WorldWideScience

Sample records for surface systems electronic

  1. Electronic system for floor surface type detection in robotics applications

    Science.gov (United States)

    Tarapata, Grzegorz; Paczesny, Daniel; Tarasiuk, Łukasz

    2016-11-01

    The paper reports a recognizing method base on ultrasonic transducers utilized for the surface types detection. Ultra-sonic signal is transmitted toward the examined substrate, then reflected and scattered signal goes back to another ultra-sonic receiver. Thee measuring signal is generated by a piezo-electric transducer located at specified distance from the tested substrate. The detector is a second piezo-electric transducer located next to the transmitter. Depending on thee type of substrate which is exposed by an ultrasonic wave, the signal is partially absorbed inn the material, diffused and reflected towards the receiver. To measure the level of received signal, the dedicated electronic circuit was design and implemented in the presented systems. Such system was designed too recognize two types of floor surface: solid (like concrete, ceramic stiles, wood) and soft (carpets, floor coverings). The method will be applied in electronic detection system dedicated to autonomous cleaning robots due to selection of appropriate cleaning method. This work presents the concept of ultrasonic signals utilization, the design of both the measurement system and the measuring stand and as well number of wide tests results which validates correctness of applied ultrasonic method.

  2. Conversion electron surface imaging

    CERN Document Server

    Irwin, G M; Wehner, A

    1999-01-01

    A method of imaging the Moessbauer absorption over the surface of a sample based on counting conversion electrons emitted from the surface following resonant absorption of gamma radiation is described. This Conversion Electron Surface Imaging (CESI) method is somewhat analogous to Magnetic Resonance Imaging (MRI), particularly chemical shift imaging, and similar tomographic reconstruction techniques are involved in extracting the image. The theory behind the technique and a prototype device is described, as well as the results of proof-of-principle experiments which demonstrate the function of the device. Eventually this same prototype device will be part of a system to determine the spatial variation of the Moessbauer spectrum over the surface of a sample. Applications include imaging of variations of surface properties of steels and other iron containing alloys, as well as other surfaces over which sup 5 sup 7 Fe has been deposited.

  3. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  4. A high-mobility electronic system at an electrolyte-gated oxide surface

    Science.gov (United States)

    Gallagher, Patrick; Lee, Menyoung; Petach, Trevor A.; Stanwyck, Sam W.; Williams, James R.; Watanabe, Kenji; Taniguchi, Takashi; Goldhaber-Gordon, David

    2015-03-01

    Electrolyte gating is a powerful technique for accumulating large carrier densities at a surface. Yet this approach suffers from significant sources of disorder: electrochemical reactions can damage or alter the sample, and the ions of the electrolyte and various dissolved contaminants sit Angstroms from the electron system. Accordingly, electrolyte gating is well suited to studies of superconductivity and other phenomena robust to disorder, but of limited use when reactions or disorder must be avoided. Here we demonstrate that these limitations can be overcome by protecting the sample with a chemically inert, atomically smooth sheet of hexagonal boron nitride. We illustrate our technique with electrolyte-gated strontium titanate, whose mobility when protected with boron nitride improves more than 10-fold while achieving carrier densities nearing 1014 cm-2. Our technique is portable to other materials, and should enable future studies where high carrier density modulation is required but electrochemical reactions and surface disorder must be minimized.

  5. Formation of the surface alloys by high-intensity pulsed electron beam irradiation of the coating/substrate system

    Science.gov (United States)

    Ivanov, Yu F.; Petrikova, E. A.; Teresov, A. D.; Krysina, O. V.; Rygina, M. E.

    2015-04-01

    The results of the analysis of the structure and properties of the surface layer of aluminum A7 subjected to alloying by the intense pulsed electron beam melting of the film / substrate system. Fold increase in strength and tribological properties of the modified surface layer due to the formation of submicro - nanoscale multiphase structure have been revealed.

  6. Appendage mountable electronic devices conformable to surfaces

    Science.gov (United States)

    Rogers, John; Ying, Ming; Bonifas, Andrew; Lu, Nanshu

    2017-01-24

    Disclosed are appendage mountable electronic systems and related methods for covering and conforming to an appendage surface. A flexible or stretchable substrate has an inner surface for receiving an appendage, including an appendage having a curved surface, and an opposed outer surface that is accessible to external surfaces. A stretchable or flexible electronic device is supported by the substrate inner and/or outer surface, depending on the application of interest. The electronic device in combination with the substrate provides a net bending stiffness to facilitate conformal contact between the inner surface and a surface of the appendage provided within the enclosure. In an aspect, the system is capable of surface flipping without adversely impacting electronic device functionality, such as electronic devices comprising arrays of sensors, actuators, or both sensors and actuators.

  7. Appendage mountable electronic devices conformable to surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, John; Ying, Ming; Bonifas, Andrew; Lu, Nanshu

    2017-01-24

    Disclosed are appendage mountable electronic systems and related methods for covering and conforming to an appendage surface. A flexible or stretchable substrate has an inner surface for receiving an appendage, including an appendage having a curved surface, and an opposed outer surface that is accessible to external surfaces. A stretchable or flexible electronic device is supported by the substrate inner and/or outer surface, depending on the application of interest. The electronic device in combination with the substrate provides a net bending stiffness to facilitate conformal contact between the inner surface and a surface of the appendage provided within the enclosure. In an aspect, the system is capable of surface flipping without adversely impacting electronic device functionality, such as electronic devices comprising arrays of sensors, actuators, or both sensors and actuators.

  8. Detecting Cannabis Use on the Human Skin Surface via an Electronic Nose System

    Directory of Open Access Journals (Sweden)

    Andreas Voss

    2014-07-01

    Full Text Available The most commonly used drug testing methods are based on the analysis of hair and urine using gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry or immunoassay screening. These methods are time-consuming and partly expensive. One alternative method could be the application of an “electronic nose” (eNose. We have developed an eNose to detect directly on the human skin surface metabolic changes in the human body odor caused by cannabis consumption. Twenty cannabis-smoking and 20 tobacco-smoking volunteers were enrolled in this study. For the sensor signal data processing, two different methods were applied: Principle component analysis (PCA with discriminant analysis, and the method of pattern recognition with subsequent support vector machines (SVM processing. The PCA analysis achieved a correct classification of 70%, whereas the SVM obtained an accuracy of 92.5% (sensitivity 95%, specificity 90% between cannabis-consuming volunteers and tobacco-smoking subjects. This study shows evidence that a low-cost, portable and fast-working eNose system could be useful for health protection, security agencies and for forensic investigations. The ability to analyze human body odor with an eNose opens up a wide field for diagnosing other drugs and also various diseases.

  9. Theoretical investigation of the electronic structure and quantum transport in the graphene-C(111) diamond surface system.

    Science.gov (United States)

    Selli, Daniele; Baburin, Igor; Leoni, Stefano; Zhu, Zhen; Tománek, David; Seifert, Gotthard

    2013-10-30

    We investigate the interaction of a graphene monolayer with the C(111) diamond surface using ab initio density functional theory. To accommodate the lattice mismatch between graphene and diamond, the overlayer deforms into a wavy structure that binds strongly to the diamond substrate. The detached ridges of the wavy graphene overlayer behave electronically as free-standing polyacetylene chains with delocalized π electrons, separated by regions containing only sp(3) carbon atoms covalently bonded to the (111) diamond surface. We performed quantum transport calculations for different geometries of the system to study how the buckling of the graphene layer and the associated bonding to the diamond substrate affect the transport properties. The system displays high carrier mobility along the ridges and a wide transport gap in the direction normal to the ridges. These intriguing, strongly anisotropic transport properties qualify the hybrid graphene-diamond system as a viable candidate for electronic nanodevices.

  10. Investigation of two-dimensional electron systems at low density on hydrogen-terminated silicon (111) surface

    Science.gov (United States)

    Hu, Binhui; Kott, Tomasz M.; Kane, B. E.

    2013-03-01

    Two-dimensional electron systems (2DESs) on hydrogen-terminated Si(111) surfaces show very high quality. The peak electron mobility of 325,000 cm2/Vs can be reached at T =90 mK and 2D electron density n2 d = 4 . 15 ×1011 cm-2, and the device shows the fractional quantum hall effect[1]. 2DESs on H-Si(111) at lower densities may exhibit new physics, because both valley degeneracy and effective mass lead to a large Wigner-Seitz radius rs at accessible densities. In these devices, phosphorus ion implantation is used to defined the contacts to the 2DESs[2]. The contacts themselves work at low temperature. However, at lower 2D electron density (ion implantation annealing parameters are adjusted to mitigate the issue. Possible measurement technique is also explored to overcome the problem.

  11. Final Report DE-EE0005380: Assessment of Offshore Wind Farm Effects on Sea Surface, Subsurface and Airborne Electronic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Hao [The University of Texas at Austin; Hamilton, Mark F. [The University of Texas at Austin Applied Research Laboratories; Bhalla, Rajan [Science Applications International Corporation; Brown, Walter E. [The University of Texas at Austin Applied Research Laboratories; Hay, Todd A. [The University of Texas at Austin Applied Research Laboratories; Whitelonis, Nicholas J. [The University of Texas at Austin; Yang, Shang-Te [The University of Texas at Austin; Naqvi, Aale R. [The University of Texas at Austin

    2013-09-30

    Offshore wind energy is a valuable resource that can provide a significant boost to the US renewable energy portfolio. A current constraint to the development of offshore wind farms is the potential for interference to be caused by large wind farms on existing electronic and acoustical equipment such as radar and sonar systems for surveillance, navigation and communications. The US Department of Energy funded this study as an objective assessment of possible interference to various types of equipment operating in the marine environment where offshore wind farms could be installed. The objective of this project was to conduct a baseline evaluation of electromagnetic and acoustical challenges to sea surface, subsurface and airborne electronic systems presented by offshore wind farms. To accomplish this goal, the following tasks were carried out: (1) survey electronic systems that can potentially be impacted by large offshore wind farms, and identify impact assessment studies and research and development activities both within and outside the US, (2) engage key stakeholders to identify their possible concerns and operating requirements, (3) conduct first-principle modeling on the interactions of electromagnetic signals with, and the radiation of underwater acoustic signals from, offshore wind farms to evaluate the effect of such interactions on electronic systems, and (4) provide impact assessments, recommend mitigation methods, prioritize future research directions, and disseminate project findings. This report provides a detailed description of the methodologies used to carry out the study, key findings of the study, and a list of recommendations derived based the findings.

  12. Twelve-point scale grading system of scanning electron microscopic examination to investigate subtle changes in damaged hair surface.

