate the magnetization reversion of molecule-magnet induced by the back action of spin-polarized current in the sequential tunnel regime. The asymptotic magnetization of molecular magnet and spin-polarization of transport current are obtained as functions of time by means of time-dependent solution of the rate equation. It is found that the antiparallel configuration of the ferromagnetic electrodes and molecular anisotropy easy-axis is an effective structure to reverse both the magnetization of molecule-magnet and spin-polarization of the transport current. Particularly the non-collinear angle dependence provides useful knowledge for the quantum manipulation of molecule-magnet and spin polarized electron-transport.

  19. Antireflection coating of barriers to enhance electron tunnelling: exploring the matter wave analogy of superluminal optical phase velocity.

    Science.gov (United States)

    Zhao, Zijun C; McKenzie, David R

    2017-10-06

    The tunnelling of electrons through barriers is important in field emission sources and in interconnects within electronic devices. Here we use the analogy between the electromagnetic wave equation and the Schrodinger equation to find potential barriers that, when added before an existing barrier, increase the transmission probability. A single pre-barrier of negative potential behaves as a dielectric "antireflection coating", as previously reported. However, we obtain an unexpected and much greater enhancement of transmission when the pre-barrier has a positive potential of height smaller than the energy of the incident electron, an unfamiliar optical case, corresponding to media with superluminal phase velocities as in dilute free electron media and anomalous dispersion at X-ray frequencies. We use a finite difference time domain algorithm to evaluate the transmission through a triangular field emission barrier with a pre-barrier that meets the new condition. We show that the transmission is enhanced for an incident wavepacket, producing a larger field emission current than for an uncoated barrier. Examples are given of available materials to enhance transmission in practical applications. The results are significant for showing how to increase electron transmission in field emission and at interconnects between dissimilar materials in all types of electronic devices.

  20. Equipment concept design and development plans for microgravity science and applications research on space station: Combustion tunnel, laser diagnostic system, advanced modular furnace, integrated electronics laboratory

    Science.gov (United States)

    Uhran, M. L.; Youngblood, W. W.; Georgekutty, T.; Fiske, M. R.; Wear, W. O.

    1986-01-01

    Taking advantage of the microgravity environment of space NASA has initiated the preliminary design of a permanently manned space station that will support technological advances in process science and stimulate the development of new and improved materials having applications across the commercial spectrum. Previous studies have been performed to define from the researcher's perspective, the requirements for laboratory equipment to accommodate microgravity experiments on the space station. Functional requirements for the identified experimental apparatus and support equipment were determined. From these hardware requirements, several items were selected for concept designs and subsequent formulation of development plans. This report documents the concept designs and development plans for two items of experiment apparatus - the Combustion Tunnel and the Advanced Modular Furnace, and two items of support equipment the Laser Diagnostic System and the Integrated Electronics Laboratory. For each concept design, key technology developments were identified that are required to enable or enhance the development of the respective hardware.

  1. Proton tunneling in solids

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, J.

    1998-10-01

    The tunneling rate of the proton and its isotopes between interstitial sites in solids is studied theoretically. The phonons and/or the electrons in the solid have two effects on the tunneling phenomenon. First, they suppress the transfer integral between two neighbouring states. Second, they give rise to a finite lifetime of the proton state. Usually the second effect is large and the tunneling probability per unit time (tunneling rate) can be defined. In some cases, however, a coherent tunneling is expected and actually observed. (author)

  2. Statistical process control for electron beam monitoring.

    Science.gov (United States)

    López-Tarjuelo, Juan; Luquero-Llopis, Naika; García-Mollá, Rafael; Quirós-Higueras, Juan David; Bouché-Babiloni, Ana; Juan-Senabre, Xavier Jordi; de Marco-Blancas, Noelia; Ferrer-Albiach, Carlos; Santos-Serra, Agustín

    2015-07-01

    To assess the electron beam monitoring statistical process control (SPC) in linear accelerator (linac) daily quality control. We present a long-term record of our measurements and evaluate which SPC-led conditions are feasible for maintaining control. We retrieved our linac beam calibration, symmetry, and flatness daily records for all electron beam energies from January 2008 to December 2013, and retrospectively studied how SPC could have been applied and which of its features could be used in the future. A set of adjustment interventions designed to maintain these parameters under control was also simulated. All phase I data was under control. The dose plots were characterized by rising trends followed by steep drops caused by our attempts to re-center the linac beam calibration. Where flatness and symmetry trends were detected they were less-well defined. The process capability ratios ranged from 1.6 to 9.3 at a 2% specification level. Simulated interventions ranged from 2% to 34% of the total number of measurement sessions. We also noted that if prospective SPC had been applied it would have met quality control specifications. SPC can be used to assess the inherent variability of our electron beam monitoring system. It can also indicate whether a process is capable of maintaining electron parameters under control with respect to established specifications by using a daily checking device, but this is not practical unless a method to establish direct feedback from the device to the linac can be devised. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  3. Electron processing at low energies: from basics to environmental and biological applications.

    Science.gov (United States)

    Illenberger, Eugen

    2006-10-01

    Electron initiated reactions play a key role in nearly any field of pure and applied sciences, in the gas phase as well as in condensed phases or at interfaces. This include substrate induced photochemistry, radiation damage of biological material (and, accordingly, the molecular mechanisms, how radio sensitizers used in tumour therapy operate), reactions induced by electrons in surface tunnelling microscopy (STM), or any kind of plasma used in industrial plasma processing. In each of these fields the electron-molecule interaction represents a key step within an eventually complex reaction sequence. A particularly interesting field is the interaction of electrons with molecules at energies below the level of electronic excitation. In this range many molecules exhibit large cross sections for resonant electron capture, often followed by the decomposition of the transient negative compound (M^-# ) according to e^- + M --> M^-# --> R + X^-.^ We report on such dissociative electron attachment (DEA) processes studied at different stages of aggregation, namely in single molecules under collision free conditions, in clusters formed by supersonic gas expansion, and on the surface of solids or in molecular nanofilms. In the meantime it has also been recognised that in the damage of living cells by high energy radiation the attachment of low energy secondary electrons to DNA is a key initial process leading to strand breaks. These secondary electrons are created along the ionisation track of the primary high-energy quantum. Apart from that, bio-molecular systems exhibit unique features in DEA, like bond and site selective decompositions.

  4. Strong overtones modes in inelastic electron tunneling spectroscopy with cross-conjugated molecules: a prediction from theory.

    Science.gov (United States)

    Lykkebo, Jacob; Gagliardi, Alessio; Pecchia, Alessandro; Solomon, Gemma C

    2013-10-22

    Cross-conjugated molecules are known to exhibit destructive quantum interference, a property that has recently received considerable attention in single-molecule electronics. Destructive quantum interference can be understood as an antiresonance in the elastic transmission near the Fermi energy and leading to suppressed levels of elastic current. In most theoretical studies, only the elastic contributions to the current are taken into account. In this paper, we study the inelastic contributions to the current in cross-conjugated molecules and find that while the inelastic contribution to the current is larger than for molecules without interference, the overall behavior of the molecule is still dominated by the quantum interference feature. Second, an ongoing challenge for single molecule electronics is understanding and controlling the local geometry at the molecule-surface interface. With this in mind, we investigate a spectroscopic method capable of providing insight into these junctions for cross-conjugated molecules: inelastic electron tunneling spectroscopy (IETS). IETS has the advantage that the molecule interface is probed directly by the tunneling current. Previously, it has been thought that overtones are not observable in IETS. Here, overtones are predicted to be strong and, in some cases, the dominant spectroscopic features. We study the origin of the overtones and find that the interference features in these molecules are the key ingredient. The interference feature is a property of the transmission channels of the π system only, and consequently, in the vicinity of the interference feature, the transmission channels of the σ system and the π system become equally transmissive. This allows for scattering between the different transmission channels, which serves as a pathway to bypass the interference feature. A simple model calculation is able to reproduce the results obtained from atomistic calculations, and we use this to interpret these findings.

  5. Zurek–Kibble Symmetry Breaking Process in Superconducting Rings; Spontaneous Fluxon Formation in Annular Josephson Tunnel Junctions

    DEFF Research Database (Denmark)

    Aarøe, Morten; Monaco, Roberto; Dmitriev, P

    2007-01-01

    We report on new investigations of spontaneous symmetry breaking in non-adiabatic phase transitions. This Zurek-Kibble (ZK) process is mimicked in solid state systems by trapping of magnetic flux quanta, fluxons, in a long annular Josephson tunnel junction quenched through the normal...

  6. Bilateral widespread mechanical pain sensitivity in carpal tunnel syndrome: evidence of central processing in unilateral neuropathy.

    Science.gov (United States)

    Fernández-de-las-Peñas, César; de la Llave-Rincón, Ana Isabel; Fernández-Carnero, Josué; Cuadrado, María Luz; Arendt-Nielsen, Lars; Pareja, Juan A

    2009-06-01

    The aim of this study was to investigate whether bilateral widespread pressure hypersensitivity exists in patients with unilateral carpal tunnel syndrome. A total of 20 females with carpal tunnel syndrome (aged 22-60 years), and 20 healthy matched females (aged 21-60 years old) were recruited. Pressure pain thresholds were assessed bilaterally over median, ulnar, and radial nerve trunks, the C5-C6 zygapophyseal joint, the carpal tunnel and the tibialis anterior muscle in a blinded design. The results showed that pressure pain threshold levels were significantly decreased bilaterally over the median, ulnar, and radial nerve trunks, the carpal tunnel, the C5-C6 zygapophyseal joint, and the tibialis anterior muscle in patients with unilateral carpal tunnel syndrome as compared to healthy controls (all, P < 0.001). Pressure pain threshold was negatively correlated to both hand pain intensity and duration of symptoms (all, P < 0.001). Our findings revealed bilateral widespread pressure hypersensitivity in subjects with carpal tunnel syndrome, which suggest that widespread central sensitization is involved in patients with unilateral carpal tunnel syndrome. The generalized decrease in pressure pain thresholds associated with pain intensity and duration of symptoms supports a role of the peripheral drive to initiate and maintain central sensitization. Nevertheless, both central and peripheral sensitization mechanisms are probably involved at the same time in carpal tunnel syndrome.

  7. Cobalt Chemical Vapor Deposition Process on Molybdenite Basal Plane Observed by Ultrahigh-Vacuum Scanning Tunneling Microscopy

    Science.gov (United States)

    Komiyama, Masaharu; Kiyohara, Kohei; Yoda, Eisuke; Kubota, Takeshi; Okamoto, Yasuaki

    2005-07-01

    The processes of high-temperature (473 K) resulfidation and cobalt carbonyl adsorption by chemical vapor deposition (CVD) on a cleaved basal plane of a natural molybdenite (MoS2) single crystal were examined by ultrahigh-vacuum scanning tunneling microscopy (UHV-STM) on the nanometer scale. The resulfided cleaved molybdenite basal plane showed a displacement of upper terraces, and a sinusoidal structure at step edges, both of which may be caused by the electronic effect at the surface. Cobalt carbonyl appeared to be adsorbed at both the S- and Mo-terminated edges, resulting in an agglomeration at the step edges on lower terraces with a width of a few tens of nanometers. When this surface with adsorbed carbonyl was sulfided at 513 K for 1 h, most of the adsorbed carbonyl clusters appeared to be desorbed while a small part were dispersed on the terraces in small clusters of 10-20 nm in size. The obtained results are discussed in terms of the preparation of Co-Mo hydrodesulfurization (HDS) catalysts.

  8. Electron tunneling through molecule-electrode contacts of single alkane molecular junctions: experimental determination and a practical barrier model.

    Science.gov (United States)

    Wang, Kun; Xu, Bingqian

    2016-04-14

    An advanced understanding of the molecule-electrode contact interfaces of single-molecule junctions is a necessity for real world application of future single-molecule devices. This study aims to elucidate the change in the contact tunnelling barrier induced by junction extension and how this change affects the resulting junction conductance. The contact barrier of Au-octanedithiol/octanediamine-Au junctions was studied under triangle (TRI) mechanical modulations using the modified scanning tunneling microscopy (STM) break junction technique. The experimental results reveal that as the junction separation extends, the contact barrier of octanedithiol follows a unique trend, a linear increase followed by a plateau in barrier height, which is in contrast to that of octanediamine, a nearly rectangle barrier. We propose a modified contact barrier model for the unique barrier shape of octanedithiol, based on which the calculation agrees well with the experimental data. This study shows unprecedented experimental features of the molecule-electrode contact barrier of single-molecule junctions and provides new insights into the nature of contact effect in determining electron transport through single-molecule junctions.

  9. Spatially resolved electron tunneling spectroscopy on single crystalline Rb{sub 3}C{sub 60}

    Energy Technology Data Exchange (ETDEWEB)

    Jess, P.; Hubler, U. [Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Behler, S. [Lawrence Berkeley Laboratory, University of California--Berkeley, Berkeley, California 94720 (United States); Thommen-Geiser, V.; Lang, H.P.; Guentherodt, H. [Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)

    1996-03-01

    A Rb{sub 3}C{sub 60} single crystal ({ital T}{sub {ital c}}=30.5 K) is investigated in the superconducting state at 2.8 K by scanning tunneling microscopy and scanning tunneling spectroscopy (STS). STS data reveals a spatial variation of the superconducting energy gap {Delta} on a scale of 50 nm ({Delta}=2.6{endash}5.2 meV; 2{Delta}/{ital k}{sub {ital BT}}{sub {ital c}}=2.0{endash}4.0). This behavior is attributed to varying stoichiometry on the sample surface. An investigation of a Rb{sub 3}C{sub 60} facet shows that {ital I}({ital V}) characteristics even vary on molecular scale. {ital I}({ital V}) curves acquired between fullerene molecules exhibit a nonvanishing slope at zero bias whereas {ital I}({ital V}) characteristics measured above molecules exhibit vanishing slope at zero bias. {copyright} {ital 1996 American Vacuum Society}

  10. System of video observation for electron beam welding process

    Science.gov (United States)

    Laptenok, V. D.; Seregin, Y. N.; Bocharov, A. N.; Murygin, A. V.; Tynchenko, V. S.

    2016-04-01

    Equipment of video observation system for electron beam welding process was developed. Construction of video observation system allows to reduce negative effects on video camera during the process of electron beam welding and get qualitative images of this process.

  11. Hot-Electron Tunneling sensors for high-resolution x-ray and gamma-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mears, C.A.; Labov, S.E.; Frank, M.; Netel, H.

    1997-02-07

    Over the past 2 years, we have been studying the use of Hot Electron Tunneling sensors for use in high-energy-resolution x-ray and gamma-ray spectrometers. These sensors promise several advantages over existing cryogenic sensors, including simultaneous high count rate and high resolution capability, and relative ease of use. Using simple shadow mask lithography, we verified the basic principles of operation of these devices and discovered new physics in their thermal behavior as a function applied voltage bias. We also began to develop ways to use this new sensor in practical x-ray and gamma-ray detectors based on superconducting absorbers. This requires the use of quasiparticle trapping to concentrate the signal in the sensing elements.

  12. [Scanning electron microscopic investigations of cutting edge quality in lamellar keratotomy using the Wavelight femtosecond laser (FS-200) : What influence do spot distance and an additional tunnel have?

    Science.gov (United States)

    Hammer, T; Höche, T; Heichel, J

    2018-01-01

    Femtosecond lasers (fs-lasers) are established cutting instruments for the creation of LASIK flaps. Previous studies often showed even rougher surfaces after application of fs-laser systems compared to lamellar keratotomy with mechanical microkeratomes. When cutting the cornea with fs-lasers, an intrastromal gas development occurs, which has a potentially negative influence on the cutting quality if the gas cannot be dissipated; therefore, manufacturers have chosen the way of gas assimilation in so-called pockets. The investigated system creates a tunnel which opens under the conjunctiva. The aim of this study was to investigate the effects of a tunnel as well as the influence of different spot distances on the quality of cut surfaces and edges. In this experimental study on freshly enucleated porcine eyes (n = 15), the following cuts were carried out with the FS-200 (Wavelight, Erlangen, Germany): 1. standard setting (spot and line separation 8 µm), 2. with tunnel for gas drainage, 3. without gas-conducting tunnel, 4. with increased spot spacing (spot and line separation 9 μm instead of 8 μm) and 5. with reduced spot spacing (spot and line separation 7 μm instead of 8 μm). Subsequently, scanning electron microscopy (FEI Quanta 650, Hillsboro, OR) of the cut edges and surfaces as well as the gas drain tunnel were performed. The evaluation was based on an established score. The current fs-laser system (200 Hz) is able to create smooth cutting surfaces and sharp edges. The changed density of laser pulses compared to the standard settings with a reduced or increased distance between the pulses, did not achieve any further improvement in the surface quality. The gas-conducting tunnel could be detected by scanning electron microscope. In the case of cutting without a tunnel, roughened surfaces and irregularities on the cutting edges were found. When the FS-200 fs-laser is used, LASIK cuts with very smooth cut surfaces and sharp cutting

  13. Assessment of pseudo-bilayer structures in the heterogate germanium electron-hole bilayer tunnel field-effect transistor

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, J. L., E-mail: jose.padilladelatorre@epfl.ch; Alper, C.; Ionescu, A. M. [Nanoelectronic Devices Laboratory, École Polytechnique Fédérale de Lausanne, Lausanne CH-1015 (Switzerland); Medina-Bailón, C.; Gámiz, F. [Departamento de Electrónica y Tecnología de los Computadores, Universidad de Granada, Avda. Fuentenueva s/n, 18071 Granada (Spain)

    2015-06-29

    We investigate the effect of pseudo-bilayer configurations at low operating voltages (≤0.5 V) in the heterogate germanium electron-hole bilayer tunnel field-effect transistor (HG-EHBTFET) compared to the traditional bilayer structures of EHBTFETs arising from semiclassical simulations where the inversion layers for electrons and holes featured very symmetric profiles with similar concentration levels at the ON-state. Pseudo-bilayer layouts are attained by inducing a certain asymmetry between the top and the bottom gates so that even though the hole inversion layer is formed at the bottom of the channel, the top gate voltage remains below the required value to trigger the formation of the inversion layer for electrons. Resulting benefits from this setup are improved electrostatic control on the channel, enhanced gate-to-gate efficiency, and higher I{sub ON} levels. Furthermore, pseudo-bilayer configurations alleviate the difficulties derived from confining very high opposite carrier concentrations in very thin structures.

  14. Transmission electron microscopy study investigating Li intercalation in tunnel structured ζ-V2O5 nanowire

    Science.gov (United States)

    Mukherjee, Arijita; Yoo, Hyun Deog; Nolis, Gene; Andrews, Justin; Banerjee, Sarbajit; Cabana, Jordi; Klie, Robert; Joint Center for Energy Storage Research Collaboration

    Energy storage research has become quite relevant in recent years with the advent of smarter electronic devices and electric vehicles that demand more efficient options. Orthorhombic α-V2O5 has been known as a versatile intercalation cathode host for lithium and beyond Li cations, such as Na and Mg. Recent reports have established that a novel tunnel structured polymorph, ζ-V2O5 can perform better as a cathode material, and can intercalate Li and Mg chemically. This contribution will focus on an in depth study of phase formation upon electrochemical Li intercalation of this new polymorph, ζ-V2O5 using aberration corrected scanning transmission electron microscopy(STEM) electron energy loss spectroscopy(EELS) and energy dispersive X ray spectroscopy(EDX). Results will also be presented investigating Mg and Na intercalation into this ζ-V2O5 polymorph and compare the electrochemical performance in the various scenarios directly with structural changes at an atomic scale. This work is supported by Joint Center for Energy Storage Research(JCESR).

  15. Electron correlation in tunneling ionization of diatomic molecules: An application of the many-electron weak-field asymptotic theory with a generalized-active-space partition scheme

    Science.gov (United States)

    Yue, Lun; Bauch, Sebastian; Madsen, Lars Bojer

    2017-10-01

    The many-electron weak-field asymptotic theory (ME-WFAT) for static tunneling ionization [O. I. Tolstikhin et al., Phys. Rev. A 89, 013421 (2014), 10.1103/PhysRevA.89.013421] is applied to diatomic molecules. In the ME-WFAT, the dependence of the ionization rate on the molecular orientation with respect to the static field direction is determined by the structure factor, which in turn depends on the asymptotic tail of the Dyson orbital. We extract the latter by the time-dependent generalized-active-space configuration-interaction method [S. Bauch et al., Phys. Rev. A 90, 062508 (2014), 10.1103/PhysRevA.90.062508], which takes into account electron correlation effects systematically. Results for the orientation-dependent structure factor are presented for H2 and LiH. Compared to mean-field Hartree-Fock results, the inclusion of electron-electron correlation affects the structure factor, and hence the rate, even for these simple systems.

  16. Solution processed aluminum paper for flexible electronics.

    Science.gov (United States)

    Lee, Hye Moon; Lee, Ha Beom; Jung, Dae Soo; Yun, Jung-Yeul; Ko, Seung Hwan; Park, Seung Bin

    2012-09-11

    As an alternative to vacuum deposition, preparation of highly conductive papers with aluminum (Al) features is successfully achieved by the solution process consisting of Al precursor ink (AlH(3){O(C(4)H(9))(2)}) and low temperature stamping process performed at 110 °C without any serious hydroxylation and oxidation problems. Al features formed on several kinds of paper substrates (calendar, magazine, and inkjet printing paper substrates) are less than ~60 nm thick, and their electrical conductivities were found to be as good as thermally evaporated Al film or even better (≤2 Ω/□). Strong adhesion of Al features to paper substrates and their excellent flexibility are also experimentally confirmed by TEM observation and mechanical tests, such as tape and bending tests. The solution processed Al features on paper substrates show different electrical and mechanical performance depending on the paper type, and inkjet printing paper is found to be the best substrate with high and stable electrical and mechanical properties. The Al conductive papers produced by the solution process may be applicable in disposal paper electronics.

  17. Attoclock reveals natural coordinates of the laser-induced tunnelling current flow in atoms

    DEFF Research Database (Denmark)

    Pfeiffer, Adrian N.; Cirelli, Claudio; Smolarski, Mathias

    2012-01-01

    In the research area of strong-laser-field interactions and attosecond science1, tunnelling of an electron through the barrier formed by the electric field of the laser and the atomic potential is typically assumed to be the initial key process that triggers subsequent dynamics1, 2, 3. Here we use...... the attoclock technique4 to obtain experimental information about the electron tunnelling geometry (the natural coordinates of the tunnelling current flow) and exit point. We confirm vanishing tunnelling delay time, show the importance of the inclusion of Stark shifts5, 6 and report on multi-electron effects...

  18. The Superluminal Tunneling Story

    OpenAIRE

    Aichmann, Horst; Nimtz, Günter

    2013-01-01

    Since 1992 experimental evidence of superluminal (faster than light, FTL) signals are causing much excitement in the physical community and in the media. Superluminal signal velocity and zero time tunneling was first observed in an analog tunneling experiment with microwaves. Recently, the conjectured zero time of electron was claimed to be observed in ionizing helium. The FTL signal velocity was reproduced with infrared light and with various tunneling barriers in several laboratories worldw...

  19. Electronic transport through EuO spin-filter tunnel junctions

    KAUST Repository

    Jutong, Nuttachai

    2012-11-12

    Epitaxial spin-filter tunnel junctions based on the ferromagnetic semiconductor europium monoxide (EuO) are investigated by means of density functional theory. In particular, we focus on the spin transport properties of Cu(100)/EuO(100)/Cu(100) junctions. The dependence of the transmission coefficient and the current-voltage curves on the interface spacing and EuO thickness is explained in terms of the EuO density of states and the complex band structure. Furthermore, we also discuss the relation between the spin transport properties and the Cu-EuO interface geometry. The level alignment of the junction is sensitively affected by the interface spacing, since this determines the charge transfer between EuO and the Cu electrodes. Our calculations indicate that EuO epitaxially grown on Cu can act as a perfect spin filter, with a spin polarization of the current close to 100%, and with both the Eu-5d conduction-band and the Eu-4f valence-band states contributing to the coherent transport. For epitaxial EuO on Cu, a symmetry filtering is observed, with the Δ1 states dominating the transmission. This leads to a transport gap larger than the fundamental EuO band gap. Importantly, the high spin polarization of the current is preserved up to large bias voltages.

  20. Physiological Evidence for Isopotential Tunneling in the Electron Transport Chain of Methane-Producing Archaea.

    Science.gov (United States)

    Duszenko, Nikolas; Buan, Nicole R

    2017-09-15

    Many, but not all, organisms use quinones to conserve energy in their electron transport chains. Fermentative bacteria and methane-producing archaea (methanogens) do not produce quinones but have devised other ways to generate ATP. Methanophenazine (MPh) is a unique membrane electron carrier found in Methanosarcina species that plays the same role as quinones in the electron transport chain. To extend the analogy between quinones and MPh, we compared the MPh pool sizes between two well-studied Methanosarcina species, Methanosarcina acetivorans C2A and Methanosarcina barkeri Fusaro, to the quinone pool size in the bacterium Escherichia coli We found the quantity of MPh per cell increases as cultures transition from exponential growth to stationary phase, and absolute quantities of MPh were 3-fold higher in M. acetivorans than in M. barkeri The concentration of MPh suggests the cell membrane of M. acetivorans , but not of M. barkeri , is electrically quantized as if it were a single conductive metal sheet and near optimal for rate of electron transport. Similarly, stationary (but not exponentially growing) E. coli cells also have electrically quantized membranes on the basis of quinone content. Consistent with our hypothesis, we demonstrated that the exogenous addition of phenazine increases the growth rate of M. barkeri three times that of M. acetivorans Our work suggests electron flux through MPh is naturally higher in M. acetivorans than in M. barkeri and that hydrogen cycling is less efficient at conserving energy than scalar proton translocation using MPh. IMPORTANCE Can we grow more from less? The ability to optimize and manipulate metabolic efficiency in cells is the difference between commercially viable and nonviable renewable technologies. Much can be learned from methane-producing archaea (methanogens) which evolved a successful metabolic lifestyle under extreme thermodynamic constraints. Methanogens use highly efficient electron transport systems and

  1. Quantum-well charge and voltage distribution in a metal–insulator–semiconductor structure upon resonant electron Tunneling

    Energy Technology Data Exchange (ETDEWEB)

    Vexler, M. I., E-mail: vexler@mail.ioffe.ru; Illarionov, Yu. Yu.; Grekhov, I. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2017-04-15

    The prerequisites for electron storage in the quantum well of a metal–oxide–p{sup +}-Si resonant-tunneling structure and the effect of the stored charge on the voltage distribution are theoretically investigated. Systems with SiO{sub 2}, HfO{sub 2}, and TiO{sub 2} insulators are studied. It is demonstrated that the occurrence of a charge in the well in the case of resonant transport can be expected in structures on substrates with an acceptor concentration from (5–6) × 10{sup 18} to (2–3) × 10{sup 19} cm{sup –3} in the range of oxide thicknesses dependent on this concentration. In particular, the oxide layer thickness in the structures with SiO{sub 2}/p{sup +}-Si(10{sup 19} cm{sup –3}) should exceed ~3 nm. The electron density in the well can reach ~10{sup 12} cm{sup –2} and higher. However, the effect of this charge on the electrostatics of the structure becomes noticeable only at relatively high voltages far above the activation of resonant transport through the first subband.

  2. STAR Performance with SPEAR (Signal Processing Electronic Attack RFIC)

    Science.gov (United States)

    2017-03-01

    STAR Performance with SPEAR ( Signal Processing Electronic Attack RFIC) Luciano Boglione, Clayton Davis, Joel Goodman, Matthew McKeon, David...Parrett, Sanghoon Shin and Naomi Walker Naval Research Laboratory Washington, DC, 20375 Figure 1: The Signal Processing Electronic Attack RFIC...SPEAR) system. Abstract: The Signal Processing Electronic Attack RFIC (SPEAR) is a simultaneous transmit and receive (STAR) system capable of

  3. Dopant induced single electron tunneling within the sub-bands of single silicon NW tri-gate junctionless n-MOSFET

    Science.gov (United States)

    Uddin, Wasi; Georgiev, Yordan M.; Maity, Sarmistha; Das, Samaresh

    2017-09-01

    We report 1D electron transport of silicon junctionless tri-gate n-type transistor at 4.2 K. The step like curve observed in the current voltage characteristic suggests 1D transport. Besides the current steps for 1D transport, we found multiple spikes within individual steps, which we relate to inter-band single electron tunneling, mediated by the charged dopants available in the channel region. Clear Coulomb diamonds were observed in the stability diagram of the device. It is shown that a uniformly doped silicon nanowire can provide us the window for the single electron tunnelling. Back-gate versus front-gate color plot, where current is in a color scale, shows a crossover of the increased conduction region. This is a clear indication of the dopant-dopant interaction. It has been shown that back-gate biasing can be used to tune the coupling strength between the dopants.

  4. A Document Imaging Technique for Implementing Electronic Loan Approval Process

    National Research Council Canada - National Science Library

    J. Manikandan; C.S. Celin; V.M. Gayathri

    2015-01-01

    ...), research fields, crime investigation fields and military fields. In this paper, we proposed a document image processing technique, for establishing electronic loan approval process (E-LAP) [2...

  5. Resonant structures in the low-energy electron continuum for single ionization of atoms in the tunnelling regime

    Energy Technology Data Exchange (ETDEWEB)

    Rudenko, A; Zrost, K; Schroeter, C D; Jesus, V L B de; Feuerstein, B; Moshammer, R; Ullrich, J [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-67119 Heidelberg (Germany)

    2004-12-28

    We present high-resolution fully differential experimental data on single ionization of He, Ne and Ar by ultra-short (25 fs, 6 fs) 795 nm laser pulses at intensities 0.15-2.0 x 10{sup 15} W cm{sup -2}. We show that the ATI-like pattern can survive deep in the tunnelling regime and that the atomic structure plays an important role in the formation of the low-energy photoelectron spectra even at high intensities. The absence of ponderomotive shifts, the splitting of the peaks and their degeneration for few-cycle pulses indicate that the observed structures originate from a resonant process. (letter to the editor)

  6. Organic electronic devices with multiple solution-processed layers

    Science.gov (United States)

    Forrest, Stephen R.; Lassiter, Brian E.; Zimmerman, Jeramy D.

    2015-08-04

    A method of fabricating a tandem organic photosensitive device involves depositing a first layer of an organic electron donor type material film by solution-processing of the organic electron donor type material dissolved in a first solvent; depositing a first layer of an organic electron acceptor type material over the first layer of the organic electron donor type material film by a dry deposition process; depositing a conductive layer over the interim stack by a dry deposition process; depositing a second layer of the organic electron donor type material over the conductive layer by solution-processing of the organic electron donor type material dissolved in a second solvent, wherein the organic electron acceptor type material and the conductive layer are insoluble in the second solvent; depositing a second layer of an organic electron acceptor type material over the second layer of the organic electron donor type material film by a dry deposition process, resulting in a stack.

  7. Scanning tunneling microscopy and spectroscopy studies of the heavy-electron superconductor TlNi2Se2

    Science.gov (United States)

    Wilfert, Stefan; Schmitt, Martin; Schmidt, Henrik; Mauerer, Tobias; Sessi, Paolo; Wang, Hangdong; Mao, Qianhui; Fang, Minghu; Bode, Matthias

    2018-01-01

    We report on the structural and superconducting electronic properties of the heavy-electron superconductor TlNi2Se2 . By using a variable-temperature scanning tunneling microscopy (VT-STM) the coexistence of (√{2 }×√{2 }) R 45∘ and (2 ×1 ) surface reconstructions is observed. Similar to earlier observations on the "122" family of Fe-based superconductors, we find that their respective surface fraction strongly depends on the temperature during cleavage, the measurement temperature, and the sample's history. Cleaving at low temperature predominantly results in the (√{2 }×√{2 }) R 45∘ -reconstructed surface. A detailed analysis of the (√{2 }×√{2 }) R 45∘ -reconstructed domains identifies (2 ×1 ) -ordered dimers, tertramers, and higher order even multimers as domain walls. Higher cleaving temperatures and the warming of low-temperature-cleaved samples increases the relative weight of the (2 ×1 ) surface reconstruction. By slowly increasing the sample temperature Ts inside the VT-STM we find that the (√{2 }×√{2 }) R 45∘ surface reconstructions transforms into the (2 ×1 ) structure at Ts=123 K. We identify the polar nature of the TlNi2Se2 (001) surface as the most probable driving mechanism of the two reconstructions, as both lead to a charge density ρ =0.5 e- , thereby avoiding divergent electrostatic potentials and the resulting "polar catastrophe." Low-temperature scanning tunneling spectroscopy (STS) performed with normal metal and superconducting probe tips shows a superconducting gap which is best fit with an isotropic s wave. We could not detect any correlation between the local surface reconstruction, suggesting that the superconductivity is predominantly governed by TlNi2Se2 bulk properties. Correspondingly, temperature- and field-dependent data reveal that both the critical temperature and critical magnetic field are in good agreement with bulk values obtained earlier from transport measurements. In the superconducting state

  8. Quantum Tunnelling to the Origin and Evolution of Life.

    Science.gov (United States)

    Trixler, Frank

    2013-08-01

    Quantum tunnelling is a phenomenon which becomes relevant at the nanoscale and below. It is a paradox from the classical point of view as it enables elementary particles and atoms to permeate an energetic barrier without the need for sufficient energy to overcome it. Tunnelling might seem to be an exotic process only important for special physical effects and applications such as the Tunnel Diode, Scanning Tunnelling Microscopy (electron tunnelling) or Near-field Optical Microscopy operating in photon tunnelling mode. However, this review demonstrates that tunnelling can do far more, being of vital importance for life: physical and chemical processes which are crucial in theories about the origin and evolution of life can be traced directly back to the effects of quantum tunnelling. These processes include the chemical evolution in stellar interiors and within the cold interstellar medium, prebiotic chemistry in the atmosphere and subsurface of planetary bodies, planetary habitability via insolation and geothermal heat as well as the function of biomolecular nanomachines. This review shows that quantum tunnelling has many highly important implications to the field of molecular and biological evolution, prebiotic chemistry and astrobiology.

  9. Strong overtones modes in inelastic electron tunneling spectroscopy with cross-conjugated molecules

    DEFF Research Database (Denmark)

    Jørgensen, Jacob Lykkebo; Gagliardi, Alessio; Pecchia, Alessandro

    2013-01-01

    Cross-conjugated molecules are known to exhibit destructive quantum interference, a property that has recently received considerable attention in single-molecule electronics. Destructive quantum interference can be understood as an antiresonance in the elastic transmission near the Fermi energy...... is larger than for molecules without interference, the overall behavior of the molecule is still dominated by the quantum interference feature. Second, an ongoing challenge for single molecule electronics is understanding and controlling the local geometry at the molecule-surface interface...... that overtones are not observable in IETS. Here, overtones are predicted to be strong and, in some cases, the dominant spectroscopic features. We study the origin of the overtones and find that the interference features in these molecules are the key ingredient. The interference feature is a property...

  10. Low energy anomalies in electron tunneling through strongly asymmetric Majorana nanowire

    OpenAIRE

    Shkop, A. D.; Parafilo, A. V.; Krive, I. V.; Shekhter, R. I.

    2016-01-01

    Electron transport through Majorana nanowire with strongly asymmetric couplings to normal metal leads is considered. In three terminal geometry (electrically grounded nanowire) it is shown that the presence of unbiased electrode restores zero-bias anomaly even for strong Majorana energy splitting. For effectively two-terminal geometry we show that electrical current through asymmetric Majorana junction is qualitatively different from the analogous current through a resonant (Breit-Wigner) level.

  11. A simulation study on the mode conversion process from slow Z-mode to LO mode by the tunneling effect and variations of beaming angle

    Science.gov (United States)

    Kalaee, Mohammad Javad; Katoh, Yuto

    2014-12-01

    For a particular angle of incidence wave, it is possible for a slow Z-mode wave incident on an inhomogeneous plasma slab to be converted into an LO mode wave. But for another wave normal angle of the incident wave, it has been considered impossible, since an evanescence region exists between two mode branches. In this case we expect that the mode conversion takes place through the tunneling effect. We investigate the effect of the spatial scale of the density gradient on the mode conversion efficiency in an inhomogeneous plasma where the mode conversion can occur only by the tunneling effect. We use the computer simulation solving Maxwell's equations and the motion of a cold electron fluid. By considering the steepness of the density gradient, the simulation results show the efficient mode conversion could be expected even in the case that the mismatch of the refractive indexes prevents the close coupling of plasma waves. Also, we show for these cases the beaming angle does not correspond to Jones' formula. This effect leads to the angles larger and smaller than the angle estimated by the formula. This type of mode conversion process becomes important in a case where the different plasmas form a discontinuity at their contact boundary.

  12. Passive fire protection measures for concrete tunnels

    NARCIS (Netherlands)

    Both, C.; Haar, P.W. van de; Tan, G.L.; Wolsink, G.M.

    1999-01-01

    executed or in the process of designing; worth mentioning are the Western Scheld tunnel (approximately 2x6.5 km), the tunnels in the Betuwe railway and the tunnels in the HSL (high velocity train) railway. The most prominent of these tunnels will be executed as bored tunnels. The Directorate-General

  13. 78 FR 68981 - Electronic Retirement Processing

    Science.gov (United States)

    2013-11-18

    ... Folder (eOPF) means an electronic version of the hardcopy Official Personnel Folder (OPF), providing Web-enabled access for federal employees and HR staff to view eOPF documents. Electronic Retirement Record...OPF) data; and (3) Documents, including hardcopy versions of the Individual Retirement Record (SF 2806...

  14. The Beginner's Guide to Wind Tunnels with TunnelSim and TunnelSys

    Science.gov (United States)

    Benson, Thomas J.; Galica, Carol A.; Vila, Anthony J.

    2010-01-01

    The Beginner's Guide to Wind Tunnels is a Web-based, on-line textbook that explains and demonstrates the history, physics, and mathematics involved with wind tunnels and wind tunnel testing. The Web site contains several interactive computer programs to demonstrate scientific principles. TunnelSim is an interactive, educational computer program that demonstrates basic wind tunnel design and operation. TunnelSim is a Java (Sun Microsystems Inc.) applet that solves the continuity and Bernoulli equations to determine the velocity and pressure throughout a tunnel design. TunnelSys is a group of Java applications that mimic wind tunnel testing techniques. Using TunnelSys, a team of students designs, tests, and post-processes the data for a virtual, low speed, and aircraft wing.

  15. Electron tunneling transport across heterojunctions between europium sulfide and indium arsenide

    Science.gov (United States)

    Kallaher, Raymond L.

    This dissertation presents research done on utilizing the ferromagnetic semiconductor europium sulfide (EuS) to inject spin polarized electrons into the non-magnetic semiconductor indium arsenide (InAs). There is great interest in expanding the functionality of modern day electronic circuits by creating devices that depend not only on the flow of charge in the device, but also on the transport of spin through the device. Within this mindset, there is a concerted effort to establish an efficient means of injecting and detecting spin polarized electrons in a two dimensional electron system (2DES) as the first step in developing a spin based field effect transistor. Thus, the research presented in this thesis has focused on the feasibility of using EuS, in direct electrical contact with InAs, as a spin injecting electrode into an InAs 2DES. Doped EuS is a concentrated ferromagnetic semiconductor, whose conduction band undergoes a giant Zeeman splitting when the material becomes ferromagnetic. The concomitant difference in energy between the spin-up and spin-down energy bands makes the itinerant electrons in EuS highly spin polarized. Thus, in principle, EuS is a good candidate to be used as an injector of spin polarized electrons into non-magnetic materials. In addition, the ability to adjust the conductivity of EuS by varying the doping level in the material makes EuS particularly suited for injecting spins into non-magnetic semiconductors and 2DES. For this research, thin films of EuS have been grown via e-beam evaporation of EuS powder. This growth technique produces EuS films that are sulfur deficient; these sulfur vacancies act as intrinsic electron donors and the resulting EuS films behave like heavily doped ferromagnetic semiconductors. The growth parameters and deposition procedures were varied and optimized in order to fabricate films that have minimal crystalline defects. Various properties and characteristics of these EuS films were measured and compared to

  16. Flexible MgO Barrier Magnetic Tunnel Junctions.

    Science.gov (United States)

    Loong, Li Ming; Lee, Wonho; Qiu, Xuepeng; Yang, Ping; Kawai, Hiroyo; Saeys, Mark; Ahn, Jong-Hyun; Yang, Hyunsoo

    2016-07-01

    Flexible MgO barrier magnetic tunnel junction (MTJ) devices are fabricated using a transfer printing process. The flexible MTJ devices yield significantly enhanced tunneling magnetoresistance of ≈300% and improved abruptness of switching, as residual strain in the MTJ structure is released during the transfer process. This approach could be useful for flexible electronic systems that require high-performance memory components. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. STM based inelastic electron tunneling spectroscopy on NdBa{sub 2}Cu{sub 3}O{sub 7-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Das, Pintu [Institute of Experimental Physics, University of Saarland, 66041, Saarbruecken (Germany); Max Planck Institute of Chemical Physics of Solids, Noethnitzer Str. 40, 01187 Dresden (Germany); Koblischka, Michael R.; Hartmann, Uwe [Institute of Experimental Physics, University of Saarland, 66041, Saarbruecken (Germany); Rosner, Helge [Max Planck Institute of Chemical Physics of Solids, Noethnitzer Str. 40, 01187 Dresden (Germany); Wolf, Thomas [Forschungzentrum Karlsruhe GmbH, Institute of Solid State Physics, 76021 Karlsruhe (Germany)

    2008-07-01

    Inelastic electron tunneling spectroscopy (IETS) is a very powerful tool to detect collective excitations in conducting materials. Due to inelastic excitation by tunneling electrons, a very weak kink is usually observed in dI/dV curves at the bias voltage corresponding to the excitation energy. In IETS on s wave superconductors, phonon modes ({omega}{sub ph}) were observed at energies given by E = {delta}+ {Dirac_h}{omega}{sub ph}, where {delta} is the energy gap. Recently IETS using scanning tunneling spectroscopy (STS) has been used to detect a bosonic mode in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}. In the STS data obtained on NdBa{sub 2}Cu{sub 3}O{sub 7-{delta}} single crystals, we observed peaks in d{sup 2}I/dV{sup 2} curves beyond the coherence peaks from which collective excitation energies of {proportional_to}23 meV and {proportional_to} 34 meV have been found for the samples with T{sub c} of 93.5 K and 95.5 K respectively. Band structure calculation shows that there is no structure in the density of state at the observed energies which thus supports the presumption that the observed kinks in dI/dV curves are due to inelastic scattering of electrons.