    Science.gov (United States)

    Lee, S Y; Choi, A R; Baek, J H; Kim, H O; Shin, M K; Koh, J S

    2016-11-01

    To assess the hair surface condition, scanning electron microscope (SEM) is commonly used and it remains an indispensable hair morphology characterization technique. Yet, the technique is criticized for having subjective viewpoints and limitations in distinguishing the appearance of cuticle layers. The aim of this study is to establish an objective classification system and also to subdivide by detailed description of damaged cuticle layers. Hair samples were collected from female subjects (n = 500) who participated in hair efficacy study and Asian hair bunches (n = 180) that were previously collected. Damage to hair was initiated by chemical, heat stress and ultraviolet irradiation. We suggested the grading criterion on a 12-point scale and compared with a wide range grading system on a 5-point scale. We evaluated other hair surface-related parameters such as hair luster-ring and combing load to verify the validity and efficacy of our new grading system. The grading criterion on our 12-point scale revealed an improved discrimination compared to the wide range grading system. Hair surface-related parameters were significantly improved after hair care product, and these tendencies were likely to be determined to be similarly improved using the 12-point scale grading system. The 12-point scale classification system was demonstrated to be a more precise standardization and appropriate evaluation method to investigate the subtle distinction of the hair shaft after hair care product application. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Electron beam focusing system

    Energy Technology Data Exchange (ETDEWEB)

    Dikansky, N.; Nagaitsev, S.; Parkhomchuk, V.

    1997-09-01

    The high energy electron cooling requires a very cold electron beam. Thus, the electron beam focusing system is very important for the performance of electron cooling. A system with and without longitudinal magnetic field is presented for discussion. Interaction of electron beam with the vacuum chamber as well as with the background ions and stored antiprotons can cause the coherent electron beam instabilities. Focusing system requirements needed to suppress these instabilities are presented.

  14. ANALYSIS OF PASSIVATED SURFACES FOR MASS SPECTROMETER INLET SYSTEMS BY AUGER ELECTRON AND X-RAY PHOTOELECTRON SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Ajo, H.; Clark, E.

    2010-09-01

    Stainless steel coupons approximately 0.5' in diameter and 0.125' thick were passivated with five different surface treatments and an untreated coupon was left as a control. These surface treatments are being explored for use in tritium storage containers. These coupons were made to allow surface analysis of the surface treatments using well-know surface analysis techniques. Depth profiles using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were performed on these coupons to characterize the surface and near surface regions. Scanning electron microscope (SEM) images were collected as well. All of the surface treatments studied here appear to change the surface morphology dramatically, as evidenced by lack of tool marks on the treated samples. In terms of the passivation treatment, Vendors A-D appeared to have oxide layers that were very similar in thickness to each other (0.7-0.9 nm thick) as well as the untreated samples (the untreated sample oxide layers appeared to be somewhat larger). Vendor E's silicon coating appears to be on the order of 200 nm thick.

  15. STEP electronic system design

    Science.gov (United States)

    Couch, R. H.; Johnson, J. W.

    1984-01-01

    The STEP electronic system design is discussed. The purpose of the design is outlined. The electronic system design is summarized and it is found that: an effective conceptual system design is developed; the design represents a unique set of capabilities; makes efficient use of available orbiter resources; the system capabilities exceed identified potential experiment needs.

  16. An AES Study of the Room Temperature Surface Conditioning of Technological Metal Surfaces by Electron Irradiation

    CERN Document Server

    Scheuerlein, C; Taborelli, M; Brown, A; Baker, M A

    2002-01-01

    The modifications to technological copper and niobium surfaces induced by 2.5 keV electron irradiation have been investigated in the context of the conditioning process occurring in particle accelerator ultra high vacuum systems. Changes in the elemental surface composition have been found using Scanning Auger Microscopy (SAM) by monitoring the carbon, oxygen and metal Auger peak intensities as a function of electron irradiation in the dose range 10-6 to 10-2 C mm-2. The surface analysis results are compared with electron dose dependent secondary electron and electron stimulated desorption yield measurements. Initially the electron irradiation causes a surface cleaning through electron stimulated desorption, in particular of hydrogen. During this period both the electron stimulated desorption and secondary electron yield decrease as a function of electron dose. When the electron dose exceeds 10-4 C mm-2 electron stimulated desorption yields are reduced by several orders of magnitude and the electron beam indu...

  17. High-resolution spectroscopy using synchrotron radiation for surface structure determination and the study of correlated electron systems

    Energy Technology Data Exchange (ETDEWEB)

    Moler, E.J. Jr.

    1996-05-01

    The surface structure of three molecular adsorbate systems on transition metal surfaces, ({radical}3 x {radical}3)R30{degrees} and (1.5 x 1.5)R18{degrees} CO adsorbed on Cu(111), and c(2x2) N2/Ni(100), have been determined using Angle-Resolved Photoemission Extended Fine Structure (ARPEFS). The adsorption site and bond lengths are reported for the adsorbate-metal bond and the first two substrate layers. The ARPEFS diffraction pattern of the shake-up peak for c(2x2) N2/Ni(100) is also discussed. A unique method of experimentally determining the angular momentum and intrinsic/extrinsic origin of core-level satellites is presented. We show for the first time that satellite peaks not associated with chemically differentiated atomic species display an ARPEFS intensity oscillation. Specifically, we present data for the C 1s from ({radical}3x{radical}3)R30 CO/Cu(111) and p2mg(2x1)CO/Ni(110), N is from c(2x2) N2/Ni(100), and Ni 3p from clean nickel(111). The satellite peaks in all cases exhibit ARPEFS curves which indicate an angular momentum identical to the main peak and are of an intrinsic nature. A Fourier Transform Soft X-ray spectrometer (FF-SX) has been designed and is under construction for the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The spectrometer is designed for ultra-high resolution theoretical resolving power E/{Delta}E{approx}-10{sup 6} in the photon energy region of 60-120 eV. This instrument is expected to provide experimental results which sensitively test models of correlated electron processes in atomic and molecular physics. The design criteria and consequent technical challenges posed by the short wavelengths of x-rays and desired resolving power are discussed. The fundamental and practical aspects of soft x-ray interferometry are also explored.

  18. Electronics circuits and systems

    CERN Document Server

    Bishop, Owen

    2011-01-01

    The material in Electronics - Circuits and Systems is a truly up-to-date textbook, with coverage carefully matched to the electronics units of the 2007 BTEC National Engineering and the latest AS and A Level specifications in Electronics from AQA, OCR and WJEC. The material has been organized with a logical learning progression, making it ideal for a wide range of pre-degree courses in electronics. The approach is student-centred and includes: numerous examples and activities; web research topics; Self Test features, highlighted key facts, formulae and definitions. Ea

  19. Electronics circuits and systems

    CERN Document Server

    Bishop, Owen

    2007-01-01

    The material in Electronics - Circuits and Systems is a truly up-to-date textbook, with coverage carefully matched to the electronics units of the 2007 BTEC National Engineering and the latest AS and A Level specifications in Electronics from AQA, OCR and WJEC. The material has been organized with a logical learning progression, making it ideal for a wide range of pre-degree courses in electronics. The approach is student-centred and includes: numerous examples and activities; web research topics; Self Test features, highlighted key facts, formulae and definitions. Each chapter ends with a set

  20. Electronic components and systems

    CERN Document Server

    Dennis, W H

    2013-01-01

    Electronic Components and Systems focuses on the principles and processes in the field of electronics and the integrated circuit. Covered in the book are basic aspects and physical fundamentals; different types of materials involved in the field; and passive and active electronic components such as capacitors, inductors, diodes, and transistors. Also covered in the book are topics such as the fabrication of semiconductors and integrated circuits; analog circuitry; digital logic technology; and microprocessors. The monograph is recommended for beginning electrical engineers who would like to kn

  1. Surfaces and interfaces of electronic materials

    CERN Document Server

    Brillson, Leonard J

    2012-01-01

    An advanced level textbook covering geometric, chemical, and electronic structure of electronic materials, and their applications to devices based on semiconductor surfaces, metal-semiconductor interfaces, and semiconductor heterojunctions. Starting with the fundamentals of electrical measurements on semiconductor interfaces, it then describes the importance of controlling macroscopic electrical properties by atomic-scale techniques. Subsequent chapters present the wide range of surface and interface techniques available to characterize electronic, optical, chemical, and structural propertie

  2. Precision Assembly of Systems on Surfaces (PASS)

    Science.gov (United States)

    2015-02-06

    Precision Assembly of Systems on Surfaces ( PASS ) This program was directed at generating functionalized surfaces and assemblies for electronic and...journals: Number of Papers published in non peer-reviewed journals: Final Report: Precision Assembly of Systems on Surfaces ( PASS ) Report Title This...PRECISION ASSEMBLY OF SYSTEMS ON SURFACES ( PASS ) PI: Timothy M. Swager Massachusetts Institute of Technology Final Report: DARPA, Defense

  3. Electron-electron interactions in disordered systems

    CERN Document Server

    Efros, AL

    1985-01-01

    ``Electron-Electron Interactions in Disordered Systems'' deals with the interplay of disorder and the Coulomb interaction. Prominent experts give state-of-the-art reviews of the theoretical and experimental work in this field and make it clear that the interplay of the two effects is essential, especially in low-dimensional systems.

  4. MDT DCS Electronics System

    CERN Document Server

    Tsarouchas, Charilaos; Gazis, Evangelos; Tsipolitis, Georgios

    This note has the aim to present the Detector Control System for the Monitor- ing of the electronics values of MDT chambers in ATLAS experiment in CERN. This system is decided to be called in short ELTX. The principal task of DCS is to enable and ensure the coherent and safe oper- ation of the detector. The interaction of detector expers, users or shifters to the detector hardware is also done via DCS. This is the responsible system of moni- toring the operational parameters and the overall state of the detector, the alarm generation and handling, the connection of hardware values to databases and the interaction with the DAQ system. Through this thesis, one can see what ELTX system has to offer as a Detector Control System and in detail, what is the hardware to be controlled and monitored. Moreover it is presented the mainstream of central Atlas DCS concerning the active interfaces.ELTX is a system following these standards.

  5. Development of Surface Acoustic Wave Electronic Nose

    Directory of Open Access Journals (Sweden)

    S.K. Jha

    2010-07-01

    Full Text Available The paper proposes an effective method to design and develop surface acoustic wave (SAW sensor array-based electronic nose systems for specific target applications. The paper suggests that before undertaking full hardware development empirically through hit and trial for sensor selection, it is prudent to develop accurate sensor array simulator for generating synthetic data and optimising sensor array design and pattern recognition system. The latter aspects are most time-consuming and cost-intensive parts in the development of an electronic nose system. This is because most of the electronic sensor platforms, circuit components, and electromechanical parts are available commercially-off-the-shelve (COTS, whereas knowledge about specific polymers and data analysis software are often guarded due to commercial or strategic interests. In this study, an 11-element SAW sensor array is modelled to detect and identify trinitrotoluene (TNT and dinitrotoluene (DNT explosive vapours in the presence of toluene, benzene, di-methyl methyl phosphonate (DMMP and humidity as interferents. Additive noise sources and outliers were included in the model for data generation. The pattern recognition system consists of: (i a preprocessor based on logarithmic data scaling, dimensional autoscaling, and singular value decomposition-based denoising, (ii principal component analysis (PCA-based feature extractor, and (iii an artificial neural network (ANN classifier. The efficacy of this approach is illustrated by presenting detailed PCA analysis and classification results under varied conditions of noise and outlier, and by analysing comparative performance of four classifiers (neural network, k-nearest neighbour, naïve Bayes, and support vector machine.Defence Science Journal, 2010, 60(4, pp.364-376, DOI:http://dx.doi.org/10.14429/dsj.60.493

  6. Electronic Correlations in Electron Transfer Systems

    Science.gov (United States)

    Bulla, Ralf; Tornow, Sabine; Anders, Frithjof

    Electron transfer processes play a central role in many chemical and biological systems. Already the transfer of a single electron from the donor to the acceptor can be viewed as a complicated many-body problem, due to the coupling of the electron to the infinitely many environmental degrees of freedom, realized by density fluctuations of the solvent or molecular vibrations of the protein matrix. We focus on the quantum mechanical modelling of two-electron transfer processes whose dynamics is governed by the Coulomb interaction between the electrons as well as the environmental degrees of freedoms represented by a bosonic bath. We identify the regime of parameters in which concerted transfer of the two electrons occurs and discuss the influence of the Coulomb repulsion and the coupling strength to the environment on the electron transfer rate. Calculations are performed using the non-perturbative numerical renormalization group approach for both equilibrium and non-equilibrium properties.