  18. Forecasting and prevention of water inrush during the excavation process of a diversion tunnel at the Jinping II Hydropower Station, China.

    Science.gov (United States)

    Hou, Tian-Xing; Yang, Xing-Guo; Xing, Hui-Ge; Huang, Kang-Xin; Zhou, Jia-Wen

    2016-01-01

    Estimating groundwater inflow into a tunnel before and during the excavation process is an important task to ensure the safety and schedule during the underground construction process. Here we report a case of the forecasting and prevention of water inrush at the Jinping II Hydropower Station diversion tunnel groups during the excavation process. The diversion tunnel groups are located in mountains and valleys, and with high water pressure head. Three forecasting methods are used to predict the total water inflow of the #2 diversion tunnel. Furthermore, based on the accurate estimation of the water inrush around the tunnel working area, a theoretical method is presented to forecast the water inflow at the working area during the excavation process. The simulated results show that the total water flow is 1586.9, 1309.4 and 2070.2 m(3)/h using the Qshima method, Kostyakov method and Ochiai method, respectively. The Qshima method is the best one because it most closely matches the monitoring result. According to the huge water inflow into the #2 diversion tunnel, reasonable drainage measures are arranged to prevent the potential disaster of water inrush. The groundwater pressure head can be determined using the water flow velocity from the advancing holes; then, the groundwater pressure head can be used to predict the possible water inflow. The simulated results show that the groundwater pressure head and water inflow re stable and relatively small around the region of the intact rock mass, but there is a sudden change around the fault region with a large water inflow and groundwater pressure head. Different countermeasures are adopted to prevent water inrush disasters during the tunnel excavation process. Reasonable forecasting the characteristic parameters of water inrush is very useful for the formation of prevention and mitigation schemes during the tunnel excavation process.

  19. Safety analysis and hazard control during food processing and storage in the BIO-Plex Interconnecting Transfer Tunnel.

    Science.gov (United States)

    Hentges, D L

    2000-01-01

    The food system, being designed for the BIO-Plex (Bioregenerative Planetary Life Support Systems Test Complex), will be a plant-based diet that requires most of the food to be grown, processed, and prepared in the BIO-Plex. Conversion of crops to edible foods will require extensive food processing within the closed environment of this habitat. Because all consumables in the BIO-Plex will be recycled and reused, food safety is a primary concern. Multifunctional equipment necessary for food processing of the baseline crops (wheat, soybeans, rice, peanuts, dried beans, potatoes, sweet potatoes, lettuce, chard, tomatoes, green onions, carrots, and radishes) was identified. Recommendations for placement of the food processing equipment in the Interconnecting Transfer Tunnel (ITT) of the BIO-Plex were made to facilitate the processing flow diagrams, increase work efficiency, and prevent cross-contamination of pathogens and antinutrients. Sanitation equipment and procedures necessary during food processing in the ITT are described.

  20. Evidence of two-electron tunneling interference in Nb/InAs junctions

    OpenAIRE

    Badolato, Antonio; Giazotto, Francesco; Lazzarino, Marco; Pingue, Pasqualantonio; Beltram, Fabio; Lucheroni, Carlo; Fazio, Rosario

    2000-01-01

    The impact of junction transparency in driving phase-coherent charge transfer across diffusive semiconductor-superconductor junctions is demonstrated. We present conductivity data for a set of Nb-InAs junctions differing only in interface transparency. Our experimental findings are analyzed within the quasi-classical Green-function approach and unambiguously show the physical processes giving rise to the observed excess zero-bias conductivity.

  1. Resonant two-electron processes in ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Zavodszky, P.A. E-mail: paz@phys.ksu.edu; Richard, P.; Bhalla, C.P

    1999-06-03

    A review of some of the recent results in an effort to obtain electron-ion differential scattering cross sections using fast ion-atom collisions is given. In the projectile frame, if we neglect the effects from the target nucleus, the ion-atom collision can be described as an electron-ion scattering process where the energy distribution of the impinging quasi-free electrons is determined by the Compton-profile of the target. In this electron scattering model (ESM), in addition to the direct electron scattering, doubly excited state formation of the projectile ion is also possible. This is a resonant process in which the doubly excited states can subsequently decay by ejecting Auger-electrons. We have studied elastic, inelastic and superelastic electron scattering as a function of incoming electron energy by observing the outgoing electron energy in the ion-atom collision emission spectra.

  2. Signal processing and analysis in a buffet onset wind tunnel campaign

    Directory of Open Access Journals (Sweden)

    Mihai Victor PRICOP

    2015-06-01

    Full Text Available The purpose of the current work is to determine the buffet onset boundary in the case of an airliner type of wind tunnel model having a presumably laminar wing. A complex wind tunnel campaign took place, providing an important amount of data from a variety of sensors: steady and non-steady pressure sensors, strain gauges and accelerometer. The last two types of sensors are useful for buffeting investigation, which is the structural vibration and are considered to provide global indications. Pressure signals are providing local indications and also global when properly integrated in global indices. The paper shows the difficulties encountered in using global indicators, which fail to identify the buffeting and the delicate analysis of pressure signals and their qualitative analysis, which provide a good insight into the phenomena and are clearly indicating the buffet onset boundary, with the proper extrapolation.

  3. Current gain above 10 in sub-10 nm base III-Nitride tunneling hot electron transistors with GaN/AlN emitter

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhichao, E-mail: zcyang.phys@gmail.com; Zhang, Yuewei; Krishnamoorthy, Sriram; Nath, Digbijoy N. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Khurgin, Jacob B. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2016-05-09

    We report on a tunneling hot electron transistor amplifier with common-emitter current gain greater than 10 at a collector current density in excess of 40 kA/cm{sup 2}. The use of a wide-bandgap GaN/AlN (111 nm/2.5 nm) emitter was found to greatly improve injection efficiency of the emitter and reduce cold electron leakage. With an ultra-thin (8 nm) base, 93% of the injected hot electrons were collected, enabling a common-emitter current gain up to 14.5. This work improves understanding of the quasi-ballistic hot electron transport and may impact the development of high speed devices based on unipolar hot electron transport.

  4. Aeolian process of the dried-up riverbeds of the Hexi Corridor, China: a wind tunnel experiment.

    Science.gov (United States)

    Zhang, Caixia; Wang, Xunming; Dong, Zhibao; Hua, Ting

    2017-08-01

    Wind tunnel studies, which remain limited, are an important tool to understand the aeolian processes of dried-up riverbeds. The particle size, chemical composition, and the mineral contents of sediments arising from the dried river beds are poorly understood. Dried-up riverbeds cover a wide area in the Hexi Corridor, China, and comprise a complex synthesis of different land surfaces, including aeolian deposits, pavement surfaces, and Takyr crust. The results of the present wind tunnel experiment suggest that aeolian transport from the dried-up riverbeds of the Hexi Corridor ranges from 0 to 177.04 g/m(2)/min and that dry riverbeds could be one of the main sources of dust emissions in this region. As soon as the wind velocity reaches 16 m/s and assuming that there are abundant source materials available, aeolian transport intensity increases rapidly. The dried-up riverbed sediment and the associated aeolian transported material were composed mainly of fine and medium sands. However, the transported samples were coarser than the bed samples, because of the sorting effect of the aeolian processes on the sediment. The aeolian processes also led to regional elemental migration and mineral composition variations.

  5. Electronic repository and standardization of processes and electronic documents in transport

    Directory of Open Access Journals (Sweden)

    Tomasz DĘBICKI

    2007-01-01

    Full Text Available The article refers to the idea of the use of electronic repository to store standardised scheme of processes between a Logistics Service Provider and its business partners. Application of repository for automatic or semi-automatic configuration of interoperability in electronic data interchange between information systems of differentcompanies based on transport (road, rail, sea and combined related processes. Standardisation includes processes, scheme of cooperation and related to them, electronic messages.

  6. Tunable electron affinity with electronic band alignment of solution processed dielectric

    Science.gov (United States)

    Mondal, Sandip; Venkataraman, V.

    2017-07-01

    We report the tunability of the electronic band structure, especially the electron affinity, of an all-inorganic precursor processed sol-gel aluminium oxide phosphate dielectric by the influence of processing temperature. The dielectric offers tunable electron affinity ranging from 1.42 eV to 0.72 eV with the change in processing temperature from as-prepared to 1000 °C, respectively. The remarkable change in electron affinity is ascribed to the variation in the bulk oxygen concentration in solution processed oxide. As a result, the leakage current of the dielectric is affected significantly by a factor of ˜103.

  7. Charge Transport in 2D DNA Tunnel Junction Diodes

    KAUST Repository

    Yoon, Minho

    2017-11-06

    Recently, deoxyribonucleic acid (DNA) is studied for electronics due to its intrinsic benefits such as its natural plenitude, biodegradability, biofunctionality, and low-cost. However, its applications are limited to passive components because of inherent insulating properties. In this report, a metal-insulator-metal tunnel diode with Au/DNA/NiOx junctions is presented. Through the self-aligning process of DNA molecules, a 2D DNA nanosheet is synthesized and used as a tunneling barrier, and semitransparent conducting oxide (NiOx ) is applied as a top electrode for resolving metal penetration issues. This molecular device successfully operates as a nonresonant tunneling diode, and temperature-variable current-voltage analysis proves that Fowler-Nordheim tunneling is a dominant conduction mechanism at the junctions. DNA-based tunneling devices appear to be promising prototypes for nanoelectronics using biomolecules.

  8. Process-Oriented Measurement Using Electronic Tangibles

    Science.gov (United States)

    Veerbeek, Jochanan; Verhaegh, Janneke; Elliott, Julian G.; Resing, Wilma C. M.

    2017-01-01

    This study evaluated a new measure for analyzing the process of children's problem solving in a series completion task. This measure focused on a process that we entitled the "Grouping of Answer Pieces" (GAP) that was employed to provide information on problem representation and restructuring. The task was conducted using an electronic…

  9. Signal processing and electronic noise in LZ

    Science.gov (United States)

    Khaitan, D.

    2016-03-01

    The electronics of the LUX-ZEPLIN (LZ) experiment, the 10-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), consists of low-noise dual-gain amplifiers and a 100-MHz, 14-bit data acquisition system for the TPC PMTs. Pre-prototypes of the analog amplifiers and the 32-channel digitizers were tested extensively with simulated pulses that are similar to the prompt scintillation light and the electroluminescence signals expected in LZ. These studies are used to characterize the noise and to measure the linearity of the system. By increasing the amplitude of the test signals, the effect of saturating the amplifier and the digitizers was studied. The RMS ADC noise of the digitizer channels was measured to be 1.19± 0.01 ADCC. When a high-energy channel of the amplifier is connected to the digitizer, the measured noise remained virtually unchanged, while the noise added by a low-energy channel was estimated to be 0.38 ± 0.02 ADCC (46 ± 2 μV). A test facility is under construction to study saturation, mitigate noise and measure the performance of the LZ electronics and data acquisition chain.

  10. Short tunnels.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1965-01-01

    Before dealing with the question of lighting short tunnels, it is necessary define what is meant by a tunnel and when it should be called 'short'. Confined to motorized road traffic the following is the most apt definition of a tunnel: every form of roofing-over a road section, irrespective of it

  11. Transport properties of magnetic tunnel junctions with Co2MnSi electrode: influence of temperature-dependent interface magnetization and electronic band structure

    Energy Technology Data Exchange (ETDEWEB)

    Schmalhorst, Jan; Thomas, Andy; Schebaum, Oliver; Ebke, Daniel; Sacher, Marc; Huetten, Andreas; Reiss, Guenter [Thin Films and Nano Structures, Department of Physics, Bielefeld University (Germany); Turchanin, Andrej; Goelzhaeuser, Armin [Department of Physics, Bielefeld University (Germany); Arenholz, Elke [Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2007-07-01

    The investigation of the temperature-dependent magnetic and chemical properties of the Co{sub 2}MnSi/Al-O interface in Co{sub 2}MnSi/Al-O/Co-Fe MTJs showed, that with increasing degree of disorder, interfacial magnetic moments are reduced and their temperature dependences are more pronounced. Magnon excitation is stronger at the Co{sub 2}MnSi/Al-O interface compared with Co-Fe-B based tunnel junctions and bulk Co{sub 2}MnSi. We suggest, that mainly this contributes to the larger bias voltage and temperature dependence of the TMR in the Co{sub 2}MnSi based junctions by means of enhanced magnon-assisted tunneling. Furthermore, several fingerprints of the ideal Co2MnSi bandstructure of atomically ordered Co{sub 2}MnSi films are revealed by the XAS-, XMCD- and XPS-investigations in accordance with SPR-KKR calculations. Finally, we suggest that the observed inversion of the TMR effect occuring when electrons are tunneling from the Co-Fe into the atomically ordered Co{sub 2}MnSi electrode is the most striking bandstructure effect.

  12. Interpreting tunneling time in circularly polarized strong-laser ionization

    CERN Document Server

    Yuan, MingHu; Chu, TianShu; Liu, HongPing

    2016-01-01

    We propose a method to study the tunneling process by analyzing the time-dependent ionization yield in circularly polarized laser. A numerical calculation shows that for an atom exposed to a long laser pulse, if its initial electronic state wave function is non-spherical symmetric, the delayed phase shift of the ionization rate vs. the laser cycle period in real time in the region close to the peak intensity of the laser pulse can be used to probe the tunneling time. In this region, an obvious delay phase shift is observed, showing the tunneling time is in order of tens of attoseconds. Further study shows the atom has a longer tunneling time in the ionization under a shorter wavelength laser pulse. In our method, a Wigner rotation technique is employed to numerically solve the time-dependent Schr\\"odinger equation of a single-active-electron in a three dimensional spherical coordinate system.

  13. Using annotations in an electronic process handbook to systematically incorporate experience into processes

    OpenAIRE

    Becker-Kornstaedt, U.; Reinert, R.

    2001-01-01

    Knowledge and experience are key assets in software process improvement. An instrument to communicate software process knowledge to the people performing the process are process handbooks in printed or file-based form. However, even in the electronic form, these handbooks still lack adequate support to incorporate experience gained during process execution. This paper presents the concept of an electronic process handbook that allows users to incorporate their experience into the process hand...

  14. Preliminary Performance Data on General Electric Integrated Electronic Control Operating on J47 RX1-3 Turbojet Engine in NACA Altitude Wind Tunnel

    Science.gov (United States)

    Blivas, Darnold; Taylor, Burt L., III

    1950-01-01

    Performance data obtained with recording oscillographs are presented to show the transient response of the General Electric Integrated Electronic Control operating on the J47 RXl-3 turbo-Jet engine over a range of altitudes from 10,000 to 45,000 feet and at ram pressure ratios of 1.03 and 1.4. These data represent the performance of the final control configuration developed after an investigation of the engine transient behavior in the NACA altitude wind tunnel. Oscillograph traces of controlled accelerations (throttle bursts),oontrolled decelerations (throttle chops), and controlled altitude starts are presented.

  15. Computer Simulation of Electron Positron Annihilation Processes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, y

    2003-10-02

    With the launching of the Next Linear Collider coming closer and closer, there is a pressing need for physicists to develop a fully-integrated computer simulation of e{sup +}e{sup -} annihilation process at center-of-mass energy of 1TeV. A simulation program acts as the template for future experiments. Either new physics will be discovered, or current theoretical uncertainties will shrink due to more accurate higher-order radiative correction calculations. The existence of an efficient and accurate simulation will help us understand the new data and validate (or veto) some of the theoretical models developed to explain new physics. It should handle well interfaces between different sectors of physics, e.g., interactions happening at parton levels well above the QCD scale which are described by perturbative QCD, and interactions happening at much lower energy scale, which combine partons into hadrons. Also it should achieve competitive speed in real time when the complexity of the simulation increases. This thesis contributes some tools that will be useful for the development of such simulation programs. We begin our study by the development of a new Monte Carlo algorithm intended to perform efficiently in selecting weight-1 events when multiple parameter dimensions are strongly correlated. The algorithm first seeks to model the peaks of the distribution by features, adapting these features to the function using the EM algorithm. The representation of the distribution provided by these features is then improved using the VEGAS algorithm for the Monte Carlo integration. The two strategies mesh neatly into an effective multi-channel adaptive representation. We then present a new algorithm for the simulation of parton shower processes in high energy QCD. We want to find an algorithm which is free of negative weights, produces its output as a set of exclusive events, and whose total rate exactly matches the full Feynman amplitude calculation. Our strategy is to create

  16. Front and backside processed thin film electronic devices

    Science.gov (United States)

    Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.; Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang

    2010-10-12

    This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

  17. Analytical expression for the tunnel current through the redox-mediated tunneling contact in the case of the adiabatic electron transfer at one of the working electrodes and any possible type of the electron transfer at the other electrode

    Science.gov (United States)

    Medvedev, Igor G.

    2017-11-01

    We study the tunnel current through a one-level redox molecule immersed into the electrolyte solution for the case when the coupling of the molecule to one of the working electrodes is strong while it is arbitrary to the other electrode. Using the Feynman-Vernon influence functional theory and the perturbation expansion of the effective action of the classical oscillator coupled both to the valence level of the redox molecule and to the thermal bath representing the classical fluctuations of the polarization of the solvent, we obtain, following the canonical way, the Langevin equation for the oscillator. It is found that for the aqueous electrolyte solution, the damping and the stochastic forces which arise due to the tunnel current are much smaller than those due to the thermal bath and therefore can be neglected. We estimate the higher-order corrections to the effective action and show that the Langevin dynamics takes place in this case for arbitrary parameters of the tunneling junction under the condition of the strong coupling of the redox molecule to one of the working electrodes. Then the steady-state coordinate distribution function of the oscillator resulting from the corresponding Fokker-Planck equation is the Boltzmann distribution function which is determined by the adiabatic free energy surface arising from the mean current-induced force. It enables us to obtain the expression for the tunnel current in the case when the coupling of the redox molecule to one of the working electrodes is strong while it is arbitrary to the other electrode.

  18. Digital signal processing in power electronics control circuits

    CERN Document Server

    Sozański, Krzysztof

    2017-01-01

    This book discusses problems concerning the design and realization of digital control algorithms for power electronics circuits using digital signal processing (DSP) methods. It includes Matlab examples for illustration of considered problems.

  19. Investigation of the electron capture process in semiclassical plasma

    Directory of Open Access Journals (Sweden)

    Seisembayeva Madina M.

    2016-06-01

    Full Text Available In this work, the process of electron capture in partially ionized plasma is considered. Electron-atom interaction was described by the effective interaction potential, which takes into account the screening effect at large distances and the diffraction effect at the small distances. The results of numerical calculations of the electron capture radius, differential cross-section for different values of the coupling and density parameters are presented. The differential cross-section was obtained on the basis of perturbation theory and also by solving of the equation of motion of the projectile electron.

  20. Spin-polarized scanning tunnelling microscopy

    CERN Document Server

    Bode, M

    2003-01-01

    The recent experimental progress in spin-polarized scanning tunnelling microscopy (SP-STM) - a magnetically sensitive imaging technique with ultra-high resolution - is reviewed. The basics of spin-polarized electron tunnelling are introduced as they have been investigated in planar tunnel junctions for different electrode materials, i.e. superconductors, optically excited GaAs, and ferromagnets. It is shown that ferromagnets and antiferromagnets are suitable tip materials for the realization of SP-STM. Possible tip designs and modes of operations are discussed for both classes of materials. The results of recent spatially resolved measurements as performed with different magnetic probe tips and using different modes of operation are reviewed and discussed in terms of applicability to surfaces, thin films, and nanoparticles. The limits of spatial resolution, and the impact of an external magnetic field on the imaging process.

  1. Characterization of Neutral Radicals from a Dissociative Electron Attachment Process

    Science.gov (United States)

    Li, Zhou; Milosavljević, Aleksandar R.; Carmichael, Ian; Ptasinska, Sylwia

    2017-08-01

    Despite decades of gas-phase studies on dissociative electron attachment (DEA) to various molecules, as yet there has been no direct detection and characterization of the neutral radical species produced by this process. In this study, we performed stepwise electron spectroscopy to directly measure and characterize the neutrals produced upon zero-electron-energy DEA to the model molecule, carbon tetrachloride (CCl4 ). We observed the direct yield of the trichloromethyl radical (CCl3. ) formed by DEA to CCl4 and measured the appearance energies of all the other neutral species. By combining these experimental findings with high-level quantum chemical calculations, we performed a complete analysis of both the DEA to CCl4 and the subsequent electron-impact ionization of CCl3. . This work paves the way toward a complete experimental characterization of DEA processes, which will lead to a better understanding of the low-energy electron-induced formation of radical species.

  2. Estimation of the Processing Parameters in Electron Beam Thermal Treatments

    Directory of Open Access Journals (Sweden)

    DULAU Mircea

    2014-05-01

    Full Text Available Electron beam have many special properties which make them particularly well suited for use in materials handling through melting, welding, surface treatment, etc., taking into account that this manufacturing is performed in vacuum. The use of electron beam for surface limited heat treatment of workpiece has brought about a noticeable extension of the beam technologies. Some theoretical aspects and simulation results are presented in this paper, considering a high power electron beam processing system and Matlab facilities. This paper can be used in power engineering and electro-technologies fields as a guideline, in order to simulate and analyse the process parameters.

  3. LEP tunnel monorail

    CERN Multimedia

    1985-01-01

    A monorail from CERN's Large Electron Positron collider (LEP, for short). It ran around the 27km tunnel, transporting equipment and personnel. With its 27-kilometre circumference, LEP was the largest electron-positron accelerator ever built and ran from 1989 to 2000. During 11 years of research, LEP's experiments provided a detailed study of the electroweak interaction. Measurements performed at LEP also proved that there are three – and only three – generations of particles of matter. LEP was closed down on 2 November 2000 to make way for the construction of the Large Hadron Collider in the same tunnel.

  4. Theoretical study on the electronic structure of triphenyl sulfonium salts: Electronic excitation and electron transfer processes

    Science.gov (United States)

    Petsalakis, Ioannis D.; Theodorakopoulos, Giannoula; Lathiotakis, Nektarios N.; Georgiadou, Dimitra G.; Vasilopoulou, Maria; Argitis, Panagiotis

    2014-05-01

    Density functional theory (DFT) and Time Dependent DFT calculations on triphenyl sulfonium cation (TPS) and the salts of TPS with triflate, nonaflate, perfluoro-1-octanesulfonate and hexafluoro antimonate anions are presented. These systems are widely used as cationic photoinitiators and as electron ejection layer for polymer light-emitting diodes. While some differences exist in the electronic structure of the different salts, their lowest energy intense absorption maxima are calculated at nearly the same energy for all systems. The first excited state of TPS and of the TPS salts is dissociating. Electron addition to the TPS salts lowers their energy by 1.0-1.33 eV.

  5. Acoustic Data Processing and Transient Signal Analysis for the Hybrid Wing Body 14- by 22-Foot Subsonic Wind Tunnel Test

    Science.gov (United States)

    Bahr, Christopher J.; Brooks, Thomas F.; Humphreys, William M.; Spalt, Taylor B.; Stead, Daniel J.

    2014-01-01

    An advanced vehicle concept, the HWB N2A-EXTE aircraft design, was tested in NASA Langley's 14- by 22-Foot Subsonic Wind Tunnel to study its acoustic characteristics for var- ious propulsion system installation and airframe con gurations. A signi cant upgrade to existing data processing systems was implemented, with a focus on portability and a re- duction in turnaround time. These requirements were met by updating codes originally written for a cluster environment and transferring them to a local workstation while en- abling GPU computing. Post-test, additional processing of the time series was required to remove transient hydrodynamic gusts from some of the microphone time series. A novel automated procedure was developed to analyze and reject contaminated blocks of data, under the assumption that the desired acoustic signal of interest was a band-limited sta- tionary random process, and of lower variance than the hydrodynamic contamination. The procedure is shown to successfully identify and remove contaminated blocks of data and retain the desired acoustic signal. Additional corrections to the data, mainly background subtraction, shear layer refraction calculations, atmospheric attenuation and microphone directivity corrections, were all necessary for initial analysis and noise assessments. These were implemented for the post-processing of spectral data, and are shown to behave as expected.

  6. Analyses of tunnel stability under dynamic loads

    OpenAIRE

    Oraee, B; Hosseini, N.; Oraee, K; Gholinejad, M

    2011-01-01

    Tunnels as any other structures are affected by different loads and stresses. Generally, the loads on tunnels consist of both static and dynamic loads. These loads must both be considered in the tunnel design process. In this paper, the stability state of Jiroft water-transform tunnel is evaluated. Firstly, the in-situ stresses and then using Kirschs equations the induced stresses due to static loads in walls and crown of tunnel are calculated. Consequently, the strain caused by probable eart...

  7. Electron beam irradiation processing for industrial and medical applications

    Science.gov (United States)

    Ozer, Zehra Nur

    2017-09-01

    In recent years, electron beam processing has been widely used for medical and industrial applications. Electron beam accelerators are reliable and durable equipments that can produce ionizing radiation when it is needed for a particular commercial use. On the industrial scale, accelerators are used to generate electrons in between 0.1-100 MeV energy range. These accelerators are used mainly in plastics, automotive, wire and electric cables, semiconductors, health care, aerospace and environmental industries, as well as numerous researches. This study presents the current applications of electron beam processing in medicine and industry. Also planned study of a design for such a system in the energy range of 200-300 keV is introduced.

  8. Quality control of the documentation process in electronic economic activities

    Directory of Open Access Journals (Sweden)

    Krutova A.S.

    2017-06-01

    Full Text Available It is proved that the main tool that will provide adequate information resources e economic activities of social and economic relations are documenting quality control processes as the basis of global information space. Directions problems as formation evaluation information resources in the process of documentation, namely development tools assess the efficiency of the system components – qualitative assessment; development of mathematical modeling tools – quantitative evaluation. A qualitative assessment of electronic documentation of economic activity through exercise performance, efficiency of communication; document management efficiency; effectiveness of flow control operations; relationship management effectiveness. The concept of quality control process documents electronically economic activity to components which include: the level of workflow; forms adequacy of information; consumer quality documents; quality attributes; type of income data; condition monitoring systems; organizational level process documentation; attributes of quality, performance quality consumer; type of management system; type of income data; condition monitoring systems. Grounded components of the control system electronic document subjects of economic activity. Detected components IT-audit management system economic activity: compliance audit; audit of internal control; detailed multilevel analysis; corporate risk assessment methodology. The stages and methods of processing electronic transactions economic activity during condition monitoring of electronic economic activity.

  9. Theory of dissociative tunneling ionization

    CERN Document Server

    Svensmark, Jens; Madsen, Lars Bojer

    2016-01-01

    We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is found by using the Born-Oppenheimer (BO) approximation in conjunction with the reflection principle. These spectra are compared to exact non-BO ab initio spectra obtained through model calculations with a quantum mechanical treatment of both the electronic and nuclear degrees freedom. In the regime where the BO approximation is applicable imaging of the BO nuclear wave function is demonstrated to be possible through reverse use of the reflection principle, when accounting appropriately for the electronic ionization rate. A qualitative difference between the exact and BO wave functions in the asymptotic region of large electronic distances is shown. Additionally the behavior of the wave function across the turning line is seen to be reminiscent of light refraction. For weak fiel...

  10. Quantum information processing with electronic and nuclear spins in semiconductors

    Science.gov (United States)

    Klimov, Paul Victor

    Traditional electronic and communication devices operate by processing binary information encoded as bits. Such digital devices have led to the most advanced technologies that we encounter in our everyday lives and they influence virtually every aspect of our society. Nonetheless, there exists a much richer way to encode and process information. By encoding information in quantum mechanical states as qubits, phenomena such as coherence and entanglement can be harnessed to execute tasks that are intractable to digital devices. Under this paradigm, it should be possible to realize quantum computers, quantum communication networks and quantum sensors that outperform their classical counterparts. The electronic spin states of color-center defects in the semiconductor silicon carbide have recently emerged as promising qubit candidates. They have long-lived quantum coherence up to room temperature, they can be controlled with mature magnetic resonance techniques, and they have a built-in optical interface operating near the telecommunication bands. In this thesis I will present two of our contributions to this field. The first is the electric-field control of electron spin qubits. This development lays foundation for quantum electronics that operate via electrical gating, much like traditional electronics. The second is the universal control and entanglement of electron and nuclear spin qubits in an ensemble under ambient conditions. This development lays foundation for quantum devices that have a built-in redundancy and can operate in real-world conditions. Both developments represent important steps towards practical quantum devices in an electronic grade material.

  11. Adhesives technology for electronic applications materials, processing, reliability

    CERN Document Server

    Licari, James J

    2011-01-01

    Adhesives are widely used in the manufacture and assembly of electronic circuits and products. Generally, electronics design engineers and manufacturing engineers are not well versed in adhesives, while adhesion chemists have a limited knowledge of electronics. This book bridges these knowledge gaps and is useful to both groups. The book includes chapters covering types of adhesive, the chemistry on which they are based, and their properties, applications, processes, specifications, and reliability. Coverage of toxicity, environmental impacts and the regulatory framework make this book par

  12. High-Throughput Printing Process for Flexible Electronics

    Science.gov (United States)

    Hyun, Woo Jin

    Printed electronics is an emerging field for manufacturing electronic devices with low cost and minimal material waste for a variety of applications including displays, distributed sensing, smart packaging, and energy management. Moreover, its compatibility with roll-to-roll production formats and flexible substrates is desirable for continuous, high-throughput production of flexible electronics. Despite the promise, however, the roll-to-roll production of printed electronics is quite challenging due to web movement hindering accurate ink registration and high-fidelity printing. In this talk, I will present a promising strategy for roll-to-roll production using a novel printing process that we term SCALE (Self-aligned Capillarity-Assisted Lithography for Electronics). By utilizing capillarity of liquid inks on nano/micro-structured substrates, the SCALE process facilitates high-resolution and self-aligned patterning of electrically functional inks with greatly improved printing tolerance. I will show the fabrication of key building blocks (e.g. transistor, resistor, capacitor) for electronic circuits using the SCALE process on plastics.

  13. Electronic Structure on (001) Surface of BaFe2As2 Parent Compound Studied with Scanning Tunneling Spectroscopy

    Science.gov (United States)

    Jayasundara, D. R.; Li, A.; Xuan, Y.; O'Neal, J. P.; Pan, S. H.; Jin, R.; Plummer, E. W.; Jin, R.; Sefat, A. S.; McGuire, M. A.; Sales, B. C.; Mandrus, D.

    2009-03-01

    Doping can drive some metallic pnictide compounds to superconducting phase. The microscopic mechanism of this phase transition has still not been understood. Starting with the parent compound, we have used a UHV Low Temperature STM to study the density of states on the (001) surface of single crystal BaFe2As2. The tunneling spectrum varies depending on the local environment. All the spectrums have the same background with density of states depression near the Fermi energy, but some of them show different anomalies. We attribute some of these anomalies to surface states. These results may provide useful information to those surface techniques other than STM.

  14. Exploring the Tilt-Angle Dependence of electron tunneling across Molecular junction of Self-Assembled Alkanethiols

    DEFF Research Database (Denmark)

    Frederiksen, Thomas; Munuera, C.; Ocal, C.

    2009-01-01

    by contacting the molecular layers with the tip of a conductive force microscope. Measurements done under low-load conditions permit us to obtain reliable tilt-angle and molecular length dependencies of the low-bias conductance through the alkanethiol layers. The observed dependence on tilt-angle is stronger...... for the longer molecular chains. Our calculations confirm the observed trends and explain them as a result of two mechanisms, namely, a previously proposed intermolecular tunneling enhancement as well as a hitherto overlooked tilt-dependent molecular gate effect....

  15. Design and Analysis of CMOS-Compatible III-V Compound Electron-Hole Bilayer Tunneling Field-Effect Transistor for Ultra-Low-Power Applications.

    Science.gov (United States)

    Kim, Sung Yoon; Seo, Jae Hwa; Yoon, Young Jun; Lee, Ho-Young; Lee, Seong Min; Cho, Seongjae; Kang, In Man

    2015-10-01

    In this work, we design and analyze complementary metal-oxide-semiconductor (CMOS)-compatible III-V compound electron-hole bilayer (EHB) tunneling field-effect transistors (TFETs) by using two-dimensional (2D) technology computer-aided design (TCAD) simulations. A recently proposed EHB TFET exploits a bias-induced band-to-band tunneling (BTBT) across the electron-hole bilayer by an electric field from the top and bottom gates. This is in contrast to conventional planar p(+)-p(-)-n TFETs, which utilize BTBT across the source-to-channel junction. We applied III-V compound semiconductor materials to the EHB TFETs in order to enhance the current drivability and switching performance. Devices based on various compound semiconductor materials have been designed and analyzed in terms of their primary DC characteristics. In addition, the operational principles were validated by close examination of the electron concentrations and energy-band diagrams under various operation conditions. The simulation results of the optimally designed In0.533Ga0.47As EHB TFET show outstanding performance, with an on-state current (Ion) of 249.5 μA/μm, subthreshold swing (S) of 11.4 mV/dec, and threshold voltage (Vth) of 50 mV at VDS = 0.5 V. Based on the DC-optimized InGaAs EHB TFET, the CMOS inverter circuit was simulated in views of static and dynamic behaviors of the p-channel device with exchanges between top and bottom gates or between source and drain electrodes maintaining the device structure.

  16. High mobility, printable, and solution-processed graphene electronics.

    Science.gov (United States)

    Wang, Shuai; Ang, Priscilla Kailian; Wang, Ziqian; Tang, Ai Ling Lena; Thong, John T L; Loh, Kian Ping

    2010-01-01

    The ability to print graphene sheets onto large scale, flexible substrates holds promise for large scale, transparent electronics on flexible substrates. Solution processable graphene sheets derived from graphite can form stable dispersions in solutions and are amenable to bulk scale processing and ink jet printing. However, the electrical conductivity and carrier mobilities of this material are usually reported to be orders of magnitude poorer than that of the mechanically cleaved counterpart due to its higher density of defects, which restricts its use in electronics. Here, we show that by optimizing several key factors in processing, we are able to fabricate high mobility graphene films derived from large sized graphene oxide sheets, which paves the way for all-carbon post-CMOS electronics. All-carbon source-drain channel electronics fabricated from such films exhibit significantly improved transport characteristics, with carrier mobilities of 365 cm(2)/(V.s) for hole and 281 cm(2)/(V.s) for electron, measured in air at room temperature. In particular, intrinsic mobility as high as 5000 cm(2)/(V.s) can be obtained from such solution-processed graphene films when ionic screening is applied to nullify the Coulombic scattering by charged impurities.

  17. Ensuring high quality and efficiency of the worksin the process of constructing the tunnels of in-situ concrete

    Directory of Open Access Journals (Sweden)

    Ginzburg Aleksandr Vladimirovich

    2014-01-01

    Full Text Available In the article the author describes the importance of the technological regulations development in the process of constructing various transport constructions: tunnels, subways, bridges and other important objects. In the article the peculiarities of the technological regulations development are fully taken into account; the dependence of the depth of their development and the quality of the concrete constructions, as well as the speed of the objects of transport infrastructure construction, including the examples of building the road tunnels in Moscow. The course of their development is shown with account for the main provisions, which should be included in technological regulations in order to ensure the most complete coverage of the issues arising in engineering, laboratory and Supervisory structure in the process of performing the works. The author proposes new effective materials and technologies of works. In particular, sufficient attention is paid to self-compacting concrete — a new type of concrete, which is able to flow and compact under its own weight, completely filling the formwork even in case of dense reinforcement, while maintaining the homogeneity and having no seals. The application experience of concrete self-sealing in the construction of the metro showed that labor costs for the concrete mixture sealing were 5-6 times reduced, and the speed of laying the concrete increased 2-3 times. When laying self-compacting concrete high-quality surfaces are formed, which do not require additional costs to bring them to the design parameters. In addition, the work shows the parameters of the technological processes and sets various types of works sequence: the article describes the features of formwork, placement and curing of the concrete in terms of year-round construction, shows the importance of thermo physical calculations of concrete hardening and the efficiency of using self-sealing concrete. Sufficient attention is also paid to

  18. LETTER TO THE EDITOR: Resonant structures in the low-energy electron continuum for single ionization of atoms in the tunnelling regime

    Science.gov (United States)

    Rudenko, A.; Zrost, K.; Schröter, C. D.; de Jesus, V. L. B.; Feuerstein, B.; Moshammer, R.; Ullrich, J.

    2004-12-01

    We present high-resolution fully differential experimental data on single ionization of He, Ne and Ar by ultra-short (25 fs, 6 fs) 795 nm laser pulses at intensities 0.15-2.0 × 1015 W cm-2. We show that the ATI-like pattern can survive deep in the tunnelling regime and that the atomic structure plays an important role in the formation of the low-energy photoelectron spectra even at high intensities. The absence of ponderomotive shifts, the splitting of the peaks and their degeneration for few-cycle pulses indicate that the observed structures originate from a resonant process.

  19. Carpal tunnel syndrome diagnosis by a self-normalization process and ultrasound compound imaging.

    Science.gov (United States)

    Liao, Yin-Yin; Wu, Chin-Chou; Kuo, Tai-Tzung; Chen, Jiann-Perng; Hsu, Yen-Wei; Yeh, Chih-Kuang

    2012-12-01

    Carpal tunnel syndrome (CTS) is the common entrapment neuropathy that occurs due to compression of the median nerve at the wrist. Ultrasound images have been used to highlight anatomical variants of the median nerve, and CTS is thought to be associated to enlargement of the cross-sectional area (CSA) of the median nerve. However, there remains controversy regarding the most appropriate cutoff values of the computer measurements including the CSA, flattening ratio, and palmar bowing of median nerve, especially given that they can be influenced by image artifacts and factors that differ between individual patients. This study proposed a modified ultrasound compound imaging technique by moving fingers to reduce image artifacts, and the estimates of the normalized CSA [i.e., CSA at the wrist (CSAw) to CSA at the midforearm] with the aim of reducing discrepancies in CSA estimates and improving the ability of CTS discrimination. The subjects were examined with their arms supine and while they were making repetitive movements of their fingers (from an open palm into a clenched fist) within 3 s. By a commercial ultrasound scanner with a 10-MHz linear array transducer, a total of 70 images were acquired in each subject. The frame rate of ultrasound system was 25 fps. Nine frames in the acquisition sequence that had produced partial speckle decorrelation were incoherently added to form a compound image, and the inplane motion of them was corrected using the multilevel block-sum pyramid algorithm. The manual contours outlined by ten experimenters and three physicians were used to test the performance in determining the boundary of the median nerve. The receiver operating characteristic (ROC) curve was used to evaluate the usefulness of the estimates in distinguishing healthy volunteers from CTS patients. The manual contours of the median nerve in the compound images had an average area overlap exceeding 90% and relatively small area errors. The areas under the ROC curve

  20. Laser and electron beam processing of silicon and gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, J.

    1979-10-01

    Laser (photon) and electron beams provide a controlled source of heat by which surface layers of silicon and gallium arsenide can be rapidly melted and cooled with rates exceeding 10/sup 80/C/sec. The melting process has been used to remove displacement damage in ion implanted Si and GaAs, to remove dislocations, loops and precipitates in silicon and to study impurity segregation and solubility limits. The mechanisms associated with various phenomena will be examined. The possible impact of laser and electron beam processing on device technology, particularly with respect to solar cells is discussed.

  1. Personal and occupational risk factors for carpal tunnel syndrome in meat processing industry workers in Northern Italy

    Directory of Open Access Journals (Sweden)

    Matteo Riccò

    2017-04-01

    Full Text Available Background: Carpal tunnel syndrome (CTS is a musculoskeletal condition that often impairs the fitness to work. Our aim is to retrospectively evaluate the association between physical exposures in meat processing industry in Northern Italy and the CTS, taking into account non-occupational factors. Material and Methods: A cross-sectional study was performed to include 434 workers (236 males, 198 females, 37.0±10.6 years old, working age: 12.6±10.8 years from meat processing industries. Signs and symptoms were collected at the compulsory occupational medical surveillance. Occupational risk factors were assessed through a questionnaire and direct assessment by investigators. Adjusted odds ratios (ORadj for factors of interest were estimated through binary logistic regression. Results: Diagnosis of the CTS was reported for 61 out of 434 subjects (14.1% for an incidence of 11.3/1000 person- years. In general, signs and symptoms for the CTS were associated with the following demographic factors: smoking history (OR = 1.909, 95% confidence interval (CI: 1.107–3.293, previous traumas of the upper limb (OR = 3.533, 95% CI: 1.743–7.165, hypothyroidism status (OR = 7.897, 95% CI: 2.917–21.38 and, in the case of female participants only, previous pregnancies (OR = 2.807, 95% CI: 1.200–6.566 as well as a personal history of oral contraceptive therapy and/or steroidal replacement therapy (OR = 11.57, 95% CI: 4.689–28.56. The carpal tunnel syndrome cases were associated with the following occupational factors (> 4 h/day: forceful hand exertion (ORadj = 3.548, 95% CI: 1.379–9.131, repeated trauma of the hand (ORadj = 3.602, 95% CI: 1.248– 10.395, repeated movements of the wrist (ORadj = 2.561, 95% CI: 1.100–5.960. Conclusions: Increasing levels of hand activity and force were associated with the increased CTS prevalence among participants. Recommendations have to be provided in order to reduce occupational exposure to these risk factors and

  2. Personal and occupational risk factors for carpal tunnel syndrome in meat processing industry workers in Northern Italy.

    Science.gov (United States)

    Riccò, Matteo; Signorelli, Carlo

    2017-03-24

    Carpal tunnel syndrome (CTS) is a musculoskeletal condition that often impairs the fitness to work. Our aim is to retrospectively evaluate the association between physical exposures in meat processing industry in Northern Italy and the CTS, taking into account non-occupational factors. A cross-sectional study was performed to include 434 workers (236 males, 198 females, 37.0±10.6 years old, working age: 12.6±10.8 years) from meat processing industries. Signs and symptoms were collected at the compulsory occupational medical surveillance. Occupational risk factors were assessed through a questionnaire and direct assessment by investigators. Adjusted odds ratios (ORadj) for factors of interest were estimated through binary logistic regression. Diagnosis of the CTS was reported for 61 out of 434 subjects (14.1%) for an incidence of 11.3/1000 person- years. In general, signs and symptoms for the CTS were associated with the following demographic factors: smoking history (OR = 1.909, 95% confidence interval (CI): 1.107-3.293), previous traumas of the upper limb (OR = 3.533, 95% CI: 1.743-7.165), hypothyroidism status (OR = 7.897, 95% CI: 2.917-21.38) and, in the case of female participants only, previous pregnancies (OR = 2.807, 95% CI: 1.200-6.566) as well as a personal history of oral contraceptive therapy and/or steroidal replacement therapy (OR = 11.57, 95% CI: 4.689-28.56). The carpal tunnel syndrome cases were associated with the following occupational factors (> 4 h/day): forceful hand exertion (ORadj = 3.548, 95% CI: 1.379-9.131), repeated trauma of the hand (ORadj = 3.602, 95% CI: 1.248- 10.395), repeated movements of the wrist (ORadj = 2.561, 95% CI: 1.100-5.960). Increasing levels of hand activity and force were associated with the increased CTS prevalence among participants. Recommendations have to be provided in order to reduce occupational exposure to these risk factors and improve medical surveillance. Med Pr 2017;68(2):199-209.

  3. Influence of scattering processes on electron quantum states in nanowires

    Directory of Open Access Journals (Sweden)

    Pozdnyakov Dmitry

    2007-01-01

    Full Text Available AbstractIn the framework of quantum perturbation theory the self-consistent method of calculation of electron scattering rates in nanowires with the one-dimensional electron gas in the quantum limit is worked out. The developed method allows both the collisional broadening and the quantum correlations between scattering events to be taken into account. It is an alternativeper seto the Fock approximation for the self-energy approach based on Green’s function formalism. However this approach is free of mathematical difficulties typical to the Fock approximation. Moreover, the developed method is simpler than the Fock approximation from the computational point of view. Using the approximation of stable one-particle quantum states it is proved that the electron scattering processes determine the dependence of electron energy versus its wave vector.

  4. Low energy electron beam processing of YBCO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chromik, Š., E-mail: stefan.chromik@savba.sk [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Camerlingo, C. [CNR-SPIN, Istituto Superconduttori, Materiali Innovativi e Dispositivi, via Campi Flegrei 34, 80078 Pozzuoli (Italy); Sojková, M.; Štrbík, V.; Talacko, M. [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Malka, I.; Bar, I.; Bareli, G. [Department of Physics, Ben Gurion University of the Negev, P.O.B. 653, 84105 Beer Sheva (Israel); Jung, G. [Department of Physics, Ben Gurion University of the Negev, P.O.B. 653, 84105 Beer Sheva (Israel); Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland)

    2017-02-15

    Highlights: • Improvement of superconducting properties of irradiated bridges under certain conditions. • 30 keV irradiation influence CuO{sub 2} planes as well as oxygen chains. • Direct confirmation of changes in oxygen chains using micro-Raman spectroscopy. • Possibility of electron writing. - Abstract: Effects of low energy 30 keV electron irradiation of superconducting YBa{sub 2}Cu{sub 3}O{sub 7−δ} thin films have been investigated by means of transport and micro-Raman spectroscopy measurements. The critical temperature and the critical current of 200 nm thick films initially increase with increasing fluency of the electron irradiation, reach the maximum at fluency 3 − 4 × 10{sup 20} electrons/cm{sup 2}, and then decrease with further fluency increase. In much thinner films (75 nm), the critical temperature increases while the critical current decreases after low energy electron irradiation with fluencies below 10{sup 20} electrons/cm{sup 2}. The Raman investigations suggest that critical temperature increase in irradiated films is due to healing of broken Cu−O chains that results in increased carrier’s concentration in superconducting CuO{sub 2} planes. Changes in the critical current are controlled by changes in the density of oxygen vacancies acting as effective pinning centers for flux vortices. The effects of low energy electron irradiation of YBCO turned out to result from a subtle balance of many processes involving oxygen removal, both by thermal activation and kick-off processes, and ordering of chains environment by incident electrons.

  5. Electronic/photonic interfaces for ultrafast data processing.

    Energy Technology Data Exchange (ETDEWEB)

    Overberg, Mark E.; Geib, Kent Martin; Serkland, Darwin Keith; Hsu, Alan Yuan-Chun; Keeler, Gordon Arthur; Finnegan, Patrick Sean (LMATA Government Services, LLC, Albuquerque, NM)

    2008-09-01

    This report summarizes a 3-month program that explored the potential areas of impact for electronic/photonic integration technologies, as applied to next-generation data processing systems operating within 100+ Gb/s optical networks. The study included a technology review that targeted three key functions of data processing systems, namely receive/demultiplexing/clock recovery, data processing, and transmit/multiplexing. Various technical approaches were described and evaluated. In addition, we initiated the development of high-speed photodetectors and hybrid integration processes, two key elements of an ultrafast data processor. Relevant experimental results are described herein.

  6. Crystallographic data processing for free-electron laser sources

    Energy Technology Data Exchange (ETDEWEB)

    White, Thomas A., E-mail: taw@physics.org; Barty, Anton; Stellato, Francesco [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Holton, James M. [University of California, San Francisco, CA 94158 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kirian, Richard A. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Arizona State University, Tempe, AZ 85287 (United States); Zatsepin, Nadia A. [Arizona State University, Tempe, AZ 85287 (United States); Chapman, Henry N. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2013-07-01

    A processing pipeline for diffraction data acquired using the ‘serial crystallography’ methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A processing pipeline for diffraction data acquired using the ‘serial crystallography’ methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A detailed analysis of the nature and impact of indexing ambiguities is presented. Simulations of the Monte Carlo integration scheme, which accounts for the partially recorded nature of the diffraction intensities, are presented and show that the integration of partial reflections could be made to converge more quickly if the bandwidth of the X-rays were to be increased by a small amount or if a slight convergence angle were introduced into the incident beam.

  7. 78 FR 30934 - Certain Consumer Electronics With Display and Processing Capabilities; Notice of Receipt of...

    Science.gov (United States)

    2013-05-23

    ... COMMISSION Certain Consumer Electronics With Display and Processing Capabilities; Notice of Receipt of... received a complaint entitled Certain Consumer Electronics with Display and Processing Capabilities, DN... within the United States after importation of certain consumer electronics with display and processing...

  8. DESORPTION OF Te CAPPING LAYER FROM ZnTe (100: AUGER SPECTROSCOPY, LOW-ENERGY ELECTRON DIFFRACTION AND SCANNING TUNNELING MICROSCOPY

    Directory of Open Access Journals (Sweden)

    K. K. Sossoe

    2016-01-01

    Full Text Available The influence of the annealing temperature to desorb a protective Te capping layer of the zinc telluride (ZnTe (100 surface was investigated. The surface reconstruction of the ZnTe (100 upon the removal of a Te capping layer grown by the molecular beam epitaxy was characterized by different methods. Auger spectroscopy brought out the chemical composition of the surface before and after annealing; the Low-energy electron diffraction (LEED gave information about the crystallographic structure. The surface crystallographic configurations of tellurium Te (c (2x2 and Te (c (2x1 are confirmed by scanning tunneling microscopy (STM. Such a study reveals a phase transition from a rich-Te to a poor-Te surface as the annealing temperature increases. 

  9. The application of a linear electron accelerator in radiation processing

    Science.gov (United States)

    Ruiying, Zhou; Binglin, Wang; Wenxiu, Chen; Yongbao, Gu; Yinfen, Zhang; Simin, Qian; Andong, Liu; Peide, Wang

    A 3-5 MeV electron beam generated by a BF-5 type linear electron accelerator has been used in some radiation processing works, such as, (1) The cross-linking technology by radiation for the polyethylene foaming processing --- the correlation between the cross-linkage and the absorbed dose, the relation between the elongation of foaming polyethylene and the dose, the relation between the size of the cavities and the gelatin rate and the optimum range of dosage for foaming have been found. (2) The research work on the fast switch thyristor irradiated by electron beam --- The relation between the absorbed dose and the life-time of minority carriers has been studied and the optimum condition for radiation processing was determined. This process is much better than the conventional gold diffusion in raising the quality and end-product rate of these devices. Besides, we have made some testing works on the hereditary mutation of plant seeds and microorganism mutation induced by electron radiation and radiation sterilization for some medical instruments and foods.

  10. MODELING OF ELECTRONIC GASOLINE INJECTION PROCESSES IN TWO STROKE ENGINE

    Directory of Open Access Journals (Sweden)

    Hraivoronskyi, Y.

    2013-06-01

    Full Text Available Basic provision of the processes developed mode, occurring in ignition fuel system with electronically controlled two stroke engine with positive ignition are given. Fuel injection process’ calculation results for the case of placing fuel injector into intake system presented.

  11. Development of Electronic Data Processing /EDP/ augmented management system

    Science.gov (United States)

    Scott, J. E.; Waddleton, T. R.

    1968-01-01

    To tailor the existing Unified Flight Analysis System to management data rather than technical data, a pilot model could be produced in breadboard form, using electronic data processing, in a matter of a few months at very moderate cost. Such a system lends itself to continuous refinement.

  12. Electronic Structure on (001) Surface of Co-doped BaFe2As2 Studied with Scanning Tunneling Spectroscopy

    Science.gov (United States)

    Li, A.; Jayasundara, D. R.; Xuan, Y.; O'Neal, J. P.; Chen, Y.; Kim, W.; Ting, C. S.; Pan, S. H.; Jin, R.; Plummer, E. W.; Jin, R.; Sefat, A. S.; McGuire, M. A.; Sales, B. C.; Mandrus, D.

    2009-03-01

    Co-doping makes the pnictide compound BaFe2As2 superconducting. We cleave the single crystals of this compound in UHV and study their surfaces with a low temperature STM. In this talk, we present the scanning tunneling spectrums obtained on the (001) surface of the optimally doped BaFe2As2 single crystals (Tc = 23K) and compare these spectrums with the ones obtained on the surface of the parent compound. We have found that the major feature of the spectrums on the superconducting compounds is the opening of a superconducting gap of about 6 meV for the optimally doped one. We have also observed other detailed spectrum features. We will discuss the relation between spectrum features and the local environment and also present some theoretical fit to the superconducting energy gap spectrum.

  13. Tunneling of heat: Beyond linear response regime

    Science.gov (United States)

    Walczak, Kamil; Saroka, David

    2018-02-01

    We examine nanoscale processes of heat (energy) transfer as carried by electrons tunneling via potential barriers and molecular interconnects between two heat reservoirs (thermal baths). For that purpose, we use Landauer-type formulas to calculate thermal conductance and quadratic correction to heat flux flowing via quantum systems. As an input, we implement analytical expressions for transmission functions related to simple potential barriers and atomic bridges. Our results are discussed with respect to energy of tunneling electrons, temperature, the presence of resonant states, and specific parameters characterizing potential barriers as well as heat carriers. The simplicity of semi-analytical models developed by us allows to fit experimental data and extract crucial information about the values of model parameters. Further investigations are expected for more realistic transmission functions, while time-dependent aspects of nanoscale heat transfer may be addressed by using the concept of wave packets scattered on potential barriers and point-like defects within regular (periodic) nanostructures.

  14. Ab initio quantum mechanical/molecular mechanical simulation of electron transfer process: fractional electron approach.

    Science.gov (United States)

    Zeng, Xiancheng; Hu, Hao; Hu, Xiangqian; Cohen, Aron J; Yang, Weitao

    2008-03-28

    Electron transfer (ET) reactions are one of the most important processes in chemistry and biology. Because of the quantum nature of the processes and the complicated roles of the solvent, theoretical study of ET processes is challenging. To simulate ET processes at the electronic level, we have developed an efficient density functional theory (DFT) quantum mechanical (QM)/molecular mechanical (MM) approach that uses the fractional number of electrons as the order parameter to calculate the redox free energy of ET reactions in solution. We applied this method to study the ET reactions of the aqueous metal complexes Fe(H(2)O)(6)(2+/3+) and Ru(H(2)O)(6)(2+/3+). The calculated oxidation potentials, 5.82 eV for Fe(II/III) and 5.14 eV for Ru(II/III), agree well with the experimental data, 5.50 and 4.96 eV, for iron and ruthenium, respectively. Furthermore, we have constructed the diabatic free energy surfaces from histogram analysis based on the molecular dynamics trajectories. The resulting reorganization energy and the diabatic activation energy also show good agreement with experimental data. Our calculations show that using the fractional number of electrons (FNE) as the order parameter in the thermodynamic integration process leads to efficient sampling and validate the ab initio QM/MM approach in the calculation of redox free energies.

  15. A Document Imaging Technique for Implementing Electronic Loan Approval Process

    Directory of Open Access Journals (Sweden)

    J. Manikandan

    2015-04-01

    Full Text Available The image processing is one of the leading technologies of computer applications. Image processing is a type of signal processing, the input for image processor is an image or video frame and the output will be an image or subset of image [1]. Computer graphics and computer vision process uses an image processing techniques. Image processing systems are used in various environments like medical fields, computer-aided design (CAD, research fields, crime investigation fields and military fields. In this paper, we proposed a document image processing technique, for establishing electronic loan approval process (E-LAP [2]. Loan approval process has been tedious process, the E-LAP system attempts to reduce the complexity of loan approval process. Customers have to login to fill the loan application form online with all details and submit the form. The loan department then processes the submitted form and then sends an acknowledgement mail via the E-LAP to the requested customer with the details about list of documents required for the loan approval process [3]. The approaching customer can upload the scanned copies of all required documents. All this interaction between customer and bank take place using an E-LAP system.

  16. Digital signal processing in power electronics control circuits

    CERN Document Server

    Sozanski, Krzysztof

    2013-01-01

    Many digital control circuits in current literature are described using analog transmittance. This may not always be acceptable, especially if the sampling frequency and power transistor switching frequencies are close to the band of interest. Therefore, a digital circuit is considered as a digital controller rather than an analog circuit. This helps to avoid errors and instability in high frequency components. Digital Signal Processing in Power Electronics Control Circuits covers problems concerning the design and realization of digital control algorithms for power electronics circuits using

  17. Spin-polarized electron tunneling across a Si delta-doped GaMnAs/n-GaAs interface

    DEFF Research Database (Denmark)

    Andresen, S.E.; Sørensen, B.S.; Lindelof, P.E.

    2003-01-01

    Spin-polarized electron coupling across a Si delta-doped GaMnAs/n-GaAs interface was investigated. The injection of spin-polarized electrons was detected as circular polarized emission from a GaInAs/GaAs quantum well light emitting diode. The angular momentum selection rules were simplified...

  18. Secondary electron emission from plasma processed accelerating cavity grade niobium

    Science.gov (United States)

    Basovic, Milos

    Advances in the particle accelerator technology have enabled numerous fundamental discoveries in 20th century physics. Extensive interdisciplinary research has always supported further development of accelerator technology in efforts of reaching each new energy frontier. Accelerating cavities, which are used to transfer energy to accelerated charged particles, have been one of the main focuses of research and development in the particle accelerator field. Over the last fifty years, in the race to break energy barriers, there has been constant improvement of the maximum stable accelerating field achieved in accelerating cavities. Every increase in the maximum attainable accelerating fields allowed for higher energy upgrades of existing accelerators and more compact designs of new accelerators. Each new and improved technology was faced with ever emerging limiting factors. With the standard high accelerating gradients of more than 25 MV/m, free electrons inside the cavities get accelerated by the field, gaining enough energy to produce more electrons in their interactions with the walls of the cavity. The electron production is exponential and the electron energy transfer to the walls of a cavity can trigger detrimental processes, limiting the performance of the cavity. The root cause of the free electron number gain is a phenomenon called Secondary Electron Emission (SEE). Even though the phenomenon has been known and studied over a century, there are still no effective means of controlling it. The ratio between the electrons emitted from the surface and the impacting electrons is defined as the Secondary Electron Yield (SEY). A SEY ratio larger than 1 designates an increase in the total number of electrons. In the design of accelerator cavities, the goal is to reduce the SEY to be as low as possible using any form of surface manipulation. In this dissertation, an experimental setup was developed and used to study the SEY of various sample surfaces that were treated

  19. Secondary Electron Emission from Plasma Processed Accelerating Cavity Grade Niobium

    Energy Technology Data Exchange (ETDEWEB)

    Basovic, Milos [Old Dominion Univ., Norfolk, VA (United States)

    2016-05-01

    Advances in the particle accelerator technology have enabled numerous fundamental discoveries in 20th century physics. Extensive interdisciplinary research has always supported further development of accelerator technology in efforts of reaching each new energy frontier. Accelerating cavities, which are used to transfer energy to accelerated charged particles, have been one of the main focuses of research and development in the particle accelerator field. Over the last fifty years, in the race to break energy barriers, there has been constant improvement of the maximum stable accelerating field achieved in accelerating cavities. Every increase in the maximum attainable accelerating fields allowed for higher energy upgrades of existing accelerators and more compact designs of new accelerators. Each new and improved technology was faced with ever emerging limiting factors. With the standard high accelerating gradients of more than 25 MV/m, free electrons inside the cavities get accelerated by the field, gaining enough energy to produce more electrons in their interactions with the walls of the cavity. The electron production is exponential and the electron energy transfer to the walls of a cavity can trigger detrimental processes, limiting the performance of the cavity. The root cause of the free electron number gain is a phenomenon called Secondary Electron Emission (SEE). Even though the phenomenon has been known and studied over a century, there are still no effective means of controlling it. The ratio between the electrons emitted from the surface and the impacting electrons is defined as the Secondary Electron Yield (SEY). A SEY ratio larger than 1 designates an increase in the total number of electrons. In the design of accelerator cavities, the goal is to reduce the SEY to be as low as possible using any form of surface manipulation. In this dissertation, an experimental setup was developed and used to study the SEY of various sample surfaces that were treated

  20. Triboelectric effect: A new perspective on electron transfer process

    Science.gov (United States)

    Pan, Shuaihang; Zhang, Zhinan

    2017-10-01

    As interest in the triboelectric effect increases in line with the development of tribo-electrification related devices, the mechanisms involved in this phenomenon require more systematic review from the dual perspectives of developed classical insights and emerging quantum understanding. In this paper, the clear energy changing and transferring process of electrons have been proposed from the quantum point of view as the trigger for the charging initiation process in the triboelectric effect, and the phonon modes on the friction surfaces are believed to hold great importance as one of the main driving forces. Compatible with Maxwell Displacement Current theory, the complete consideration for charging steady state, i.e., the competition mechanisms between the breakdown process and the continuously charging process, and the balance mechanisms of phonon-electron interaction, built voltage, and induced polarization, are illustrated. In brief, the proposed theory emphasizes the fundamental role of electron transferring in tribo-electrical fields. By comparing certain experimental results from the previous studies, the theory is justified.

  1. Probing spin-polarized tunneling at high bias and temperature with a magnetic tunnel transistor

    NARCIS (Netherlands)

    Park, B.G.; Banerjee, T.; Min, B.C.; Sanderink, Johannes G.M.; Lodder, J.C.; Jansen, R.

    2005-01-01

    The magnetic tunnel transistor (MTT) is a three terminal hybrid device that consists of a tunnel emitter, a ferromagnetic (FM) base, and a semiconductor collector. In the MTT with a FM emitter and a single FM base, spin-polarized hot electrons are injected into the base by tunneling. After

  2. Materials and processing approaches for foundry-compatible transient electronics

    Science.gov (United States)

    Chang, Jan-Kai; Fang, Hui; Bower, Christopher A.; Song, Enming; Yu, Xinge; Rogers, John A.

    2017-01-01

    Foundry-based routes to transient silicon electronic devices have the potential to serve as the manufacturing basis for “green” electronic devices, biodegradable implants, hardware secure data storage systems, and unrecoverable remote devices. This article introduces materials and processing approaches that enable state-of-the-art silicon complementary metal-oxide-semiconductor (CMOS) foundries to be leveraged for high-performance, water-soluble forms of electronics. The key elements are (i) collections of biodegradable electronic materials (e.g., silicon, tungsten, silicon nitride, silicon dioxide) and device architectures that are compatible with manufacturing procedures currently used in the integrated circuit industry, (ii) release schemes and transfer printing methods for integration of multiple ultrathin components formed in this way onto biodegradable polymer substrates, and (iii) planarization and metallization techniques to yield interconnected and fully functional systems. Various CMOS devices and circuit elements created in this fashion and detailed measurements of their electrical characteristics highlight the capabilities. Accelerated dissolution studies in aqueous environments reveal the chemical kinetics associated with the underlying transient behaviors. The results demonstrate the technical feasibility for using foundry-based routes to sophisticated forms of transient electronic devices, with functional capabilities and cost structures that could support diverse applications in the biomedical, military, industrial, and consumer industries. PMID:28652373

  3. Materials and processing approaches for foundry-compatible transient electronics

    Science.gov (United States)

    Chang, Jan-Kai; Fang, Hui; Bower, Christopher A.; Song, Enming; Yu, Xinge; Rogers, John A.

    2017-07-01

    Foundry-based routes to transient silicon electronic devices have the potential to serve as the manufacturing basis for “green” electronic devices, biodegradable implants, hardware secure data storage systems, and unrecoverable remote devices. This article introduces materials and processing approaches that enable state-of-the-art silicon complementary metal-oxide-semiconductor (CMOS) foundries to be leveraged for high-performance, water-soluble forms of electronics. The key elements are (i) collections of biodegradable electronic materials (e.g., silicon, tungsten, silicon nitride, silicon dioxide) and device architectures that are compatible with manufacturing procedures currently used in the integrated circuit industry, (ii) release schemes and transfer printing methods for integration of multiple ultrathin components formed in this way onto biodegradable polymer substrates, and (iii) planarization and metallization techniques to yield interconnected and fully functional systems. Various CMOS devices and circuit elements created in this fashion and detailed measurements of their electrical characteristics highlight the capabilities. Accelerated dissolution studies in aqueous environments reveal the chemical kinetics associated with the underlying transient behaviors. The results demonstrate the technical feasibility for using foundry-based routes to sophisticated forms of transient electronic devices, with functional capabilities and cost structures that could support diverse applications in the biomedical, military, industrial, and consumer industries.

  4. Tunneling conductance in gapped graphene-based normal metal-insulator-superconductor junctions: Case of massive Dirac electrons

    Energy Technology Data Exchange (ETDEWEB)

    Goudarzi, H., E-mail: h.goudarzi@urmia.ac.i [Department of Physics, Faculty of Science, Urmia University, P.O. Box 165, Urmia (Iran, Islamic Republic of); Sedghi, H.; Khezerlou, M.; Mabhouti, Kh. [Department of Physics, Faculty of Science, Urmia University, P.O. Box 165, Urmia (Iran, Islamic Republic of)

    2010-12-01

    We study the quantum transport property in a gapped graphene-based normal metal-insulator-superconductor junctions (NG/IG/SG), in the limit of a thin barrier. The charged fermions in NG/IG/SG structure are treated as massive relativistic particles. Based on Andreev and normal reflections in normal-superconductor graphene-based junction and BTK formalism, the tunneling conductance's in terms of some different electrostatic superconductor, U{sub 0} and barrier, V{sub 0} potential are obtained. Using the experimental based values of the Fermi energy in the NG and SG (E{sub FN} and E{sub FN} + U{sub 0}, respectively), energy gap in graphene (2mv{sub F}{sup 2}) and superconducting order parameter, {Delta}, it is shown that the conductance spectra of such system represent a new behavior, i.e. if we take |E{sub FN}-mv{sub F}{sup 2}|{yields}0, it becomes as a step function of V{sub 0}. This behavior of charge transportation can be considered as a nano switch.

  5. A Study of Vertical Transport through Graphene towards Control of Quantum Tunneling.

    Science.gov (United States)

    Zhu, Xiaodan; Lei, Sidong; Tsai, Shin-Hung; Zhang, Xiang; Liu, Jun; Yin, Gen; Tang, Min; Torres, Carlos Manuel; Navabi, Aryan; Jin, Zehua; Tsai, Shiao-Po; Qasem, Hussam; Wang, Yong; Vajtai, Robert; Lake, Roger K; Ajayan, Pulickel M; Wang, Kang L

    2018-01-04

    Vertical integration of van der Waals (vdW) materials with atomic precision is an intriguing possibility brought forward by these 2-dimensional materials. Essential to the design and analysis of these structures is a fundamental understanding of the vertical transport of charge carriers into and across vdW materials, yet little has been done in this area. In this report, we explore the important roles of single layer graphene in the vertical tunneling process as a tunneling barrier. Although a semi-metal in the lateral lattice plane, graphene together with the vdW gap act as a tunneling barrier that is nearly transparent to the vertically tunneling electrons due to its atomic thickness and the transverse momenta mismatch between the injected electrons and the graphene band structure. This is accentuated using electron tunneling spectroscopy (ETS) showing a lack of features corresponding to the Dirac cone band structure. Meanwhile, the graphene acts as a lateral conductor through which the potential and charge distribution across the tunneling barrier can be tuned. These unique properties make graphene an excellent 2-dimensional atomic grid, transparent to charge carriers, and yet can control the carrier flux via the electrical potential. A new model on the quantum capacitance's effect on vertical tunneling is developed to further elucidate the role of graphene in modulating the tunneling process. This work may serve as a general guideline for the design and analysis of vdW vertical tunneling devices and heterostructures, as well as the study of electron/spin injection through and into vdW materials.

  6. Simple characterization of electronic processes in perovskite photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Miyano, Kenjiro, E-mail: MIYANO.Kenjiro@nims.go.jp; Yanagida, Masatoshi; Tripathi, Neeti; Shirai, Yasuhiro [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2015-03-02

    Electronic properties of perovskite lead-halide photovoltaic cells have been studied. The dc current/voltage characteristics were found to be well fitted by a standard diode equation under optical excitation and in the dark, while the impedance spectroscopy revealed a pronounced slow process under light illumination, which is absent in the dark. A simple model is proposed, which can explain all aspects of the observed behavior quantitatively and consistently.

  7. DYMAC digital electronic balance. [LASL Plutonium Processing Facility

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, M.M.

    1980-06-01

    The Dynamic Materials Accountability (DYMAC) System at LASL integrates nondestructive assay (NDA) instruments with interactive data-processing equipment to provide near-real-time accountability of the nuclear material in the LASL Plutonium Processing Facility. The most widely used NDA instrument in the system is the DYMAC digital electronic balance. The DYMAC balance is a commercial instrument that has been modified at LASL for weighing material in gloveboxes and for transmitting the weight data directly to a central computer. This manual describes the balance components, details the LASL modifications, reviews a DYMAC measurement control program that monitors balance performance, and provides instructions for balance operation and maintenance.

  8. Mn Doping Effects on the Electronic Band Structure of PbS Quantum Dot Thin Films: A Scanning Tunneling Microscopy Analysis

    Science.gov (United States)

    Yost, Andrew J.; Rimal, Gaurab; Tang, Jinke; Chien, Teyu

    A thorough understanding of the phenomena associated with doping of transition metals in semiconductors is important for the development of semiconducting electronic technologies such as semiconducting quantum dot sensitized solar cells (QDSSC). Manganese doping is of particular interest in a PbS QD as it is potentially capable of increasing overall QDSSC performance. Here we present scanning tunneling microscopy and spectroscopy studies about the effects of Manganese doping on the energy band structures of PbS semiconducting QD thin films, grown using pulsed laser deposition. As a result of Manganese doping in the PbS QD thin films, a widening of the electronic band gap was observed, which is responsible for the observed increase in resistivity. Furthermore, a loss of long range periodicity observed by XRD, upon incorporation of Manganese, indicates that the Manganese dopants also induce a large amount of grain boundaries. This work was supported by the following: U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering, DEFG02-10ER46728 and the National Science Foundation Grant #0948027.

  9. A wind tunnel study of the effects of collision processes on the shape and oscillation for moderate-size raindrops

    Science.gov (United States)

    Szakáll, Miklós; Kessler, Simon; Diehl, Karoline; Mitra, Subir K.; Borrmann, Stephan

    2014-06-01

    Drop-drop collision experiments were carried out at the Mainz vertical wind tunnel. Water drops of 2.5 mm diameter were freely floated at their terminal velocities in a vertical air stream and collided with 0.5 mm diameter droplets. The collisions were recorded with a high speed digital video camera at a frame rate of 1000 per second. Altogether 116 collision events were observed, 75 of which ended with coalescence, and the rest with filament type breakup. The coalescence efficiency and its dependence on the Weber number and on the eccentricity of the colliding drops showed good agreement with earlier numerical studies. Thirty-six recorded collisions were further analyzed in order to characterize the oscillation behavior of large drops after a collisional excitation. Besides the introduction of the experimental method for studying the raindrop collisions, the study primarily focused on the characterization of the average value and the amplitude of the axis ratio variation, the active oscillation modes and their frequencies, and the decay of the oscillations excited by the collision. In spite of the fact that the amplitude of the axis ratio variation increased up to 4 to 6 times of its value before collision - depending on whether the collision ended with coalescence or breakup -, the average axis ratios increased by less than 1%. Since the sizes of largest drops after collision remained practically unchanged during the collision process, the frequencies of the active fundamental (n = 2) oscillation modes of the drops did not change significantly either. Instantaneously after collision the transverse oscillation mode and the whole body rotation dominated, while at a later instant the oblate-prolate mode determined again the drop shape alteration. It was further found that the damping of the oscillation after collision can be adequately described by the viscous decay of a liquid spherical drop.

  10. A magnetic tunnel junction with an L2{sub 1}-ordered Co{sub 2}FeSi electrode formed by all room-temperature fabrication processes

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Yuichi; Yamada, Shinya; Maeda, Yuya [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Miyao, Masanobu [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); CREST, Japan Science and Technology Agency, Chiyoda, Tokyo 102-0076 (Japan); Hamaya, Kohei, E-mail: hamaya@ed.kyushu-u.ac.jp [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

    2014-04-30

    We explore magnetic tunnel junctions consisting of Co{sub 60}Fe{sub 40}/AlO{sub x}/Co{sub 2}FeSi trilayers on Si(111) by room-temperature molecular beam epitaxy. Even for the all room-temperature fabrication processes, the Co{sub 2}FeSi layer includes L2{sub 1}-ordered structures. We demonstrate reproducible tunneling magnetoresistance ratios of ∼ 44% and ∼ 28% at 30 K and 300 K, respectively. Assuming the same room-temperature spin polarization (P) of CoFe alloys, P for Co{sub 2}FeSi grown at room temperature is larger than that for D0{sub 3}-Fe{sub 3}Si grown at 130 °C. - Highlights: • Room-temperature fabrication processes of magnetic tunnel junctions were developed. • Room-temperature grown Co{sub 2}FeSi film formed an L2{sub 1}-ordered structure. • Spin polarization for the L2{sub 1}-Co{sub 2}FeSi was higher than 130 °C-grown D0{sub 3}-Fe{sub 3}Si.

  11. WFI electronics and on-board data processing

    Science.gov (United States)

    Plattner, Markus; Albrecht, Sebastian; Bayer, Jörg; Brandt, Soeren; Drumm, Paul; Hälker, Olaf; Kerschbaum, Franz; Koch, Anna; Kuvvetli, Irfan; Meidinger, Norbert; Ott, Sabine; Ottensamer, Roland; Reiffers, Jonas; Schanz, Thomas; Skup, Konrad; Steller, Manfred; Tenzer, Chris; Thomas, Chris

    2016-07-01

    The Wide Field Imager is one of two instruments on-board the future ATHENA X-ray observatory. Its main scientific objective is to perform a sky survey in the energy range of 0.2 keV up to 15 keV with an end-of-life spectral resolution (FWHM) better than 170 eV (at 7 keV) and a frame rate of at least 200 Hz. The field of view will be 40 arcmin squared wherefore a focal plane array with 4 large sensors each with a size of 512 times 512 pixels will be developed. Additionally, a fast detector with a size of 64 times 64 pixels and a frame rate of 12.5 kHz will be implemented in order to enhance the instrument with high count rate detection of bright sources. The data processing electronics within the WFI instrument is distributed over several subsystems: DEPFET sensors sensitive in the x-ray energy regime and front-end electronics are located inside the Camera Head. Data pre-processing inside the Detector Electronics will be performed in an FPGA-based frame-processor. FPGA external memory will be used to store offset and noise maps wherefore memory controllers have to be developed. Fast read and write access to the maps combined with robustness against radiation damage (e.g. bit-flips) has to be ensured by the frame-processor design.

  12. Electronic Transport in Single Molecule Junctions: Control of the Molecule-Electrode Coupling Through Intramolecular Tunneling Barriers

    DEFF Research Database (Denmark)

    Danilov, Andrey; Kubatkin, Sergey; Kafanov, Sergey

    2008-01-01

    We report on single molecule electron transport measurements of two oligophenylenevinylene (OPV3) derivatives placed in a nanogap between gold (Au) or lead (Pb) electrodes in a field effect transistor device. Both derivatives contain thiol end groups that allow chemical binding to the electrodes...

  13. Direct Visualization of Laser-Driven Electron Multiple Scattering and Tunneling Distance in Strong-Field Ionization

    NARCIS (Netherlands)

    Witte, S.; Hickstein, D.D.; Ranitovic, P.; Tong, X.-M.; Huismans, Y.; Arpin, P.; Zhou, X.; Keister, K.E.; Hogle, C.W.; Zhang, B.; Ding, C.; Johnsson, P.; Toshima, N.; Vrakking, M.J.J.; Murnane, M.M.; Kapteyn, H.C.

    2012-01-01

    Using a simple model of strong-field ionization of atoms that generalizes the well-known 3-step model from 1D to 3D, we show that the experimental photoelectron angular distributions resulting from laser ionization of xenon and argon display prominent structures that correspond to electrons that

  14. Tunneling in high-K isomeric decays

    CERN Document Server

    Shizuma, T; Shimizu, Y R

    2002-01-01

    We have systematically investigated highly-K-forbidden transitions observed in the Hf, W and Os region, using the gamma-tunneling model in which low-K and high-k states interact through a process of quantum tunneling. The measured hindrance factors are compared with the values calculated using the gamma-tunneling model. Isotope dependences of gamma-tunneling probabilities particularly for neutron-rich nuclei and the relation to stimulated decays of isomers are discussed. (author)

  15. Electron scattering disintegration processes on light nuclei in covariant approach

    Directory of Open Access Journals (Sweden)

    Kuznietsov P.E.

    2016-01-01

    Full Text Available We provide general analysis of electro-break up process of compound scalar system. We use covariant approach with conserved EM current, which gives the ability to include strong interaction into QED. Therefore, we receive the ability to describe disintegration processes on nonlocal matter fields applying standard Feynman rules of QED. Inclusion of phase exponent into wave function receives a physical sense while we deal with the dominance of strong interaction in the process. We apply Green’s function (GF formalism to describe disintegration processes. Generalized gauge invariant electro-break up process amplitude is considered. One is a sum of traditional pole series and the regular part. We explore the deposits of regular part of amplitude, and its physical sense. A transition from virtual to real photon considered in photon point limit. The general analysis for electro-break up process of component scalar system is given. Precisely conserved nuclear electromagnetic currents at arbitrary square of transited momentum are received. The only undefined quantity in theory is vertex function. Therefore, we have the opportunity to describe electron scattering processes taking into account minimal necessary set of parameters.

  16. Electron scattering disintegration processes on light nuclei in covariant approach

    Science.gov (United States)

    Kuznietsov, P. E.; Kasatkin, Yu. A.; Klepikov, V. F.

    2016-07-01

    We provide general analysis of electro-break up process of compound scalar system. We use covariant approach with conserved EM current, which gives the ability to include strong interaction into QED. Therefore, we receive the ability to describe disintegration processes on nonlocal matter fields applying standard Feynman rules of QED. Inclusion of phase exponent into wave function receives a physical sense while we deal with the dominance of strong interaction in the process. We apply Green's function (GF) formalism to describe disintegration processes. Generalized gauge invariant electro-break up process amplitude is considered. One is a sum of traditional pole series and the regular part. We explore the deposits of regular part of amplitude, and its physical sense. A transition from virtual to real photon considered in photon point limit. The general analysis for electro-break up process of component scalar system is given. Precisely conserved nuclear electromagnetic currents at arbitrary square of transited momentum are received. The only undefined quantity in theory is vertex function. Therefore, we have the opportunity to describe electron scattering processes taking into account minimal necessary set of parameters.

  17. Precision laser processing for micro electronics and fiber optic manufacturing

    Science.gov (United States)

    Webb, Andrew; Osborne, Mike; Foster-Turner, Gideon; Dinkel, Duane W.

    2008-02-01

    The application of laser based materials processing for precision micro scale manufacturing in the electronics and fiber optic industry is becoming increasingly widespread and accepted. This presentation will review latest laser technologies available and discuss the issues to be considered in choosing the most appropriate laser and processing parameters. High repetition rate, short duration pulsed lasers have improved rapidly in recent years in terms of both performance and reliability enabling flexible, cost effective processing of many material types including metal, silicon, plastic, ceramic and glass. Demonstrating the relevance of laser micromachining, application examples where laser processing is in use for production will be presented, including miniaturization of surface mount capacitors by applying a laser technique for demetalization of tracks in the capacitor manufacturing process and high quality laser machining of fiber optics including stripping, cleaving and lensing, resulting in optical quality finishes without the need for traditional polishing. Applications include telecoms, biomedical and sensing. OpTek Systems was formed in 2000 and provide fully integrated systems and sub contract services for laser processes. They are headquartered in the UK and are establishing a presence in North America through a laser processing facility in South Carolina and sales office in the North East.