  7. Cooling system for electronic components

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, William James; Colgan, Evan George; Gerken, James Dorance; Marroquin, Christopher Michael; Tian, Shurong

    2016-05-17

    Embodiments of the present invention provide for non interruptive fluid cooling of an electronic enclosure. One or more electronic component packages may be removable from a circuit card having a fluid flow system. When installed, the electronic component packages are coincident to and in a thermal relationship with the fluid flow system. If a particular electronic component package becomes non-functional, it may be removed from the electronic enclosure without affecting either the fluid flow system or other neighboring electronic component packages.

  8. Cooling system for electronic components

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, William James; Colgan, Evan George; Gerken, James Dorance; Marroquin, Christopher Michael; Tian, Shurong

    2015-12-15

    Embodiments of the present invention provide for non interruptive fluid cooling of an electronic enclosure. One or more electronic component packages may be removable from a circuit card having a fluid flow system. When installed, the electronic component packages are coincident to and in a thermal relationship with the fluid flow system. If a particular electronic component package becomes non-functional, it may be removed from the electronic enclosure without affecting either the fluid flow system or other neighboring electronic component packages.

  9. Surface-electronic-state effects in electron emission from the Be(0001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Archubi, C. D. [Instituto de Astronomia y Fisica del Espacio, casilla de correo 67, sucursal 28, C1428EGA, Buenos Aires (Argentina); Gravielle, M. S. [Instituto de Astronomia y Fisica del Espacio, casilla de correo 67, sucursal 28, C1428EGA, Buenos Aires (Argentina); Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Silkin, V. M. [Donostia International Physics Center, E-20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Facultad de Ciencias Quimicas, Universidad del Pais Vasco, Apartado 1072, E-20080 San Sebastian (Spain); IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao (Spain)

    2011-07-15

    We study the electron emission produced by swift protons impinging grazingly on a Be(0001) surface. The process is described within a collisional formalism using the band-structure-based (BSB) approximation to represent the electron-surface interaction. The BSB model provides an accurate description of the electronic band structure of the solid and the surface-induced potential. Within this approach we derive both bulk and surface electronic states, with these latter characterized by a strong localization at the crystal surface. We found that such surface electronic states play an important role in double-differential energy- and angle-resolved electron emission probabilities, producing noticeable structures in the electron emission spectra.

  10. Electron Traps at the Ice Surface

    Science.gov (United States)

    Bockstedte, Michel; Auburger, Philipp; Michl, Anja

    Water, water clusters and ice possess the fascinating ability to solvate electrons. On the surface of water cluster1 and thin crystalline ice structures on a metal substrate2 long-living solvated electron states were observed that evolve from pre-existing surface traps. The identification of such traps provides important insight into the electronic structure of the water or ice surface, and the dissociative interaction of electrons with adsorbates. Models2,3 based on the bilayer terminated Ih-(0001) surface related such traps to orientational defects or vacancies. So far, the understanding of the electronic structure of the ice surface with the electron traps is incomplete. Here we address this issue including also water ad-structures4 within hybrid density functional theory and many-body perturbation theory (G0W0). We identify a hierachy of traps with increasing vertical electron affinity, ranging from hexagon adrows to clusters of orientational defects and vacancies with dangling OH-groups. Siefermann and Abel, Angew. Chem. Int. Ed. 50, 5264 (2011). Bovensiepen et al., J. Chem. Phys. C 113, 979 (2013). Hermann et al., J. Phys.: cond. matter 20, 225003 (2008). Mehlhorn and Morgenstern, Phys. Rev. Lett. 99, 246101 (2007)

  11. Power Electronics System Communications

    OpenAIRE

    Milosavljevic, Ivana

    1999-01-01

    This work investigates communication issues in high-frequency power converters. A novel control communication network (Power Electronics System Network or PES Net) is proposed for modular, medium and high-power, converters. The network protocol, hardware and software are designed and implemented. The PES Net runs at 125 Mb/s over plastic optical fiber allowing converter switching frequencies in excess of 100 kHz. Communication control is implemented in a fie...

  12. Nonlocal bacterial electron transfer to hematite surfaces

    Science.gov (United States)

    Rosso, Kevin M.; Zachara, John M.; Fredrickson, Jim K.; Gorby, Yuri A.; Smith, Steven C.

    2003-03-01

    Mechanisms by which dissimilatory iron-reducing bacteria utilize iron and manganese oxide minerals as terminal electron acceptors for respiration are poorly understood. In the absence of exogenous electron shuttle compounds, extracellular electron transfer is generally thought to occur through the interfacial contact area between mineral surfaces and attached cells. Possible alternative reduction pathways have been proposed based on the discovery of a link between an excreted quinone and dissimilatory reduction. In this study, we utilize a novel experimental approach to demonstrate that Shewanella putrefaciens reduces the surface of crystalline iron oxides at spatial locations that are distinct from points of attachment.

  13. Electronics for embedded systems

    CERN Document Server

    Bindal, Ahmet

    2017-01-01

    This book provides semester-length coverage of electronics for embedded systems, covering most common analog and digital circuit-related issues encountered while designing embedded system hardware. It is written for students and young professionals who have basic circuit theory background and want to learn more about passive circuits, diode and bipolar transistor circuits, the state-of-the-art CMOS logic family and its interface with older logic families such as TTL, sensors and sensor physics, operational amplifier circuits to condition sensor signals, data converters and various circuits used in electro-mechanical device control in embedded systems. The book also provides numerous hardware design examples by integrating the topics learned in earlier chapters. The last chapter extensively reviews the combinational and sequential logic design principles to be able to design the digital part of embedded system hardware.

  14. Electron bombardment of water adsorbed on Zr(0001) surfaces

    CERN Document Server

    Ankrah, S; Ramsier, R D

    2003-01-01

    A study of the effects of electron bombardment on water adsorbed on Zr(0001) is reported. Zirconium surfaces are dosed with isotopic water mixtures at 160 K followed by electron bombardment (485 eV). The system is then probed by low energy electron diffraction, temperature programmed desorption (TPD) and Auger electron spectroscopy (AES). No evidence is found that would indicate preferential mixing of hydrogen from the bulk with isotopic water dissociation products during TPD. However, electron bombardment results in the sharpening of a hydrogen/deuterium desorption peak near 320 K and the production of water near 730 K at low water exposures. In addition, although water does not oxidize Zr(0001) thermally, electron bombardment of adsorbed water induces a shift of about 2 eV in the Zr AES features indicating that the surface is partially oxidized by electron bombardment.

  15. Structural Dynamics of Electronic Systems

    Science.gov (United States)

    Suhir, E.

    2013-03-01

    The published work on analytical ("mathematical") and computer-aided, primarily finite-element-analysis (FEA) based, predictive modeling of the dynamic response of electronic systems to shocks and vibrations is reviewed. While understanding the physics of and the ability to predict the response of an electronic structure to dynamic loading has been always of significant importance in military, avionic, aeronautic, automotive and maritime electronics, during the last decade this problem has become especially important also in commercial, and, particularly, in portable electronics in connection with accelerated testing of various surface mount technology (SMT) systems on the board level. The emphasis of the review is on the nonlinear shock-excited vibrations of flexible printed circuit boards (PCBs) experiencing shock loading applied to their support contours during drop tests. At the end of the review we provide, as a suitable and useful illustration, the exact solution to a highly nonlinear problem of the dynamic response of a "flexible-and-heavy" PCB to an impact load applied to its support contour during drop testing.

  16. Dynamics of electron in a surface quantum well

    Institute of Scientific and Technical Information of China (English)

    Wang Li-Fei; Yang Guang-Can

    2009-01-01

    This paper studies the quantum dynamics of electrons in a surface quantum well in the time domain with autocorrelation of wave packet. The evolution of the wave packet for different manifold eigenstates with finite and infinite lifetimes is investigated analytically. It is found that the quantum coherence and evolution of the surface electronic wave packet can be controlled by the laser central energy and electric field. The results show that the finite lifetime of excited states expedites the dephasing of the coherent electronic wave packet significantly. The correspondence between classical and quantum mechanics is shown explicitly in the system.

  17. Ultrastructure of the surface structures and electron immunogold labeling of peptide immunoreactivity in the nervous system of Pseudothoracocotyla indica (Polyopisthocotylea: Monogenea).

    Science.gov (United States)

    Brennan, G P; Ramasamy, P

    1996-01-01

    Transmission electron microscope studies of the tegument of the tropical marine fish monogenean parasite Pseudothoracocotyla indica describe surface specialisations and detail the ultrastructure of the tegument and the haptor. The tegument consists of a syncytium, numerous electron-dense granules, electron-lucent vesicles and large multivesicular bodies. The posterior tegumental syncytium is infolded to form tegumental ridges that are present on both the ventral and dorsal surfaces. A thin coat of glycocalyx is present on the tegument surface. In contrast, the tegumental syncytium of the haptor is relatively thin, containing electron-dense granules and various-sized electron-lucent vesicles. Exocytosis of the electron-dense and electron-lucent vesicles apparently occurs in the syncytium of the haptor and general body surface. Tegumental damage was observed on the dorsal surface in the mid-body region and may possibly have been due to natural mechanical forces. The haptor consists of electron-dense clamp sclerites embedded within a matrix covered by the tegumental syncytium. The sclerites are connected to each other and to the basal lamina by radially oriented muscle fibres. The haptor is richly supplied with non-myelinated nerve axons. Both uniciliated and non-ciliated presumed sensory structures are present on the body surface and haptor. Uniciliated sensory structures were found mainly around the oral sucker. Groups of neurons and nerve processes containing neurosecretory vesicles were frequently observed in the vicinity of the clamps. Electron immunogold labelling studies demonstrated that neuropeptide F [NPF (Moniezia expansa)] immunoreactivity was confined to electron-dense-cored neurosecretory vesicles in nerve fibres from the posterior and haptor regions of the fluke.

  18. Surface structure and electronic properties of materials

    Science.gov (United States)

    Siekhaus, W. J.; Somorjai, G. A.