  18. Programmable ferroelectric tunnel memristor

    Directory of Open Access Journals (Sweden)

    Andy eQuindeau

    2014-02-01

    Full Text Available We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8]O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us to develop a characteristic transfer function that has only one parameter viz. the characteristic switching time and fully predicts the resistive states of this type of memristor.

  19. Material Processing Opportunites Utilizing a Free Electron Laser

    Science.gov (United States)

    Todd, Alan

    1996-11-01

    Many properties of photocathode-driven Free Electron Lasers (FEL) are extremely attractive for material processing applications. These include: 1) broad-band tunability across the IR and UV spectra which permits wavelength optimization, depth deposition control and utilization of resonance phenomena; 2) picosecond pulse structure with continuous nanosecond spacing for optimum deposition efficiency and minimal collateral damage; 3) high peak and average radiated power for economic processing in quantity; and 4) high brightness for spatially defined energy deposition and intense energy density in small spots. We discuss five areas: polymer, metal and electronic material processing, micromachining and defense applications; where IR or UV material processing will find application if the economics is favorable. Specific examples in the IR and UV, such as surface texturing of polymers for improved look and feel, and anti-microbial food packaging films, which have been demonstrated using UV excimer lamps and lasers, will be given. Unfortunately, although the process utility is readily proven, the power levels and costs of lamps and lasers do not scale to production margins. However, from these examples, application specific cost targets ranging from 0.1=A2/kJ to 10=A2/kJ of delivered radiation at power levels from 10 kW to 500 kW, have been developed and are used to define strawman FEL processing systems. Since =46EL radiation energy extraction from the generating electron beam is typically a few percent, at these high average power levels, economic considerations dictate the use of a superconducting RF accelerator with energy recovery to minimize cavity and beam dump power loss. Such a 1 kW IR FEL, funded by the US Navy, is presently under construction at the Thomas Jefferson National Accelerator Facility. This dual-use device, scheduled to generate first light in late 1997, will test both the viability of high-power FELs for shipboard self-defense against cruise

  20. Integration of health service with electronic nursery care process

    Directory of Open Access Journals (Sweden)

    Merih Yeliz Doğan

    2017-01-01

    Full Text Available You This study aims to provide to integrate the health service with electronic nursery care process and so do create lingua franca. This research has been done between April 2010 and January 2012 in a teaching and research hospital where is specialized on obstetrician and gynecology. 280 nurse are the sample of the study. The datas are collected by using a survey with 22 questions. After the observations and evaluations, in case of standards 40 nursery care process about most experienced problems in gynecology, obstetrician and pediatry clinics is formed and its infrastructure for integrating these flow diagrams to the data processing system is prepared. For working the new system, instructive sessions is done. After the applications, the using of process approach in nursery care service and the pleasure of the nurses are analysed. The datas are analysed by using percentage calculation, t-test and variant analysis test in case of SPSS programme. In this study, 3 different application for the usage of process approach is used. These applications are done in different 15 bedded clinics and in differrent times. In the first application, empty forms which have standard format, are given to the nurses to complete.In the second application, the forms which special nursery activity has been wrritten on, are given to the nurses to sign their own activity and in the third application, the standard process approach which has been integrated to electronic system and which is special to patient, is requested to use. After all aplications, according to analysation of the results, the usage of the process’ method rates are; 10% is for first method, 40% is for second method and 90% is for third method. Especially, the nursery process approach which has been integrated to electronic system is used more desirous. According to the nurses’ opinion, this system increases the creation of lingua franca, data security and effective time management. It is

  1. 76 FR 55944 - In the Matter of Certain Electronic Devices With Image Processing Systems, Components Thereof...

    Science.gov (United States)

    2011-09-09

    ... COMMISSION In the Matter of Certain Electronic Devices With Image Processing Systems, Components Thereof, and... importation of certain electronic devices with image processing systems, components thereof, and associated... having graphics processing units (``GPUs'') supplied by NVIDIA Corporation (``NVIDIA'') infringe any...

  2. Spinoff from Wind Tunnel Technology

    Science.gov (United States)

    1985-01-01

    Douglas Juanarena, a former NASA Langley instrument design engineer, found a solution to the problem of long, repetitive tunnel runs needed to measure airflow pressures. Electronically scanned pressure (ESP) replaced mechanical systems with electronic sensors. Juanarena licensed the NASA-patented technology and now manufactures ESP modules for research centers, aerospace companies, etc.

  3. Advanced electrical and electronics materials processes and applications

    CERN Document Server

    Gupta, K M

    2015-01-01

    This comprehensive and unique book is intended to cover the vast and fast-growing field of electrical and electronic materials and their engineering in accordance with modern developments.   Basic and pre-requisite information has been included for easy transition to more complex topics. Latest developments in various fields of materials and their sciences/engineering, processing and applications have been included. Latest topics like PLZT, vacuum as insulator, fiber-optics, high temperature superconductors, smart materials, ferromagnetic semiconductors etc. are covered. Illustrations and exa

  4. Spectroscopic Imaging Scanning Tunneling Microscopy Studies of Electronic Structure in the Superconducting and Pseudogap Phases of Cuprate High-Tc Superconductors

    Science.gov (United States)

    Fujita, Kazuhiro; Schmidt, Andrew R.; Kim, Eun-Ah; Lawler, Michael J.; Lee, Dung Hai; Davis, J. C.; Eisaki, Hiroshi; Uchida, Shin-ichi

    2012-01-01

    One of the key motivations for the development of atomically resolved spectroscopic imaging scanning tunneling microscopy (SI-STM) has been to probe the electronic structure of cuprate high temperature superconductors. In both the d-wave superconducting (dSC) and the pseudogap (PG) phases of underdoped cuprates, two distinct classes of electronic states are observed using SI-STM. The first class consists of the dispersive Bogoliubov quasiparticles of a homogeneous d-wave superconductor. These are detected below a lower energy scale |E|=Δ0 and only upon a momentum space (k-space) arc which terminates near the lines connecting k=±(π/a0,0) to k=±(0,π/a0). Below optimal doping, this ``nodal'' arc shrinks continuously with decreasing hole density. In both the dSC and PG phases, the only broken symmetries detected in the |E|≤Δ0 states are those of a d-wave superconductor. The second class of states occurs at energies near the pseudogap energy scale |E|˜ Δ1 which is associated conventionally with the ``antinodal'' states near k=±(π/a0,0) and k=±(0,π/a0). We find that these states break the expected 90°-rotational (C4) symmetry of electronic structure within CuO2 unit cells, at least down to 180°-rotational (C2) symmetry (nematic) but in a spatially disordered fashion. This intra-unit-cell C4 symmetry breaking coexists at |E|˜Δ1 with incommensurate conductance modulations locally breaking both rotational and translational symmetries (smectic). The characteristic wavevector Q of the latter is determined, empirically, by the k-space points where Bogoliubov quasiparticle interference terminates, and therefore evolves continuously with doping. The properties of these two classes of |E|˜Δ1 states are indistinguishable in the dSC and PG phases. To explain this segregation of k-space into the two regimes distinguished by the symmetries of their electronic states and their energy scales |E|˜Δ1 and |E|≤Δ0, and to understand how this impacts the electronic

  5. Direction of CRT waste glass processing: electronics recycling industry communication.

    Science.gov (United States)

    Mueller, Julia R; Boehm, Michael W; Drummond, Charles

    2012-08-01

    Cathode Ray Tube, CRT, waste glass recycling has plagued glass manufacturers, electronics recyclers and electronics waste policy makers for decades because the total supply of waste glass exceeds demand, and the formulations of CRT glass are ill suited for most reuse options. The solutions are to separate the undesirable components (e.g. lead oxide) in the waste and create demand for new products. Achieving this is no simple feat, however, as there are many obstacles: limited knowledge of waste glass composition; limited automation in the recycling process; transportation of recycled material; and a weak and underdeveloped market. Thus one of the main goals of this paper is to advise electronic glass recyclers on how to best manage a diverse supply of glass waste and successfully market to end users. Further, this paper offers future directions for academic and industry research. To develop the recommendations offered here, a combination of approaches were used: (1) a thorough study of historic trends in CRT glass chemistry; (2) bulk glass collection and analysis of cullet from a large-scale glass recycler; (3) conversations with industry members and a review of potential applications; and (4) evaluation of the economic viability of specific uses for recycled CRT glass. If academia and industry can solve these problems (for example by creating a database of composition organized by manufacturer and glass source) then the reuse of CRT glass can be increased. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Radio-frequency shot-noise measurement in a magnetic tunnel junction with a MgO barrier

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Mushtaq; Park, Junghwan; Song, Woon; Chong, Yonuk [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Lee, Yeonsub; Min, Byoungchul; Shin, Kyungho [Korea Institute of Science and Technology, Seoul (Korea, Republic of); Ryu, Sangwan [Chonnam National University, Gwangju (Korea, Republic of); Khim, Zheong [Seoul National University, Seoul (Korea, Republic of)

    2010-10-15

    We measured the noise power of a magnetic tunnel junction in the frequency range of 710 {approx} 1200 MHz. A low-noise cryogenic HEMT amplifier was used to measure the small noise signal at a high frequency with wide bandwidth. The MgO-barrier tunnel junction showed large tunnel magnetoresistance ratio of 215% at low temperature, which indicates electronic transport through the tunnel barrier without any significant spin-flip scattering. In the bias-dependent noise measurement, however, the zero-bias shot noise was enhanced compared to the value expected from a perfect tunnel barrier or the value observed from a good Al-AlO{sub x}-Al tunnel junction. We assume that this enhanced noise comes from inelastic tunneling processes through the barrier, which may be related to the observed zero-bias anomaly in the differential resistance of the tunnel junctions. We present a simple phenomenological model for how the inelastic scattering process can enhance the zero-bias noise in a tunnel junction.

  7. On-line monitoring of food fermentation processes using electronic noses and electronic tongues: a review.

    Science.gov (United States)

    Peris, Miguel; Escuder-Gilabert, Laura

    2013-12-04

    Fermentation processes are often sensitive to even slight changes of conditions that may result in unacceptable end-product quality. Thus, close follow-up of this type of processes is critical for detecting unfavorable deviations as early as possible in order to save downtime, materials and resources. Nevertheless the use of traditional analytical techniques is often hindered by the need for expensive instrumentation and experienced operators and complex sample preparation. In this sense, one of the most promising ways of developing rapid and relatively inexpensive methods for quality control in fermentation processes is the use of chemical multisensor systems. In this work we present an overview of the most important contributions dealing with the monitoring of fermentation processes using electronic noses and electronic tongues. After a brief description of the fundamentals of both types of devices, the different approaches are critically commented, their strengths and weaknesses being highlighted. Finally, future trends in this field are also mentioned in the last section of the article. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. The importance of lead-free electronics processes

    Energy Technology Data Exchange (ETDEWEB)

    Meltzer, M

    1999-10-21

    The Environmental Protection Agency (EPA) is placing increased importance on reducing lead-bearing wastes. Toward this end, the EPA has proposed that reporting thresholds for the Toxic Release Inventory (TRI) be lowered to ten pounds of lead content per year. The US electronics industry is also placing a high priority on lead reduction or elimination. The Association of Connecting Electronics Industries, which is the major trade association for electronics packaging, including printed circuit (PC) board manufacturers, has launched a lead-free initiative that seeks to eliminate lead in solder, in PC board etch resists and finish coats, and as tinning for component leads. Europe and Japan are also considering various regulations that will phase out lead in the next few years. In response to EPA and electronics industry priorities, the DOE complex will soon need to address lead phase-out issues. LLNL is now developing approaches for eliminating lead from PC board etch-resist operations. LLNL is seeking funding to continue this work and to eliminate other major uses of lead in electronics operations, particularly in hot-air solder leveling as a PC board finish, and tin-lead solder for component assembly operations. LLNL seeks to take a proactive leadership role in the DOE complex with respect to the elimination of lead. The envisioned lead-elimination project will be approximately two years in length. During the first year, lead-free etch resists and finish coats will be analyzed, and the best ones identified for electronics assembly and PC board fabrication. During the second year, lead-free solders will be examined and tested for compatibility with alternative PC board finish coats. Cost avoidance opportunities resulting from lead elimination include avoided TRI reporting expenses and reduction in PC board fabrication-related wastes through implementation of more efficient fabrication processes. Integrated Safety Management considerations are also relevant. Handling

  9. Electron beam processing of fresh produce - A critical review

    Science.gov (United States)

    Pillai, Suresh D.; Shayanfar, Shima

    2018-02-01

    To meet the increasing global demand for fresh produce, robust processing methods that ensures both the safety and quality of fresh produce are needed. Since fresh produce cannot withstand thermal processing conditions, most of common safety interventions used in other foods are ineffective. Electron beam (eBeam) is a non-thermal technology that can be used to extend the shelf life and ensure the microbiological safety of fresh produce. There have been studies documenting the application of eBeam to ensure both safety and quality in fresh produce, however, there are still unexplored areas that still need further research. This is a critical review on the current literature on the application of eBeam technology for fresh produce.

  10. Discrete simulation applied to the production process of electronic components

    Directory of Open Access Journals (Sweden)

    Willians dos Santos Lúcio

    2017-07-01

    Full Text Available The objective of this research is to demonstrate through simulation techniques and analyses performed in production systems of a company located in the city of Guarulhos and which produces an electronic component that has plastic, acrylic and steel, the improvements that can be applied in it with the use of a specialist software to assist in troubleshooting and help the manager in decision making. For the study, concepts of simulation, Monte Carlo method, queueing theory and the software Arena will be used. By simulating processes and evaluating performance, the software offers reports that assist the manager to see more clearly potential bottlenecks and points of improvement in process, thus effectively contributing to the company's competitiveness on the market. With the study presented in this article it will be possible to verify the importance of the use of this tool.

  11. Radiation processing of liquid with low energy electron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Makuuchi, Keizo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2003-02-01

    Radiation induced emulsion polymerization, radiation vulcanization of NR latex (RVNRL) and radiation degradation of natural polymers were selected and reviewed as the radiation processing of liquid. The characteristic of high dose rate emulsion polymerization is the occurrence of cationic polymerization. Thus, it can be used for the production of new materials that cannot be obtained by radical polymerization. A potential application will be production of polymer emulsion that can be used as water-borne UV/EB curing resins. The technology of RVNRL by {gamma}-ray has been commercialized. RVNRL with low energy electron accelerator is under development for further vulcanization cost reduction. Vessel type irradiator will be favorable for industrial application. Radiation degradation of polysaccharides is an emerging and promising area of radiation processing. However, strict cost comparison between liquid irradiation with low energy EB and state irradiation with {gamma}-ray should be carried out. (author)

  12. Medium and high energy electron beam processing system

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwagi, Masayuki [Nissin-High Voltage Co., Ltd., Kyoto (Japan)

    2003-02-01

    Electron Beam Processing System (EPS) is a useful and powerful tool for industrial irradiation process. The specification of EPS is decided by consideration to irradiate what material with how thick and wide, how much dose, how to handle, in what atmosphere. In designing an EPS, it is necessary to consider safety measure such as x-ray shielding, ozone control and interlock system. The initial costs to install typical EPS are estimated for acceleration voltages from 500 kV to 5 MV, including following items; those are electron beam machine, x-ray shielding, auxiliary equipment, material handling, survey for installation, ozone exhaust duct, cooling water system, wiring and piping. These prices are reference only because the price should be changed for each case. The price of x-ray shielding should be changed by construction cost. Auxiliary equipment includes window, cooling blower, ozone exhaust blower and SF6 gas handling equipment. In installation work at site, actual workers of 3 - 4 persons for 2 months are necessary. Material handling system is considered only rolls provided in the shielding room as reference. In addition to the initial installation, operators and workers may be required to wear a personal radiation monitor. An x-ray monitor of suitable design should be installed outside the shield room to monitor x-ray level in the working area. (Y. Tanaka)

  13. In-Process Thermal Imaging of the Electron Beam Freeform Fabrication Process

    Science.gov (United States)

    Taminger, Karen M.; Domack, Christopher S.; Zalameda, Joseph N.; Taminger, Brian L.; Hafley, Robert A.; Burke, Eric R.

    2016-01-01

    Researchers at NASA Langley Research Center have been developing the Electron Beam Freeform Fabrication (EBF3) metal additive manufacturing process for the past 15 years. In this process, an electron beam is used as a heat source to create a small molten pool on a substrate into which wire is fed. The electron beam and wire feed assembly are translated with respect to the substrate to follow a predetermined tool path. This process is repeated in a layer-wise fashion to fabricate metal structural components. In-process imaging has been integrated into the EBF3 system using a near-infrared (NIR) camera. The images are processed to provide thermal and spatial measurements that have been incorporated into a closed-loop control system to maintain consistent thermal conditions throughout the build. Other information in the thermal images is being used to assess quality in real time by detecting flaws in prior layers of the deposit. NIR camera incorporation into the system has improved the consistency of the deposited material and provides the potential for real-time flaw detection which, ultimately, could lead to the manufacture of better, more reliable components using this additive manufacturing process.

  14. Closed-Loop Process Control for Electron Beam Freeform Fabrication and Deposition Processes

    Science.gov (United States)

    Taminger, Karen M. (Inventor); Hafley, Robert A. (Inventor); Martin, Richard E. (Inventor); Hofmeister, William H. (Inventor)

    2013-01-01

    A closed-loop control method for an electron beam freeform fabrication (EBF(sup 3)) process includes detecting a feature of interest during the process using a sensor(s), continuously evaluating the feature of interest to determine, in real time, a change occurring therein, and automatically modifying control parameters to control the EBF(sup 3) process. An apparatus provides closed-loop control method of the process, and includes an electron gun for generating an electron beam, a wire feeder for feeding a wire toward a substrate, wherein the wire is melted and progressively deposited in layers onto the substrate, a sensor(s), and a host machine. The sensor(s) measure the feature of interest during the process, and the host machine continuously evaluates the feature of interest to determine, in real time, a change occurring therein. The host machine automatically modifies control parameters to the EBF(sup 3) apparatus to control the EBF(sup 3) process in a closed-loop manner.

  15. Method for identifying biochemical and chemical reactions and micromechanical processes using nanomechanical and electronic signal identification

    Science.gov (United States)

    Holzrichter, John F.; Siekhaus, Wigbert J.

    1997-01-01

    A scanning probe microscope, such as an atomic force microscope (AFM) or a scanning tunneling microscope (STM), is operated in a stationary mode on a site where an activity of interest occurs to measure and identify characteristic time-varying micromotions caused by biological, chemical, mechanical, electrical, optical, or physical processes. The tip and cantilever assembly of an AFM is used as a micromechanical detector of characteristic micromotions transmitted either directly by a site of interest or indirectly through the surrounding medium. Alternatively, the exponential dependence of the tunneling current on the size of the gap in the STM is used to detect micromechanical movement. The stationary mode of operation can be used to observe dynamic biological processes in real time and in a natural environment, such as polymerase processing of DNA for determining the sequence of a DNA molecule.

  16. Double-Barrier Resonant Tunneling in Three and Two Dimensions

    Science.gov (United States)

    Zaslavsky, Alexander

    Double-barrier resonant tunneling devices have attracted great scientific interest, both as novel physical systems based on strong size quantization that exhibit unusual transport behavior and also as a promising class of semiconductor structures for high-speed electronic devices. This thesis describes the physics of transport in double-barrier structures fabricated by conventional planar growth, where the fundamental process involves tunneling from three-dimensional (3D) into two-dimensional (2D) densities of electronic states, as well as in novel 2D double-barrier structures fabricated by regrowth, where 2D electrons tunnel into well-separated ID quantum wire subbands. A brief introduction to the basic theory of resonant tunneling and the results of low-temperature I(V) transport measurements on high -quality planar double-barrier devices is presented in Chapter 1. Chapter 2 examines the bistable I(V) characteristic observed in specially designed asymmetric devices, with the intrinsic nature of this effect confirmed by parallel field magnetotunneling measurements. In Chapter 3 transverse field magnetotunneling is employed to experimentally verify the energy and transverse momentum selection rules that govern transport in resonant tunneling devices. Chapter 4 focuses on the fabrication of 2D resonant tunneling devices by liquid phase epitaxial regrowth on patterned substrates. A brief overview of liquid phase epitaxy and two different in-situ patterning techniques--selective meltback and cleaving inside the chamber--are presented. The measurements of the 2D device fabricated by regrowth on cleaved substrates are presented and analyzed in Chapter 5. The new possibilities opened up by the cleaved substrate regrowth techniques are also discussed, including the realization of an edge -regrown superlattice with novel high-field transport characteristics.

  17. Studies of electron correlation in the photoionization process

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, Richard Allen [Univ. of California, Berkeley, CA (United States)

    1979-03-01

    Electron correlation is a result of the interaction of two or more electrons confined in a region of space, and may conveniently be treated under the formalism of configuration interaction (CI). Photoionization provides a rather direct experimental method for studying configuration interaction. The types of CI involved in the photoionization process can be divided into three categories: initial state configuration interaction (ISCI), final ionic state configuration interaction (FISCI), and continuum state configuration interaction (CSCI). This thesis deals with experimental studies which reveal how the various types of CI may become manifested in photoionization. The experimental methods utilized in this work are photoelectron spectroscopy (PES), electron impact spectroscopy (EIS), and time-resolved fluorescence spectroscopy. The EIS was carried out following the discovery that the UV lamp on a Perkin-Elmer photoelectron spectrometer could be utilized as a source of low energy electrons. The time-resolved fluorescence work utilized both the tunability and the time structure of the radiation available at the Stanford Synchrotron Radiation Laboratory (SSRL). A commercial photoelectron spectrometer equipped with a conventional UV lamp (Hei, Nei) was employed for some of the PES studies, and a novel time-of-flight photoelectron spectrometer was developed for the PES work performed using synchrotron radiation. The PES of Ba, Sm, Eu, and Yb was studied using both Hei (22.22 eV) and Nei (16.85 eV) radiation. Satellite structure observed in these spectra using Nei (and for Yb, Hei also) radiation could be satisfactorily explained by ISCI alone. The Hei spectra of Sm, Eu, and, in particular, Ba showed dramatic changes in the satellite population which could only be explained by a new mechanism, autoionization, which is a special form of CSCI. The detailed nature of this mechanism was explored in Ba using synchrotron radiation. It was found that the autoionizing level decays

  18. Modification by H-termination in growth process of titanium silicide on Si(0 0 1)-2 x 1 observed with scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, T., E-mail: d08gd201@ynu.ac.jp [Faculty of Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501 (Japan); Shudo, K.; Sato, K.; Ohno, S.; Nishioka, H.; Iida, T.; Toramaru, M.; Tanaka, M. [Faculty of Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501 (Japan)

    2009-11-30

    Formation processes of titanium silicide on hydrogen-terminated H/Si(0 0 1)-2 x 1 surface are studied at the atomic scale with a scanning tunneling microscopy (STM). Square-shaped nanoislands were observed on the Ti/H/Si(0 0 1) surface after annealed at 873-1073 K. These are the epitaxial nanoislands moderately grown due to the local orientation relationship between C49-TiSi{sub 2} and Si(0 0 1), because passivation by surface hydrogen on Si(0 0 1) suppresses active and complex bond formation of Ti-Si.

  19. Hardware and software for automating the process of studying high-speed gas flows in wind tunnels of short-term action

    Science.gov (United States)

    Yakovlev, V. V.; Shakirov, S. R.; Gilyov, V. M.; Shpak, S. I.

    2017-10-01

    In this paper, we propose a variant of constructing automation systems for aerodynamic experiments on the basis of modern hardware-software means of domestic development. The structure of the universal control and data collection system for performing experiments in wind tunnels of continuous, periodic or short-term action is proposed. The proposed hardware and software development tools for ICT SB RAS and ITAM SB RAS, as well as subsystems based on them, can be widely applied to any scientific and experimental installations, as well as to the automation of technological processes in production.

  20. Electronic processes in uniaxially stressed p-type germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dubon, Jr., Oscar Danilo [Univ. of California, Berkeley, CA (United States)

    1996-02-01

    Effect of uniaxial stress on acceptor-related electronic processes in Ge single crystals doped with Ga, Be, and Cu were studied by Hall and photo-Hall effect measurements in conjunction with infrared spectroscopy. Stress dependence of hole lifetime in p-type Ge single crystals is used as a test for competing models of non-radiative capture of holes by acceptors. Photo-Hall effect shows that hole lifetime in Ga- and Be-doped Ge increases by over one order of magnitude with uniaxial stress at liq. He temps. Photo-Hall of Ge:Be shows a stress-induced change in the temperature dependence of hole lifetime. This is consistent with observed increase of responsivity of Ge:Ga detectors with uniaxial stress. Electronic properties of Ge:Cu are shown to change dramatically with uniaxial stress; the results provide a first explanation for the performance of uniaxially stressed, Cu-diffused Ge:Ga detectors which display a high conductivity in absence of photon signal and therefore have poor sensitivity.

  1. Automation of the electron-beam welding process

    Science.gov (United States)

    Koleva, E.; Dzharov, V.; Kardjiev, M.; Mladenov, G.

    2016-03-01

    In this work, the automatic control is considered of the vacuum and cooling systems of the located in the IE-BAS equipment for electron-beam welding, evaporation and surface modification. A project was elaborated for the control and management based on the development of an engineering support system using existing and additional technical means of automation. Optimization of the indicators, which are critical for the duration of reaching the working regime and stopping the operation of the installation, can be made using experimentally obtained transient characteristics. The automation of the available equipment aimed at improving its efficiency and the repeatability of the obtained results, as well as at stabilizing the process parameters, should be integrated in an Engineering Support System which, besides the operator supervision, consists of several subsystems for equipment control, data acquisition, information analysis, system management and decision-making support.

  2. BACTERIAL LEACHING OF ELECTRONIC SCRAP: INFLUENCE OF PROCESS PARAMETERS

    Directory of Open Access Journals (Sweden)

    Luciana Harue Yamane

    2013-03-01

    Full Text Available The application of bacterial leaching in the ore treatment is already known and also can be applied such as treatment of electronic waste to copper recovery. This paper investigates the influence of process parameters (pulp density, inoculums volume, rotation speed and initial concentration of ferrous iron on bacterial leaching of copper from printed circuit board of computers using the bacterium Acidithiobacillus ferrooxidans–LR. Printed circuit boards from computers were comminuted using a hammer mill. The powder obtained was magnetically separated and the non-magnetic material used in this study. A shake flask study was carried out on the non-magnetic material using a shaker. The results show that Acidithiobacillus ferrooxidans–LR can leach 99% of copper from printed circuit boards (non–magnetic material under the determined conditions through of the studies.

  3. Nanowire resonant tunneling diodes

    Science.gov (United States)

    Björk, M. T.; Ohlsson, B. J.; Thelander, C.; Persson, A. I.; Deppert, K.; Wallenberg, L. R.; Samuelson, L.

    2002-12-01

    Semiconductor heterostructures and their implementation into electronic and photonic devices have had tremendous impact on science and technology. In the development of quantum nanoelectronics, one-dimensional (1D) heterostructure devices are receiving a lot of interest. We report here functional 1D resonant tunneling diodes obtained via bottom-up assembly of designed segments of different semiconductor materials in III/V nanowires. The emitter, collector, and the central quantum dot are made from InAs and the barrier material from InP. Ideal resonant tunneling behavior, with peak-to-valley ratios of up to 50:1 and current densities of 1 nA/μm2 was observed at low temperatures.

  4. Inelastic scattering in resonant tunneling

    DEFF Research Database (Denmark)

    Wingreen, Ned S.; Jacobsen, Karsten Wedel; Wilkins, John W.

    1989-01-01

    The exact resonant-tunneling transmission probability for an electron interacting with phonons is presented in the limit that the elastic coupling to the leads is independent of energy. The phonons produce transmission sidebands but do not affect the integrated transmission probability or the esc......The exact resonant-tunneling transmission probability for an electron interacting with phonons is presented in the limit that the elastic coupling to the leads is independent of energy. The phonons produce transmission sidebands but do not affect the integrated transmission probability...

  5. Electron transmission through molecules and molecular layers: Theory and Simulations

    Science.gov (United States)

    Nitzan, Abraham

    2000-03-01

    Several aspects of electron transmission through molecular layers will be discussed. (a) The mechanism of electron tunneling through a narrow water barrier between two Pt(100) metal surfaces was studied by numerical simulations.[1] Assuming that the water configuration is static on the time scale of the electron motion, the tunneling probability show distinct resonance structures below the vacuum barrier. These resonances are shown to be associated with molecular cavities in which the electron is trapped between repulsive oxygen cores. The lifetimes of these resonances are found to be of the order 10 fs or less. (b) The concept of 'tunneling time' is revisited and this time is analyzed for a simple superexchange model of electron transfer.[2] This time is computed also for electron tunneling through water and its relation to the resonance features observed in that process and to their lifetime is discussed.[3] (c) Theoretical models that analyze thermal effects in resonance tunneling are presented.[4] References 1. U. Peskin, A. Edlund, I. Bar-On , M. Galperin and A. Nitzan, Transient resonance structures in electron tunneling through water, J. Chem. Phys. 111, 7558 (1999). 2. A. Nitzan, J. Jortner, J. Wilkie and M. Ratner, Tunneling time for electron transfer reactions, to be published. 3. M. Galperin and A. Nitzan, Tunneling time for electron transfer through water, to be published. 4. D. Segal, A. Nitzan, W. B. Davis, M. R. Wasielewski, and M. A. Ratner, Electron Transfer Rates in Bridged Molecular Systems II: A steady state analysis of coherent tunneling and thermal transitions, J. Phys. Chem., in press.

  6. 78 FR 4418 - Electronic Submission Process for Requesting Export Certificates From the Center for Devices and...

    Science.gov (United States)

    2013-01-22

    ... HUMAN SERVICES Food and Drug Administration Electronic Submission Process for Requesting Export... Administration, HHS. ACTION: Notice. SUMMARY: The Food and Drug Administration (FDA) is announcing the availability of an electronic submission process for requesting export certificates for products regulated by...

  7. Math modeling of electronic processes and deep level ionization kinetic

    Directory of Open Access Journals (Sweden)

    A. V. Budanov

    2016-01-01

    Full Text Available Mathematical model of kinetics of charge deep levels in the forbidden band of the semiconductor, which takes into account the processes of carriers charge exchange between deep levels and both allowed bands, which adequately describes the nature of the non-exponential relaxation capacity, is proposed. A method for determining the spectrum of deep level transient spectroscopy having greater accuracy and resolution in comparison with traditional methods using a relaxation time approximation. The results of numerical experiments using the kinetics charge deep levels model in the frameworks of proposed approximations are presented. Account of generational and recombination components of charge exchange processes of all deep levels in the forbidden band of the semiconductor leads to the conclusion that the kinetics of ionization of these centers, in general, does not obey the Boltzmann statistics. Account of charge exchange processes between the deep levels a significantly effects on their recharge kinetics. Numerical analysis results show that the processes of deep levels ionization are more complicated than the staged-type kinetics. It is shown that in most cases stagedtype kinetics at deep level transient spectroscopy leads to significant methodological error in the parameters determination. From the results of numerical analysis follows, that the density of surface electronic states has a significant impact on the overall recharged kinetics of deep levels. Donor deep levels recharge analysis revealed not only the features of the deep levels ionization in semiconductors, but also allowed to answer some questions that are typical to all deep-level transient spectroscopy in general.

  8. Finite Element Models for Electron Beam Freeform Fabrication Process

    Science.gov (United States)

    Chandra, Umesh

    2012-01-01

    Electron beam freeform fabrication (EBF3) is a member of an emerging class of direct manufacturing processes known as solid freeform fabrication (SFF); another member of the class is the laser deposition process. Successful application of the EBF3 process requires precise control of a number of process parameters such as the EB power, speed, and metal feed rate in order to ensure thermal management; good fusion between the substrate and the first layer and between successive layers; minimize part distortion and residual stresses; and control the microstructure of the finished product. This is the only effort thus far that has addressed computer simulation of the EBF3 process. The models developed in this effort can assist in reducing the number of trials in the laboratory or on the shop floor while making high-quality parts. With some modifications, their use can be further extended to the simulation of laser, TIG (tungsten inert gas), and other deposition processes. A solid mechanics-based finite element code, ABAQUS, was chosen as the primary engine in developing these models whereas a computational fluid dynamics (CFD) code, Fluent, was used in a support role. Several innovative concepts were developed, some of which are highlighted below. These concepts were implemented in a number of new computer models either in the form of stand-alone programs or as user subroutines for ABAQUS and Fluent codes. A database of thermo-physical, mechanical, fluid, and metallurgical properties of stainless steel 304 was developed. Computing models for Gaussian and raster modes of the electron beam heat input were developed. Also, new schemes were devised to account for the heat sink effect during the deposition process. These innovations, and others, lead to improved models for thermal management and prediction of transient/residual stresses and distortions. Two approaches for the prediction of microstructure were pursued. The first was an empirical approach involving the

  9. Scanning electron microscope automatic defect classification of process induced defects

    Science.gov (United States)

    Wolfe, Scott; McGarvey, Steve

    2017-03-01

    With the integration of high speed Scanning Electron Microscope (SEM) based Automated Defect Redetection (ADR) in both high volume semiconductor manufacturing and Research and Development (R and D), the need for reliable SEM Automated Defect Classification (ADC) has grown tremendously in the past few years. In many high volume manufacturing facilities and R and D operations, defect inspection is performed on EBeam (EB), Bright Field (BF) or Dark Field (DF) defect inspection equipment. A comma separated value (CSV) file is created by both the patterned and non-patterned defect inspection tools. The defect inspection result file contains a list of the inspection anomalies detected during the inspection tools' examination of each structure, or the examination of an entire wafers surface for non-patterned applications. This file is imported into the Defect Review Scanning Electron Microscope (DRSEM). Following the defect inspection result file import, the DRSEM automatically moves the wafer to each defect coordinate and performs ADR. During ADR the DRSEM operates in a reference mode, capturing a SEM image at the exact position of the anomalies coordinates and capturing a SEM image of a reference location in the center of the wafer. A Defect reference image is created based on the Reference image minus the Defect image. The exact coordinates of the defect is calculated based on the calculated defect position and the anomalies stage coordinate calculated when the high magnification SEM defect image is captured. The captured SEM image is processed through either DRSEM ADC binning, exporting to a Yield Analysis System (YAS), or a combination of both. Process Engineers, Yield Analysis Engineers or Failure Analysis Engineers will manually review the captured images to insure that either the YAS defect binning is accurately classifying the defects or that the DRSEM defect binning is accurately classifying the defects. This paper is an exploration of the feasibility of the

  10. Advanced power electronics converters PWM converters processing AC voltages

    CERN Document Server

    dos Santos, Euzeli

    2014-01-01

    This book covers power electronics, in depth, by presenting the basic principles and application details, which can be used both as a textbook and reference book.  Introduces a new method to present power electronics converters called Power Blocks Geometry. Applicable for courses focusing on power electronics, power electronics converters, and advanced power converters. Offers a comprehensive set of simulation results to help understand the circuits presented throughout the book

  11. Modeling and characterization of double resonant tunneling diodes for application as energy selective contacts in hot carrier solar cells

    Science.gov (United States)

    Jehl, Zacharie; Suchet, Daniel; Julian, Anatole; Bernard, Cyril; Miyashita, Naoya; Gibelli, Francois; Okada, Yoshitaka; Guillemolles, Jean-Francois

    2017-02-01

    Double resonant tunneling barriers are considered for an application as energy selective contacts in hot carrier solar cells. Experimental symmetric and asymmetric double resonant tunneling barriers are realized by molecular beam epitaxy and characterized by temperature dependent current-voltage measurements. The negative differential resistance signal is enhanced for asymmetric heterostructures, and remains unchanged between low- and room-temperatures. Within Tsu-Esaki description of the tunnel current, this observation can be explained by the voltage dependence of the tunnel transmission amplitude, which presents a resonance under finite bias for asymmetric structures. This effect is notably discussed with respect to series resistance. Different parameters related to the electronic transmission of the structure and the influence of these parameters on the current voltage characteristic are investigated, bringing insights on critical processes to optimize in double resonant tunneling barriers applied to hot carrier solar cells.

  12. Time dependence of tunnel statistics and the energy resolution of superconducting tunnel junctions

    Science.gov (United States)

    Verhoeve, P.; Hartog, R. den; Kozorezov, A.; Martin, D.; van Dordrecht, A.; Wigmore, J. K.; Peacock, A.

    2002-11-01

    Multiple tunneling of quasiparticle charge carriers in a superconducting tunnel junction (STJ) enhances the signal generated by a photon absorption event. It is also an additional source of noise, responsible for a substantial degradation of the energy resolution. Although tunneling is a binomial chance process, governed by a constant tunneling probability, the resulting cumulative statistics of tunnelled quasiparticles depend on time. In particular, the variance of the total number of tunneled quasiparticles reaches a minimum after a finite integration time, corresponding to a minimum in the spectral linewidth. Since the intrinsic energy resolution of the present generation of STJs is mainly limited by the scatter on the number of tunneled quasiparticles, the improvement of the tunnel noise can be experimentally tested by variation of the pulse integration time. An analytical theory is developed that describes the relation between the tunnel noise and the transfer function of the pulse integration hardware for an STJ characterized by a quasiparticle tunnel and loss time in each electrode. We present experiments that demonstrate that the noise contribution from multiple tunnelling is not constant during the time that the quasiparticles are present in the STJ, and that by proper filtering of the STJ pulses the tunnel noise can be optimized at a level which lies well below the canonical tunnel limit.

  13. Tunneling Flight Time, Chemistry, and Special Relativity.

    Science.gov (United States)

    Petersen, Jakob; Pollak, Eli

    2017-09-07

    Attosecond ionization experiments have not resolved the question "What is the tunneling time?". Different definitions of tunneling time lead to different results. Second, a zero tunneling time for a material particle suggests that the nonrelativistic theory includes speeds greater than the speed of light. Chemical reactions, occurring via tunneling, should then not be considered in terms of a nonrelativistic quantum theory calling into question quantum dynamics computations on tunneling reactions. To answer these questions, we define a new experimentally measurable paradigm, the tunneling flight time, and show that it vanishes for scattering through an Eckart or a square barrier, irrespective of barrier length or height, generalizing the Hartman effect. We explain why this result does not lead to experimental measurement of speeds greater than the speed of light. We show that this tunneling is an incoherent process by comparing a classical Wigner theory with exact quantum mechanical computations.

  14. Tunneling Time and Weak Measurement in Strong Field Ionization

    Science.gov (United States)

    Zimmermann, Tomáš; Mishra, Siddhartha; Doran, Brent R.; Gordon, Daniel F.; Landsman, Alexandra S.

    2016-06-01

    Tunneling delays represent a hotly debated topic, with many conflicting definitions and little consensus on when and if such definitions accurately describe the physical observables. Here, we relate these different definitions to distinct experimental observables in strong field ionization, finding that two definitions, Larmor time and Bohmian time, are compatible with the attoclock observable and the resonance lifetime of a bound state, respectively. Both of these definitions are closely connected to the theory of weak measurement, with Larmor time being the weak measurement value of tunneling time and Bohmian trajectory corresponding to the average particle trajectory, which has been recently reconstructed using weak measurement in a two-slit experiment [S. Kocsis, B. Braverman, S. Ravets, M. J. Stevens, R. P. Mirin, L. K. Shalm, and A. M. Steinberg, Science 332, 1170 (2011)]. We demonstrate a big discrepancy in strong field ionization between the Bohmian and weak measurement values of tunneling time, and we suggest this arises because the tunneling time is calculated for a small probability postselected ensemble of electrons. Our results have important implications for the interpretation of experiments in attosecond science, suggesting that tunneling is unlikely to be an instantaneous process.

  15. Carpal Tunnel Syndrome

    Science.gov (United States)

    ... a passing cramp? It could be carpal tunnel syndrome. The carpal tunnel is a narrow passageway of ... three times more likely to have carpal tunnel syndrome than men. Early diagnosis and treatment are important ...