    1975-01-01

    A surface potential model is developed to explain dopant effects on chemical vapor deposition. Auger analysis of the interaction between allotropic forms of carbon and silicon films has shown Si-C formation for all forms by glassy carbon. LEED intensity measurements have been used to determine the mean square displacement of surface atoms of silicon single crystals, and electron loss spectroscopy has shown the effect of structure and impurities on surface states located within the band gap. A thin film of Al has been used to enhance film crystallinity at low temperature.

  19. Electric field distribution of electron emitter surfaces

    Science.gov (United States)

    Tagawa, M.; Takenobu, S.; Ohmae, N.; Umeno, M.

    1987-03-01

    The electric field distribution of a tungsten field emitter surface and a LaB6 thermionic emitter surface has been studied. The computer simulation of electric field distribution on the emitter surface was carried out with a charge simulation method. The electric field distribution of the LaB6 thermionic emitter was experimentally evaluated by the Schottky plot. Two independent equations are necessary for obtaining local electric field and work function; the Fowler-Nordheim equation and the equation of total energy distribution of emitted electron being used to evaluate the electric field distribution of the tungsten field emitter. The experimental results agreed with the computer simulation.

  20. Atomic arrangements and electronic properties of semiconductor surfaces and interfaces

    Science.gov (United States)

    Chadi, D. J.; Martin, R. M.

    1982-05-01

    The areas of research during the past 12 months have included: step-formation energies and domain orientation at Si(111) surfaces; the electronic structure of the Al-GaAs(110) surface chemisorption system; density-functional calculations of bulk properties of GaAs and of (100)GaAs-Ge interfaces; demonstration of the importance of correlation effects on the atomic and electronic structure of Si(111) surfaces; and derivation of an exact scaling law for the resistance of a thin wire for the one dimensional Anderson model containing Loth diagonal and off-diagonal disorder.

  1. Electron beam induced surface activation of oxide surfaces for nanofabrication

    Energy Technology Data Exchange (ETDEWEB)

    Vollnhals, Florian; Seiler, Steffen; Walz, Marie-Madeleine; Steinrueck, Hans-Peter; Marbach, Hubertus [Lehrstuhl fuer Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen (Germany); Woolcot, Tom; Thornton, Geoff [London Centre for Nanotechnology and Department of Chemistry, University College London (United Kingdom)

    2012-07-01

    The controlled fabrication of structures on the nanoscale is a major challenge in science and engineering. Direct-write techniques like Electron Beam Induced Deposition (EBID) were shown to be suitable tools in this context. Recently, Electron Beam Induced Surface Activation (EBISA) has been introduced as a new focused electron beam technique. In EBISA, a surface, e.g. SiO{sub 2}, is irradiated by a focused electron beam, resulting in an activation of the exposed area. The activated area can then react and decompose precursor gases like iron pentacarbonyl, Fe(CO){sub 5}. This leads to a primary deposit, which continues to grow autocatalytically as long as Fe(CO){sub 5} is supplied, resulting in pure (> 90 % at.), crystalline iron nanostructures. We expand the use of this concept by exploring EBISA to produce metallic nanostructures on TiO{sub 2}(110) in UHV; atomistic insight into the process is obtained via Scanning Tunneling Microscopy (STM) and chemical insight via Auger Electron Spectroscopy (AES).

  2. Method of evaluation of electron transfer kinetics of a surface-confined redox system by means of Fourier transformed square wave voltammetry.

    Science.gov (United States)

    Huang, Xinjian; Wang, Lishi; Liao, Shijun

    2008-07-15

    A new form of Fourier transformed square wave voltammetry (FT-SWV) is proposed to simplify and accelerate the electron transfer kinetics evaluation procedures for surface-confined redox systems. Even harmonic frequencies, which are derived from the nonlinear Faradaic response, will arise in the power spectrum after Fourier transformation of the current response of FT-SWV. The profile of the even harmonic power spectra is bell-shaped and shows a maximum at a certain frequency. The electrode kinetics-dependent maximum and the corresponding frequency are equivalent to the so-called "quasi-reversible maximum" and "critical frequency" (fmax) in traditional SWV, respectively. The critical frequency can be regarded as a frequency that is synchronized to the electron transfer rate constant (k(0)). As a result, it can serve as a probe of k(0) by means of a very simple equation, k(0) = kmax fmax. Compared with traditional cyclic voltammetry, square wave voltammetry, alternating current voltammetry, and several other voltammetric techniques, this method exhibits great advantages for its simplicity, rapidity, and sensitivity.

  3. Enhanced Electron-Phonon Coupling at Metal Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Plummer, Ward E.

    2010-08-04

    The Born-Oppenheimer approximation (BOA) decouples electronic from nuclear motion, providing a focal point for most quantum mechanics textbooks. However, a multitude of important chemical, physical and biological phenomena are driven by violations of this approximation. Vibronic interactions are a necessary ingredient in any process that makes or breaks a covalent bond, for example, conventional catalysis or enzymatically delivered biological reactions. Metastable phenomena associated with defects and dopants in semiconductors, oxides, and glasses entail violation of the BOA. Charge exchange in inorganic polymers, organic slats and biological systems involves charge- induced distortions of the local structure. A classic example is conventional superconductivity, which is driven by the electron-lattice interaction. High-resolution angle-resolved photoemission experiments are yielding new insight into the microscopic origin of electron-phonon coupling (EPC) in anisotropic two-dimensional systems. Our recent surface phonon measurement on the surface of a high-Tc material clearly indicates an important momentum dependent EPC in these materials. In the last few years we have shifted our research focus from solely looking at electron phonon coupling to examining the structure/functionality relationship at the surface of complex transition metal compounds. The investigation on electron phonon coupling has allowed us to move to systems where there is coupling between the lattice, the electrons and the spin.

  4. [Electronic poison information management system].

    Science.gov (United States)

    Kabata, Piotr; Waldman, Wojciech; Kaletha, Krystian; Sein Anand, Jacek

    2013-01-01

    We describe deployment of electronic toxicological information database in poison control center of Pomeranian Center of Toxicology. System was based on Google Apps technology, by Google Inc., using electronic, web-based forms and data tables. During first 6 months from system deployment, we used it to archive 1471 poisoning cases, prepare monthly poisoning reports and facilitate statistical analysis of data. Electronic database usage made Poison Center work much easier.

  5. Treatment of surfaces with low-energy electrons

    Science.gov (United States)

    Frank, L.; Mikmeková, E.; Lejeune, M.

    2017-06-01

    Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications.

  6. Electron Stimulated Desorption of Condensed Gases on Cryogenic Surfaces

    CERN Document Server

    Tratnik, H; Hilleret, Noël

    2005-01-01

    In ultra-high vacuum systems outgassing from vacuum chamber walls and desorption from surface adsorbates are usually the factors which in°uence pressure and residual gas composition. In particular in beam vacuum systems of accelerators like the LHC, where surfaces are exposed to intense synchro- tron radiation and bombardment by energetic ions and electrons, properties like the molecular desorption yield or secondary electron yield can strongly in°uence the performance of the accelerator. In high-energy particle accelerators operating at liquid helium temperature, cold surfaces are exposed to the bombardment of energetic photons, electrons and ions. The gases released by the subsequent desorption are re-condensed on the cold surfaces and can be re-desorbed by the impinging electrons and ions. The equilibrium coverage reached on the surfaces exposed to the impact of energetic particles depends on the desorption yield of the condensed gases and can a®ect the operation of the accelerator by modifying th...

  7. Electronic Resource Management Systems

    Directory of Open Access Journals (Sweden)

    Mark Ellingsen

    2004-10-01

    Full Text Available Computer applications which deal with electronic resource management (ERM are quite a recent development. They have grown out of the need to manage the burgeoning number of electronic resources particularly electronic journals. Typically, in the early years of e-journal acquisition, library staff provided an easy means of accessing these journals by providing an alphabetical list on a web page. Some went as far as categorising the e-journals by subject and then grouping the journals either on a single web page or by using multiple pages. It didn't take long before it was recognised that it would be more efficient to dynamically generate the pages from a database rather than to continually edit the pages manually. Of course, once the descriptive metadata for an electronic journal was held within a database the next logical step was to provide administrative forms whereby that metadata could be manipulated. This in turn led to demands for incorporating more information and more functionality into the developing application.

  8. Thermodynamic responses of electronic systems

    Science.gov (United States)

    Franco-Pérez, Marco; Ayers, Paul W.; Gázquez, José L.; Vela, Alberto

    2017-09-01

    We present how the framework of the temperature-dependent chemical reactivity theory can describe the panorama of different types of interactions between an electronic system and external reagents. The key reactivity indicators are responses of an appropriate state function (like the energy or grand potential) to the variables that determine the state of the system (like the number of electrons/chemical potential, external potential, and temperature). We also consider the response of the average electron density to appropriate perturbations. We present computable formulas for these reactivity indicators and discuss their chemical utility for describing electronic, electrostatic, and thermal changes associated with chemical processes.

  9. Electronic structure of disordered alloys, surfaces and interfaces

    CERN Document Server

    Turek, Ilja; Kudrnovský, Josef; Šob, Mojmír; Weinberger, Peter

    1997-01-01

    At present, there is an increasing interest in the prediction of properties of classical and new materials such as substitutional alloys, their surfaces, and metallic or semiconductor multilayers. A detailed understanding based on a thus of the utmost importance for fu­ microscopic, parameter-free approach is ture developments in solid state physics and materials science. The interrela­ tion between electronic and structural properties at surfaces plays a key role for a microscopic understanding of phenomena as diverse as catalysis, corrosion, chemisorption and crystal growth. Remarkable progress has been made in the past 10-15 years in the understand­ ing of behavior of ideal crystals and their surfaces by relating their properties to the underlying electronic structure as determined from the first principles. Similar studies of complex systems like imperfect surfaces, interfaces, and mul­ tilayered structures seem to be accessible by now. Conventional band-structure methods, however, are of limited use ...

  10. Electronic Structure and Catalysis on Metal Surfaces

    Science.gov (United States)

    Greeley, Jeff; Norskov, Jens K.; Mavrikakis, Manos

    2002-10-01

    The powerful computational resources available to scientists today, together with recent improvements in electronic structure calculation algorithms, are providing important new tools for researchers in the fields of surface science and catalysis. In this review, we discuss first principles calculations that are now capable of providing qualitative and, in many cases, quantitative insights into surface chemistry. The calculations can aid in the establishment of chemisorption trends across the transition metals, in the characterization of reaction pathways on individual metals, and in the design of novel catalysts. First principles studies provide an excellent fundamental complement to experimental investigations of the above phenomena and can often allow the elucidation of important mechanistic details that would be difficult, if not impossible, to determine from experiments alone.

  11. Effect of surfactant-induced cell surface modifications on electron transport system and catechol 1,2-dioxygenase activities and phenanthrene biodegradation by Citrobacter sp. SA01.