  16. Power Electronic Packaging Design, Assembly Process, Reliability and Modeling

    CERN Document Server

    Liu, Yong

    2012-01-01

    Power Electronic Packaging presents an in-depth overview of power electronic packaging design, assembly,reliability and modeling. Since there is a drastic difference between IC fabrication and power electronic packaging, the book systematically introduces typical power electronic packaging design, assembly, reliability and failure analysis and material selection so readers can clearly understand each task's unique characteristics. Power electronic packaging is one of the fastest growing segments in the power electronic industry, due to the rapid growth of power integrated circuit (IC) fabrication, especially for applications like portable, consumer, home, computing and automotive electronics. This book also covers how advances in both semiconductor content and power advanced package design have helped cause advances in power device capability in recent years. The author extrapolates the most recent trends in the book's areas of focus to highlight where further improvement in materials and techniques can d...

  17. Investigation into scanning tunnelling luminescence microscopy

    CERN Document Server

    Manson-Smith, S K

    2001-01-01

    This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provi...

  18. Electronic characterization of LaAlO{sub 3}-SrTiO{sub 3} interfaces by scanning tunneling spectroscopy; Elektronische Charakterisierung von LaAlO{sub 3}-SrTiO{sub 3}-Grenzflaechen mittels Rastertunnelspektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Breitschaft, Martin

    2010-10-22

    When LaAlO{sub 3} is epitaxially grown on TiO{sub 2}-terminated SrTiO{sub 3}, an electrically conducting interface is generated. In this respect, the physical properties of the interface differ substantially from those of both LaAlO{sub 3} and SrTiO{sub 3}, which are electrically insulating in bulk form. This dissertation looks into the question of the microscopic structure of the conducting two-dimensional interface electron system. Comparing the electronic density of states of LaAlO{sub 3}-SrTiO{sub 3} interfaces measured by scanning tunneling spectroscopy with results of density functional theory, the interface electron system is found to be substantially coined by the hosting transition metal lattices. The comparison yields a detailed picture of the microscopic structure of the interface electron system. (orig.)

  19. Electronic Processes at Organic−Organic Interfaces: Insight from Modeling and Implications for Opto-electronic Devices †

    KAUST Repository

    Beljonne, David

    2011-02-08

    We report on the recent progress achieved in modeling the electronic processes that take place at interfaces between π-conjugated materials in organic opto-electronic devices. First, we provide a critical overview of the current computational techniques used to assess the morphology of organic: organic heterojunctions; we highlight the compromises that are necessary to handle large systems and multiple time scales while preserving the atomistic details required for subsequent computations of the electronic and optical properties. We then review some recent theoretical advances in describing the ground-state electronic structure at heterojunctions between donor and acceptor materials and highlight the role played by charge-transfer and long-range polarization effects. Finally, we discuss the modeling of the excited-state electronic structure at organic:organic interfaces, which is a key aspect in the understanding of the dynamics of photoinduced electron-transfer processes. © 2010 American Chemical Society.

  20. Distilling two-center-interference information during tunneling of aligned molecules with orthogonally polarized two-color laser fields

    Science.gov (United States)

    Gao, F.; Chen, Y. J.; Xin, G. G.; Liu, J.; Fu, L. B.

    2017-12-01

    When electrons tunnel through a barrier formed by the strong laser field and the two-center potential of a diatomic molecule, a double-slit-like interference can occur. However, this interference effect can not be probed directly right now, as it is strongly coupled with other dynamical processes during tunneling. Here, we show numerically and analytically that orthogonally polarized two-color (OTC) laser fields are capable of resolving the interference effect in tunneling, while leaving clear footprints of this effect in photoelectron momentum distributions. Moreover, this effect can be manipulated by changing the relative field strength of OTC fields.

  1. Signal processing inspired from the olfactory bulb for electronic noses

    Science.gov (United States)

    Jing, Ya-Qi; Meng, Qing-Hao; Qi, Pei-Feng; Zeng, Ming; Liu, Ying-Jie

    2017-01-01

    A bio-inspired signal processing method is proposed for electronic noses (e-noses). The proposed method contains an olfactory bulb model and a feature generation step. The structure of the olfactory bulb model is similar to the anatomical structure of mammals’ olfactory bulb. It consists of olfactory receptor neurons, mitral cells, granule cells, periglomerular cells, and short axon cells. This model uses gas sensors’ original response curves and transforms them to neuron spiking series no matter what kind the response curve is. This largely simplifies the follow-up feature generation step. Recurrence quantification analysis is employed to perform feature generation and the five most important features are selected. Finally, in order to verify the performance of the proposed method, seven kinds of Chinese liquors are tested and three classification methods are used to classify them. The experimental results demonstrate that the proposed method has a higher classification rate (99.05%) and also a steadier performance with the change of sensor number and types than the classic one.

  2. Accelerating VASP electronic structure calculations using graphic processing units

    KAUST Repository

    Hacene, Mohamed

    2012-08-20

    We present a way to improve the performance of the electronic structure Vienna Ab initio Simulation Package (VASP) program. We show that high-performance computers equipped with graphics processing units (GPUs) as accelerators may reduce drastically the computation time when offloading these sections to the graphic chips. The procedure consists of (i) profiling the performance of the code to isolate the time-consuming parts, (ii) rewriting these so that the algorithms become better-suited for the chosen graphic accelerator, and (iii) optimizing memory traffic between the host computer and the GPU accelerator. We chose to accelerate VASP with NVIDIA GPU using CUDA. We compare the GPU and original versions of VASP by evaluating the Davidson and RMM-DIIS algorithms on chemical systems of up to 1100 atoms. In these tests, the total time is reduced by a factor between 3 and 8 when running on n (CPU core + GPU) compared to n CPU cores only, without any accuracy loss. © 2012 Wiley Periodicals, Inc.

  3. Cross section database for collision processes of helium atom with charged particles. 1. Electron impact processes

    Energy Technology Data Exchange (ETDEWEB)

    Ralchenko, Yu.V.; Janev, R.K.; Kato, T. [National Inst. for Fusion Science, Toki, Gifu (Japan); Fursa, D.V.; Bray, I. [Flinder Univ., Adelaide (Australia); Heer, F.J. de [FOM Institute for Atomic and Molecular Physics, Amsterdam (Netherlands)

    2000-10-01

    A comprehensive and critically assessed cross section database for the inelastic collision processes of ground state and excited helium atoms colliding with electrons, protons and multiply-charged ions has been prepared at the Data and Planning Center at NIFS. The present report describes the first part of the database containing the recommended data for electron impact excitation and ionization of neutral helium. An states (atomic terms) with n {<=} 4 are treated individually while the states with n > 4 are considered degenerate. For the processes involving transitions to and from n > 4 levels, suitable cross section scaling relations are presented. For a large number of electron impact transitions, both from the ground and excited states, new convergent close coupling (CCC) calculations were performed to achieve a high accuracy of the data. The evaluated/recommended cross section data are presented by analytic fit functions which preserve the correct asymptotic behavior of the cross sections. The cross sections are also displayed in a graphical form. (author)

  4. Estimation of the Processing Parameters in Electron Beam Thermal Treatments

    OpenAIRE

    Dulau, Mircea

    2014-01-01

    Electron beam have many special properties which make them particularly well suited for use in materials handling through melting, welding, surface treatment, etc., taking into account that this manufacturing is performed in vacuum. The use of electron beam for surface limited heat treatment of workpiece has brought about a noticeable extension of the beam technologies. Some theoretical aspects and simulation results are presented in this paper, considering a high power electron beam processi...

  5. Frame Stability of Tunnel‐Structured Cryptomelane Nanofibers: The Role of Tunnel Cations

    DEFF Research Database (Denmark)

    Gao, Tao; Norby, Poul

    2013-01-01

    The role of tunnel K+ ions on the growth and stability of tunnel‐structured cryptomelane‐type MnO2 nanofibers (denoted as cryptomelane nanofibers hereafter) has been discussed by means of X‐ray diffraction and electron microscopy. Cryptomelane nanofibers with typical diameters of 20–80 nm...... precursor to the tunnel‐structured cryptomelane, in which the K+ ions play important roles in templating and stabilizing the tunneled framework. The presence of tunnel K+ ions also enhances the frame stability of the cryptomelane nanofibers at elevated temperatures. The formation of a layered KxMn2O4 (x ≈ 0.......26) with a hexagonal phase structure has been observed at about 900 °C. The transformation from tunneled cryptomelane to layered KxMn2O4 also follows the dissolution–recrystallization growth mechanism, in which the diffusion of K+ ions at high temperatures represents a critical process. The topological correlation...

  6. Investigation on the formation process of single-crystalline GaO x barrier in Fe/GaO x /MgO/Fe magnetic tunnel junctions

    Science.gov (United States)

    Krishna, N. S.; Doko, N.; Matsuo, N.; Saito, H.; Yuasa, S.

    2017-11-01

    We have grown Fe(0 0 1)/GaO x (0 0 1)/MgO(0 0 1)/Fe(0 0 1) magnetic tunnel junctions (MTJs) with or without in situ annealing after the deposition of GaO x layer and performed structural characterizations by focusing on the formation process of the single-crystalline GaO x . It was found that, even without the in situ annealing, the as-grown GaO x grown on the MgO was mostly single-crystalline except near the surface region (amorphous). The crystallization temperature of the amorphous region was reduced from 500 °C down to 250 °C by depositing the Fe upper electrode (poly-crystalline). It was clarified that the crystallization of the amorphous region near the Fe/GaO x interface caused the realignments of the crystal grains in the poly-crystalline Fe upper electrode, and, as a result, the fully epitaxial Fe/GaO x /MgO/Fe structure is eventually formed. All the MTJs showed high tunneling magnetoresistance ratios (about 100%) at room temperature, which was almost independent of the formation temperature of the single-crystalline GaO x .

  7. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc bias...

  8. Process-induced damage and its recovery for a CoFeB-MgO magnetic tunnel junction with perpendicular magnetic easy axis

    Science.gov (United States)

    Kinoshita, Keizo; Honjo, Hiroaki; Fukami, Shunsuke; Sato, Hideo; Mizunuma, Kotaro; Tokutome, Keiichi; Murahata, Michio; Ikeda, Shoji; Miura, Sadahiko; Kasai, Naoki; Ohno, Hideo

    2014-10-01

    We investigate the effect of process-induced damage (PID) caused by reactive ion etching using methanol (Me-OH) gas on the magnetic properties of the CoFeB free layer in a magnetic tunnel junction with a perpendicular easy axis (p-MTJ), and on the tunnel magnetoresistance (TMR) ratio of CoFeB-MgO p-MTJs. The dot pattern of the MTJ stack with size varied from 65 to 430 nm etched by the Me-OH plasma showed a smaller coercivity (Hc) than that fabricated by Ar ion milling. The increase in Hc was observed in the dot pattern of large size (430 nm) upon increasing He/H2 plasma treatment temperature after the Me-OH etching. A possible origin of the increase in Hc is the increase in nucleation field after He/H2 treatment. This suggests that Hc of the large dot pattern has the potential to be an index for detecting PID during the MTJ fabrication process. The TMR ratio of CoFeB-MgO p-MTJ deteriorated after the Me-OH plasma etching. This PID was considered to be due to oxidation from the pattern edge of the CoFeB free layer of the MTJ. The recovery process by the He/H2 plasma treatment was examined just after the Me-OH etching to reduce the oxidized part. The median TMR ratio of 102%, which is 5% higher than that of the sample without the He/H2 treatment, was observed after applying this reductive treatment at 180 °C. In addition, the recovery process had scalability with MTJ size, as the effect was observed more clearly in the MTJ smaller than 97 nm.

  9. Construction of a four tip scanning tunneling microscope/scanning electron microscope combination and conductivity measurements of silicide nanowires; Aufbau einer Vierspitzen-Rastertunnelmikroskop/Rasterelektronenmikroskop-Kombination und Leitfaehigkeitsmessungen an Silizid Nanodraehten

    Energy Technology Data Exchange (ETDEWEB)

    Zubkov, Evgeniy

    2013-09-01

    In this work the combination of a four-tip scanning tunneling microscope with a scanning electron microscope is presented. By means of this apparatus it is possible to perform the conductivity measurements on the in-situ prepared nanostructures in ultra-high vacuum. With the aid of a scanning electron microscope (SEM), it becomes possible to position the tunneling tips of the four-tip scanning tunneling microscope (STM), so that an arrangement for a four-point probe measurement on nanostructures can be obtained. The STM head was built according to the novel coaxial Beetle concept. This concept allows on the one hand, a very compact arrangement of the components of the STM and on the other hand, the new-built STM head has a good mechanical stability, in order to achieve atomic resolution with all four STM units. The atomic resolution of the STM units was confirmed by scanning a Si(111)-7 x 7 surface. The thermal drift during the STM operation, as well as the resonant frequencies of the mechanical structure of the STM head, were determined. The scanning electron microscope allows the precise and safe navigation of the tunneling tips on the sample surface. Multi tip spectroscopy with up to four STM units can be performed synchronously. To demonstrate the capabilities of the new-built apparatus the conductivity measurements were carried out on metallic yttrium silicide nanowires. The nanowires were prepared by the in-situ deposition of yttrium on a heated Si(110) sample surface. Current-voltage curves were recorded on the nanowires and on the wetting layer in-between. The curves indicate an existence of the Schottky barrier between the yttrium silicide nanowires and the silicon bulk. By means of the two-tip measurements with a gate, the insulating property of the Schottky barrier has been confirmed. Using this Schottky barrier, it is possible to limit the current to the nanowire and to prevent it from flowing through the silicon bulk. A four-tip resistance measurement

  10. Understanding the thermal sciences in the electron beam melting process through in-situ process monitoring

    Science.gov (United States)

    Raplee, J.; Plotkowski, A.; Kirka, M. M.; Dinwiddie, R.; Dehoff, R. R.; Babu, S. S.

    2017-04-01

    Additive Manufacturing provides the opportunity to fabricate components of nearly limitless complexity compared to that of traditional manufacturing techniques. However, thermal gyrations imparted into the material from the passing of the heat source cause challenges in fabricating complex structures with the proper process parameters. While the thermal history of the material can be simulated, validating the simulations requires access to thermal data generated through in-situ process monitoring. While generation of in-situ thermal data seems trivial, acquiring and developing reliable calibrations for metallic materials is difficult due to the physical state of the material transitioning from powder to liquid to a solid. To be discussed is the methodology taken to integrate IR in-situ process monitoring within the electron beam melting process and the approach developed to accurately correlate a materials emissivity to temperature during the build process. Further the wealth of information contained within the thermal data will be discussed in the context of understanding of microstructural evolutions within the material during the build process, identification of material defects, and ability to determining the similarity/repeatability of builds fabricated with identical processing parameters as based only on the thermal signature of the build.

  11. Influence on surface characteristics of electron beam melting process (EBM) by varying the process parameters

    Science.gov (United States)

    Dolimont, Adrien; Michotte, Sebastien; Rivière-Lorphèvre, Edouard; Ducobu, François; Vivès, Solange; Godet, Stéphane; Henkes, Tom; Filippi, Enrico

    2017-10-01

    The use of additive manufacturing processes keeps growing in aerospace and biomedical industry. Among the numerous existing technologies, the Electron Beam Melting process has advantages (good dimensional accuracy, fully dense parts) and disadvantages (powder handling, support structure, high surface roughness). Analyzes of the surface characteristics are interesting to get a better understanding of the EBM operations. But that kind of analyzes is not often found in the literature. The main goal of this study is to determine if it is possible to improve the surface roughness by modifying some parameters of the process (scan speed function, number of contours, order of contours, etc.) on samples with different thicknesses. The experimental work on the surface roughness leads to a statistical analysis of 586 measures of EBM simple geometry parts.

  12. 78 FR 38072 - Certain Consumer Electronics With Display and Processing Capabilities; Institution of...

    Science.gov (United States)

    2013-06-25

    ... INTERNATIONAL TRADE COMMISSION [Inv. No. 337-TA-884] Certain Consumer Electronics With Display and... electronics with display and processing capabilities by reason of infringement of U.S. Patent No. 6,650,327... after importation of certain consumer electronics with display and processing capabilities by reason of...

  13. 75 FR 38118 - In the Matter of Certain Electronic Devices With Image Processing Systems, Components Thereof...

    Science.gov (United States)

    2010-07-01

    ... COMMISSION In the Matter of Certain Electronic Devices With Image Processing Systems, Components Thereof, and... certain electronic devices with image processing systems, components thereof, and associated software that... importation, and the sale within the United States after importation of certain electronic devices with image...

  14. Tunneling spectroscopy on grain boundary junctions in electron-doped high-temperature superconductors; Tunnelspektroskopie an Korngrenzenkontakten aus elektronendotierten Hochtemperatur-Supraleitern

    Energy Technology Data Exchange (ETDEWEB)

    Welter, B.

    2007-12-07

    Some methods are developed anf presented, by means of which from experimental tunnel spectra, especially on symmetric SIS contacts, informations about the properties of electrodes and tunnel barriers can be obtained. Especially a procedure for the numerical unfolding of symmetric SIS spectra is proposed. Furthermore a series of models is summarized, which can explain the linear background conductivity observed in many spectra on high-temperature superconductors. The results of resistance measurements on film bridges are presented. Especially different methods for the determination of H{sub c2}(T) respectively H{sub c2}(0) are presented and applied to the experimental data. Finally the results of the tunnel-spectroscopy measurements are shown.

  15. [Terminal electron acceptor process in landfill leachate pollution plume].

    Science.gov (United States)

    Dong, Jun; Zhao, Yong-Sheng; Zhang, Wei-Hong; Hong, Mei; Liu, Ying-Ying; Han, Rong

    2008-03-01

    A soil column filled with sandy soil was constructed to investigate changes of terminal electron acceptors (TEA) and TOC in redox zones of landfill leachate pollution plume, and their models were established, respectively. Results indicated that the time of peak-concentration appearance of different reducing products was related to the ability of terminal electron acceptors to compete for terminal electrons. The most competitive ones showed sharp concentration increased earlier. For example, the peak concentration of NO2(-) appeared earlier than that of Fe2+. The concentration of TOC increased in methanogenic zone, iron reduction zone, nitrate reduction zone and oxygen reduction zone, and its rate was 8.27, 8.56, 8.85, 9.06 and 9.11 mg/(L h), respectively. Degradation rate of contaminants by different microbes mainly depended on the amount and availability of terminal electron acceptors. The reaction rate was related to ability of terminal electron acceptors to compete for terminal electron, that is the stronger the ability of terminal electron acceptors to compete for terminal electrons, the easier could be used and consumed by microorganisms and the more sensitive to reflect on environmental pollution.

  16. The growth of epitaxial iron oxides on platinum (111) as studied by X-ray photoelectron diffraction, scanning tunneling microscopy, and low energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong -Joo [Univ. of California, Berkeley, CA (United States)

    1995-05-01

    Three complementary surface structure probes, x-ray photoelectron diffraction (XPD), scanning tunneling microscopy (STM), and low-energy electron diffraction (LEED) have been combined in a single instrument. This experimental system has been utilized to study the structure and growth mechanisms of iron oxide films on Pt(111); these films were formed by first depositing a single overlayer of Fe with a certain coverage in monolayers (ML`s), and then thermally oxidizing it in an oxygen atmosphere. For films up to ~1 ML in thickness, a bilayer of Fe and O similar to those in FeO(111) is found to form. In agreement with prior studies, STM and LEED show this to be an incommensurate oxide film forming a lateral superlattice with short- and long-range periodicities of ~3.1 Å and ~26.0 Å. XPD in addition shows a topmost oxygen layer to be relaxed inward by -0.6 Å compared to bulk FeO(111), and these are new structural conclusions. The oxygen stacking in the FeO(111) bilayer is dominated by one of two possible binding sites. For thicker iron oxide films from 1.25 ML to 3.0 ML, the growth mode is essentially Stranski-Krastanov: iron oxide islands form on top of the FeO(111) bilayer mentioned above. For iron oxide films of 3.0 ML thickness, x-ray photoelectron spectroscopy (XPS) yields an Fe 2p3/2 binding energy and an Fe:O stoichiometry consistent with the presence of Fe3O4. Our XPD data further prove this overlayer to be Fe3O4(111)-magnetite in two almost equally populated domains with a 180° rotation between them. The structural parameters for this Fe3O4 overlayer generally agree with those of a previous LEED study, except that we find a significant difference in the first Fe-O interplanar spacing. This work demonstrates the considerable benefits to be derived by using this set of complementary surface structure probes in such epitaxial growth studies.

  17. On the question of democratization of the electoral process: the essence and instruments of electronic marketing

    Directory of Open Access Journals (Sweden)

    Mykhalchuk Svitlana Olexandrivna

    2016-07-01

    Full Text Available The article examines the essence and instruments of electronic marketing as a factor of democratization of the electoral process. The author analyses the concepts of political, electoral and electronic marketing. The article outlines the levels of development of electronic marketing in political activity. Electronic marketing is substantiated as a component of political theory and practice. The author pays special attention to the extension and intensification of electoral marketing functions through the use of electronic mechanisms.

  18. The future of electronic power processing and conversion

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Consoli, A.; Ferreira, J.A.

    2005-01-01

    . - A large penetration of power electronics into power systems will happen within the next 25-30 years. The main transmission grid will not be affected. The power electronics development will be in distributed generation and in the loads. - The success of the integrated starter/generator, hybrid or electric...... cars depends on political decisions more than on technological advances. However, the success of a recent Japanese hybrid car and the cost of oil could trigger the critical momentum for large-scale use of power electronics in automotive applications. - We are moving toward standardized power supply...

  19. Electron Processing at 50 eV of Terphenylthiol Self-Assembled Monolayers: Contributions of Primary and Secondary Electrons.

    Science.gov (United States)

    Houplin, Justine; Dablemont, Céline; Sala, Leo; Lafosse, Anne; Amiaud, Lionel

    2015-12-22

    Aromatic self-assembled monolayers (SAMs) can serve as platforms for development of supramolecular assemblies driven by surface templates. For many applications, electron processing is used to locally reinforce the layer. To achieve better control of the irradiation step, chemical transformations induced by electron impact at 50 eV of terphenylthiol SAMs are studied, with these SAMs serving as model aromatic SAMs. High-resolution electron energy loss spectroscopy (HREELS) and electron-stimulated desorption (ESD) of neutral fragment measurements are combined to investigate electron-induced chemical transformation of the layer. The decrease of the CH stretching HREELS signature is mainly attributed to dehydrogenation, without a noticeable hybridization change of the hydrogenated carbon centers. Its evolution as a function of the irradiation dose gives an estimate of the effective hydrogen content loss cross-section, σ = 2.7-4.7 × 10(-17) cm(2). Electron impact ionization is the major primary mechanism involved, with the impact electronic excitation contributing only marginally. Therefore, special attention is given to the contribution of the low-energy secondary electrons to the induced chemistry. The effective cross-section related to dissociative secondary electron attachment at 6 eV is estimated to be 1 order of magnitude smaller. The 1 eV electrons do not induce significant chemical modification for a 2.5 mC cm(-2) dose, excluding their contribution.

  20. Theory of interrelated electron and proton transfer processes

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2003-01-01

    A simple theory of elementary act of interrelated reactions of electron and proton transfer is developed. Mechanisms of synchronous and multistage transfer and coherent transitions via a dynamically populated intermediate state are discussed. Formulas for rate constants of adiabatic and nonadiaba......A simple theory of elementary act of interrelated reactions of electron and proton transfer is developed. Mechanisms of synchronous and multistage transfer and coherent transitions via a dynamically populated intermediate state are discussed. Formulas for rate constants of adiabatic...

  1. Antenna-coupled photon emission from hexagonal boron nitride tunnel junctions

    Science.gov (United States)

    Parzefall, M.; Bharadwaj, P.; Jain, A.; Taniguchi, T.; Watanabe, K.; Novotny, L.

    2015-12-01

    The ultrafast conversion of electrical signals to optical signals at the nanoscale is of fundamental interest for data processing, telecommunication and optical interconnects. However, the modulation bandwidths of semiconductor light-emitting diodes are limited by the spontaneous recombination rate of electron-hole pairs, and the footprint of electrically driven ultrafast lasers is too large for practical on-chip integration. A metal-insulator-metal tunnel junction approaches the ultimate size limit of electronic devices and its operating speed is fundamentally limited only by the tunnelling time. Here, we study the conversion of electrons (localized in vertical gold-hexagonal boron nitride-gold tunnel junctions) to free-space photons, mediated by resonant slot antennas. Optical antennas efficiently bridge the size mismatch between nanoscale volumes and far-field radiation and strongly enhance the electron-photon conversion efficiency. We achieve polarized, directional and resonantly enhanced light emission from inelastic electron tunnelling and establish a novel platform for studying the interaction of electrons with strongly localized electromagnetic fields.

  2. Electron beam processed plasticized epoxy coatings for surface protection

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Mervat S. [National Center for Radiation Research and Technology, Nasr City (Egypt); Mohamed, Heba A., E-mail: hebaamohamed@gmail.com [National Research Center, Dokki (Egypt); Kandile, Nadia G. [University College for Girls, Ain Shams University (Egypt); Said, Hossam M.; Mohamed, Issa M. [National Center for Radiation Research and Technology, Nasr City (Egypt)

    2011-10-17

    Highlights: {center_dot} Coating formulations with EA 70%, HD 20%, and castor oil 10% under 1 Mrad pass{sup -1} irradiation dose showed the best adhesion and passed bending tests. {center_dot} The prepared EP-SF-An adduct improve anti-corrosion properties of coatings without any significant effect on physical, mechanical and chemical properties of the cured film. The optimum amount of aniline adduct as corrosion inhibitor was found to be 0.4 g for 100 g of coating formulation. {center_dot} The corrosion inhibition efficiency of the prepared adduct competed the commercial efficiency. - Abstract: Epoxy acrylate oligomer (EA) was plasticized by adding different plasticizers such as epoxidized soybean oil, glycerol and castor oil and cured by electron beam (EB). Different irradiation doses (1, 2.5 and 5 Mrad pass{sup -1}) were used in the curing process. The effect of both different irradiation doses and plasticizers on the end use performance properties of epoxy acrylate coating namely, pencil hardness, bending test, adhesion test, acid and alkali resistance test were studied. It was observed that incorporation of castor oil in epoxy acrylate diluted by 1,6-hexanediol diacrylate (HD) monomer with a ratio (EA 70%, HD 20%, castor oil 10%) under 1 Mrad pass{sup -1} irradiation dose improved the physical, chemical and mechanical properties of cured films than the other plasticizer. Sunflower free fatty acid was epoxidized in situ under well established conditions. The epoxidized sunflower free fatty acids (ESFA) were subjected to react with aniline in sealed ampoules under inert atmosphere at 140 deg. C. The produced adducts were added at different concentrations to epoxy acrylate coatings under certain EB irradiation dose and then evaluated as corrosion inhibitors for carbon steel surfaces in terms of weight loss measurements and corrosion resistance tests. It was found that, addition of 0.4 g of aniline adduct to 100 g epoxy acrylate formula may give the best corrosion

  3. Scale invariance of a diode-like tunnel junction

    Science.gov (United States)

    Cabrera, Hugo; Zanin, Danilo Andrea; de Pietro, Lorenzo Giuseppe; Michaels, Thomas; Thalmann, Peter; Ramsperger, Urs; Vindigni, Alessandro; Pescia, Danilo

    2013-03-01

    In Near Field-Emission SEM (NFESEM), electrostatic considerations favor a diode-like tunnel junction consisting of an atomic-sized source mounted at the apex of a thin wire placed at nanometric distances from a collector. The quantum mechanical tunnel process, instead, can provide a barrier toward miniaturization. In the first place, it deteriorates the generation of electrons by introducing non-linearities within the classically forbidden zone that exponentially increase with decreasing sizes. In addition, in the direct tunnelling regime, i.e. when the distance between emitter and collector d approaches the subnanometer range, a characteristic length appears, making the cross-over from the (almost) scale-invariant electric-field assisted regime to the essentially different STM-regime. We have observed that the experimental data relating the current I to the two experimental variables V (bias voltage between tip and collector) and d can be made (almost) collapse onto a ``scaling curve'' relating I to the single variable V .d-λ , λ being some exponent that depends solely on the geometry of the junction. This scaling property can be used to highlight non-linear aspects of the quantum mechanical tunnelling process.

  4. Evaluation of an Experimental Model for Flat-Fan Nozzles Drift in Wind Tunnel by Image Processing

    Directory of Open Access Journals (Sweden)

    S.H Fattahi

    2014-09-01

    Full Text Available Each year, millions of liters of toxic liquid, are used to combat with pests and plant diseases in farms. The wide spread use of chemical pesticides causes great environmental hazards. Particles drift is one of the main problems in spraying which results in the contamination of farm lands, humans and animals. Management of particle size is regarded as the main factor in drift control. In this study, the effect of some parameters on the size of deposited particles on non-target areas was studied using statistical method. The effects of nozzle type (orifice size, spraying pressure, spraying boom height and wind speed as effective factors on drift were examined. A horizontal wind tunnel with working section of 0.47 m wide, 0.75 m height and 5.5 m long was used for testing. Experiment was performed in the form of factorial split-plot based on randomized complete block design with two replications. Droplets were measured in the treatment combinations of the type of flat-fan nozzle with three orifice area (11003- 0.87 mm2, 11004-1.18 mm2 and 11006- 1.8 mm2, spraying pressure (150, 275 and 400 kpa, wind speed (1, 2 and 3 m s-1 and the boom height of (0.35, 0.55 and 0.75 m. Water-sensitive papers were used at intervals of 0.8, 1.6 and 2.4 m from the tip of nozzles for detecting droplets size. The factors of pressure, speed and height had positive effects on the droplet size at the desired distance, but the effect of nozzle size on droplet size was negative. In the regression model the coefficients of speed was higher than the others.

  5. Scanning tunneling spectroscopy of graphene on graphite.

    Science.gov (United States)

    Li, Guohong; Luican, Adina; Andrei, Eva Y

    2009-05-01

    We report low temperature high magnetic field scanning tunneling microscopy and spectroscopy of graphene flakes on graphite that exhibit the structural and electronic properties of graphene decoupled from the substrate. Pronounced peaks in the tunneling spectra develop with increasing field revealing a Landau level sequence that provides a direct way to identify graphene and to determine the degree of its coupling to the substrate. The Fermi velocity and quasiparticle lifetime, obtained from the positions and width of the peaks, provide access to the electron-phonon and electron-electron interactions.

  6. Analysis of electron capture process in charge pumping sequence using time domain measurements

    Energy Technology Data Exchange (ETDEWEB)

    Hori, Masahiro, E-mail: hori@eng.u-toyama.ac.jp; Watanabe, Tokinobu; Ono, Yukinori [Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Tsuchiya, Toshiaki [Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504 (Japan)

    2014-12-29

    A method for analyzing the electron capture process in the charge pumping (CP) sequence is proposed and demonstrated. The method monitors the electron current in the CP sequence in time domain. This time-domain measurements enable us to directly access the process of the electron capture to the interface defects, which are obscured in the conventional CP method. Using the time-domain measurements, the rise time dependence of the capture process is systematically investigated. We formulate the capture process based on the rate equation and derive an analytic form of the current due to the electron capture to the defects. Based on the formula, the experimental data are analyzed and the capture cross section is obtained. In addition, the time-domain data unveil that the electron capture process completes before the electron channel opens, or below the threshold voltage in a low frequency range of the pulse.

  7. Theory of the magnon-mediated tunnel magneto-Seebeck effect

    Science.gov (United States)

    Flebus, Benedetta; Bauer, Gerrit E. W.; Duine, Rembert A.; Tserkovnyak, Yaroslav

    2017-09-01

    The tunnel magneto-Seebeck effect is the dependence of the thermopower of magnetic tunnel junctions on the magnetic configuration. It is conventionally interpreted in terms of a thermoelectric generalization of the tunnel magnetoresistance. Here, we investigate the heat-driven electron transport in these junctions associated with electron-magnon scattering, using stochastic Landau-Lifshitz phenomenology and quantum kinetic theory. Our findings challenge the widely accepted single-electron picture of the tunneling thermopower in magnetic junctions.

  8. Processes of electron attachment and detachment in near breakdown conditions in air plasma

    Science.gov (United States)

    Ardelyan, N.; Bychkov, V.; Belousov, A.; Kosmachevskii, K.

    2017-11-01

    Results of theoretical research on ionization of dry air at different low and moderate values of constant electric field are described. Special attention to the processes of electron attachment to oxygen molecules and electron detachment from negative ions has been paid. New data on the detachment of electrons from oxygen molecular negative ions are taken into account.

  9. High Surface Area Tunnels in Hexagonal WO₃.

    Science.gov (United States)

    Sun, Wanmei; Yeung, Michael T; Lech, Andrew T; Lin, Cheng-Wei; Lee, Chain; Li, Tianqi; Duan, Xiangfeng; Zhou, Jun; Kaner, Richard B

    2015-07-08

    High surface area in h-WO3 has been verified from the intracrystalline tunnels. This bottom-up approach differs from conventional templating-type methods. The 3.67 Å diameter tunnels are characterized by low-pressure CO2 adsorption isotherms with nonlocal density functional theory fitting, transmission electron microscopy, and thermal gravimetric analysis. These open and rigid tunnels absorb H(+) and Li(+), but not Na(+) in aqueous electrolytes without inducing a phase transformation, accessing both internal and external active sites. Moreover, these tunnel structures demonstrate high specific pseudocapacitance and good stability in an H2SO4 aqueous electrolyte. Thus, the high surface area created from 3.67 Å diameter tunnels in h-WO3 shows potential applications in electrochemical energy storage, selective ion transfer, and selective gas adsorption.

  10. Tunneling field effect transistor technology

    CERN Document Server

    Chan, Mansun

    2016-01-01

    This book provides a single-source reference to the state-of-the art in tunneling field effect transistors (TFETs). Readers will learn the TFETs physics from advanced atomistic simulations, the TFETs fabrication process and the important roles that TFETs will play in enabling integrated circuit designs for power efficiency. · Provides comprehensive reference to tunneling field effect transistors (TFETs); · Covers all aspects of TFETs, from device process to modeling and applications; · Enables design of power-efficient integrated circuits, with low power consumption TFETs.

  11. Nature of "superluminal" barrier tunneling.

    Science.gov (United States)

    Winful, Herbert G

    2003-01-17

    We show that the distortionless tunneling of electromagnetic pulses through a barrier is a quasistatic process in which the slowly varying envelope of the incident pulse modulates the amplitude of a standing wave. For pulses longer than the barrier width, the barrier acts as a lumped element with respect to the pulse envelope. The envelopes of the transmitted and reflected fields can adiabatically follow the incident pulse with only a small delay that originates from energy storage. The theory presented here provides a physical explanation of the tunneling process and resolves the mystery of apparent superluminality.

  12. On the question of democratization of the electoral process: the essence and instruments of electronic marketing

    OpenAIRE

    Mykhalchuk Svitlana Olexandrivna

    2016-01-01

    The article examines the essence and instruments of electronic marketing as a factor of democratization of the electoral process. The author analyses the concepts of political, electoral and electronic marketing. The article outlines the levels of development of electronic marketing in political activity. Electronic marketing is substantiated as a component of political theory and practice. The author pays special attention to the extension and intensification of electoral marketing functions...

  13. Equalization-enhanced phase noise for coherent-detection systems using electronic digital signal processing.

    Science.gov (United States)

    Shieh, William; Ho, Keang-Po

    2008-09-29

    In coherent optical systems employing electronic digital signal processing, the fiber chromatic dispersion can be gracefully compensated in electronic domain without resorting to optical techniques. Unlike optical dispersion compensator, the electronic equalizer enhances the impairments from the laser phase noise. This equalization-enhanced phase noise (EEPN) imposes a tighter constraint on the receive laser phase noise for transmission systems with high symbol rate and large electronically-compensated chromatic dispersion.

  14. System design and verification process for LHC programmable trigger electronics

    CERN Document Server

    Crosetto, D

    1999-01-01

    The rapid evolution of electronics has made it essential to design systems in a technology-independent form that will permit their realization in any future technology. This article describes two practical projects that have been developed for fast, programmable, scalable, modular electronics for the first-level trigger of Large Hadron Collider (LHC) experiments at CERN, Geneva. In both projects, one for the front-end electronics and the second for executing first- level trigger algorithms, the whole system requirements were constrained to two types of replicated components. The overall problem is described, the 3D-Flow design is introduced as a novel solution, and current solutions to the problem are described and compared with the 3D-Flow solution. The design/verification methodology proposed allows the user's real-time system algorithm to be verified down to the gate-level simulation on a technology- independent platform, thus yielding the design for a system that can be implemented with any technology at ...

  15. Electronic Versus Manual Data Processing: Evaluating the Use of Electronic Health Records in Out-of-Hospital Clinical Research

    Science.gov (United States)

    Newgard, Craig D.; Zive, Dana; Jui, Jonathan; Weathers, Cody; Daya, Mohamud

    2011-01-01

    Objectives To compare case ascertainment, agreement, validity, and missing values for clinical research data obtained, processed, and linked electronically from electronic health records (EHR), compared to “manual” data processing and record abstraction in a cohort of out-ofhospital trauma patients. Methods This was a secondary analysis of two sets of data collected for a prospective, population-based, out-of-hospital trauma cohort evaluated by 10 emergency medical services (EMS) agencies transporting to 16 hospitals, from January 1, 2006 through October 2, 2007. Eighteen clinical, operational, procedural, and outcome variables were collected and processed separately and independently using two parallel data processing strategies, by personnel blinded to patients in the other group. The electronic approach included electronic health record data exports from EMS agencies, reformatting and probabilistic linkage to outcomes from local trauma registries and state discharge databases. The manual data processing approach included chart matching, data abstraction, and data entry by a trained abstractor. Descriptive statistics, measures of agreement, and validity were used to compare the two approaches to data processing. Results During the 21-month period, 418 patients underwent both data processing methods and formed the primary cohort. Agreement was good to excellent (kappa 0.76 to 0.97; intraclass correlation coefficient 0.49 to 0.97), with exact agreement in 67% to 99% of cases, and a median difference of zero for all continuous and ordinal variables. The proportions of missing out-of-hospital values were similar between the two approaches, although electronic processing generated more missing outcomes (87 out of 418, 21%, 95% CI = 17% to 25%) than the manual approach (11 out of 418, 3%, 95% CI = 1% to 5%). Case ascertainment of eligible injured patients was greater using electronic methods (n = 3,008) compared to manual methods (n = 629). Conclusions In this

  16. Role of Water in Electron-Initiated Processes and Radical Chemistry: Issues and Scientific Advances

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, Bruce C.; Dixon, David A.; Camaioni, Donald M.; Chipman, Daniel M.; Johnson, Mark A.; Jonah, Charles D.; Kimmel, Greg A.; Miller, John H.; Rescigno, Tom; Rossky, Peter J.; Xantheas, Sotiris S.; Colson, Steve D.; Laufer, Allan H.; Ray, Douglas; Barbara, Paul F.; Bartels, David M.; Bowen, Kit H.; Becker, Kurt H.; Bradforth, Stephen E.; Carmichael, Ian; Coe, James V.; Corrales, L. Rene; Cowin, James P.; Dupuis, Michel; Eisenthal, Kenneth B.; Franz, James A.; Gutowski, Maciej S.; Jordon, Kenneth D.; Kay, Bruce D.; La Verne, Jay A.; Lymar, Sergei V.; Madey, Theodore E.; Mccurdy, C. W.; Meisel, Dan; Mukamel, Shaul; Nilsson, Anders R.; Orlando, Thomas M.; Petrik, Nikolay G.; Pimblott, Simon M.; Rustad, James R.; Schenter, Gregory K.; Singer, Sherwin J.; Tokmakoff, Andrei; Wang, Lai-Sheng; Wittig, Curt; Zwier, Timothy S.

    2005-01-12

    An understanding of electron-initiated processes in aqueous systems and the subsequent radical chemistry these processes induce is significant in such diverse fields as waste remediation and environmental cleanup, radiation processing, nuclear reactors, and medical diagnosis and therapy. We review the state of the art in the physical chemistry and chemical physics of electron-initiated processes in aqueous systems and raise critical research issues and fundamental questions that remain unanswered.

  17. Multi-electron processes in slow He2+-Nacollisions measured with MOTRIMS

    NARCIS (Netherlands)

    Knoop, S; Turkstra, JW; Morgenstern, R; Olson, RE; Hoekstra, R

    We have measured multi-electron processes in collisions of He2+ ions on Na at 6 keV/amu impact energy with the MOTRIMS technique, in which a laser-cooled target is used for recoil ion momentum spectroscopy. Beside true single and double electron capture, processes involving ionization have been

  18. Extracellular sheets and tunnels modulate glutamate diffusion in hippocampal neuropil.

    Science.gov (United States)

    Kinney, Justin P; Spacek, Josef; Bartol, Thomas M; Bajaj, Chandrajit L; Harris, Kristen M; Sejnowski, Terrence J

    2013-02-01

    Although the extracellular space in the neuropil of the brain is an important channel for volume communication between cells and has other important functions, its morphology on the micron scale has not been analyzed quantitatively owing to experimental limitations. We used manual and computational techniques to reconstruct the 3D geometry of 180 μm(3) of rat CA1 hippocampal neuropil from serial electron microscopy and corrected for tissue shrinkage to reflect the in vivo state. The reconstruction revealed an interconnected network of 40-80 nm diameter tunnels, formed at the junction of three or more cellular processes, spanned by sheets between pairs of cell surfaces with 10-40 nm width. The tunnels tended to occur around synapses and axons, and the sheets were enriched around astrocytes. Monte Carlo simulations of diffusion within the reconstructed neuropil demonstrate that the rate of diffusion of neurotransmitter and other small molecules was slower in sheets than in tunnels. Thus, the non-uniformity found in the extracellular space may have specialized functions for signaling (sheets) and volume transmission (tunnels). Copyright © 2012 Wiley Periodicals, Inc.

  19. Electron Number Diagram for Study of Corrosion Processes.

    Science.gov (United States)

    1986-09-26

    electrodeposition, hydrometallurgy and geochemistry. Work has focused the single redox element systems Cu, Cr, Fe, S and U and the two redox element systems...find use in such diverse fields as hydrometallurgy , sulfur removal processes, electrolytic processes and geochemistry. 3. SUKMARY OF MST DURTANT RJLTS A

  20. Quantum electron transfer processes induced by thermo-coherent ...

    Indian Academy of Sciences (India)

    WINTEC

    Katz et al11 and by Silbey et al12 along with a bridge mediated processes in refs 13–15. Another major change in the work of ET processes was appeared to ... transfer rate27,28 for the solvent mode and intramolecu- lar mode to incorporate the quantum nature of the potential surfaces of the reactants and products. As a.

  1. Icing Research Tunnel

    Science.gov (United States)

    Chennault, Jonathan

    2004-01-01

    The Icing Research Tunnel in Building 11 at the NASA Glenn Research Center is committed to researching the effects of in flight icing on aircraft and testing ways to stop the formation of hazardous icing conditions on planes. During this summer, I worked here with Richard DelRosa, the lead engineer for this area. address one of the major concerns of aviation: icing conditions. During the war, many planes crashed (especially supply planes going over the.Himalayas) because ice built up in their wings and clogged the engines. To this day, it remains the largest ice tunnel in the world, with a test section that measures 6 feet high, 9 feet long, and 20 feet wide. It can simulate airspeeds from 50 to 300 miles per hour at temperatures as low as -50 Fahrenheit. Using these capabilities, IRT can simulate actual conditions at high altitudes. The first thing I did was creating a cross reference in Microsoft Excel. It lists commands for the DPU units that control the pressure and temperature variations in the tunnel, as well as the type of command (keyboard, multiplier, divide, etc). The cross reference also contains the algorithm for every command, and which page it is listed in on the control sheet (visual Auto-CAD graphs, which I helped to make). I actually spent most of the time on the computer using Auto-CAD. I drew a diagram of the entire icing tunnel and then drew diagrams of its various parts. Between my mentor and me, we have drawings of every part of it, from the spray bars to the thermocouples, power cabinets, input-output connectors for power systems, and layouts of various other machines. I was also responsible for drawing schematics for the Escort system (which controls the spray bars), the power system, DPUs, and other electrical systems. In my spare time, I am attempting to build and program the "toddler". Toddler is a walking robot that I have to program in PBASIC language. When complete, it should be able to walk on level terrain while avoiding obstacles in

  2. Technology and equipment for processing diamond materials of modern electronics

    Directory of Open Access Journals (Sweden)

    Mityagin A. Yu.

    2009-02-01

    Full Text Available The methods of selection and sorting of diamonds according to their physical properties by modern physical methods of the analysis are developed, as well as the technologies of precision laser cutting of diamonds, their processing on a basis of thermochemical reactions in gas environment. The experimental installation for polishing and grinding of diamond plates, installation for slicing, installation for plasma-chemical processing are created. The techniques of surface roughness measurement of the processed plates and control of roughness parameters are developed. Some experimental results are given.

  3. Nanomaterials processing toward large-scale flexible/stretchable electronics

    Science.gov (United States)

    Takahashi, Toshitake

    In recent years, there has been tremendous progress in large-scale mechanically flexible electronics, where electrical components are fabricated on non-crystalline substrates such as plastics and glass. These devices are currently serving as the basis for various applications such as flat-panel displays, smart cards, and wearable electronics. In this thesis, a promising approach using chemically synthesized nanomaterials is explored to overcome various obstacles current technology faces in this field. Here, we use chemically synthesized semiconducting nanowires (NWs) including group IV (Si, Ge), III-V (InAs) and II-IV (CdS, CdSe) NWs, and semiconductor-enriched SWNTs (99 % purity), and developed reliable, controllable, and more importantly uniform assembly methods on 4-inch wafer-scale flexible substrates in the form of either parallel NW arrays or SWNT random networks, which act as the active components in thin film transistors (TFTs). Thusly obtained TFTs composed of nanomaterials show respectable electrical and optical properties such as 1) cut-off frequency, ft ~ 1 GHz and maximum frequency of oscillation, fmax ~ 1.8 GHz from InAs parallel NW array TFTs with channel length of ~ 1.5 μm, 2) photodetectors covering visible wavelengths (500-700 nm) using compositionally graded CdSxSe1-x (0 x-ray imaging device is also achieved by combining organic photodiodes with this backplane technology.

  4. Electronic Questionnaires for Investigations Processing (e-QIP)

    Data.gov (United States)

    Office of Personnel Management — e-QIP is a web-based automated system that was designed to facilitate the processing of standard investigative forms used when conducting background investigations...

  5. Scanning Tunneling Spectroscopy of Graphene on Graphite

    OpenAIRE

    Li, Guohong; Luican, Adina; Andrei, Eva Y.

    2008-01-01

    We report low temperature high magnetic field scanning tunneling microscopy and spectroscopy of graphene flakes on graphite that exhibit the structural and electronic properties of graphene decoupled from the substrate. Pronounced peaks in the tunneling spectra develop with field revealing a Landau level sequence that provides a direct way to identify graphene and to determine the degree of its coupling to the substrate. The Fermi velocity and quasiparticle lifetime, obtained from the positio...

  6. On electronic process guides for IT service management

    OpenAIRE

    Mora, Manuel; O?Connor, Rory; Gelman, Ovsei

    2010-01-01

    IT practitioners interested in implementing IT Service Management processes (like ISO/IEC 20000; CMMI-SVC, ITIL v2, or ITIL v3, or proprietary process models as ITUP (IBM), MOF 3.0/4.0 (Microsoft) are faced with the challenge to consult complex documents for learning and training purposes.. Such documents contain an inherent complexity by the number of schemes, categories, activities, roles, forms, techniques, concepts, attributes, and their interrelationships. Given this problem, a research ...

  7. Step tunneling enhanced asymmetry in metal-insulator-insulator-metal (MIIM) diodes for rectenna applications

    Science.gov (United States)

    Alimardani, N.; Conley, J. F.

    2013-09-01

    We combine nanolaminate bilayer insulator tunnel barriers (Al2O3/HfO2, HfO2/Al2O3, Al2O3/ZrO2) deposited via atomic layer deposition (ALD) with asymmetric work function metal electrodes to produce MIIM diodes with enhanced I-V asymmetry and non-linearity. We show that the improvements in MIIM devices are due to step tunneling rather than resonant tunneling. We also investigate conduction processes as a function of temperature in MIM devices with Nb2O5 and Ta2O5 high electron affinity insulators. For both Nb2O5 and Ta2O5 insulators, the dominant conduction process is established as Schottky emission at small biases and Frenkel-Poole emission at large biases. The energy depth of the traps that dominate Frenkel-Poole emission in each material are estimated.

  8. Carpal tunnel biopsy

    Science.gov (United States)

    ... tunnel Images Carpal tunnel syndrome Surface anatomy - normal palm Surface anatomy - normal wrist Carpal biopsy References Calandruccio ... CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. ...

  9. Transonic Dynamics Tunnel (TDT)

    Data.gov (United States)

    Federal Laboratory Consortium — The Transonic Dynamics Tunnel (TDT) is a continuous flow wind-tunnel facility capable of speeds up to Mach 1.2 at stagnation pressures up to one atmosphere. The TDT...

  10. Hypersonic Tunnel Facility (HTF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Hypersonic Tunnel Facility (HTF) is a blow-down, non-vitiated (clean air) free-jet wind tunnel capable of testing large-scale, propulsion systems at Mach 5, 6,...

  11. Carpal tunnel repair - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100078.htm Carpal tunnel repair - series—Normal anatomy To use the sharing ... in the wrist and the wrist bones (carpal tunnel). Review Date 4/18/2017 Updated by: C. ...

  12. Road and Railroad Tunnels

    Data.gov (United States)

    Department of Homeland Security — Tunnels in the United States According to the HSIP Tiger Team Report, a tunnel is defined as a linear underground passageway open at both ends. This dataset is based...

  13. Quantum theory of tunneling

    CERN Document Server

    Razavy, Mohsen

    2014-01-01

    In this revised and expanded edition, in addition to a comprehensible introduction to the theoretical foundations of quantum tunneling based on different methods of formulating and solving tunneling problems, different semiclassical approximations for multidimensional systems are presented. Particular attention is given to the tunneling of composite systems, with examples taken from molecular tunneling and also from nuclear reactions. The interesting and puzzling features of tunneling times are given extensive coverage, and the possibility of measurement of these times with quantum clocks are critically examined. In addition by considering the analogy between evanescent waves in waveguides and in quantum tunneling, the times related to electromagnetic wave propagation have been used to explain certain aspects of quantum tunneling times. These topics are treated in both non-relativistic as well as relativistic regimes. Finally, a large number of examples of tunneling in atomic, molecular, condensed matter and ...

  14. Tunneling into quantum wires: Regularization of the tunneling Hamiltonian and consistency between free and bosonized fermions

    Science.gov (United States)

    Filippone, Michele; Brouwer, Piet W.

    2016-12-01

    Tunneling between a point contact and a one-dimensional wire is usually described with the help of a tunneling Hamiltonian that contains a δ function in position space. Whereas the leading-order contribution to the tunneling current is independent of the way this δ function is regularized, higher-order corrections with respect to the tunneling amplitude are known to depend on the regularization. Instead of regularizing the δ function in the tunneling Hamiltonian, one may also obtain a finite tunneling current by invoking the ultraviolet cutoffs in a field-theoretic description of the electrons in the one-dimensional conductor, a procedure that is often used in the literature. For the latter case, we show that standard ultraviolet cutoffs lead to different results for the tunneling current in fermionic and bosonized formulations of the theory, when going beyond leading order in the tunneling amplitude. We show how to recover the standard fermionic result using the formalism of functional bosonization and revisit the tunneling current to leading order in the interacting case.

  15. Tunnel and Station Cost Methodology : Mined Tunnels

    Science.gov (United States)

    1983-01-01

    The main objective of this study was to develop a model for estimating the cost of subway station and tunnel construction. This report describes a cost estimating methodology for subway tunnels that can be used by planners, designers, owners, and gov...

  16. Solution-processable organic dielectrics for graphene electronics.

    Science.gov (United States)

    Mattevi, Cecilia; Colléaux, Florian; Kim, HoKwon; Lin, Yen-Hung; Park, Kyung T; Chhowalla, Manish; Anthopoulos, Thomas D

    2012-08-31

    We report the fabrication, at low-temperature, of solution processed graphene transistors based on carefully engineered graphene/organic dielectric interfaces. Graphene transistors based on these interfaces show improved performance and reliability when compared with traditional SiO(2) based devices. The dielectric materials investigated include Hyflon AD (Solvay), a low-k fluoropolymer, and various organic self-assembled monolayer (SAM) nanodielectrics. Both types of dielectric are solution processed and yield graphene transistors with similar operating characteristics, namely high charge carrier mobility, hysteresis free operation, negligible doping effect and improved operating stability as compared to bare SiO(2) based devices. Importantly, the use of SAM nanodielectrics enables the demonstration of low operating voltage ( transistors with tunable doping characteristics through molecular engineering of the SAM's molecular length and terminal group. The work is a significant step towards graphene microelectronics where large-volume and low-temperature processing are required.

  17. Reprint of : Heat pump driven by the shot noise of a tunnel contact

    Science.gov (United States)

    Hussein, Robert; Kohler, Sigmund; Sols, Fernando

    2016-08-01

    We investigate a mechanism for cooling a lead based on a process that replaces hot electrons by cold ones. The central idea is that a double quantum dot with an inhomogeneous Zeeman splitting acts as energy filter for the transported electrons. The setup is such that hot electrons with spin up are removed, while cold electrons with spin down are added. The required non-equilibrium condition is provided by the capacitive coupling of one quantum dot to the shot noise of a strongly biased quantum point contact in the tunneling limit. Special attention is paid to the identification of an operating regime in which the net electrical current vanishes.

  18. Heat pump driven by the shot noise of a tunnel contact

    Science.gov (United States)

    Hussein, Robert; Kohler, Sigmund; Sols, Fernando

    2016-03-01

    We investigate a mechanism for cooling a lead based on a process that replaces hot electrons by cold ones. The central idea is that a double quantum dot with an inhomogeneous Zeeman splitting acts as energy filter for the transported electrons. The setup is such that hot electrons with spin up are removed, while cold electrons with spin down are added. The required non-equilibrium condition is provided by the capacitive coupling of one quantum dot to the shot noise of a strongly biased quantum point contact in the tunneling limit. Special attention is paid to the identification of an operating regime in which the net electrical current vanishes.

  19. Molecular series-tunneling junctions.

    Science.gov (United States)

    Liao, Kung-Ching; Hsu, Liang-Yan; Bowers, Carleen M; Rabitz, Herschel; Whitesides, George M

    2015-05-13

    Charge transport through junctions consisting of insulating molecular units is a quantum phenomenon that cannot be described adequately by classical circuit laws. This paper explores tunneling current densities in self-assembled monolayer (SAM)-based junctions with the structure Ag(TS)/O2C-R1-R2-H//Ga2O3/EGaIn, where Ag(TS) is template-stripped silver and EGaIn is the eutectic alloy of gallium and indium; R1 and R2 refer to two classes of insulating molecular units-(CH2)n and (C6H4)m-that are connected in series and have different tunneling decay constants in the Simmons equation. These junctions can be analyzed as a form of series-tunneling junctions based on the observation that permuting the order of R1 and R2 in the junction does not alter the overall rate of charge transport. By using the Ag/O2C interface, this system decouples the highest occupied molecular orbital (HOMO, which is localized on the carboxylate group) from strong interactions with the R1 and R2 units. The differences in rates of tunneling are thus determined by the electronic structure of the groups R1 and R2; these differences are not influenced by the order of R1 and R2 in the SAM. In an electrical potential model that rationalizes this observation, R1 and R2 contribute independently to the height of the barrier. This model explicitly assumes that contributions to rates of tunneling from the Ag(TS)/O2C and H//Ga2O3 interfaces are constant across the series examined. The current density of these series-tunneling junctions can be described by J(V) = J0(V) exp(-β1d1 - β2d2), where J(V) is the current density (A/cm(2)) at applied voltage V and βi and di are the parameters describing the attenuation of the tunneling current through a rectangular tunneling barrier, with width d and a height related to the attenuation factor β.

  20. Electronic data processing codes for California wildland plants

    Science.gov (United States)

    Merton J. Reed; W. Robert Powell; Bur S. Bal

    1963-01-01

    Systematized codes for plant names are helpful to a wide variety of workers who must record the identity of plants in the field. We have developed such codes for a majority of the vascular plants encountered on California wildlands and have published the codes in pocket size, using photo-reductions of the output from data processing machines. A limited number of the...

  1. Asymmetric tunneling model of forward leakage current in GaN/InGaN light emitting diodes

    Directory of Open Access Journals (Sweden)

    Ting Zhi

    2015-08-01

    Full Text Available Through investigating the temperature dependent current-voltage (T-I-V properties of GaN based blue and green LEDs in this study, we propose an asymmetric tunneling model to understand the leakage current below turn-on voltage (V < 3.2 V: At the forward bias within 1.5 V ∼ 2.1 V (region 1, the leakage current is main attributed to electrons tunneling from the conduction band of n-type GaN layer to the valence band of p-type GaN layer via defect states in space-charge region (SCR; While, at the forward bias within 2 V ∼ 2.4 V (region 2, heavy holes tunneling gradually becomes dominant at low temperature (T < 200K as long as they can overcome the energy barrier height. The tunneling barrier for heavy holes is estimated to be lower than that for electrons, indicating the heavy holes might only tunnel to the defect states. This asymmetric tunneling model shows a novel carrier transport process, which provides better understanding of the leakage characteristics and is vital for future device improvements.

  2. Scanning tunneling microscopy study of morphology and electronic properties in (K{sub 0.7}Na{sub 0.3})Fe{sub 2−y}Se{sub 2} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Trifonov, A. S., E-mail: trifonov.artem@phys.msu.ru; Presnov, D. E. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 1(2), Leninskie Gory, GSP-1, Moscow 119991 (Russian Federation); Low Temperature Physics and Superconductivity Department, Physics Faculty, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Ovchenkov, Y. A. [Low Temperature Physics and Superconductivity Department, Physics Faculty, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Belosludov, R. [Institute for Materials Research, Tohoku University, 980-8577 Sendai (Japan); Boltalin, A. I.; Liu, M.; Morozov, I. V. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Nejo, H. [National Institute for Material Science, Tsukuba 305-0047 (Japan); Vasiliev, A. N. [Low Temperature Physics and Superconductivity Department, Physics Faculty, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Theoretical Physics and Applied Mathematics Department, Institute of Physics and Technology, Ural Federal University, Ekaterinburg 620002 (Russian Federation); National University of Science and Technology ' MISiS' , Moscow 119049 (Russian Federation)

    2014-07-28

    We investigated the microstructure of the iron selenide superconductor (K{sub 0.7}Na{sub 0.3})Fe{sub 2−y}Se{sub 2} with a T{sub c} = 32 K and a near 100% Meissner screening volume fraction. Topography and electron transport properties were studied using electron microscopy and ultra-high vacuum scanning tunneling microscopy (STM) techniques. Room temperature STM measurements reliably identify spatial variations of the local electronic properties of this material. The studied crystals consist of continuous regions with significantly different shapes of current-voltage curves reflecting different electronic transport properties of these regions. Fitting of the local current-voltage curves with the Simmons model for metal-dielectric-metal structure confirmed a phase separation in the sample to a metal and semiconducting phases. The observed regions have dimensions in the range of several tenths of a micrometer and indicate a phase separation in the sample.

  3. Tandem Solar Cells from Solution-Processed CdTe and PbS Quantum Dots Using a ZnTe-ZnO Tunnel Junction.

    Science.gov (United States)

    Crisp, Ryan W; Pach, Gregory F; Kurley, J Matthew; France, Ryan M; Reese, Matthew O; Nanayakkara, Sanjini U; MacLeod, Bradley A; Talapin, Dmitri V; Beard, Matthew C; Luther, Joseph M

    2017-02-08

    We developed a monolithic CdTe-PbS tandem solar cell architecture in which both the CdTe and PbS absorber layers are solution-processed from nanocrystal inks. Due to their tunable nature, PbS quantum dots (QDs), with a controllable band gap between 0.4 and ∼1.6 eV, are a promising candidate for a bottom absorber layer in tandem photovoltaics. In the detailed balance limit, the ideal configuration of a CdTe (Eg = 1.5 eV)-PbS tandem structure assumes infinite thickness of the absorber layers and requires the PbS band gap to be 0.75 eV to theoretically achieve a power conversion efficiency (PCE) of 45%. However, modeling shows that by allowing the thickness of the CdTe layer to vary, a tandem with efficiency over 40% is achievable using bottom cell band gaps ranging from 0.68 and 1.16 eV. In a first step toward developing this technology, we explore CdTe-PbS tandem devices by developing a ZnTe-ZnO tunnel junction, which appropriately combines the two subcells in series. We examine the basic characteristics of the solar cells as a function of layer thickness and bottom-cell band gap and demonstrate open-circuit voltages in excess of 1.1 V with matched short circuit current density of 10 mA/cm(2) in prototype devices.

  4. Use of beam deflection to control an electron beam wire deposition process

    Science.gov (United States)

    Taminger, Karen M. (Inventor); Hofmeister, William H. (Inventor); Hafley, Robert A. (Inventor)

    2013-01-01

    A method for controlling an electron beam process wherein a wire is melted and deposited on a substrate as a molten pool comprises generating the electron beam with a complex raster pattern, and directing the beam onto an outer surface of the wire to thereby control a location of the wire with respect to the molten pool. Directing the beam selectively heats the outer surface of the wire and maintains the position of the wire with respect to the molten pool. An apparatus for controlling an electron beam process includes a beam gun adapted for generating the electron beam, and a controller adapted for providing the electron beam with a complex raster pattern and for directing the electron beam onto an outer surface of the wire to control a location of the wire with respect to the molten pool.

  5. On-line monitoring of food fermentation processes using electronic noses and electronic tongues: A review.

    OpenAIRE

    Peris Tortajada, Miguel; Escuder Gilabert, Laura

    2013-01-01

    Fermentation processes are often sensitive to even slight changes of conditions that may result in unacceptable end-product quality. Thus, close follow-up of this type of processes is critical for detecting unfavorable deviations as early as possible in order to save downtime, materials and resources. Nevertheless the use of traditional analytical techniques is often hindered by the need for expensive instrumentation and experienced operators and complex sample preparation. In this sense, one...

  6. The Future of Electronic Power Processing and Conversion: Highlights from FEPPCON IX

    DEFF Research Database (Denmark)

    Enslin, Johan H.; Blaabjerg, Frede; Tan, Don F.D.

    2017-01-01

    Since 1991, every second year the IEEE Power Electronics Society (PELS) has organized the technical long-range planning meeting "Future of Electronic Power Processing and Conversion" (FEPPCON). FEPPCON IX was held 12-16 June 2017 in beautiful Kruger Park in South Africa (Figure 1). The overall goal...... of the meeting was to discuss challenges, opportunities, and research directions beyond 2025 for power electronics and systems technology....

  7. Fire safety assessment of tunnel structures

    DEFF Research Database (Denmark)

    Gkoumas, Konstantinos; Giuliani, Luisa; Petrini, Francesco

    2011-01-01

    durability provisions, commitment to environmental aspects, issues of sustainability and safety assurance, for their whole lifecycle. The design for safety of tunnel infrastructures is a multifaceted process, since there are many aspects that need to be accounted for, regarding different aspects (e.......g. structural and non structural, organizational, human behavior). This is even more truth for the fire safety design of such structures. Fire safety in tunnels is challenging because of the particular environment, bearing in mind also that a fire can occur in different phases of the tunnel’s lifecycle. Plans...... for upgrading fire safety provisions and tunnel management are also important for existing tunnels. In this study, following a brief introduction of issues regarding the above mentioned aspects, the structural performance of a steel rib for a tunnel infrastructure subject to fire is assessed by means...

  8. Statistical approach to tunneling time in attosecond experiments

    Science.gov (United States)

    Demir, Durmuş; Güner, Tuğrul

    2017-11-01

    Tunneling, transport of particles through classically forbidden regions, is a pure quantum phenomenon. It governs numerous phenomena ranging from single-molecule electronics to donor-acceptor transition reactions. The main problem is the absence of a universal method to compute tunneling time. This problem has been attacked in various ways in the literature. Here, in the present work, we show that a statistical approach to the problem, motivated by the imaginary nature of time in the forbidden regions, lead to a novel tunneling time formula which is real and subluminal (in contrast to various known time definitions implying superluminal tunneling). In addition to this, we show explicitly that the entropic time formula is in good agreement with the tunneling time measurements in laser-driven He ionization. Moreover, it sets an accurate range for long-range electron transfer reactions. The entropic time formula is general enough to extend to the photon and phonon tunneling phenomena.

  9. Electronic dissipation processes during chemical reactions on surfaces

    CERN Document Server

    Stella, Kevin

    2012-01-01

    Hauptbeschreibung Every day in our life is larded with a huge number of chemical reactions on surfaces. Some reactions occur immediately, for others an activation energy has to be supplied. Thus it happens that though a reaction should thermodynamically run off, it is kinetically hindered. Meaning the partners react only to the thermodynamically more stable product state within a mentionable time if the activation energy of the reaction is supplied. With the help of catalysts the activation energy of a reaction can be lowered. Such catalytic processes on surfaces are widely used in industry. A

  10. Electronics and Sensor Study with the OKI SOI process

    CERN Document Server

    Arai, Yasuo

    2007-01-01

    While the SOI (Silicon-On-Insulator) device concept is very old, commercialization of the technology is relatively new and growing rapidly in high-speed processor and lowpower applications. Furthermore, features such as latch-up immunity, radiation hardness and high-temperature operation are very attractive in high energy and space applications. Once high-quality bonded SOI wafers became available in the late 90s, it opened up the possibility to get two different kinds of Si on a single wafer. This makes it possible to realize an ideal pixel detector; pairing a fully-depleted radiation sensor with CMOS circuitry in an industrial technology. In 2005 we started Si pixel R&D with OKI Electric Ind. Co., Ltd. which is the first market supplier of Fully-Depleted SOI products. We have developed processes for p+/n+ implants to the substrate and for making connections between the implants and circuits in the OKI 0.15μm FD-SOI CMOS process. We have preformed two Multi Project Wafer (MPW) runs using this SOI proces...

  11. Recent Advances in Photoinduced Electron Transfer Processes of Fullerene-Based Molecular Assemblies and Nanocomposites

    Directory of Open Access Journals (Sweden)

    Osamu Ito

    2012-05-01

    Full Text Available Photosensitized electron-transfer processes of fullerenes hybridized with electron donating or other electron accepting molecules have been surveyed in this review on the basis of the recent results reported mainly from our laboratories. Fullerenes act as photo-sensitizing electron acceptors with respect to a wide variety of electron donors; in addition, fullerenes in the ground state also act as good electron acceptors in the presence of light-absorbing electron donors such as porphyrins. With single-wall carbon nanotubes (SWCNTs, the photoexcited fullerenes act as electron acceptor. In the case of triple fullerene/porphyrin/SWCNT architectures, the photoexcited porphyrins act as electron donors toward the fullerene and SWCNT. These mechanisms are rationalized with the molecular orbital considerations performed for these huge supramolecules. For the confirmation of the electron transfer processes, transient absorption methods have been used, in addition to time-resolved fluorescence spectral measurements. The kinetic data obtained in solution are found to be quite useful to predict the efficiencies of photovoltaic cells.

  12. Recent advances in photoinduced electron transfer processes of fullerene-based molecular assemblies and nanocomposites.

    Science.gov (United States)

    Ito, Osamu; D'Souza, Francis

    2012-05-16

    Photosensitized electron-transfer processes of fullerenes hybridized with electron donating or other electron accepting molecules have been surveyed in this review on the basis of the recent results reported mainly from our laboratories. Fullerenes act as photo-sensitizing electron acceptors with respect to a wide variety of electron donors; in addition, fullerenes in the ground state also act as good electron acceptors in the presence of light-absorbing electron donors such as porphyrins. With single-wall carbon nanotubes (SWCNTs), the photoexcited fullerenes act as electron acceptor. In the case of triple fullerene/porphyrin/SWCNT architectures, the photoexcited porphyrins act as electron donors toward the fullerene and SWCNT. These mechanisms are rationalized with the molecular orbital considerations performed for these huge supramolecules. For the confirmation of the electron transfer processes, transient absorption methods have been used, in addition to time-resolved fluorescence spectral measurements. The kinetic data obtained in solution are found to be quite useful to predict the efficiencies of photovoltaic cells.

  13. New Applications of Scanning Tunneling Microscopy

    Science.gov (United States)

    Smith, Douglas Philip Edward

    This dissertation describes the application of the scanning tunneling microscope (STM) technique to four new fields of study: thin organic films, phonon spectroscopy of bulk surfaces, the vibrational spectroscopy of molecules, and the tribological forces which occur between STM tip and sample. Images with atomic resolution were obtained with speeds approaching video rates. Two types of microscopes were used: one operated at room temperature in air, another at 4.2K in liquid helium. At room temperature, the STM was able to image molecules of cadmium arachidate deposited onto graphite by the Langmuir-Blodgett technique. The packing of molecules in the lipid bilayer was found to be partially ordered, with density of 1 molecule per 19.4 square angstroms. At liquid-helium temperature, inelastic electron processes were detected, and it was possible to determine within an area of a few square angstroms where the vibrational excitations occurred. On a bare graphite substrate, phonons of the sample and tip caused step increases in the tunneling conductivity at the phonon energies. Molecules of sorbic acid could be resolved when deposited onto graphite, and these molecules caused spatially localized peaks in conductivity at the energies of the bond vibrations. Although the STM is usually considered a non-contact instrument, under certain circumstances the tip and sample exerted strong forces on each other. With a tungsten tip and a graphite sample, friction and mechanical deformations on the atomic scale were observed.

  14. 12 CFR 617.7005 - When may electronic communications be used in the borrower rights process?

    Science.gov (United States)

    2010-01-01

    ... borrower rights process? Qualified lenders may use, with the parties' agreement, electronic commerce (E-commerce), including electronic communications for borrower rights disclosures. Part 609 of this chapter addresses when a qualified lender may use E-commerce. Consistent with these rules, a qualified lender should...

  15. Counterfeit Electronics Detection Using Image Processing and Machine Learning

    Science.gov (United States)

    Asadizanjani, Navid; Tehranipoor, Mark; Forte, Domenic

    2017-01-01

    Counterfeiting is an increasing concern for businesses and governments as greater numbers of counterfeit integrated circuits (IC) infiltrate the global market. There is an ongoing effort in experimental and national labs inside the United States to detect and prevent such counterfeits in the most efficient time period. However, there is still a missing piece to automatically detect and properly keep record of detected counterfeit ICs. Here, we introduce a web application database that allows users to share previous examples of counterfeits through an online database and to obtain statistics regarding the prevalence of known defects. We also investigate automated techniques based on image processing and machine learning to detect different physical defects and to determine whether or not an IC is counterfeit.

  16. Influence of the charge changing processes on proton induced electron emission from polycrystalline aluminium

    CERN Document Server

    Pauly, N; Rösler, M

    2003-01-01

    Charge changing processes are known to have a strong influence on ion-induced electron emission characteristics. However, up to now, only a few theoretical models incorporate electron capture and loss cross-sections. For protons with velocities around 1 a.u., a correct theoretical model of the various charge changing processes undergone by the proton is necessary. In particular, all the electrons excited in the different processes have to be taken into account. It is precisely the aim of the present paper to give a description of all the possible charge changing processes and to incorporate these processes in a Monte Carlo simulation of proton induced electron emission from polycrystalline aluminium. The influence of charge changing processes on backward electron emission yield is evaluated. The contributions of H sup + , H sup 0 , H sup - fractions as well as of electrons excited by the charge changing processes for incident H sup + (1

  17. Neuroreceptor Activation by Vibration-Assisted Tunneling

    CERN Document Server

    Hoehn, Ross D; Neven, Hartmut; Kais, Sabre

    2015-01-01

    G protein-coupled receptors (GPCRs) constitute a large family of receptor proteins that sense molecular signals on the exterior of a cell and activate signal transduction pathways within the cell. Modeling how an agonist activates such a receptor is fundamental for an understanding of a wide variety of physiological processes and it is of tremendous value for pharmacology and drug design. Inelastic electron tunneling spectroscopy (IETS) has been proposed as a model for the mechanism by which olfactory GPCRs are activated by a bound agonist. We apply this hypothesis to GPCRs within the mammalian nervous system using quantum chemical modeling. We found that non-endogenous agonists of the serotonin receptor share a particular IET spectral aspect both amongst each other and with the serotonin molecule: a peak whose intensity scales with the known agonist potencies. We propose an experiential validation of this model by utilizing lysergic acid dimethylamide (DAM-57), an ergot derivative, and its deuterated isotopo...

  18. Tunnelling in Soft Soil : Tunnel Boring Machine Operation and Soil Response

    NARCIS (Netherlands)

    Festa, D.; Broere, W.; Bosch, J.W.

    Constructing tunnels in soft soil with the use of Tunnel Boring Machines may induce settlements including soil movements ahead of the face, soil relaxation into the tail void, possible heave due to grouting, long lasting consolidation processes, and potentially several other mechanisms. A

  19. PP-EPDM thermoplastic vulcanisates (TPVs by electron induced reactive processing

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available Reactive processing combines melt mixing process and chemical reaction simultaneously. TPVs are produced by such reactive processing. Polymer modification with high energy electrons is based on generation of excited atoms or molecules and ions for subsequent molecular changes via radical induced chemical reactions. In the present study, electron induced reactive processing is used for the development of TPVs. A 1.5 MeV electron accelerator was directly coupled to an internal mixer in order to induce chemical reactions by energy input via high energy electrons under dynamic conditions of melt mixing of polypropylene (PP and ethylene propylene diene monomer rubber (EPDM. The influence of absorbed dose (25 to 100 kGy as well as electron energy (1.5 and 0.6 MeV and electron treatment time (15 to 60 s have been studied. Increased values of both tensile strength and elongation at break of the TPVs indicate in-situ compatibilisation of PP and EPDM as well as cross-linking in the EPDM phase upon electron induced reactive processing. Dynamic mechanical analyses showed a decrease in value of glass transition temperature peak of EPDM in tangent delta curve with increasing dose. This also indicates higher degree of cross-linking in EPDM phase, which is further supported by a gel content that is higher than the EPDM content itself in the blend.

  20. Writing argumentative texts: The effects of electronic outlining on students’ writing product and process

    NARCIS (Netherlands)

    De Smet, Milou; Brand-Gruwel, Saskia; Leijten, Mariëlle; Kirschner, Paul A.

    2012-01-01

    De Smet, M. J. R., Brand-Gruwel, S., Leijten, M., & Kirschner, P. A. (2012, November). Writing argumentative texts: The effects of electronic outlining on students’ writing product and process. Paper presentation at ICO Fall School 2012, Girona, Spain.

  1. 76 FR 70490 - Certain Electronic Devices With Graphics Data Processing Systems, Components Thereof, and...

    Science.gov (United States)

    2011-11-14

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Electronic Devices With Graphics Data Processing Systems, Components Thereof, and Associated Software; Institution of Investigation AGENCY: U.S. International Trade Commission. ACTION: Notice...

  2. Modification to the MAPS interview process and electronic form

    CERN Multimedia

    HR Department

    2006-01-01

    Based on the first year of experience with e-MAPS and the feedback from departmental users, a number of modifications to the MAPS interview process and form have been introduced for the 2006 exercise. Definition of signatories The top of the form now also shows the name of the Group Leader and Department Head. This is especially useful in cases of detachment. Corrections can be made via the MAPS Coordinator. 'Send back' facility The possibility to send the MAPS report one step backwards, i.e. from Group Leader to supervisor, from Staff Member to Group Leader, and from Group Leader to Staff Member is only available to the MAPS coordinators. The form should only be sent back to correct factual errors or oversights, and any send- backs will be recorded. Link between 'training' part and 'training' application When entering a training objective for 2006, a search menu allows selection from various CERN internal training courses or from conferences. It is still important, however, to first read the descri...

  3. Modification to the MAPS interview process and electronic form

    CERN Multimedia

    HR Department

    2006-01-01

    Based on the first year of experience with e-MAPS and the feedback from departmental users, a number of modifications to the MAPS interview process and the form have been introduced for the 2006 exercise. Definition of signatories The top of the form now also shows the name of the group leader and department head. This is especially useful in cases of detachment. Corrections can be made via the MAPS Coordinator. 'Send back' facility The possibility to send the MAPS report one step backwards is only available to the MAPS coordinators, i.e., from group leader to supervisor, from staff member to group leader, and from group leader to staff member. The form should only be sent back to correct factual errors or oversights, and any send backs will be tracked. Link 'training' part to 'training' application When entering a training objective for 2006, a search menu allows selection from various CERN internal training courses or from conferences. It remains important however to first read the description of the...

  4. Electron Beam Welding: study of process capability and limitations towards development of nuclear components

    Science.gov (United States)

    Vadolia, Gautam R.; Premjit Singh, K.

    2017-04-01

    Electron Beam Welding (EBW) technology is an established and widely adopted technique in nuclear research and development area. Electron beam welding was thought of as a candidate process for ITER Vacuum Vessel Fabrication. Dhruva Reactor at BARC, Mumbai and Niobium superconducting accelerator cavity at BARC has adopted the EB welding technique as a fabrication route. Study of process capability and limitations based on available literature is consolidated in this short review paper.

  5. Present status of radiation processing and its future development by using electron accelerator in Vietnam

    Energy Technology Data Exchange (ETDEWEB)

    Tran Khac An; Tran Tich Canh; Doan Binh [Research and Development Center for Radiation Technology (VINAGAMMA), Ho Chi Minh (Viet Nam); Nguyen Quoc Hien [Nuclear Research Institute (NRI), Dalat (Viet Nam)

    2003-02-01

    In Vietnam, studies on Radiation Processing have been carried out since 1983. Some results are applicable in the field of agriculture, health and foodstuff, some researches were developed to commercial scale and others have high potential for development by using electron accelerator. The paper offers the present status of radiation processing and also give out the growing tendency of using electron accelerator in the future. (author)

  6. Multiple Ligament Reconstruction Femoral Tunnels: Intertunnel Relationships and Guidelines to Avoid Convergence.

    Science.gov (United States)

    Moatshe, Gilbert; Brady, Alex W; Slette, Erik L; Chahla, Jorge; Turnbull, Travis Lee; Engebretsen, Lars; LaPrade, Robert F

    2017-03-01

    Knee dislocations often require multiple concurrent ligament reconstructions, which involve creating several tunnels in the distal femur. Therefore, the risk of tunnel convergence is increased because of the limited bone volume within the distal aspect of the femur. To assess the risk of tunnel convergence and determine the optimal reconstruction tunnel orientations for multiple ligament reconstructions in the femur. Descriptive laboratory study. Three-dimensional knee models were developed from computed tomography scans of 21 patients. Medical image processing software was used to create tunnels for each of the primary ligamentous structures, replicating a surgical approach that would be used in multiple ligament reconstructions. Thereafter, the tunnel orientation was varied in surgically relevant directions to determine orientations that minimized the risk of tunnel convergence. The orientation of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) tunnels was held constant throughout the study, while the orientation of the fibular collateral ligament (FCL), popliteus tendon (PLT), superficial medial collateral ligament (sMCL), and posterior oblique ligament (POL) tunnels was varied to avoid convergence. A high risk of tunnel convergence was observed between the FCL and ACL tunnels when the FCL tunnel was aimed at 0° in the axial and coronal planes. Aiming the FCL tunnel 35° anteriorly minimized convergence with the ACL tunnel. No tunnel convergence was observed for the PLT tunnel aimed 35° anteriorly and parallel to the FCL tunnel. To avoid convergence between the sMCL and PCL tunnels, the sMCL tunnels should be aimed 40° proximally in the coronal plane and 20° to 40° anteriorly. During concomitant POL reconstruction, the sMCL should be aimed 40° proximally and anteriorly and the POL 20° proximally and anteriorly. The PLT and POL tunnels aimed at 0° in both the coronal and axial planes had an increased risk of violating the

  7. Integrating atomic layer deposition and ultra-high vacuum physical vapor deposition for in situ fabrication of tunnel junctions.

    Science.gov (United States)

    Elliot, Alan J; Malek, Gary A; Lu, Rongtao; Han, Siyuan; Yu, Haifeng; Zhao, Shiping; Wu, Judy Z

    2014-07-01

    Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin, pristine dielectrics on metal substrates, which is essential to many electronic devices. Tunnel junctions are an excellent example which require a leak-free, ultrathin dielectric tunnel barrier of typical thickness around 1 nm between two metal electrodes. A challenge in the development of ultrathin dielectric tunnel barriers using ALD is controlling the nucleation of dielectrics on metals with minimal formation of native oxides at the metal surface for high-quality interfaces between the tunnel barrier and metal electrodes. This poses a critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor deposition. In order to address these challenges, a viscous-flow ALD chamber was designed and interfaced to an UHV magnetron sputtering chamber via a load lock. A sample transportation system was implemented for in situ sample transfer between the ALD, load lock, and sputtering chambers. Using this integrated ALD-UHV sputtering system, superconductor-insulator-superconductor (SIS) Nb-Al/Al2O2/Nb Josephson tunnel junctions were fabricated with tunnel barriers of thickness varied from sub-nm to ~1 nm. The suitability of using an Al wetting layer for initiation of the ALD Al2O3 tunnel barrier was investigated with ellipsometry, atomic force microscopy, and electrical transport measurements. With optimized processing conditions, leak-free SIS tunnel junctions were obtained, demonstrating the viability of this integrated ALD-UHV sputtering system for the fabrication of tunnel junctions and devices comprised of metal-dielectric-metal multilayers.