    Science.gov (United States)

    Li, Feng; Zhu, Lizhong

    2012-11-01

    In order to better understand how surfactants affect biodegradation of hydrophobic organic compounds (HOCs), Tween 80 and sodium dodecyl benzene sulfonate (SDBS), were selected to investigate effects on cell surface hydrophobicity (CSH), electron transport system (ETS) activities and phenanthrene biodegradation by Citrobacter sp. SA01. Tween 80 and SDBS increased CSH by 19.8-25.2%, ETS activities by 352.1-376.0μmol/gmin, catechol 1,2-dioxygenase (C12) activities by 50.8-52.7U/L, and phenanthrene biodegradation by 8.9-17.2% separately in the presence of 50mg/L of surfactants as compared to in their absence. Lipopolysaccharide (LPS) release was 334.7μg/mg in the presence of both surfactants whereas in their absence only 8.6-44.4μg/mg of LPS was released. Thus, enhanced LPS release probably increased ETS and C12 activities as well as phenanthrene biodegradation by increasing CSH. The results demonstrate that surfactant-enhanced CSH provides a simple, yet effective strategy for field applications of surfactant-enhanced bioremediation of HOCs.

  12. Photoelectron spectroscopy bulk and surface electronic structures

    CERN Document Server

    Suga, Shigemasa

    2014-01-01

    Photoelectron spectroscopy is now becoming more and more required to investigate electronic structures of various solid materials in the bulk, on surfaces as well as at buried interfaces. The energy resolution was much improved in the last decade down to 1 meV in the low photon energy region. Now this technique is available from a few eV up to 10 keV by use of lasers, electron cyclotron resonance lamps in addition to synchrotron radiation and X-ray tubes. High resolution angle resolved photoelectron spectroscopy (ARPES) is now widely applied to band mapping of materials. It attracts a wide attention from both fundamental science and material engineering. Studies of the dynamics of excited states are feasible by time of flight spectroscopy with fully utilizing the pulse structures of synchrotron radiation as well as lasers including the free electron lasers (FEL). Spin resolved studies also made dramatic progress by using higher efficiency spin detectors and two dimensional spin detectors. Polarization depend...

  13. Determination of the surface composition of binary alloys by Auger electron spectroscopy: the gold--silver and gold--tin systems

    Energy Technology Data Exchange (ETDEWEB)

    Overbury, S.H.

    1976-11-01

    Auger electron spectroscopy was exploited as a means of determining the surface phase diagram of Au--Ag and Au--Sn alloys. Polycrystalline Au--Ag alloy foils of a wide range of composition (atom fractions of 0.15 to 0.97) were cleaned. The intensities of the Auger emission from transitions at several energies were measured and normalized to those of pure Au and Ag. The surface monolayer compositions of the alloys were determined. The Auger data was consistent with enrichment of Ag in the surface monolayer. Ingots of Au--Sn with bulk composition between 50 and 99 at % Au were prepared. The bulk structure and composition of these complex alloys were characterized by electron microprobe, x-ray diffraction, x-ray fluorescence and optical microscopy. The samples were cleaned and equilibrated in ultra high vacuum and the intensities of the Auger emission from transitions at several energies were measured and normalized to those of pure Au and pure Sn. Using the intensity model, the normalized Auger intensity ratios were used to determine the surface monolayer composition. Enrichment of Sn was found in the surface monolayer for disordered zeta and ..cap alpha.. phase alloys. The highly ordered delta (50.0 at % Au) phase alloy was found to exhibit no surface segregation. The surfaces of two phase alloys (delta and zeta) were found to be describable by the lever rule. The results were interpreted in terms of the bulk structures, ordering properties, and driving force for segregation of the alloys. The effects of ion sputtering upon the surface of Au--Ag and Au--Sn alloys were also investigated.

  14. Vessel Electronic Reporting System (VERS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The VERS system is composed of a database and other related applications which facilitate the reporting of electronically collected research data via Fisheries...

  15. Electronical Health Record's Systems. Interoperability

    Directory of Open Access Journals (Sweden)

    Simona Angela Apostol

    2008-01-01

    Full Text Available #Understanding the importance that the electronic medical health records system has, with its various structural types and grades, has led to the elaboration of a series of standards and quality control methods, meant to control its functioning. In time, the electronic health records system has evolved along with the medical data’s change of structure. Romania has not yet managed to fully clarify this concept, various definitions still being encountered, such as “Patient’s electronic chart”, “Electronic health file”. A slow change from functional interoperability (OSI level 6 to semantic interoperability (level 7 is being aimed at the moment. This current article will try to present the main electronic files models, from a functional interoperability system’s possibility to be created perspective.

  16. Some unusual electronic patterns on graphite surface

    Indian Academy of Sciences (India)

    Shyam K Choudhury; Anjan K Gupta

    2008-02-01

    We report on the observation of some unusual electronic patterns on a graphite surface using scanning tunneling spectroscopy (STM). We attribute these patterns to different types of strain near the surface. One such pattern seen on a particular layer comprises of two-dimensional spatially varying super-lattice and one-dimensional fringes. This pattern is present in a finite region of a layer on the surface confined between two carbon fibers. We attribute this spatially varying super-lattice structure to the shear strain generated in the top layer due to the restraining fibers. We have also developed a model with the Moirµe rotation hypothesis that gives us a better insight into such large-scale spatially varying patterns. We have been able to model the above-observed pattern. We also report another pattern near a defect, which we attribute to the change in density of states due to the physical buckling of the top graphite layer. Part of this buckled layer is found to be buried under another layer and this region shows a reversed contrast and thus supporting our idea of buckling. We also performed tunneling spectroscopy measurements on various regions of these patterns which show significant variations in the density of states.

  17. Electronic structure of graphene on Ni surfaces with different orientation

    Energy Technology Data Exchange (ETDEWEB)

    Pudikov, D.A., E-mail: gelbry@gmail.com; Zhizhin, E.V.; Rybkin, A.G.; Rybkina, A.A.; Zhukov, Y.M.; Vilkov, O. Yu.; Shikin, A.M.

    2016-08-15

    An experimental study of the graphene, synthesized by propylene cracking on Ni surfaces with different orientation: (100) and (111), using angle-resolved photoemission, has been performed. It has been shown that graphene on Ni(111) had a perfect lateral structure due to consistency of their lattices, whereas graphene/Ni(100) consisted of a lot of domains. For both systems electronic structure was quite similar and demonstrated a strong bonding of graphene to the underlying Ni surface. After Au intercalation the electronic structure of graphene in both systems was shifted to the Fermi level and became linear in the vicinity of the K point of the Brillouin zone. - Highlights: • Graphene on Ni(111) is well-ordered, whereas on Ni(100) – multi-domain. • Graphene on Ni(111) and Ni(100) is strongly bonded with substrate. • Intercalation of Au atoms restores the linearity in dispersion and makes graphene quasi-free on both Ni(100) and Ni(111).

  18. Electric field cancellation on quartz: a Rb adsorbate induced negative electron affinity surface

    CERN Document Server

    Sedlacek, J A; Rittenhouse, S T; Weck, P F; Sadeghpour, H R; Shaffer, J P

    2015-01-01

    We investigate the (0001) surface of single crystal quartz with a submonolayer of Rb adsorbates. Using Rydberg atom electromagnetically induced transparency, we investigate the electric fields resulting from Rb adsorbed on the quartz surface, and measure the activation energy of the Rb adsorbates. We show that the adsorbed Rb induces a negative electron affinity (NEA) on the quartz surface. The NEA surface allows low energy electrons to bind to the surface and cancel the electric field from the Rb adsorbates. Our results are important for integrating Rydberg atoms into hybrid quantum systems and the fundamental study of atom-surface interactions, as well as applications for electrons bound to a 2D surface.

  19. Generation of surface electrons in femtosecond laser-solid interactions

    Institute of Scientific and Technical Information of China (English)

    XU; Miaohua; LI; Yutong; YUAN; Xiaohui; ZHENG; Zhiyuan; LIANG; Wenxi; YU; Quanzhi; ZHANG; Yi; WANG; Zhaohua; WEI; Zhiyi; ZHANG; Jie

    2006-01-01

    The characteristics of hot electrons produced by p-polarized femtosecond laser-solid interactions are studied. The experimental results show that the outgoing electrons are mainly emitted in three directions: along the target surface, the normal direction and the laser backward direction. The electrons flowing along the target surface are due to the confinement of the electrostatic field and the surface magnetic field, while the electrons in the normal direction due to the resonant absorption.

  20. Component reliability for electronic systems

    CERN Document Server

    Bajenescu, Titu-Marius I

    2010-01-01

    The main reason for the premature breakdown of today's electronic products (computers, cars, tools, appliances, etc.) is the failure of the components used to build these products. Today professionals are looking for effective ways to minimize the degradation of electronic components to help ensure longer-lasting, more technically sound products and systems. This practical book offers engineers specific guidance on how to design more reliable components and build more reliable electronic systems. Professionals learn how to optimize a virtual component prototype, accurately monitor product reliability during the entire production process, and add the burn-in and selection procedures that are the most appropriate for the intended applications. Moreover, the book helps system designers ensure that all components are correctly applied, margins are adequate, wear-out failure modes are prevented during the expected duration of life, and system interfaces cannot lead to failure.

  1. Fundamentals of electronic systems design

    CERN Document Server

    Lienig, Jens

    2017-01-01

    This textbook covers the design of electronic systems from the ground up, from drawing and CAD essentials to recycling requirements. Chapter by chapter, it deals with the challenges any modern system designer faces: the design process and its fundamentals, such as technical drawings and CAD, electronic system levels, assembly and packaging issues and appliance protection classes, reliability analysis, thermal management and cooling, electromagnetic compatibility (EMC), all the way to recycling requirements and environmental-friendly design principles. Enables readers to face various challenges of designing electronic systems, including coverage from various engineering disciplines; Written to be accessible to readers of varying backgrounds; Uses illustrations extensively to reinforce fundamental concepts; Organized to follow essential design process, although chapters are self-contained and can be read in any order.

  2. 76 FR 31456 - Special Conditions: Gulfstream Model GVI Airplane; Electronic Flight Control System: Control...

    Science.gov (United States)

    2011-06-01

    ...; Electronic Flight Control System: Control Surface Position Awareness AGENCY: Federal Aviation Administration... design features include an electronic flight control system. The applicable airworthiness regulations do... an electronic flight control system and no direct coupling from the cockpit controller to the...

  3. Micro-Electronic Nose System

    Science.gov (United States)

    Zee, Frank C.