  8. Integrating atomic layer deposition and ultra-high vacuum physical vapor deposition for in situ fabrication of tunnel junctions

    Science.gov (United States)

    Elliot, Alan J.; Malek, Gary A.; Lu, Rongtao; Han, Siyuan; Yu, Haifeng; Zhao, Shiping; Wu, Judy Z.

    2014-07-01

    Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin, pristine dielectrics on metal substrates, which is essential to many electronic devices. Tunnel junctions are an excellent example which require a leak-free, ultrathin dielectric tunnel barrier of typical thickness around 1 nm between two metal electrodes. A challenge in the development of ultrathin dielectric tunnel barriers using ALD is controlling the nucleation of dielectrics on metals with minimal formation of native oxides at the metal surface for high-quality interfaces between the tunnel barrier and metal electrodes. This poses a critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor deposition. In order to address these challenges, a viscous-flow ALD chamber was designed and interfaced to an UHV magnetron sputtering chamber via a load lock. A sample transportation system was implemented for in situ sample transfer between the ALD, load lock, and sputtering chambers. Using this integrated ALD-UHV sputtering system, superconductor-insulator-superconductor (SIS) Nb-Al/Al2O2/Nb Josephson tunnel junctions were fabricated with tunnel barriers of thickness varied from sub-nm to ˜1 nm. The suitability of using an Al wetting layer for initiation of the ALD Al2O3 tunnel barrier was investigated with ellipsometry, atomic force microscopy, and electrical transport measurements. With optimized processing conditions, leak-free SIS tunnel junctions were obtained, demonstrating the viability of this integrated ALD-UHV sputtering system for the fabrication of tunnel junctions and devices comprised of metal-dielectric-metal multilayers.

  9. The effect of electron processes on metal walls in magnetized microdischarges

    Science.gov (United States)

    Levko, Dmitry; Raja, Laxminarayan L.

    2017-10-01

    The influence of the electron reflection and secondary electron emission due to electron impact on a microdischarge with magnetized electrons and unmagnetized ions is analyzed using a one-dimensional Particle-in-Cell Monte Carlo collision model. For low gas pressure (below 10 Torr), the accounting for the electron processes on the walls results in a significant decrease of the breakdown voltage and allows one to increase both the plasma density and the discharge current. The generation of much denser plasma shrinks the cathode sheath to such an extent that the Larmor radius of emitted electrons becomes a few times larger than the sheath thickness. This leads to the expansion of the region of dense plasma toward the anode, which decreases the frequency of the ionization instability and decreases the number of striations obtained in the cathode-anode gap.

  10. Tunneling magnetoresistance in Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2016-11-09

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green\\'s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  11. Resonant tunnel magnetoresistance in double-barrier planar magnetic tunnel junctions

    KAUST Repository

    Useinov, A. N.

    2011-08-24

    We present a theoretical approach to calculate the spin-dependent current and tunnel magnetoresistance (TMR) in a double-barrier magnetic tunnel junction (DMTJ), in which the magnetization of the middle ferromagnetic metal layer can be aligned parallel or antiparallel in relation to the fixed magnetizations of the left and right ferromagnetic electrodes. The electron transport through the DMTJ is considered as a three-dimensional problem, taking into account all transmitting electron trajectories as well as the spin-dependent momentum conservation law. The dependence of the transmission coefficient and spin-polarized currents on the applied voltage is derived as an exact solution to the quantum-mechanical problem for the spin-polarized transport. In the range of the developed physical model, the resonant tunneling, nonresonant tunneling, and enhanced spin filtering can be explained; the simulation results are in good agreement with experimental data.

  12. Tunnel magnetoresistance in epitaxially grown magnetic tunnel junctions using Heusler alloy electrode and MgO barrier

    Energy Technology Data Exchange (ETDEWEB)

    Tsunegi, S.; Sakuraba, Y.; Oogane, M.; Telling, N. D.; Shelford, L. R.; Arenholz, E.; van der Laan, G.; Hicken, R. J.; Takanashi, K.; Ando, Y.

    2009-07-01

    Epitaxially grown magnetic tunnel junctions (MTJs) with a stacking structure of Co{sub 2}MnSi/MgO/CoFe were fabricated. Their tunnel magnetoresistance (TMR) effects were investigated. The TMR ratio and tunnelling conductance characteristics of MTJs were considerably different between those with an MgO barrier prepared using sputtering (SP-MTJ) and those prepared using EB evaporation (EB-MTJ). The EB-MTJ exhibited a very large TMR ratio of 217% at room temperature and 753% at 2 K. The bias voltage dependence of the tunnelling conductance in the parallel magnetic configuration for the EB-MTJ suggests that the observed large TMR ratio at RT results from the coherent tunnelling process through the crystalline MgO barrier. The tunnelling conductance in the anti-parallel magnetic configuration suggests that the large temperature dependence of the TMR ratio results from the inelastic spin-flip tunnelling process.

  13. Tunnel magnetoresistance in ferromagnetic double-barrier planar junctions: coherent tunneling regime

    CERN Document Server

    Wilczynski, M

    2000-01-01

    Coherent tunneling in a double-barrier system consisting of two external ferromagnetic electrodes and a nonmagnetic central one is studied theoretically within the free-electron approximation. It is shown that the junction resistance depends on the relative orientation of magnetic moments of the ferromagnetic electrodes (so-called tunnel magnetoresistance). The magnetoresistance vs. thickness of the central electrode shows pronounced peaks related to the resonant tunneling through the whole system. Variation of the magnetoresistance with bias voltage is also studied. This variation is generally nonmonotonous.

  14. Behaviour of tunnelling transition rate of argon atom exposed to ...

    Indian Academy of Sciences (India)

    in the strong laser field ionization of atoms and molecules. Tunnel ionization takes place when the electric field changes the atomic potential and electron sees a very small mod- ified potential and can tunnel through it. Keldysh [4] made the first attempt to perform a general analysis of ionization of atoms by laser radiation as ...

  15. Hot Electron Injection into Uniaxially Strained Silicon

    Science.gov (United States)

    Kim, Hyun Soo

    In semiconductor spintronics, silicon attracts great attention due to the long electron spin lifetime. Silicon is also one of the most commonly used semiconductor in microelectronics industry. The spin relaxation process of diamond crystal structure such as silicon is dominant by Elliot-Yafet mechanism. Yafet shows that intravalley scattering process is dominant. The conduction electron spin lifetime measured by electron spin resonance measurement and electronic measurement using ballistic hot electron method well agrees with Yafet's theory. However, the recent theory predicts a strong contribution of intervalley scattering process such as f-process in silicon. The conduction band minimum is close the Brillouin zone edge, X point which causes strong spin mixing at the conduction band. A recent experiment of electric field-induced hot electron spin relaxation also shows the strong effect of f-process in silicon. In uniaxially strained silicon along crystal axis [100], the suppression of f-process is predicted which leads to enhance electron spin lifetime. By inducing a change in crystal structure due to uniaxial strain, the six fold degeneracy becomes two fold degeneracy, which is valley splitting. As the valley splitting increases, intervalley scattering is reduced. A recent theory predicts 4 times longer electron spin lifetime in 0.5% uniaxially strained silicon. In this thesis, we demonstrate ballistic hot electron injection into silicon under various uniaxial strain. Spin polarized hot electron injection under strain is experimentally one of the most challenging part to measure conduction electron spin lifetime in silicon. Hot electron injection adopts tunnel junction which is a thin oxide layer between two conducting materials. Tunnel barrier, which is an oxide layer, is only 4 ˜ 5 nm thick. Also, two conducting materials are only tens of nanometer. Therefore, under high pressure to apply 0.5% strain on silicon, thin films on silicon substrate can be easily

  16. Comparative study of hydrolytic and electron-driven processes in carboplatin biotransformation.

    Science.gov (United States)

    Kuduk-Jaworska, Janina; Jański, Jerzy J; Roszak, Szczepan

    2017-05-01

    The results of computational simulation of reaction courses mimicking the transformation of carboplatin from pro-drug into its active shape, responsible for cytotoxic effect, are reported. Implementing the density functional theory (DFT) calculations and the supermolecular approach, we explored the pathways representing two disparate models of carboplatin bioactivation: (1) based on paradigm of carboplatin aquation, and (2) based on new hypothesis that transformation is controlled by electron-transfer processes. The calculated geometrical and thermodynamic parameters were used for evaluation of pathways. In contrast to carboplatin hydrolysis, representing a typical two stage SN2 mechanism, the postulated electron-driven reactions proceed under the dissociative electron attachment (DEA) mechanism. The reaction profiles predict endothermic effect in both stages of hydrolytic course and final exothermic effects for electron-driven processes. The most effective are hybrid processes including two-stages: water and subsequent electron impact on transformed carboplatin. The aqua-products, manifesting strong electron-affinity, can be the active form of drug capable to cytotoxic interaction with DNA, not only as alkylating agent but also as electron-acceptor. Concluding, the hybrid transformation of carboplatin is more favourable than hydrolytic. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. PROCESS DEVELOPMENT FOR THE RECOVERY OF CRITICAL MATERIALS FROM ELECTRONIC WASTE

    Energy Technology Data Exchange (ETDEWEB)

    Lister, T. E.; Diaz, L. A.; Clark, G. G.; Keller, P.

    2016-09-01

    As electronic technology continues to evolve there is a growing need to develop processes which recover valuable material from antiquated technology. This need follows from the environmental challenges associated with the availability of raw materials and fast growing generation of electronic waste. Although just present in small quantities in electronic devices, the availability of raw materials, such as rare earths and precious metals, becomes critical for the production of high tech electronic devices and the development of green technologies (i.e. wind turbines, electric motors, and solar panels). Therefore, the proper recycling and processing of increasing volumes of electronic waste present an opportunity to stabilize the market of critical materials, reducing the demand of mined products, and providing a proper disposal and treatment of a hazardous waste stream. This paper will describe development and techno-economic assessment of a comprehensive process for the recovery of value and critical materials from electronic waste. This hydrometallurgical scheme aims to selectively recover different value segments in the materials streams (base metals, precious metals, and rare earths). The economic feasibility for the recovery of rare earths from electronic waste is mostly driven by the efficient recovery of precious metals, such as Au and Pd (ca. 80 % of the total recoverable value). Rare earth elements contained in magnets (speakers, vibrators and hard disk storage) can be recovered as a mixture of rare earths oxides which can later be reduced to the production of new magnets.

  18. Adjustable tunneling barrier in bi-based high-Tc cross-whisker junctions

    Science.gov (United States)

    Kizilaslan, O.; Simsek, Y.; Aksan, M. A.; Koval, Y.; Yakinci, M. E.; Müller, P.

    2015-02-01

    We present a study of cross-whisker junctions with electronically modified tunneling barriers. Cross-whisker junctions were successfully prepared by annealing two crossed Bi-based whisker bars at temperatures of around 840 °C. In addition to the artificially produced junction at the interface, intrinsic Josephson junctions in the respective bars of the cross were observed. The artificial junction exhibited reproducible and almost ideal junction characteristics. The tunneling barrier/interface properties were controlled by carrier injection in c-axis direction. Using this process, we were able to reduce the tunneling resistance from 408 Ω to 30 Ω. At the same time, the critical current did rise by a factor of 4. Subsequently, the critical current was doubled while the tunneling resistance stayed constant. We interpret this observation in terms of the counter-play between transparency of the barrier and the carrier concentration of the electrodes. In this sense, we can consider the current injection procedure as an electronic gluing process of the two cross-junction whisker bars.

  19. Microsystem Aeromechanics Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — The Microsystem Aeromechanics Wind Tunnel advances the study of fundamental flow physics relevant to micro air vehicle (MAV) flight and assesses vehicle performance...

  20. Molecular view of an electron transfer process essential for iron–sulfur protein biogenesis

    Science.gov (United States)

    Banci, Lucia; Bertini, Ivano; Calderone, Vito; Ciofi-Baffoni, Simone; Giachetti, Andrea; Jaiswal, Deepa; Mikolajczyk, Maciej; Piccioli, Mario; Winkelmann, Julia

    2013-01-01

    Biogenesis of iron–sulfur cluster proteins is a highly regulated process that requires complex protein machineries. In the cytosolic iron–sulfur protein assembly machinery, two human key proteins—NADPH-dependent diflavin oxidoreductase 1 (Ndor1) and anamorsin—form a stable complex in vivo that was proposed to provide electrons for assembling cytosolic iron–sulfur cluster proteins. The Ndor1–anamorsin interaction was also suggested to be implicated in the regulation of cell survival/death mechanisms. In the present work we unravel the molecular basis of recognition between Ndor1 and anamorsin and of the electron transfer process. This is based on the structural characterization of the two partner proteins, the investigation of the electron transfer process, and the identification of those protein regions involved in complex formation and those involved in electron transfer. We found that an unstructured region of anamorsin is essential for the formation of a specific and stable protein complex with Ndor1, whereas the C-terminal region of anamorsin, containing the [2Fe-2S] redox center, transiently interacts through complementary charged residues with the FMN-binding site region of Ndor1 to perform electron transfer. Our results propose a molecular model of the electron transfer process that is crucial for understanding the functional role of this interaction in human cells. PMID:23596212

  1. Understanding the Role of Water on Electron-Initiated Processes and Radical Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, Bruce C [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Colson, Steven D [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Laufer, Allan H [US Department of Energy Office of Science Office of Basic Energy Sciences; Ray, Douglas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2003-06-10

    On September 26–28, 2002, a workshop entitled “Understanding the Role of Water on Electron-Initiated Processes and Radical Chemistry” was held to assess new research opportunities in electron-driven processes and radical chemistry in aqueous systems. Of particular interest was the unique and complex role that the structure of water plays in influencing these processes. Novel experimental and theoretical approaches to solving long-standing problems in the field were explored. A broad selection of participants from universities and the national laboratories contributed to the workshop, which included scientific and technical presentations and parallel sessions for discussions and report writing.

  2. Investigation of a tunnel pasteurizer for “Nocellara del Belice” table olives processed according to the “Castelvetrano method”

    Directory of Open Access Journals (Sweden)

    Catania, P.

    2014-12-01

    Full Text Available The influence of pasteurization temperature and time of treatment on the flesh firmness and the evolution of microbial communities was studied for table olives Cv. Nocellara del Belice, packed in glass jars and processed with a tunnel pasteurizer. The experiment was first carried out on the laboratory level in order to select the optimal combination of pasteurization time/temperature so as to obtain the proper balance between the consistency of the pulp and the microbiological quality of the final product. Pasteurization at industrial scale was then carried out in a tunnel pasteurizer applying the treatment at 75 °C for 8 min in the thermal center of the jars. Besides flesh firmness and microbial evolutions, the pH, total titratable acidity (TTA and color were evaluated for the table olives during storage at 6, 12 and 15 months from packing. The table olives showed a high stability and acceptable flesh firmness for the entire period under observation. Specifically, olive pulp texture decreased during the storage period, but the softening was most evident in the deeper layers of the pulp. The results indicated that the storage period should not exceed 6 months. Although the hygiene is preserved, after this period the firmness might not be acceptable to consumers.En el presente trabajo se estudió la influencia de la temperatura y del tiempo de pasteurización en la firmeza de la pulpa y la evolución de las comunidades microbianas para la aceituna de mesa “Nocellara del Belice” procesadas con un pasteurizador de túnel. El experimento se llevó a cabo preliminarmente a nivel de laboratorio con el fin de seleccionar la combinación óptima de tiempo/temperatura de pasteurización para obtener el compromiso adecuado entre la consistencia de la pulpa y la calidad microbiológica del producto final. A continuación se llevó a cabo la pasteurización en escala industrial dentro de un pasteurizador de túnel aplicando el tratamiento a 75 ° C

  3. Low Voltage Electron Beam Processing Final Report CRADA No. TC-645-93-A

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wakalopulos, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-10-16

    This CRADA project was established to develop a small, inexpensive sealed-tube electron beam processing system having immediate applications in industrial, high speed manufacturing processes, and in the Department of Energy (DOE) waste treatment/cleanup operations. The technical work involved the development and demonstration of a compact, sealed, 50-75 kilovolt (kV) EB generator prototype, including controls and power supply. The specific goals of this project were to develop a low cost vacuum tube capable of shooting an electron beam several inches into the air, and to demonstrate that wide area materials processing is feasible by stacking the tubes to produce continuous beams. During the project, we successfully demonstrated the producibility of a low cost electron beam system and several material processing operations of interest to US industry, DOE and, since September 11, 2001, the Homeland Security.

  4. Dynamical quenching of tunneling in molecular magnets

    Energy Technology Data Exchange (ETDEWEB)

    José Santander, María, E-mail: maria.jose.noemi@gmail.com [Recursos Educativos Quántica, Santiago (Chile); Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Nunez, Alvaro S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile); Roldán-Molina, A. [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, Curauma, Valparaíso (Chile); Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com [Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago 9170124 (Chile); Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso (Chile)

    2015-12-15

    It is shown that a single molecular magnet placed in a rapidly oscillating magnetic field displays the phenomenon of quenching of tunneling processes. The results open a way to manipulate the quantum states of molecular magnets by means of radiation in the terahertz range. Our analysis separates the time evolution into slow and fast components thereby obtaining an effective theory for the slow dynamics. This effective theory presents quenching of the tunnel effect, in particular, stands out its difference with the so-called coherent destruction of tunneling. We support our prediction with numerical evidence based on an exact solution of Schrödinger's equation. - Highlights: • Single molecular magnets under rapidly oscillating magnetic fields is studied. • It is shown that this system displays the quenching of tunneling processes. • Our findings provide a control of quantum molecular magnets via terahertz radiation.

  5. A theory of local and global processes which affect solar wind electrons. II - Experimental support

    Science.gov (United States)

    Scudder, J. D.; Olbert, S.

    1979-01-01

    Strong observational support from data obtained on three different satellites and reported by three independent experimental groups is presented for all of the theoretically predicted correlations of a previous paper concerning local and global processes that affect solar-wind electrons. Specifically, it is shown that: (1) subthermal electrons behave most nearly as a classical gas; (2) the solar-wind extrathermal fraction of the electron density is anticorrelated within steady-state stream patterns with the local bulk speed; (3) the extrathermal electrons form a spectrally distinguishable subpopulation whose differential 'temperature' is anticorrelated with the local bulk speed; (4) the heat flux carried by electrons is anticorrelated with the bulk speed; and (5) the extrathermal 'temperature' is nearly independent of radius in the inner heliosphere. It is concluded that the previously discussed global and local Coulomb collisional effects are essential aspects of the solar-wind plasma as it is observed.

  6. Radio Wave Propagation in Tunnels

    National Research Council Canada - National Science Library

    Lee, Jeho

    2000-01-01

    This report examines the radio propagation model for narrow and long tunnels. Modal analysis is used to model the path gain in 2-D and 3-D rectangular tunnels and the coupling loss of L, T and cross tunnels...

  7. Carpal Tunnel Syndrome (For Kids)

    Science.gov (United States)

    ... OK for Kids? Your Teeth Heart Murmurs Carpal Tunnel Syndrome KidsHealth > For Kids > Carpal Tunnel Syndrome Print ... syndrome in the first place. Where Is This Tunnel? Take a look at the palm of your ...

  8. Prospects for applications of electron beams in processing of gas and oil hydrocarbons

    Science.gov (United States)

    Ponomarev, A. V.; Pershukov, V. A.; Smirnov, V. P.

    2015-12-01

    Waste-free processing of oil and oil gases can be based on electron-beam technologies. Their major advantage is an opportunity of controlled manufacturing of a wide range of products with a higher utility value at moderate temperatures and pressures. The work considers certain key aspects of electron beam technologies applied for the chain cracking of heavy crude oil, for the synthesis of premium gasoline from oil gases, and also for the hydrogenation, alkylation, and isomerization of unsaturated oil products. Electronbeam processing of oil can be embodied via compact mobile modules which are applicable for direct usage at distant oil and gas fields. More cost-effective and reliable electron accelerators should be developed to realize the potential of electron-beam technologies.

  9. Recent advances in electronic nose techniques for monitoring of fermentation process.

    Science.gov (United States)

    Jiang, Hui; Zhang, Hang; Chen, Quansheng; Mei, Congli; Liu, Guohai

    2015-12-01

    Microbial fermentation process is often sensitive to even slight changes of conditions that may result in unacceptable end-product quality. Thus, the monitoring of the process is critical for discovering unfavorable deviations as early as possible and taking the appropriate measures. However, the use of traditional analytical techniques is often time-consuming and labor-intensive. In this sense, the most effective way of developing rapid, accurate and relatively economical method for quality assurance in microbial fermentation process is the use of novel chemical sensor systems. Electronic nose techniques have particular advantages in non-invasive monitoring of microbial fermentation process. Therefore, in this review, we present an overview of the most important contributions dealing with the quality control in microbial fermentation process using the electronic nose techniques. After a brief description of the fundamentals of the sensor techniques, some examples of potential applications of electronic nose techniques monitoring are provided, including the implementation of control strategies and the combination with other monitoring tools (i.e. sensor fusion). Finally, on the basis of the review, the electronic nose techniques are critically commented, and its strengths and weaknesses being highlighted. In addition, on the basis of the observed trends, we also propose the technical challenges and future outlook for the electronic nose techniques.

  10. Electron-beam processed corn starch: evaluation of physicochemical and structural properties and technical-economic aspects of the processing

    Directory of Open Access Journals (Sweden)

    M. Braşoveanu

    2013-12-01

    Full Text Available The properties of starch can be modified by a variety of methods in order to meet desirable technological needs. Electron beam irradiation is able to induce changes in starch properties. The paper deals with investigation of physicochemical and structural modifications of corn starch processed by electron beam up to 50 kGy and evaluation of the technical-economic aspects of starch processing. Paste viscosity, pasting and peak temperatures decreased in a dose-dependent manner, indicating degradation of the macromolecule. Small circular perforations on the granule surface were observed for 50-kGy irradiated sample. Spectral characteristics suffered minor changes, suggesting that the inter- and intramolecular hydrogen bond stability was affected by the electron beam. These modified starches could find applications in foodstuffs requiring low-viscosity starch. A cost estimate of the electron beam processing of corn starch with an average absorbed dose of 30 kGy showed an increase of corn starch price by 16%.

  11. Nonlinear and Nonsymmetric Single-Molecule Electronic Properties Towards Molecular Information Processing.

    Science.gov (United States)

    Tamaki, Takashi; Ogawa, Takuji

    2017-09-05

    This review highlights molecular design for nonlinear and nonsymmetric single-molecule electronic properties such as rectification, negative differential resistance, and switching, which are important components of future single-molecule information processing devices. Perspectives on integrated "molecular circuits" are also provided. Nonlinear and nonsymmetric single-molecule electronics can be designed by utilizing (1) asymmetric molecular cores, (2) asymmetric anchoring groups, (3) an asymmetric junction environment, and (4) asymmetric electrode materials. This review mainly focuses on the design of molecular cores.

  12. Selection of the Process Parameters for the Mass Plating of Discrete Electronic Components

    OpenAIRE

    Hopper, Ann

    2014-01-01

    The miniaturisation of electronic components coupled with requirements for high temperature lead free soldering has forced the improvement of the termination finish of surface mount components to meet the critical demands of the electronic industry. In the present work the processing parameters necessary to plate miniature multilayer varistors (MLV’s) have been explored. The tooling selected was a “Rotary flow-thru’ plater” which achieved high volume plating with

  13. Charging process of polyurethane based composites under electronic irradiation: Effects of cellulose fiber content

    Science.gov (United States)

    Hadjadj, Aomar; Jbara, Omar; Tara, Ahmed; Gilliot, Mickael; Dellis, Jean-Luc

    2013-09-01

    The study deals with the charging effect of polyurethanes-based composites reinforced with cellulose fibers, under electronic beam irradiation in a scanning electron microscope. The results indicate that the leakage current and the trapped charge as well as the kinetics of charging process significantly change beyond a critical concentration of 10% cellulose fibers. These features are correlated with the cellulose concentration-dependence of the electrical properties, specifically resistivity and capacitance, of the composite.

  14. The Energy Processing by Power Electronics and its Impact on Power Quality

    OpenAIRE

    J. E.; Rocha; W.D.C Sanchez

    2012-01-01

    This paper discusses the electrical architectures adopted in wind turbines and its impact on the harmonic flux at the connected electric network. The integration of wind electric generators with the power grid needs energy processing by power electronics. It shows that different types of wind turbine generator systems use different types of electronic converters. This work provides a discussion on harmonic distortion taking place on the generator side, as well as in the power grid side. Key...

  15. Pulse radiolytic studies of electron transfer processes and applications to solar photochemistry. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Neta, P.

    1995-02-01

    The pulse radiolysis technique is applied to the study of electron transfer processes in a variety of chemical systems. Reactive intermediates are produced in solution by electron pulse irradiation and the kinetics of their reactions are followed by time resolved absorption spectrophotometry. Complementary experiments are carried out with excimer laser flash photolysis. These studies are concerned with mechanisms, kinetics, and thermodynamics of reactions of organic and inorganic radicals and unstable oxidation states of metal ions. Reactions are studied in both aqueous and non-aqueous solutions. The studies focus on the unique ability of pulse radiolysis to provide absolute rate constants for reactions of many inorganic radicals and organic peroxyl radicals, species that are key intermediates in many chemical processes. A special concern of this work is the study of electron transfer reactions of metalloporphyrins, which permits evaluation of these molecules as intermediates in solar energy conversion. Metalloporphyrins react with free radicals via electron transfer, involving the ligand or the metal center, or via bonding to the metal, leading to a variety of chemical species whose behavior is also investigated. The highlights of the results during the past three years are summarized below under the following sections: (a) electron transfer reactions of peroxyl radicals, concentrating on the characterization of new peroxyl radicals derived from vinyl, phenyl, other aryl, and pyridyl; (b) solvent effects on electron transfer reactions of inorganic and organic peroxyl radicals, including reactions with porphyrins, and (c) electron transfer and alkylation reactions of metalloporphyrins and other complexes.

  16. The effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt

    Science.gov (United States)

    Tang, C. L.; Wang, Y. X.; Ni, B.; Su, Z. P.; Reeves, G. D.; Zhang, J.-C.; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.

    2017-10-01

    Using the electron phase space density (PSD) data measured by Van Allen Probe A from January 2013 to April 2015, we investigate the effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt during 50 geomagnetic storms. A statistical study shows that the maximum electron PSDs for various μ (μ = 630, 1096, 2290, and 3311 MeV/G) at L* 4.0 after the storm peak have good correlations with storm intensity (cc 0.70). This suggests that the occurrence and magnitude of geomagnetic storms are necessary for relativistic electron enhancements at the inner edge of the outer radiation belt (L* = 4.0). For moderate or weak storm events (SYM-Hmin > -100 nT) with weak substorm activity (AEmax 0.77). For storm events with intense substorms after the storm peak, relativistic electron enhancements at L* = 4.5 and 5.0 are observed. This shows that intense substorms during the storm recovery phase are crucial to relativistic electron enhancements in the heart of the outer radiation belt. Our statistics study suggests that magnetospheric processes during geomagnetic storms have a significant effect on relativistic electron dynamics.

  17. Molecular control of electron and hole transfer processes: Theory and applications

    Energy Technology Data Exchange (ETDEWEB)

    Newton, M.D. [Brookhaven National Lab., Upton, NY (United States). Dept. of Chemistry; Cave, R.J. [Harvey Mudd Coll., Claremont, CA (United States). Dept. of Chemistry

    1996-02-01

    Recent decades have seen remarkable advances in microscopic understanding of electron transfer (ET) processes in widely ranging contexts, including solid-state, liquid solution, and complex biological assemblies. The primary goal of this chapter is to report recent advances in the modeling, calculation, and analysis of electronic coupling in complex molecular aggregates, thereby allowing an assessment of current progress toward the goal of molecular-level control and design. The control of electron transfer kinetics (i.e., enhancing desired processes, while inhibiting others) involves, of course, system energetics (especially activation and reorganization energies) as well as electronic coupling, which is most directly relevant only after the system has reached the appropriate point (or region) along the reaction coordinate. Nevertheless, to focus the discussion in this chapter, the authors will consider such energetics, and the associated molecular and solvent coordinates which control then, only to the extent that they bear on the analysis of the electronic coupling. In the following sections they first discuss the formulation of basic ET models, including the definition of initial and final states, the role of orbitals and 1-particle models in a many-electron context, the utility of various effective Hamiltonians, and the role of vibronic as well as purely electronic effects. With these theoretical tools in hand, they then examine very recent applications to complex molecular systems using the techniques of computational quantum chemistry, followed by detailed analysis of the numerical results. They then conclude with some comments regarding the current ``state of the art`` and remaining challenges.

  18. Photo-induced regeneration of hormones by electron transfer processes: Potential biological and medical consequences

    Energy Technology Data Exchange (ETDEWEB)

    Getoff, Nikola, E-mail: nikola.getoff@univie.ac.a [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria); Hartmann, Johannes [Department of Gynecologic Endocrinology and Reproduction, Medical University of Vienna, A-1090 Vienna (Austria); Schittl, Heike [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria); Gerschpacher, Marion [Department of Gynecologic Endocrinology and Reproduction, Medical University of Vienna, A-1090 Vienna (Austria); Quint, Ruth Maria [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria)

    2011-08-15

    Based on the previous results concerning electron transfer processes in biological substances, it was of interest to investigate if hormone transients resulting by e.g. electron emission can be regenerated. The presented results prove for the first time that the hormone transients originating by the electron emission process can be successfully regenerated by the transfer of electrons from a potent electron donor, such as vitamin C (VitC). Investigations were performed using progesterone (PRG), testosterone (TES) and estrone (E1) as representatives of hormones. By irradiation with monochromatic UV light ({lambda}=254 nm) in a media of 40% water and 60% ethanol, the degradation as well as the regeneration of the hormones was studied with each hormone individually and in the mixture with VitC as a function of the absorbed UV dose, using HPLC. Calculated from the obtained initial yields, the determined regeneration of PRG amounted to 52.7%, for TES to 58.6% and for E1 to 90.9%. The consumption of VitC was determined in the same way. The reported results concerning the regeneration of hormones by the transfer of electrons from an electron donor offer a new, promising method for the therapy with hormones. As a consequence of the regeneration of hormones, a decreased formation of carcinogenic metabolites is expected.

  19. The Energy Processing by Power Electronics and its Impact on Power Quality

    Directory of Open Access Journals (Sweden)

    J.E. Rocha

    2012-11-01

    Full Text Available This paper discusses the electrical architectures adopted in wind turbines and its impact on the harmonic flux at the connected electric network. The integration of wind electric generators with the power grid needs energy processing by power electronics. It shows that different types of wind turbine generator systems use different types of electronic converters. This work provides a discussion on harmonic distortion taking place on the generator side, as well as in the power grid side. Keywords: grid connection, harmonic distortion, power electronics and converters, wind energy conversion systems, wind power, wind technology, wind turbines

  20. Digging the CNGS decay tunnel

    CERN Multimedia

    Patrice Loiez

    2002-01-01

    Products of the collision between a proton beam and a graphite target will pass through a horn containing an electric field that will produce a focused beam. These particles will decay into muon neutrinos within the tunnel that is being constructed in these images. The neutrinos will then travel 730 km to Gran Sasso in Italy where huge detectors will observe the beam to study a process called neutrino oscillation.

  1. Diagnosis of Carpal Tunnel Syndrome

    OpenAIRE

    Keith, Michael Warren; Masear, Victoria; Chung, Kevin; Maupin, Kent; Andary, Michael; Amadio, Peter C.; Barth, Richard W.; Watters, William C.; Goldberg, Michael J.; Haralson, Robert H.; Turkelson, Charles M.; Wies, Janet L.

    2009-01-01

    This clinical practice guideline was created to improve patient care by outlining the appropriate information-gathering and decision-making processes involved in managing the diagnosis of carpal tunnel syndrome. The methods used to develop this clinical practice guideline were designed to combat bias, enhance transparency, and promote reproducibility. The guideline’s recommendations are as follows: The physician should obtain an accurate patient history. The physician should perform a physica...

  2. Tunneling Nanoelectromechanical Switches Based on Compressible Molecular Thin Films.

    Science.gov (United States)

    Niroui, Farnaz; Wang, Annie I; Sletten, Ellen M; Song, Yi; Kong, Jing; Yablonovitch, Eli; Swager, Timothy M; Lang, Jeffrey H; Bulović, Vladimir

    2015-08-25

    Abrupt switching behavior and near-zero leakage current of nanoelectromechanical (NEM) switches are advantageous properties through which NEMs can outperform conventional semiconductor electrical switches. To date, however, typical NEMs structures require high actuation voltages and can prematurely fail through permanent adhesion (defined as stiction) of device components. To overcome these challenges, in the present work we propose a NEM switch, termed a "squitch," which is designed to electromechanically modulate the tunneling current through a nanometer-scale gap defined by an organic molecular film sandwiched between two electrodes. When voltage is applied across the electrodes, the generated electrostatic force compresses the sandwiched molecular layer, thereby reducing the tunneling gap and causing an exponential increase in the current through the device. The presence of the molecular layer avoids direct contact of the electrodes during the switching process. Furthermore, as the layer is compressed, the increasing surface adhesion forces are balanced by the elastic restoring force of the deformed molecules which can promote zero net stiction and recoverable switching. Through numerical analysis, we demonstrate the potential of optimizing squitch design to enable large on-off ratios beyond 6 orders of magnitude with operation in the sub-1 V regime and with nanoseconds switching times. Our preliminary experimental results based on metal-molecule-graphene devices suggest the feasibility of the proposed tunneling switching mechanism. With optimization of device design and material engineering, squitches can give rise to a broad range of low-power electronic applications.

  3. Tunnel operations study.

    Science.gov (United States)

    2013-12-01

    In June 2000, the State of Alaska Department of Transportation and Public Facilities completed construction of the Whittier Access Project by converting the existing 2.5- : mile Whittier Tunnel into the worlds only dual-use highway/rail tunnel wit...

  4. Interatomic relaxation processes induced in neon dimers by electron-impact ionization

    Science.gov (United States)

    Yan, S.; Zhang, P.; Stumpf, V.; Gokhberg, K.; Zhang, X. C.; Xu, S.; Li, B.; Shen, L. L.; Zhu, X. L.; Feng, W. T.; Zhang, S. F.; Zhao, D. M.; Ma, X.

    2018-01-01

    We report an experimental observation of the interatomic Coulombic decay (ICD) and radiative charge-transfer (RCT) processes in a Ne dimer (e ,2 e ) following a 380-eV electron impact. By detecting the N e+-N e+ cation pair and one of the emitted electrons in coincidence, the fingerprint of the ICD process initiated by the inner-valence ionization of Ne is obtained. Furthermore, the experimental results and ab initio calculations together unambiguously confirm the occurrence of the RCT process, and we show that most of the low-energy electrons produced in ionization of the Ne dimers are due to the ICD, which strongly suggests the importance of the ICD in causing radiation damage in a biological medium.

  5. Real-Time Digital Signal Processing Based on FPGAs for Electronic Skin Implementation.

    Science.gov (United States)

    Ibrahim, Ali; Gastaldo, Paolo; Chible, Hussein; Valle, Maurizio

    2017-03-10

    Enabling touch-sensing capability would help appliances understand interaction behaviors with their surroundings. Many recent studies are focusing on the development of electronic skin because of its necessity in various application domains, namely autonomous artificial intelligence (e.g., robots), biomedical instrumentation, and replacement prosthetic devices. An essential task of the electronic skin system is to locally process the tactile data and send structured information either to mimic human skin or to respond to the application demands. The electronic skin must be fabricated together with an embedded electronic system which has the role of acquiring the tactile data, processing, and extracting structured information. On the other hand, processing tactile data requires efficient methods to extract meaningful information from raw sensor data. Machine learning represents an effective method for data analysis in many domains: it has recently demonstrated its effectiveness in processing tactile sensor data. In this framework, this paper presents the implementation of digital signal processing based on FPGAs for tactile data processing. It provides the implementation of a tensorial kernel function for a machine learning approach. Implementation results are assessed by highlighting the FPGA resource utilization and power consumption. Results demonstrate the feasibility of the proposed implementation when real-time classification of input touch modalities are targeted.

  6. Real-Time Digital Signal Processing Based on FPGAs for Electronic Skin Implementation †

    Directory of Open Access Journals (Sweden)

    Ali Ibrahim

    2017-03-01

    Full Text Available Enabling touch-sensing capability would help appliances understand interaction behaviors with their surroundings. Many recent studies are focusing on the development of electronic skin because of its necessity in various application domains, namely autonomous artificial intelligence (e.g., robots, biomedical instrumentation, and replacement prosthetic devices. An essential task of the electronic skin system is to locally process the tactile data and send structured information either to mimic human skin or to respond to the application demands. The electronic skin must be fabricated together with an embedded electronic system which has the role of acquiring the tactile data, processing, and extracting structured information. On the other hand, processing tactile data requires efficient methods to extract meaningful information from raw sensor data. Machine learning represents an effective method for data analysis in many domains: it has recently demonstrated its effectiveness in processing tactile sensor data. In this framework, this paper presents the implementation of digital signal processing based on FPGAs for tactile data processing. It provides the implementation of a tensorial kernel function for a machine learning approach. Implementation results are assessed by highlighting the FPGA resource utilization and power consumption. Results demonstrate the feasibility of the proposed implementation when real-time classification of input touch modalities are targeted.

  7. Real-Time Digital Signal Processing Based on FPGAs for Electronic Skin Implementation †

    Science.gov (United States)

    Ibrahim, Ali; Gastaldo, Paolo; Chible, Hussein; Valle, Maurizio

    2017-01-01

    Enabling touch-sensing capability would help appliances understand interaction behaviors with their surroundings. Many recent studies are focusing on the development of electronic skin because of its necessity in various application domains, namely autonomous artificial intelligence (e.g., robots), biomedical instrumentation, and replacement prosthetic devices. An essential task of the electronic skin system is to locally process the tactile data and send structured information either to mimic human skin or to respond to the application demands. The electronic skin must be fabricated together with an embedded electronic system which has the role of acquiring the tactile data, processing, and extracting structured information. On the other hand, processing tactile data requires efficient methods to extract meaningful information from raw sensor data. Machine learning represents an effective method for data analysis in many domains: it has recently demonstrated its effectiveness in processing tactile sensor data. In this framework, this paper presents the implementation of digital signal processing based on FPGAs for tactile data processing. It provides the implementation of a tensorial kernel function for a machine learning approach. Implementation results are assessed by highlighting the FPGA resource utilization and power consumption. Results demonstrate the feasibility of the proposed implementation when real-time classification of input touch modalities are targeted. PMID:28287448

  8. Tunnel fire dynamics

    CERN Document Server

    Ingason, Haukur; Lönnermark, Anders

    2015-01-01

    This book covers a wide range of issues in fire safety engineering in tunnels, describes the phenomena related to tunnel fire dynamics, presents state-of-the-art research, and gives detailed solutions to these major issues. Examples for calculations are provided. The aim is to significantly improve the understanding of fire safety engineering in tunnels. Chapters on fuel and ventilation control, combustion products, gas temperatures, heat fluxes, smoke stratification, visibility, tenability, design fire curves, heat release, fire suppression and detection, CFD modeling, and scaling techniques all equip readers to create their own fire safety plans for tunnels. This book should be purchased by any engineer or public official with responsibility for tunnels. It would also be of interest to many fire protection engineers as an application of evolving technical principles of fire safety.

  9. A Student-Built Scanning Tunneling Microscope

    Science.gov (United States)

    Ekkens, Tom

    2015-01-01

    Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

  10. BGO front-end electronics and signal processing in the MXGS instrument for the ASIM mission

    DEFF Research Database (Denmark)

    Skogseide, Yngve; Cenkeramaddi, Linga Reddy; Genov, Georgi

    2012-01-01

    This paper presents the Bismuth Germanate Oxide (BGO) front-end electronics design and signal processing in Modular X- and Gamma ray sensor (MXGS) instrument onboard the Atmosphere Space Interaction Monitor (ASIM) mission, funded by the European Space Agency. University of Bergen is responsible...... for the design and development of the detector layers and readout electronics for the MXGS instrument. The principal objective of the instrument is to detect Terrestrial Gamma ray Flashes (TGFs), which are related to thunderstorm activity. The digital pulse processing scheme used in the MXGS BGO detector gives...

  11. Electrons in feldspar I: On the wavefunction of electrons trapped at simple lattice defects

    DEFF Research Database (Denmark)

    Poolton, H.R.J.; Wallinga, J.; Murray, A.S.

    2002-01-01

    The purpose of this article is to make an initial consideration of the physical properties of electrons trapped at classic hydrogenic lattice defects in feldspar. We are particularly interested to determine the radial extent of the electron wavefunctions in the ground and excited states...... processes in the materials. Under low-energy optical stimulation (hnu similar to 1.4 eV), luminescence can be a competitive process between direct electron-hole tunnelling recombination (with the charge still trapped at the defect sites), and free-to-bound recombination (after the excited state electron...

  12. Approaches for ultrafast imaging of transient materials processes in the transmission electron microscope.

    Science.gov (United States)

    LaGrange, Thomas; Reed, Bryan W; Santala, Melissa K; McKeown, Joseph T; Kulovits, Andreas; Wiezorek, Jörg M K; Nikolova, Liliya; Rosei, Federico; Siwick, Bradely J; Campbell, Geoffrey H

    2012-11-01

    The growing field of ultrafast materials science, aimed at exploring short-lived transient processes in materials on the microsecond to femtosecond timescales, has spawned the development of time-resolved, in situ techniques in electron microscopy capable of capturing these events. This article gives a brief overview of two principal approaches that have emerged in the past decade: the stroboscopic ultrafast electron microscope and the nanosecond-time-resolved single-shot instrument. The high time resolution is garnered through the use of advanced pulsed laser systems and a pump-probe experimental platforms using laser-driven photoemission processes to generate time-correlated electron probe pulses synchronized with laser-driven events in the specimen. Each technique has its advantages and limitations and thus is complementary in terms of the materials systems and processes that they can investigate. The stroboscopic approach can achieve atomic resolution and sub-picosecond time resolution for capturing transient events, though it is limited to highly repeatable (>10(6) cycles) materials processes, e.g., optically driven electronic phase transitions that must reset to the material's ground state within the repetition rate of the femtosecond laser. The single-shot approach can explore irreversible events in materials, but the spatial resolution is limited by electron source brightness and electron-electron interactions at nanosecond temporal resolutions and higher. The first part of the article will explain basic operating principles of the stroboscopic approach and briefly review recent applications of this technique. As the authors have pursued the development of the single-shot approach, the latter part of the review discusses its instrumentation design in detail and presents examples of materials science studies and the near-term instrumentation developments of this technique. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Quantum Information Processing by Electron Spin Resonance in a Transistor Structure

    Science.gov (United States)

    Yablonovitch, Eli

    2001-03-01

    Isolated electron spins in low temperature semiconductors are now recognized to have considerable potential for storing and manipulating quantum information. One of the great advantages of a spin in a semiconductor is that it can be embedded into a transistor structure, and it can thereby lend itself to large-scale integration of a quantum information processor. One essential element for spin-based quantum information processing is to be able to individually address the spins, or qubits, rotations. The electron spin resonance (ESR) electrons in a GaAs/AlGaAs heterostructure can be tuned by means of a gate voltage. The front and back gates of the heterostructure produce opposite g-factor shift, suggesting that electron g-factor is being electrostatically controlled by shifting the electron wave function from one epitaxial layer to another with different g-factors. We report our observations of gate-voltage tuned ESR in a two-dimensional electron system. We demonstrate that the electrostatic field of a gate can effectively adjust the weighting of the electron wave function between heterostructure layers of different composition producing a large g-factor change. We have monitored the ESR spin flips by means of the source/drain channel current, and conversely we have tuned the spin resonance frequency by means of the gate voltage. These are two of the elementary operations required in a quantum information processor.

  14. Prioritizing the client trust factors in electronic banking using analytic hierarchy process

    Directory of Open Access Journals (Sweden)

    Hossein vazifedust

    2014-04-01

    Full Text Available This paper prioritizes the trust factors among electronic banking clients of an Iranian bank named Parsian Bank. The study first analyzes and reviews the literature and interviews with experts of electronic banking and academicians and determines client trust as the most important factor for development of electronic banking. The study also determines different factors associated with trust, which includes individual factors, banking factors and infrastructural factors. The sample populations consist of 25 experts who are academicians, managers and bank officers, clients of electronic banking. The necessary data was collected through conducting interviews and questionnaires and they are analyzed using analytic hierarchy process (AHP. The research findings indicate that the attitudinal factors, telecommunication infrastructure and cultural factors were the most influential factors accordingly and the customer orientation and ease of access were the least influential factors.

  15. Height Control and Deposition Measurement for the Electron Beam Free Form Fabrication (EBF3) Process

    Science.gov (United States)

    Seufzer, William J. (Inventor); Hafley, Robert A. (Inventor)

    2017-01-01

    A method of controlling a height of an electron beam gun and wire feeder during an electron freeform fabrication process includes utilizing a camera to generate an image of the molten pool of material. The image generated by the camera is utilized to determine a measured height of the electron beam gun relative to the surface of the molten pool. The method further includes ensuring that the measured height is within the range of acceptable heights of the electron beam gun relative to the surface of the molten pool. The present invention also provides for measuring a height of a solid metal deposit formed upon cooling of a molten pool. The height of a single point can be measured, or a plurality of points can be measured to provide 2D or 3D surface height measurements.

  16. Construction of Vibronic Diabatic Hamiltonian for Excited-State Electron and Energy Transfer Processes.

    Science.gov (United States)

    Xie, Yu; Jiang, Shengshi; Zheng, Jie; Lan, Zhenggang

    2017-12-21

    Photoinduced excited-state electron and energy transfer processes are crucial in biological photoharvesting systems and organic photovoltaic devices. We discuss the construction of a diabatic vibronic Hamiltonian for the proper treatment of these processes involving the projection approach acting on both electronic wave functions and vibrational modes. In the electronic part, the wave function projection approach is used to construct the diabatic Hamiltonian in which both local excited states and charge-transfer states are included on the same footing. For the vibrational degrees of freedom, the vibronic couplings in the diabatic Hamiltonian are obtained in the basis of the pseudonormal modes localized on each monomer site by applying delocalized-to-localized mode projection. This systematic approach allows us to construct the vibronic diabatic Hamiltonian in molecular aggregates.

  17. High Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal

    Semiconductor nanowires (NWs) have emerged as a promising technology for future electronic and optoelectronic devices. Epitaxial growth of III-V materials on Si substrates have been demonstrated, allowing for low-cost production. As the lattice matching requirements are much less strict than...... is the tunnel (Esaki) diode, which provides a low-resistance connection between junctions. We demonstrate an InP-GaAs NW axial heterostructure with tunnel diode behavior. InP and GaAs can be readily n- and p-doped, respectively, and the heterointerface is expected to have an advantageous type II band alignment...

  18. Implementing electronic data interchange (EDI) with small business suppliers in the pre-award acquisition process

    OpenAIRE

    Sergeson, Robert B.

    1993-01-01

    Approved for public release; distribution is unlimited. This thesis examines the implementation of electronic data interchange (EDI) with small business suppliers in the pre-award acquisition process. The general history and concept of EDI is discussed along with the pre- award acquisition process. The results of a small business survey are analyzed to provide insight on the barriers and impediments to implementing EDI with small business concerns. Additionally, interviews and discussions ...

  19. Simulated electronic heterodyne recording and processing of pulsed-laser holograms

    Science.gov (United States)

    Decker, A. J.

    1979-01-01

    The electronic recording of pulsed-laser holograms is proposed. The polarization sensitivity of each resolution element of the detector is controlled independently to add an arbitrary phase to the image waves. This method which can be used to simulate heterodyne recording and to process three-dimensional optical images, is based on a similar method for heterodyne recording and processing of continuous-wave holograms.

  20. Dynamical Processes in Open Quantum Systems from a TDDFT Perspective: Resonances and Electron Photoemission.

    Science.gov (United States)

    Larsen, Ask Hjorth; De Giovannini, Umberto; Rubio, Angel

    2016-01-01

    We present a review of different computational methods to describe time-dependent phenomena in open quantum systems and their extension to a density-functional framework. We focus the discussion on electron emission processes in atoms and molecules addressing excited-state lifetimes and dissipative processes. Initially we analyze the concept of an electronic resonance, a central concept in spectroscopy associated with a metastable state from which an electron eventually escapes (electronic lifetime). Resonances play a fundamental role in many time-dependent molecular phenomena but can be rationalized from a time-independent context in terms of scattering states. We introduce the method of complex scaling, which is used to capture resonant states as localized states in the spirit of usual bound-state methods, and work on its extension to static and time-dependent density-functional theory. In a time-dependent setting, complex scaling can be used to describe excitations in the continuum as well as wave packet dynamics leading to electron emission. This process can also be treated by using open boundary conditions which allow time-dependent simulations of emission processes without artificial reflections at the boundaries (i.e., borders of the simulation box). We compare in detail different schemes to implement open boundaries, namely transparent boundaries using Green functions, and absorbing boundaries in the form of complex absorbing potentials and mask functions. The last two are regularly used together with time-dependent density-functional theory to describe the electron emission dynamics of atoms and molecules. Finally, we discuss approaches to the calculation of energy and angle-resolved time-dependent pump-probe photoelectron spectroscopy of molecular systems.

  1. Efficient electron injection from solution-processed cesium stearate interlayers in organic light-emitting diodes

    NARCIS (Netherlands)

    Wetzelaer, G. A. H.; Najafi, A.; Kist, R. J. P.; Kuik, M.; Blom, P. W. M.

    2013-01-01

    The electron-injection capability of solution-processed cesium stearate films in organic light-emitting diodes is investigated. Cesium stearate, which is expected to exhibit good solubility and film formation due to its long hydrocarbon chain, is synthesized using a straightforward procedure.

  2. Electronic outlining as a writing strategy: Effects on students' writing products, mental effort and writing process

    NARCIS (Netherlands)

    De Smet, Milou; Brand-Gruwel, Saskia; Leijten, Mariëlle; Kirschner, Paul A.

    2018-01-01

    This study addresses to what extent and how electronic outlining enhances students' writing performance. To this end, the focus of this study is not only on students' final writing products but also on the organisation of the writing process (i.e., planning, translating, and reviewing) and perceived

  3. Controlling ionisation and fragmentation processes in CO2 via inelastic electron recollisions

    Directory of Open Access Journals (Sweden)

    Frasinski L. J.

    2013-03-01

    Full Text Available The angular dependence of nonsequential double ionisation and dissociation induced by laser driven inelastic electron rescattering was investigated experimentally in aligned CO2. A clear dependence on the recollision angle was found demonstrating quantum control of ionisation and dissociation processes in the strong field regime.

  4. IBIS integrated biological imaging system: electron micrograph image-processing software running on Unix workstations.

    Science.gov (United States)

    Flifla, M J; Garreau, M; Rolland, J P; Coatrieux, J L; Thomas, D

    1992-12-01

    'IBIS' is a set of computer programs concerned with the processing of electron micrographs, with particular emphasis on the requirements for structural analyses of biological macromolecules. The software is written in FORTRAN 77 and runs on Unix workstations. A description of the various functions and the implementation mode is given. Some examples illustrate the user interface.

  5. Resist and Exposure Processes for Sub-10-nm Electron and Ion Beam Lithography

    NARCIS (Netherlands)

    Sidorkin, V.A.

    2010-01-01

    The research work described in this thesis deals with studying the ultimate resolution capabilities of electron and ion beam lithography (EBL and IBL respectively) with a focus on resist and exposure processes. The aim of this research was to enlarge knowledge and improve methods on the formation of

  6. Organizational Leader Sensemaking in Healthcare Process Changes: The Development of the Electronic Medical Records Expectation Questionnaire

    Science.gov (United States)

    Riesenmy, Kelly Rouse

    2011-01-01

    Physicians play a unique role in the adoption of electronic medical records (EMR) within the healthcare organization. As leaders, they are responsible for setting the standards for this new technology within their sphere of influence while concurrently being required to learn and integrate EMR into their own workflow and process as the recipients…

  7. Writing argumentative texts: The effects of electronic outlining on students’ writing product and process

    NARCIS (Netherlands)

    De Smet, Milou; Brand-Gruwel, Saskia; Leijten, Mariëlle; Kirschner, Paul A.

    2012-01-01

    De Smet, M. J. R., Brand-Gruwel, S., Leijten, M., & Kirschner, P. A. (2012, July). Writing argumentative texts: The effects of electronic outlining on students’ writing product and process. Paper presented at the meeting of EARLI SIG Writing, Porto, Portugal.

  8. Introduction of an all-electronic administrative process for a major international pediatric surgical meeting.

    Science.gov (United States)

    Applebaum, Harry; Boles, Kay; Atkinson, James B

    2003-12-01

    The administrative process for annual meetings is time consuming and increasingly costly when accomplished by traditional postal, fax, and telephone methods. The Pacific Association of Pediatric Surgeons introduced an all-electronic communication format for its 2002 annual meeting. Attendee acceptance and administrative and financial impact were evaluated. Interested physicians were directed to a Website containing detailed information and electronic forms. E-mail was used for the abstract selection and manuscript submission processes. Attendees were surveyed to evaluate the new format. Administrative costs for the new format were compared with estimated costs for a comparable traditionally managed meeting. Attendance was similar to that at previous US meetings. Eighty-two percent of respondents approved of the all-electronic format, although 48% believed a choice should remain. None suggested a complete return to the traditional format. Abstract and manuscript processing time was reduced substantially as were administrative costs (79.43 dollars savings per physician registrant). Adoption of an all-electronic annual meeting administrative process was associated with substantial cost reduction, increased efficiency, and excellent attendee satisfaction. This technology can help avoid increased registration fees while easing the burden on physician volunteers.

  9. Electronic Data Processing. Report on Training. National EDP Skills and Training Needs Survey.

    Science.gov (United States)

    Wagner, Graham A.

    A national survey of electronic data processing (EDP) skills and training needs involved 16 representative firms that employed EDP staff. Separate semi-structured interview schedules were used to interview 266 job holders and 63 managers with responsibility for EDP staff and computing systems. Findings indicated 67 percent of EDP staff had not…

  10. The Douglas Aerophysics Laboratory Four-Foot Trisonic Wind Tunnel,

    Science.gov (United States)

    This report describes the Four-Foot Trisonic Wind Tunnel and the Douglas Aerophysics Laboratory in which it is located. It also presents the performance and operating characteristics of the tunnel, model support and design considerations for a test, diverse test capabilities, instrumentation and data recording equipment, data processing and presentation, and the customer responsibilities for obtaining optimum planning and performance of wind tunnel tests.

  11. Markovian Geology Prediction Approach and its Application in Mountain Tunnels

    OpenAIRE

    Guan, Zhenchang; Deng, Tao; Du, Saizhao; Li, Bo; Jiang, Yujing

    2012-01-01

    A geology prediction approach based on Markov random process and Bayesian updating procedure is presented in this article. It can dynamically predict the ground conditions ahead of tunnel face in a probabilistic way with very low cost, when the tunnel face advances and new geological information is revealed. The application case study on Chuangshi Tunnel project shows that the prediction results fit the real grounds condition well, especially for the short range ahead of face. This approach c...

  12. Manipulation of magnetic skyrmions with a scanning tunneling microscope

    Science.gov (United States)

    Wieser, R.; Shindou, R.; Xie, X. C.

    2017-02-01

    The dynamics of a single magnetic skyrmion in an atomic spin system under the influence of a scanning tunneling microscope is investigated by computer simulations solving the Landau-Lifshitz-Gilbert equation. Two possible scenarios are described: manipulation with aid of a spin-polarized tunneling current and by an electric field created by the scanning tunneling microscope. The dynamics during the creation and annihilation process is studied and the possibility to move single skyrmions is showed.

  13. Single-Molecule Electronics with Cross- Conjugated Molecules: Quantum Interference, IETS and Non-Equilibrium "Temperatures"

    DEFF Research Database (Denmark)

    Jørgensen, Jacob Lykkebo

    Abstract The idea of using single-molecules as components in electronic devices is fas- cinating. For this idea to come into fruition, a number of technical and theo- retical challenges must be overcome. In this PhD thesis, the electron-phonon interaction is studied for a special class of molecules......, the electrons can tunnel in- elastically from the left to the right electrode. This is the process behind inelastic electron tunnelling spectroscopy (IETS), which is a single-molecule spectroscopic method, where the vibrational ngerprint of a molecule is di- rectly observed by the tunnelling current...... This process has been studied in detail for ordinary conjugated or saturated molecules. Selection rules does not exist in IETS, but some modes are favoured over others, and this is the bases for the propensity rules in IETS that has been rationalised. In this thesis, we study IETS for cross...

  14. Fermi-edge singularity at tunneling and anisotropic magneto-tunneling in low-dimensional semiconductor structures

    Energy Technology Data Exchange (ETDEWEB)

    Larkin, Ivan A [International Institute of Physics (IIP), Universidade Federal do Rio Grande do Norte, Departamento de Fisica, Campus Universitario Lagoa Nova, Natal, RN, 59078-970 (Brazil); Vdovin, E E; Khanin, Yu N [Institute of Microelectronics Technology RAS, 142432 Chernogolovka (Russian Federation); Ujevic, Sebastian [Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Santo Andre, Sao Paulo 09210-170 (Brazil); Henini, M, E-mail: vaniala2000@yahoo.co.u [School of Physics and Astronomy, University of Nottingham, NG7 2RD (United Kingdom)

    2010-09-15

    We consider many-body enhanced electron tunneling through an InAs quantum dot in a magnetic field applied perpendicular to the tunneling direction. The critical exponent of the Fermi-edge singularity in the tunneling current is calculated as a function of the magnetic field. We use lowest Landau level approximation for the electrons in the emitter and perform scattering matrix calculations using the Born approximation. We examine in detail the anisotropic behavior of the amplitude and shape of the resonant peaks.

  15. Economic evaluation of an electrochemical process for the recovery of metals from electronic waste.

    Science.gov (United States)

    Diaz, Luis A; Lister, Tedd E

    2017-12-08

    As the market of electronic devices continues to evolve, the waste stream generated from antiquated technology is increasingly view as an alternative to substitute primary sources of critical a value metals. Nevertheless, the sustainable recovery of materials can only be achieved by environmentally friendly processes that are economically competitive with the extraction from mineral ores. Hence, This paper presents the techno-economic assessment for a comprehensive process for the recovery of metals and critical materials from e-waste, which is based in an electrochemical recovery (ER) technology. Economic comparison is performed with the treatment of e-waste via smelting, which is currently the primary route for recycling metals from electronics. Results indicate that the electrochemical recovery process is a competitive alternative for the recovery of value from electronic waste when compared with the traditional black Cu smelting process. A significantly lower capital investment, 2.9 kg e-waste per dollar of capital investment, can be achieved with the ER process vs. 1.3 kg per dollar in the black Cu smelting process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Adsorption and deposition of anthraquinone-2-carboxylic acid on alumina studied by inelastic electron tunneling spectroscopy, infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Higo, Morihide [Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan)], E-mail: higo@apc.kagoshima-u.ac.jp; Miake, Takeshi; Mitsushio, Masaru; Yoshidome, Toshifumi [Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan); Ozono, Yoshihisa [Center for Instrumental analysis, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan)

    2008-04-30

    The adsorption state of anthraquinone-2-carboxylic acid (AQ-2-COOH) deposited from acetone solutions (0.01-1.00 mg/ml) on native oxide surfaces of Al films was characterized by inelastic electron tunneling spectroscopy, infrared reflection absorption spectroscopy, and X-ray photoelectron spectroscopy. The oxide was prepared on evaporated Al films at room temperature in an oxygen-dc glow discharge. The morphology of the deposited AQ-2-COOH on the oxide surfaces was observed and analyzed by atomic force microscopy. These surface analyses showed that AQ-2-COOH is adsorbed predominantly as a uniform nanometer-scale film of carboxylate anions on the oxide surfaces deposited from solutions with concentrations lower than or equal to 0.02 mg/ml. It was found that AQ-2-COOH is adsorbed as both a uniform film of anions and as micron-sized particles of neutral molecules with heights of a few tens of nanometers when AQ-2-COOH is deposited from solutions with concentrations higher than 0.02 mg/ml. A comparison of the results obtained by these surface analytical techniques clearly shows the features and advantages of these analytical techniques.

  17. Epitaxial BaTiO{sub 3}(100) films on Pt(100): A low-energy electron diffraction, scanning tunneling microscopy, and x-ray photoelectron spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, Stefan; Huth, Michael; Schindler, Karl-Michael; Widdra, Wolf [Institute of Physics, Martin-Luther-Universitaet Halle-Wittenberg, Halle (Germany)

    2011-09-14

    The growth of epitaxial ultrathin BaTiO{sub 3} films on a Pt(100) substrate has been studied by scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and x-ray photoelectron spectroscopy (XPS). The films have been prepared by radio-frequency-assisted magnetron sputter deposition at room temperature and develop a long-range order upon annealing at 900 K in O{sub 2}. By adjusting the Ar and O{sub 2} partial pressures of the sputter gas, the stoichiometry was tuned to match that of a BaTiO{sub 3}(100) single crystal as determined by XPS. STM reveals the growth of continuous BaTiO{sub 3} films with unit cell high islands on top. With LEED already for monolayer thicknesses, the formation of a BaTiO{sub 3}(100)-(1 x 1) structure has been observed. Films of 2-3 unit cell thickness show a brilliant (1 x 1) LEED pattern for which an extended set of LEED I-V data has been acquired. At temperatures above 1050 K the BaTiO{sub 3} thin film starts to decay by formation of vacancy islands. In addition (4 x 4) and (3 x 3) surface reconstructions develop upon prolonged heating.

  18. Angle-resolved 2D imaging of electron emission processes in atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Kukk, E.; Wills, A.A.; Langer, B.; Bozek, J.D.; Berrah, N.

    2004-09-02

    A variety of electron emission processes have been studied in detail for both atomic and molecular systems, using a highly efficient experimental system comprising two time-of-flight (TOF) rotatable electron energy analyzers and a 3rd generation synchrotron light source. Two examples are used here to illustrate the obtained results. Firstly, electron emissions in the HCL molecule have been mapped over a 14 eV wide photon energy range over the Cl 2p ionization threshold. Particular attention is paid to the dissociative core-excited states, for which the Auger electron emission shows photon energy dependent features. Also, the evolution of resonant Auger to the normal Auger decay distorted by post-collision interaction has been observed and the resonating behavior of the valence photoelectron lines studied. Secondly, an atomic system, neon, in which excitation of doubly excited states and their subsequent decay to various accessible ionic states has been studied. Since these processes only occurs via inter-electron correlations, the many body dynamics of an atom can be probed, revealing relativistic effects, surprising in such a light atom. Angular distribution of the decay of the resonances to the parity unfavored continuum exhibits significant deviation from the LS coupling predictions.

  19. Low Temperature Scanning Tunneling Spectroscopy

    Science.gov (United States)

    Kirk, Michael Dominic

    A scanning tunneling microscope (STM) was designed and built to operate at liquid helium temperature and was used to measure highly localized electron tunneling spectroscopy. Several instruments were built, all capable of operating in many different environments: air, vacuum, liquid helium and in a transfer gas. An adaptation of one particular design was made into an atomic force microscope capable of operating at low temperatures. Using a low temperature STM, three adsorbed molecular species (liquid crystals, sorbic acid, and carbon monoxide), deposited on a graphite substrate, have been imaged at 4.2K. The inelastic tunneling spectra of these adsorbates show strong peaks in dI/dV vs V curves at energies that correspond to known vibrational modes. The increase in conductance at the onset of inelastic tunneling was measured to be as high as 100 times. The spatial variation of the spectra was measured and was seen to change dramatically on the scale of angstroms, suggesting that individual molecular bonds could be measured. A theoretical model is presented to explain the contrast seen in the STM images of adsorbed molecules, thereby explaining why adsorbed molecules appear to be more conductive than the background. The microscope proved very useful for measuring the energy gap of high temperature superconductors. These materials often have submicron grain sizes. For LaSrCuO, YBaCuO, and BiCaSrCuO, the conductance curves showed a large energy gap suggesting a strongly coupled superconductor. The conductance curves also indicated that intergrain tunneling may occur and that the background conductance varied linearly with the applied voltage. The crystalline structure of rm Bi_2 Sr_2 CaCu_2 O_ {8 + delta} was imaged by an STM operating in air and in ultra-high vacuum. From the STM images the bulk crystal structure model for this material was refined. Finally, the STM was used to make holes reproducibly on a graphite surface with diameters less than 40A. Because the

  20. Hybrid Orbital and Numerical Grid Representationfor Electronic Continuum Processes: Double Photoionization of Atomic Beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Yip, Frank L; McCurdy, C. William; Rescigno, Thomas N

    2010-04-19

    A general approach for ab initio calculations of electronic continuum processes is described in which the many-electron wave function is expanded using a combination of orbitals at short range and the finite-element discrete variable representation(FEM-DVR) at larger distances. The orbital portion of the basis allows the efficient construction of many-electron configurations in which some of the electrons are bound, but because the orbitals are constructed from an underlying FEM-DVR grid, the calculation of two-electron integrals retains the efficiency of the primitive FEM-DVR approach. As an example, double photoionization of beryllium is treated in a calculation in which the 1s{sup 2} core is frozen. This approach extends the use of exterior complex scaling (ECS) successfully applied to helium and H{sub 2} to calculations with two active electrons on more complicated targets. Integrated, energy-differential and triply-differential cross sections are exhibited, and the results agree well with other theoretical investigations.

  1. General risks for tunnelling projects: An overview

    Science.gov (United States)

    Siang, Lee Yong; Ghazali, Farid E. Mohamed; Zainun, Noor Yasmin; Ali, Roslinda

    2017-10-01

    Tunnels are indispensable when installing new infrastructure as well as when enhancing the quality of existing urban living due to their unique characteristics and potential applications. Over the past few decades, there has been a significant increase in the building of tunnels, world-wide. Tunnelling projects are complex endeavors, and risk assessment for tunnelling projects is likewise a complex process. Risk events are often interrelated. Occurrence of a technical risk usually carries cost and schedule consequences. Schedule risks typically impact cost escalation and project overhead. One must carefully consider the likelihood of a risk's occurrence and its impact in the context of a specific set of project conditions and circumstances. A project's goals, organization, and environment impacts in the context of a specific set of project conditions and circumstances. Some projects are primarily schedule driven; other projects are primarily cost or quality driven. Whether a specific risk event is perceived fundamentally as a cost risk or a schedule risk is governed by the project-specific context. Many researchers have pointed out the significance of recognition and control of the complexity, and risks of tunnelling projects. Although all general information on a project such as estimated duration, estimated cost, and stakeholders can be obtained, it is still quite difficult to accurately understand, predict and control the overall situation and development trends of the project, leading to the risks of tunnelling projects. This paper reviews all the key risks for tunnelling projects from several case studies that have been carried out by other researchers. These risks have been identified and reviewed in this paper. As a result, the current risk management plan in tunnelling projects can be enhanced by including all these reviewed risks as key information.

  2. Energetic electron processes fluorescence effects for structured nanoparticles X-ray analysis and nuclear medicine applications

    Energy Technology Data Exchange (ETDEWEB)

    Taborda, A.; Desbrée, A. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM/SDI/LEDI, BP-17, 31, Avenue de la Division Leclerc, 92262 Fontenay-aux-Roses (France); Carvalho, A. [IEQUALTECS, Lda, Rua Dr. Francisco Sá Carneiro, 36, 2500-065 S. Gregório CLD (Portugal); Chaves, P.C. [C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km 139.7, 2685-066 Bobadela LRS (Portugal); Reis, M.A., E-mail: mareis@ctn.tecnico.ulisboa.pt [IEQUALTECS, Lda, Rua Dr. Francisco Sá Carneiro, 36, 2500-065 S. Gregório CLD (Portugal); C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km 139.7, 2685-066 Bobadela LRS (Portugal)

    2016-08-15

    Superparamagnetic iron oxide (SPIO) nanoparticles are widely used as contrast agents for nuclear magnetic resonance imaging (MRI), and can be modified for improved imaging or to become tissue-specific or even protein-specific. The knowledge of their detailed elemental composition characterisation and potential use in nuclear medicine applications, is, therefore, an important issue. X-ray fluorescence techniques such as particle induced X-ray emission (PIXE) or X-ray fluorescence spectrometry (XRF), can be used for elemental characterisation even in problematic situations where very little sample volume is available. Still, the fluorescence coefficient of Fe is such that, during the decay of the inner-shell ionised atomic structure, keV Auger electrons are produced in excess to X-rays. Since cross-sections for ionisation induced by keV electrons, for low atomic number atoms, are of the order of 10{sup 3} barn, care should be taken to account for possible fluorescence effects caused by Auger electrons, which may lead to the wrong quantification of elements having atomic number lower than the atomic number of Fe. Furthermore, the same electron processes will occur in iron oxide nanoparticles containing {sup 57}Co, which may be used for nuclear medicine therapy purposes. In the present work, simple approximation algorithms are proposed for the quantitative description of radiative and non-radiative processes associated with Auger electrons cascades. The effects on analytical processes and nuclear medicine applications are quantified for the case of iron oxide nanoparticles, by calculating both electron fluorescence emissions and energy deposition on cell tissues where the nanoparticles may be embedded.

  3. Quantitative tunneling spectroscopy of nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    First, Phillip N; Whetten, Robert L; Schaaff, T Gregory

    2007-05-25

    The proposed goals of this collaborative work were to systematically characterize the electronic structure and dynamics of 3-dimensional metal and semiconducting nanocrystals using scanning tunneling microscopy/spectroscopy (STM/STS) and ballistic electron emission spectroscopy (BEES). This report describes progress in the spectroscopic work and in the development of methods for creating and characterizing gold nanocrystals. During the grant period, substantial effort also was devoted to the development of epitaxial graphene (EG), a very promising materials system with outstanding potential for nanometer-scale ballistic and coherent devices ("graphene" refers to one atomic layer of graphitic, sp2 -bonded carbon atoms [or more loosely, few layers]). Funding from this DOE grant was critical for the initial development of epitaxial graphene for nanoelectronics

  4. Electronic Health Record for Temporomandibular Joint Disorders – Support in Therapeutic Process

    Czech Academy of Sciences Publication Activity Database

    Hippmann, R.; Nagy, Miroslav; Dostálová, T.; Zvárová, Jana; Seydlová, M.; Feltlová, E.

    2010-01-01

    Roč. 6, č. 1 (2010), s. 27-32 ISSN 1801-5603 R&D Projects: GA MŠk(CZ) 1M06014 Institutional research plan: CEZ:AV0Z10300504 Keywords : electronic health record * automatic speech recognition * dental cross * temporomandibular joint * temporomandibular joint disorders * structured data entry * dentistry * data model * text-to-speech system * Research Diagnostic Criteria for TMD Subject RIV: IN - Informatics, Computer Science http://www.ejbi.org/en/ejbi/article/25-en-electronic-health-record-for-temporomandibular-joint-disorders-support-in-therapeutic-process.html

  5. RECOVERY OF GOLD (Au) AND SILVER (Ag) METALS IN THE ELECTRONIC WASTE THROUGH MULTILEVEL PRECIPITATION PROCESS

    OpenAIRE

    Siti Marwati; Regina Tutik Padmaningrum; Sunarto Sunarto

    2016-01-01

    This research aims to determine the percent recovery of gold (Au) and silver (Ag) in the electronic waste such as CD-RW and determine the purity of gold and silver metals in the electronic waste such as CD-RW that through multilevel precipitation process. The first step was the optimization of the concentration of thiourea and time dissolution of gold and silver in the sample. The concentration of thiourea and the time dissolution optimum obtained from conentration of gold and silver maximum....

  6. Mechanisms of dust grain charging in plasma with allowance for electron emission processes

    Energy Technology Data Exchange (ETDEWEB)

    Mol’kov, S. I.; Savin, V. N., E-mail: moped@onego.ru [Petrozavodsk State University (Russian Federation)

    2017-02-15

    The process of dust grain charging is described with allowance for secondary, ion-induced, photoelectric, and thermal electron emission from the grain surface. The roughness of the grain surface is taken into account. An intermediate charging regime involving ion–atom collisions and electron ionization in the perturbed plasma region is analyzed using the moment equations and Poisson’s equation. A calculation method is proposed that allows one to take into account the influence of all the above effects and determine the radius of the plasma region perturbed by the dust grain.

  7. Mechanisms of dust grain charging in plasma with allowance for electron emission processes

    Science.gov (United States)

    Mol'kov, S. I.; Savin, V. N.

    2017-02-01

    The process of dust grain charging is described with allowance for secondary, ion-induced, photoelectric, and thermal electron emission from the grain surface. The roughness of the grain surface is taken into account. An intermediate charging regime involving ion-atom collisions and electron ionization in the perturbed plasma region is analyzed using the moment equations and Poisson's equation. A calculation method is proposed that allows one to take into account the influence of all the above effects and determine the radius of the plasma region perturbed by the dust grain.

  8. Carpal Tunnel Syndrome

    Science.gov (United States)

    ... make CTS better and help relieve symptoms. Massage, yoga, ultrasound, chiropractic manipulation, and acupuncture are just a ... tunnel syndrome > A-Z Health Topics Related information Menopause Pregnancy The javascript used in this widget is ...

  9. Carpal Tunnel Syndrome

    Science.gov (United States)

    ... is not confined to people in a single industry or job, but is especially common in those ... tunnel syndrome. Nonsteroidal anti-inflammatory drugs, such as aspirin, ibuprofen, and other nonprescription pain relievers, may provide ...

  10. INCAS TRISONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Florin MUNTEANU

    2009-09-01

    Full Text Available The 1.2 m x 1.2 m Trisonic Blowdown Wind Tunnel is the largest of the experimental facilities at the National Institute for Aerospace Research - I.N.C.A.S. "Elie Carafoli", Bucharest, Romania. The tunnel has been designed by the Canadian company DSMA (now AIOLOS and since its commissioning in 1978 has performed high speed aerodynamic tests for more than 120 projects of aircraft, missiles and other objects among which the twin jet fighter IAR-93, the jet trainer IAR-99, the MIG-21 Lancer, the Polish jet fighter YRYDA and others. In the last years the wind tunnel has been used mostly for experimental research in European projects such as UFAST. The high flow quality parameters and the wide range of testing capabilities ensure the competitivity of the tunnel at an international level.

  11. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

    Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

  12. Wind Tunnel Testing Facilities

    Data.gov (United States)

    Federal Laboratory Consortium — NASA Ames Research Center is pleased to offer the services of our premier wind tunnel facilities that have a broad range of proven testing capabilities to customers...

  13. Wind Tunnel Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This ARDEC facility consists of subsonic, transonic, and supersonic wind tunnels to acquire aerodynamic data. Full-scale and sub-scale models of munitions are fitted...

  14. 75 FR 11889 - Request for Comments on Proposed NIH, AHRQ and CDC Process Change for Electronic Submission of...

    Science.gov (United States)

    2010-03-12

    ... HUMAN SERVICES Request for Comments on Proposed NIH, AHRQ and CDC Process Change for Electronic Submission of Grant Applications AGENCY: Department of Health and Human Services. ACTION: Process change... correction window from the electronic grant application submission process on our applicant organizations and...

  15. Autonomous Robotic Inspection in Tunnels

    Science.gov (United States)

    Protopapadakis, E.; Stentoumis, C.; Doulamis, N.; Doulamis, A.; Loupos, K.; Makantasis, K.; Kopsiaftis, G.; Amditis, A.

    2016-06-01

    In this paper, an automatic robotic inspector for tunnel assessment is presented. The proposed platform is able to autonomously navigate within the civil infrastructures, grab stereo images and process/analyse them, in order to identify defect types. At first, there is the crack detection via deep learning approaches. Then, a detailed 3D model of the cracked area is created, utilizing photogrammetric methods. Finally, a laser profiling of the tunnel's lining, for a narrow region close to detected crack is performed; allowing for the deduction of potential deformations. The robotic platform consists of an autonomous mobile vehicle; a crane arm, guided by the computer vision-based crack detector, carrying ultrasound sensors, the stereo cameras and the laser scanner. Visual inspection is based on convolutional neural networks, which support the creation of high-level discriminative features for complex non-linear pattern classification. Then, real-time 3D information is accurately calculated and the crack position and orientation is passed to the robotic platform. The entire system has been evaluated in railway and road tunnels, i.e. in Egnatia Highway and London underground infrastructure.

  16. Diagnosis of Carpal Tunnel Syndrome

    Science.gov (United States)

    Keith, Michael Warren; Masear, Victoria; Chung, Kevin; Maupin, Kent; Andary, Michael; Amadio, Peter C.; Barth, Richard W.; Watters, William C.; Goldberg, Michael J.; Haralson, Robert H.; Turkelson, Charles M.; Wies, Janet L.

    2016-01-01

    This clinical practice guideline was created to improve patient care by outlining the appropriate information-gathering and decision-making processes involved in managing the diagnosis of carpal tunnel syndrome. The methods used to develop this clinical practice guideline were designed to combat bias, enhance transparency, and promote reproducibility. The guideline’s recommendations are as follows: The physician should obtain an accurate patient history. The physician should perform a physical examination of the patient that may include personal characteristics as well as performing a sensory examination, manual muscle testing of the upper extremity, and provocative and/or discriminatory tests for alternative diagnoses. The physician may obtain electrodiagnostic tests to differentiate among diagnoses. This may be done in the presence of thenar atrophy and/or persistent numbness. The physician should obtain electrodiagnostic tests when clinical and/or provocative tests are positive and surgical management is being considered. If the physician orders electrodiagnostic tests, the testing protocol should follow the American Academy of Neurology/American Association of Neuromuscular and Electrodiagnostic Medicine/American Academy of Physical Medicine and Rehabilitation guidelines for diagnosis of carpal tunnel syndrome. In addition, the physician should not routinely evaluate patients suspected of having carpal tunnel syndrome with new technology, such as magnetic resonance imaging, computed tomography, and pressure-specified sensorimotor devices in the wrist and hand. This decision was based on an additional nonsystematic literature review following the face-to-face meeting of the work group. PMID:19474448

  17. Effect of Source, Surfactant, and Deposition Process on Electronic Properties of Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Dheeraj Jain

    2011-01-01

    Full Text Available The electronic properties of arrays of carbon nanotubes from several different sources differing in the manufacturing process used with a variety of average properties such as length, diameter, and chirality are studied. We used several common surfactants to disperse each of these nanotubes and then deposited them on Si wafers from their aqueous solutions using dielectrophoresis. Transport measurements were performed to compare and determine the effect of different surfactants, deposition processes, and synthesis processes on nanotubes synthesized using CVD, CoMoCAT, laser ablation, and HiPCO.

  18. Steel formworks for tunnelling

    OpenAIRE

    Andrić, Ante; Tešović, Snježana

    2008-01-01

    The plant used for concreting the secondary tunnel lining is described. The plant is made of three segments: sheathing, self-propelled conveyor, and concrete supply system. In addition to technical properties and other features of this plant, the authors describe the work technology, and problems encountered during concept development, design and adjustment for three-rail and four-rail formwork. The structure of formwork portal, face formwork and tunnel lay-by is described and presented, incl...

  19. Electronic health record usability: analysis of the user-centered design processes of eleven electronic health record vendors.

    Science.gov (United States)

    Ratwani, Raj M; Fairbanks, Rollin J; Hettinger, A Zachary; Benda, Natalie C

    2015-11-01

    The usability of electronic health records (EHRs) continues to be a point of dissatisfaction for providers, despite certification requirements from the Office of the National Coordinator that require EHR vendors to employ a user-centered design (UCD) process. To better understand factors that contribute to poor usability, a research team visited 11 different EHR vendors in order to analyze their UCD processes and discover the specific challenges that vendors faced as they sought to integrate UCD with their EHR development. Our analysis demonstrates a diverse range of vendors' UCD practices that fall into 3 categories: well-developed UCD, basic UCD, and misconceptions of UCD. Specific challenges to practicing UCD include conducting contextually rich studies of clinical workflow, recruiting participants for usability studies, and having support from leadership within the vendor organization. The results of the study provide novel insights for how to improve usability practices of EHR vendors. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Structural and tunneling properties of Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2013-12-06

    We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green\\'s function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the ⟨110⟩ direction showing the smallest decay with length and the largest conductance and current.