    2011-12-01

    The ability to "smell" various gas vapors and complex odors is important for many applications such as environmental monitoring for detecting toxic gases as well as quality control in the processing of food, cosmetics, and other chemical products for commercial industries. Mimicking the architecture of the biological nose, a miniature electronic nose system was designed and developed consisting of an array of sensor devices, signal-processing circuits, and software pattern-recognition algorithms. The array of sensors used polymer/carbon-black composite thin-films, which would swell or expand reversibly and reproducibly and cause a resistance change upon exposure to a wide variety of gases. Two types of sensor devices were fabricated using silicon micromachining techniques to form "wells" that confined the polymer/carbon-black to a small and specific area. The first type of sensor device formed the "well" by etching into the silicon substrate using bulk micromachining. The second type built a high-aspect-ratio "well" on the surface of a silicon wafer using SU-8 photoresist. Two sizes of "wells" were fabricated: 500 x 600 mum² and 250 x 250 mum². Custom signal-processing circuits were implemented on a printed circuit board and as an application-specific integrated-circuit (ASIC) chip. The circuits were not only able to measure and amplify the small resistance changes, which corresponded to small ppm (parts-per-million) changes in gas concentrations, but were also adaptable to accommodate the various characteristics of the different thin-films. Since the thin-films were not specific to any one particular gas vapor, an array of sensors each containing a different thin-film was used to produce a distributed response pattern when exposed to a gas vapor. Pattern recognition, including a clustering algorithm and two artificial neural network algorithms, was used to classify the response pattern and identify the gas vapor or odor. Two gas experiments were performed, one

  4. Electron beam induced oxidation of Al–Mg alloy surfaces

    NARCIS (Netherlands)

    Palasantzas, G.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2002-01-01

    Electron beam currents of a few nanoamperes, currently used in nanometer scale scanning Auger/electron microscopy, induces severe oxidation of Al–Mg alloy surfaces at room temperature. Auger peak-to-peak oxygen curves for Al–Mg surfaces support the hypothesis that the electron beam creates

  5. Electron beam induced oxidation of Al–Mg alloy surfaces

    NARCIS (Netherlands)

    Palasantzas, G.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2002-01-01

    Electron beam currents of a few nanoamperes, currently used in nanometer scale scanning Auger/electron microscopy, induces severe oxidation of Al–Mg alloy surfaces at room temperature. Auger peak-to-peak oxygen curves for Al–Mg surfaces support the hypothesis that the electron beam creates additiona

  6. Printed Carbon Nanotube Electronics and Sensor Systems.

    Science.gov (United States)

    Chen, Kevin; Gao, Wei; Emaminejad, Sam; Kiriya, Daisuke; Ota, Hiroki; Nyein, Hnin Yin Yin; Takei, Kuniharu; Javey, Ali

    2016-06-01

    Printing technologies offer large-area, high-throughput production capabilities for electronics and sensors on mechanically flexible substrates that can conformally cover different surfaces. These capabilities enable a wide range of new applications such as low-cost disposable electronics for health monitoring and wearables, extremely large format electronic displays, interactive wallpapers, and sensing arrays. Solution-processed carbon nanotubes have been shown to be a promising candidate for such printing processes, offering stable devices with high performance. Here, recent progress made in printed carbon nanotube electronics is discussed in terms of materials, processing, devices, and applications. Research challenges and opportunities moving forward from processing and system-level integration points of view are also discussed for enabling practical applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. FTU bolometer electronic system upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Pollastrone, Fabio, E-mail: fabio.pollastrone@enea.it [Associazione EURATOM-ENEA sulla Fusione, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Neri, Carlo; Florean, Marco; Ciccone, Giovanni [Associazione EURATOM-ENEA sulla Fusione, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy)

    2013-10-15

    Highlights: ► Design and realization of a new bolometer electronic system. ► Many improvements over the actual commercial system. ► Architecture based on digital electronic hardware with minimal analog front end. ► Auto off-set correction, real time visualization features and small system size. ► Test results for the electronic system. -- Abstract: The FTU (Frascati Tokamak Upgrade) requires a bolometer diagnostic in order to measure the total plasma radiation. The current diagnostic architecture is based on a full analog multichannel AC bolometer system, which uses a carrier frequency amplifier with a synchronous demodulation. Taking into account the technological upgrades in the field of electronics, it was decided to realize an upgrade for the bolometric electronic system by using a hybrid analog/digital implementation. The new system developed at the ENEA Frascati laboratories has many improvements, and mainly a massive system volume reduction, a good measurement linearity and a simplified use. The new hardware system consists of two subsystems: the Bolometer Digital Control and the Bolometer Analog System. The Bolometer Digital Control can control 16 bolometer bridges through the Bolometer Analog System. The Bolometer Digital Control, based on the FPGA architecture, is connected via Ethernet with a PC; therefore, it can receive commands settings from the PC and send the stream of bolometric measurements in real time to the PC. In order to solve the cross-talk between the bridges and the cables, each of the four bridges in the bolometer head receives a different synthesized excitation frequency. Since the system is fully controlled by a PC GUI (Graphic User Interface), it is very user friendly. Moreover, some useful features have been developed, such as: auto off-set correction, bridge amplitude regulation, software gain setting, real time visualization, frequency excitation selection and noise spectrum analyzer embedded function. In this paper, the

  8. Electron Conditioning of Technical Aluminium Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Le Pimpec, F

    2004-09-02

    The effect of electron conditioning on commercially aluminium alloys 1100 and 6063 were investigated. Contrary to the assumption that electron conditioning, if performed long enough, can reduce and stabilize the SEY to low values (= 1.3, value of many pure elements [1]), the SEY of aluminium did not go lower than 1.8. In fact, it reincreases with continued electron exposure dose.

  9. Generative electronic background music system

    Energy Technology Data Exchange (ETDEWEB)

    Mazurowski, Lukasz [Faculty of Computer Science, West Pomeranian University of Technology in Szczecin, Zolnierska Street 49, Szczecin, PL (Poland)

    2015-03-10

    In this short paper-extended abstract the new approach to generation of electronic background music has been presented. The Generative Electronic Background Music System (GEBMS) has been located between other related approaches within the musical algorithm positioning framework proposed by Woller et al. The music composition process is performed by a number of mini-models parameterized by further described properties. The mini-models generate fragments of musical patterns used in output composition. Musical pattern and output generation are controlled by container for the mini-models - a host-model. General mechanism has been presented including the example of the synthesized output compositions.

  10. Electronic stimulators for surface neural prosthesis

    Directory of Open Access Journals (Sweden)

    Broderick Barry J.

    2008-01-01

    Full Text Available This paper presents the technological advancements in neural prosthesis devices using Functional Electrical Stimulation (FES. FES refers to the restoration of motor functions lost due to spinal cord injury (SCI, stroke, head injury, or diseases such as Cerebral Palsy or Multiple Sclerosis by eliciting muscular contractions through the use of a neuromuscular electrical stimulator device. The field has developed considerably since its inception, with the miniaturisation of circuity, the development of programmable and adaptable stimulators and the enhancement of sensors used to trigger the application of stimulation to suit a variety of FES applications. This paper discusses general FES system design requirements in the context of existing commercial and research FES devices, focusing on surface stimulators for the upper and lower limbs. These devices have demonstrated feasible standing and stepping in a clinical setting with paraplegic patients, improvements in dropped foot syndrome with hemiplegic patients and aided in the restoration of grasping function in patients with upper limb motor dysfunction.

  11. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  12. Surface and volume photoemission of hot electrons from plasmonic nanoantennas

    DEFF Research Database (Denmark)

    Uskov, Alexander V.; Protsenko, Igor E.; Ikhsanov, Renat S.;

    2014-01-01

    We theoretically compare surface- and volume-based photoelectron emission from spherical nanoparticles, obtaining analytical expressions for the emission rate in both mechanisms. We show that the surface mechanism prevails, being unaffected by detrimental hot electron collisions....

  13. Surface Properties from Transconductance in Nanoscale Systems.

    Science.gov (United States)

    Lynall, David; Byrne, Kristopher; Shik, Alexander; Nair, Selvakumar V; Ruda, Harry E

    2016-10-12

    Because of the continued scaling of transistor dimensions and incorporation of nanostructured materials into modern electronic and optoelectronic devices, surfaces and interfaces have become a dominant factor dictating material properties and device performance. In this study, we investigate the temperature-dependent electronic transport properties of InAs nanowire field-effect transistors. A point where the nanowire conductance becomes independent of temperature is observed, known as the zero-temperature-coefficient. The distribution of surface states is determined by a spectral analysis of the conductance activation energy and used to develop a carrier transport model that explains the existence and gate voltage dependence of this point. We determine that the position of this point in gate voltage is directly related to the fixed oxide charge on the nanowire surface and demonstrate the utility of this method for studying surface passivations in nanoscale systems by characterizing (NH4)2Sx and H2 plasma surface treatments on InAs nanowires.

  14. Surface and volume photoemission of hot electrons from plasmonic nanoantennas

    DEFF Research Database (Denmark)

    Uskov, Alexander V.; Protsenko, Igor E.; Ikhsanov, Renat S.

    2014-01-01

    We theoretically compare surface- and volume-based photoelectron emission from spherical nanoparticles, obtaining analytical expressions for the emission rate in both mechanisms. We show that the surface mechanism prevails, being unaffected by detrimental hot electron collisions.......We theoretically compare surface- and volume-based photoelectron emission from spherical nanoparticles, obtaining analytical expressions for the emission rate in both mechanisms. We show that the surface mechanism prevails, being unaffected by detrimental hot electron collisions....

  15. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    -link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault......-tolerant adjustable speed drive systems; mission profile oriented reliability design in wind turbine and photovoltaic systems; reliability of power conversion systems in photovoltaic applications; power supplies for computers; and high-power converters. Reliability of Power Electronic Converter Systems is essential...... reading for researchers, professionals and students working with power electronics and their applications, particularly those specializing in the development and application of power electronic converters and systems....

  16. Electron-beam-assisted Scanning Tunneling Microscopy Of Insulating Surfaces

    CERN Document Server

    Bullock, E T

    2000-01-01

    Insulating materials are widely used in electronic devices. Bulk insulators and insulating films pose unique challenges for high resolution study since most commonly used charged particle surface analysis techniques are incompatible with insulating surfaces and materials. A, method of performing scanning tunneling microscopy (STM) on insulating surfaces has been investigated. The method is referred to as electron-beam assisted scanning tunneling microscopy (e-BASTM). It is proposed that by coupling the STM and the scanning electron microscopy (SEM) as one integrated device, that insulating materials may be studied, obtaining both high spatial resolution, and topographic and electronic resolution. The premise of the technique is based on two physical consequences of the interaction of an energetic electron beam (PE) with a material. First, when an electron beam is incident upon a material, low level material electrons are excited into conduction band states. For insulators, with very high secondary electron yi...

  17. Electronic properties of semiconductor surfaces and metal/semiconductor interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tallarida, M.

    2005-05-15

    , manifested by the observation of quantum well states and a surface state. The resulting shift in binding energy of both quantum well states and surface state has been interpreted in terms of the virtual crystal approximation model where the main effect of the alloying process is attributed to the change of electron density of the system. For this system, the variation of photoemission intensity as a function of photon energy has been also investigated and explained in terms of collective excitations. (orig.)

  18. Preventing colloidal fouling in reverse osmosis and nano filtration system. Application of electron beam surface analysis; Prevencion del ensuciamiento coloidal en sistemas de osmosis inversa y nanofiltracion. Aplicacion del analisis de superficies con haces de electrones.

    Energy Technology Data Exchange (ETDEWEB)

    Sanz Ataz, J.; Guerrero Gallego, L.; Taberna Camprubi, E.; Pena Garcia, N.M; Carulla Contreras, C.; Blavia Bergos, J.

    2003-07-01

    Particulate matter in natural waters and wastewaters can cause fouling in reverse osmosis and nano filtration membranes. Common foulants includes organic and inorganic colloids; hydrous aluminum and iron silicates, silt, iron and manganese oxides, calcium carbonate, microorganisms, polysaccharides, lipoproteins, biological debris, etc. Predicting fouling of dispersed materials on membrane surface and brine flow channels uses the silt density index (SDI) and modified fouling index (MFI). Scanning electron microscopy (SEM) coupled with energy X-ray microanalysis (EDX) of SDI filters contributes to obtain information about shape, size and chemical composition of foulants and cake layer. (Author) 6 refs.

  19. A scanning Auger electron spectrometer for internal surface analysis of Large Electron Positron 2 superconducting radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Benvenuti, C.; Cosso, R.; Genest, J.; Hauer, M.; Lacarrere, D.; Rijllart, A.; Saban, R. [CERN, 1211 Geneva 23 (Switzerland)

    1996-08-01

    A computer-controlled surface analysis instrument, incorporating static Auger electron spectroscopy, scanning Auger mapping, and secondary electron imaging, has been designed and built at CERN to study and characterize the inner surface of superconducting radio-frequency cavities to be installed in the Large Electron Positron collider. A detailed description of the instrument, including the analytical head, the control system, and the vacuum system is presented. Some recent results obtained from the cavities provide examples of the instrument{close_quote}s capabilities. {copyright} {ital 1996 American Institute of Physics.}

  20. Trapping Surface Electrons on Graphene Layers and Islands

    OpenAIRE

    Niesner, D.; Fauster, Th.; Dadap, J. I.; Zaki, N.; Knox, K. R.; Yeh, P. -C.; Bhandari, R.; Osgood, R. M.; Petrović, M; Kralj, M.

    2011-01-01

    We report the use of time- and angle-resolved two-photon photoemission to map the bound, unoccupied electronic structure of the weakly coupled graphene/Ir(111) system. The energy, dispersion, and lifetime of the lowest three image-potential states are measured. In addition, the weak interaction between Ir and graphene permits observation of resonant transitions from an unquenched Shockley-type surface state of the Ir substrate to graphene/Ir image-potential states. The image-potential-state l...

  1. Component Based Electronic Voting Systems

    Science.gov (United States)

    Lundin, David

    An electronic voting system may be said to be composed of a number of components, each of which has a number of properties. One of the most attractive effects of this way of thinking is that each component may have an attached in-depth threat analysis and verification strategy. Furthermore, the need to include the full system when making changes to a component is minimised and a model at this level can be turned into a lower-level implementation model where changes can cascade to as few parts of the implementation as possible.

  2. PREFACE: Strongly correlated electron systems Strongly correlated electron systems

    Science.gov (United States)

    Saxena, Siddharth S.; Littlewood, P. B.

    2012-07-01

    This special section is dedicated to the Strongly Correlated Electron Systems Conference (SCES) 2011, which was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 is dedicated to 100 years of superconductivity and covers a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The selected papers derived from invited presentations seek to deepen our understanding of the rich physical phenomena that arise from correlation effects. The focus is on quantum phase transitions, non-Fermi liquid phenomena, quantum magnetism, unconventional superconductivity and metal-insulator transitions. Both experimental and theoretical work is presented. Based on fundamental advances in the understanding of electronic materials, much of 20th century materials physics was driven by miniaturisation and integration in the electronics industry to the current generation of nanometre scale devices. The achievements of this industry have brought unprecedented advances to society and well-being, and no doubt there is much further to go—note that this progress is founded on investments and studies in the fundamentals of condensed matter physics from more than 50 years ago. Nevertheless, the defining challenges for the 21st century will lie in the discovery in science, and deployment through engineering, of technologies that can deliver the scale needed to have an impact on the sustainability agenda. Thus the big developments in nanotechnology may lie not in the pursuit of yet smaller transistors, but in the design of new structures that can revolutionise the performance of solar cells, batteries, fuel cells, light-weight structural materials, refrigeration, water purification, etc. The science presented in the papers of this special section also highlights the underlying interest in energy-dense materials, which

  3. Advanced uncooled infrared system electronics

    Science.gov (United States)

    Neal, Henry W.

    1998-07-01

    Over the past two decades, Raytheon Systems Company (RSC), formerly Texas Instruments Defense Systems & Electronics Group, developed a robust family of products based on a low- cost, hybrid ferroelectric (FE) uncooled focal-plane array (FPA) aimed at meeting the needs for thermal imaging products across both military and commercial markets. Over the years, RSC supplied uncooled infrared (IR) sensors for applications such as in combat vehicles, man-portable weaponry, personnel helmets, and installation security. Also, various commercial IR systems for use in automobiles, boats, law enforcement, hand-held applications, building/site security, and fire fighting have been developed. These products resulted in a high degree of success where cooled IR platforms are too bulky and costly, and other uncooled implementations are less reliable or lack significant cost advantage. Proof of this great success is found in the large price reductions, the unprecedented monthly production rates, and the wide diversity of products and customers realized in recent years. The ever- changing needs of these existing and potential customers continue to fuel the advancement of both the primary technologies and the production capabilities of uncooled IR systems at RSC. This paper will describe a development project intended to further advance the system electronics capabilities of future uncooled IR products.

  4. Multiscale approach to the electronic structure of doped semiconductor surfaces

    Science.gov (United States)

    Sinai, Ofer; Hofmann, Oliver T.; Rinke, Patrick; Scheffler, Matthias; Heimel, Georg; Kronik, Leeor

    2015-02-01

    The inclusion of the global effects of semiconductor doping poses a unique challenge for first-principles simulations, because the typically low concentration of dopants renders an explicit treatment intractable. Furthermore, the width of the space-charge region (SCR) at charged surfaces often exceeds realistic supercell dimensions. Here, we present a multiscale technique that fully addresses these difficulties. It is based on the introduction of a charged sheet, mimicking the SCR-related field, along with free charge which mimics the bulk charge reservoir, such that the system is neutral overall. These augment a slab comprising "pseudoatoms" possessing a fractional nuclear charge matching the bulk doping concentration. Self-consistency is reached by imposing charge conservation and Fermi level equilibration between the bulk, treated semiclassically, and the electronic states of the slab, which are treated quantum-mechanically. The method, called CREST—the charge-reservoir electrostatic sheet technique—can be used with standard electronic structure codes. We validate CREST using a simple tight-binding model, which allows for comparison of its results with calculations encompassing the full SCR explicitly. Specifically, we show that CREST successfully predicts scenarios spanning the range from no to full Fermi level pinning. We then employ it with density functional theory, obtaining insight into the doping dependence of the electronic structures of the metallic "clean-cleaved" Si(111) surface and its semiconducting (2 ×1 ) reconstructions.

  5. Magnetoconductivity of two-dimensional electron systems

    Science.gov (United States)

    Kuehnel, Frank Oliver

    The conductivity sigmaxx(o) of a low-density nondegenerate 2D electron gas is investigated under conditions where hoc ≫ kBT ≫ hgamma (oc is the cyclotron frequency and hgamma is the disorder-induced width of the Landau level). Such conditions have been met for electrons on helium surface, and can also be achieved in ultra high quality heterostructures. Because of the random potential of defects, single-electron states of the lowest Landau level form a band of a width hgamma ≪ hoc. Almost all of these states are localized. Therefore, for ho c ≫ kBT ≫ hgamma, the static single-electron conductivity sigma xx(0) may be expected to be equal to zero. Since for o ≫ gamma the conductivity should decay, on the whole sigma xx(o) has a peak at a finite frequency. From scaling arguments, we show that in the single-electron approximation sigma xx(o) ∝ omu for o → 0, with the exponent mu in the range from 0.21 to 0.22, whereas the frequency dependence of the cyclotron resonance absorption peak is non-critical. The far tails of the conductivity peaks are obtained using the method of optimal fluctuation and are shown to be Gaussian. In order to investigate the shape of the low frequency peak and cyclotron resonance absorption peak, we use the method of moments (MOM). In MOM, the low-frequency conductivity is restored from its 14 spectral moments, whereas the cyclotron resonance absorption is restored from the calculated 10 spectral moments using the continuous fraction expansion. In combination with the analytical asymptotics, both expansions converge rapidly with increasing number of included moments, and give numerically accurate results throughout the region of interest. The effect of electron-electron interaction (EEI) on the low frequency conductivity is also investigated. EEI makes the static conductivity finite. For a low-density system, the effect can be described using the notion of a fluctuational field Efl which drives an electron because of electron

  6. Dynamic screening and electron electron scattering in low-dimensional metallic systems

    Science.gov (United States)

    Silkin, V. M.; Quijada, M.; Muiño, R. Díez; Chulkov, E. V.; Echenique, P. M.

    2007-09-01

    The modification of dynamic screening in the electron-electron interaction in systems with reduced dimensionality and tunable one-particle electronic structure is studied. Two examples of such systems are considered, namely, the adsorbate-induced quantum well states at the Na adlayer covered Cu(1 1 1) surface, and metal clusters of sizes up to few nanometers. The dependence of the electron-electron decay rates on the Na coverage in the former case and on the cluster size in the latter is investigated. The role played by the dynamical screened interaction in such processes is addressed as well.

  7. Electron-Hole Counting Approach to Surface Atomic Structure

    Science.gov (United States)

    Chadi, D. J.

    The observed reconstructions of III-V semiconductor surfaces are shown to be consistent with constraints imposed by a simple "electron-hole" counting rule proposed by Pashley. The rule ensures that the predicted surfaces are nonmetallic, nonpolar, and at least, metastable since the compensation of the "donor" electrons leaves no occupied states in the upper part of the band gap which can easily induce other reconstructions. Applications of the method to the problem of surface structure and passivation are examined.

  8. Hydrophobicity of electron beam modified surface of hydroxyapatite films

    Energy Technology Data Exchange (ETDEWEB)

    Gregor, M., E-mail: gregor@fmph.uniba.sk [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia); Plecenik, T. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia); Tofail, S.A.M. [Materials & Surface Science Institute, University of Limerick, Limerick (Ireland); Zahoran, M.; Truchly, M. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia); Vargova, M. [Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, 84215 Bratislava (Slovakia); Laffir, F. [Materials & Surface Science Institute, University of Limerick, Limerick (Ireland); Plesch, G. [Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, 84215 Bratislava (Slovakia); Kus, P.; Plecenik, A. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia)

    2015-05-15

    Highlights: • Surface potential of hydroxyapatite films were modified by focused electron beam. • Micron-sized domains of modified surface potential were created. • Wettability and surface free energy of the irradiated areas was studied. • Possible mechanisms of increased surface hydrophobicity are discussed. - Abstract: Arrays of micron-sized domains of modified surface potential were created on hydroxyapatite films by mid-energy (20 keV) electron beam irradiation available in a laboratory scanning electron microscope. The dosage of electron beam was varied between 10{sup −3} and 10{sup 3} μC/cm{sup 2} to inject charge into the film surface. Contrary to the conventional electrowetting theory, the dosage of injected charge used in creating such microdomains caused a gradual increase of the water contact angle from 57° to 93° due to the elimination of the polar component of the surface free energy. Surface contamination by carbonaceous species can be held only partially responsible for such behavior at lower dosage of electron beam. A transfer of free surface charge to water and an electron beam induced disruption of polar orientation of OH ions have been attributed to be influencial factors in the overall dewetting behavior.

  9. Electronic structure of spin systems

    Energy Technology Data Exchange (ETDEWEB)

    Saha-Dasgupta, Tanusri

    2016-04-15

    Highlights: • We review the theoretical modeling of quantum spin systems. • We apply the Nth order muffin-tin orbital electronic structure method. • The method shows the importance of chemistry in the modeling. • CuTe{sub 2}O{sub 5} showed a 2-dimensional coupled spin dimer behavior. • Ti substituted Zn{sub 2}VO(PO{sub 4}){sub 2} showed spin gap behavior. - Abstract: Low-dimensional quantum spin systems, characterized by their unconventional magnetic properties, have attracted much attention. Synthesis of materials appropriate to various classes within these systems has made this field very attractive and a site of many activities. The experimental results like susceptibility data are fitted with the theoretical model to derive the underlying spin Hamiltonian. However, often such a fitting procedure which requires correct guess of the assumed spin Hamiltonian leads to ambiguity in deciding the representative model. In this review article, we will describe how electronic structure calculation within the framework of Nth order muffin-tin orbital (NMTO) based Wannier function technique can be utilized to identify the underlying spin model for a large number of such compounds. We will show examples from compounds belonging to vanadates and cuprates.

  10. Electron dynamics at surfaces induced by highly charged ions

    NARCIS (Netherlands)

    Morgenstern, R

    1998-01-01

    Energy spectra of electrons resulting from hydrogen-like multiply charged N6+ and Q(7+) ions on various surfaces are presented and discussed. Por metal target surfaces thr formation and decay of hollow atoms during the approach towards the surface is rather well understood in terms of the classical

  11. Electron dynamics at surfaces induced by highly charged ions

    NARCIS (Netherlands)

    Morgenstern, R

    Energy spectra of electrons resulting from hydrogen-like multiply charged N6+ and Q(7+) ions on various surfaces are presented and discussed. Por metal target surfaces thr formation and decay of hollow atoms during the approach towards the surface is rather well understood in terms of the classical

  12. EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems

    Science.gov (United States)

    Ronning, Filip; Batista, Cristian

    2011-03-01

    Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 2010—co-chaired by John Sarrao and Joe Thompson—followed the tradition of earlier conferences, in this century, hosted by Buzios (2008), Houston (2007), Vienna (2005), Karlsruhe (2004), Krakow (2002) and Ann Arbor (2001). Every three years since 1997, SCES has joined the International Conference on Magnetism (ICM), held in Recife (2000), Rome (2003), Kyoto (2006) and Karlsruhe (2009). Like its predecessors, SCES 2010 topics included strongly correlated f- and d-electron systems, heavy-fermion behaviors, quantum-phase transitions, non-Fermi liquid phenomena, unconventional superconductivity, and emergent states that arise from electronic correlations. Recent developments from studies of quantum magnetism and cold atoms complemented the traditional subjects and were included in SCES 2010. 2010 celebrated the 400th anniversary of Santa Fe as well as the birth of astronomy. So what's the connection to SCES? The Dutch invention of the first practical telescope and its use by Galileo in 1610 and subsequent years overturned dogma that the sun revolved about the earth. This revolutionary, and at the time heretical, conclusion required innovative combinations of new instrumentation, observation and mathematics. These same combinations are just as important 400 years later and are the foundation of scientific discoveries that were discussed

  13. Collaborative Research: Fundamental studies of plasma control using surface embedded electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Raja, Laxminarayan L. [Univ. of Texas, Austin, TX (United States); PanneerChelvam, PremKumar [Univ. of Texas, Austin, TX (United States); Levko, Dimtry [Univ. of Texas, Austin, TX (United States)

    2016-02-26

    The proposed study will investigate the effect of active electron injection of from electrode surfaces To the best of our knowledge, no such a study has ever been attempted even though it could lead to the formation of whole new classes of plasma based devices and systems. We are motivated by recent articles and simple theory which gives strong reason to believe that embedded electronic devices can be used to exert control over the SEE coefficient of semiconductor surfaces (and maybe other surface types as well). Furthermore, the research will explore how such sub-surface electronic devices can best be used to exert control over an associated plasma.

  14. Phosphogypsum surface characterisation using scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2003-01-01

    Full Text Available This paper presents the results of application of Scanning Electron Microscopy (SEM to examinations of the samples of natural gypsum and phosphogypsum. Phosphogypsum has a well developed crystalline structure, and appear in two polymorphous forms, of rombic and hexagonal shape crystals. Natural gypsum has a poorly crystalline structure. The differences in crystalline structure influence the chemical behavior of these row materials.

  15. Endor Studies of Radiation-Produced Trapped Electrons and Radicals in Disordered Systems and Radical-Matrix Interactions in Polymers and on Surfaces.

    Science.gov (United States)

    1982-04-30

    electron. 8 4. ENDOR and ELDOR of Paramagnetic Species in Disordered Matrices, L. Kevan and P.A. Narayana, Chapter IV, in Multiple Electron Resonance...electron-electron double resonance ( ELDOR ) to radicals trapped in disordered matrices such as glasses and polycrystals are dis- cussed. In...model is currently being developed which appears to give a more quantitative picture of the matrix ENDOR response. ELDOR has been used to evaluate the

  16. Electronic Nicotine Delivery Systems Key Facts Infographic

    Data.gov (United States)

    U.S. Department of Health & Human Services — Explore the Electronic Nicotine Delivery Systems Key Facts Infographic which outlines key facts related to electronic nicotine delivery systems (ENDS), including...

  17. Surface dose with grids in electron beam radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lin, K.-H.; Huang, C.-Y.; Lin, J.-P.; Chu, T.-C. E-mail: tcchu@mx.nthu.edu.tw

    2002-03-01

    This investigation attempts to solve the problem of the lack of skin-sparing effect in electron radiation therapy and to increase the tolerance of skin to radiation using the grid technique. Electron grid therapy involves the mounting of a Cerrobend grid in the electron cone. Film dosimetry was employed to measure the relative surface dose and the percentage depth dose profile of electron grid portals. Various grid hole diameters (d=0.45, 1.0, 1.5 cm) and grid hole spacings (s=0.4, 0.2 cm) were considered for electron beams from 6 to 14 MeV. Experimental results indicate that the electron grid technique can reduce the relative surface dose in electron radiation therapy. Degradations of the relative surface dose depend on the percentage of open area in the grid portal. A proper grid design allows the surface dose to be reduced and the range of nonhomogeneous doses to be limited to a depth at which the target volume can receive a homogeneous dose. The grid technique can lower the surface dose in electron radiation therapy.

  18. Evolution of electron Fermi surface with doping in cobaltates.

    Science.gov (United States)

    Ma, Xixiao; Lan, Yu; Qin, Ling; Kuang, Lülin; Feng, Shiping

    2016-08-24

    The notion of the electron Fermi surface is one of the characteristic concepts in the field of condensed matter physics, and it plays a crucial role in the understanding of the physical properties of doped Mott insulators. Based on the t-J model, we study the nature of the electron Fermi surface in the cobaltates, and qualitatively reproduce the essential feature of the evolution of the electron Fermi surface with doping. It is shown that the underlying hexagonal electron Fermi surface obeys Luttinger's theorem. The theory also predicts a Fermi-arc phenomenon at the low-doped regime, where the region of the hexagonal electron Fermi surface along the [Formula: see text]-K direction is suppressed by the electron self-energy, and then six disconnected Fermi arcs located at the region of the hexagonal electron Fermi surface along the [Formula: see text]-M direction emerge. However, this Fermi-arc phenomenon at the low-doped regime weakens with the increase of doping.

  19. Structural and electronic properties of hydrosilylated silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Baumer, A.

    2005-11-15

    The structural and electronic properties of alkyl-terminated Si surfaces prepared by thermallyinduced hydrosilylation have been studied in detail in the preceding chapters. Various surfaces have been used for the functionalization ranging from crystalline Si over amorphous hydrogenated Si to nanoscaled materials such as Si nanowires and nanoparticles. In each case, the alkyl-terminated surfaces have been compared to the native oxidized and H-terminated surfaces. (orig.)

  20. Hot-electron nanoscopy using adiabatic compression of surface plasmons

    KAUST Repository

    Giugni, Andrea

    2013-10-20

    Surface plasmon polaritons are a central concept in nanoplasmonics and have been exploited to develop ultrasensitive chemical detection platforms, as well as imaging and spectroscopic techniques at the nanoscale. Surface plasmons can decay to form highly energetic (or hot) electrons in a process that is usually thought to be parasitic for applications, because it limits the lifetime and propagation length of surface plasmons and therefore has an adverse influence on the functionality of nanoplasmonic devices. Recently, however, it has been shown that hot electrons produced by surface plasmon decay can be harnessed to produce useful work in photodetection, catalysis and solar energy conversion. Nevertheless, the surface-plasmon-to-hot-electron conversion efficiency has been below 1% in all cases. Here we show that adiabatic focusing of surface plasmons on a Schottky diode-terminated tapered tip of nanoscale dimensions allows for a plasmon-to-hot-electron conversion efficiency of ∼30%. We further demonstrate that, with such high efficiency, hot electrons can be used for a new nanoscopy technique based on an atomic force microscopy set-up. We show that this hot-electron nanoscopy preserves the chemical sensitivity of the scanned surface and has a spatial resolution below 50 nm, with margins for improvement.

  1. EVOLUTION OF IONS AFTER MULTIPLE ELECTRON-CAPTURE FROM SURFACES

    NARCIS (Netherlands)

    MORGENSTERN, R; DAS, J

    1993-01-01

    A comparison is made of the electronic processes which occur when a multiply charged ion is approaching an atomic target on the one hand or a metal surface on the other hand. In both caws three collision phases can be identified: those of attraction, of electron capture and of decay in the vacuum; i

  2. The EH101 Electronic Instrument Systems

    Directory of Open Access Journals (Sweden)

    Kieth N. Atkin

    1990-04-01

    Full Text Available This paper describes the background to the introduction of an electronic instrument system on the Anglo-Italian EH101 helicopter. The demanded flexibility to accommodate the display needs of several roles leading logically to the adoption of full colour multi-purpose display surfaces and the drive to achieve maximum commonality between military and civil variants is discussed. The configurations arrived at for both variants are described together with the operating philosophy and display formats developed during an ongoing simulator program. The paper also deals with a detailed description of the hardware implementation of the EIS including the fully integrated systems architecture and details of the symbol generators (SGs, display units (DUs and display mode selectors (DMSs. Emphasis is placed on the robust integrity characteristics and reversionary switching philosophy of the system."

  3. Modeling of power electronic systems with EMTP

    Science.gov (United States)

    Tam, Kwa-Sur; Dravid, Narayan V.

    1989-01-01

    In view of the potential impact of power electronics on power systems, there is need for a computer modeling/analysis tool to perform simulation studies on power systems with power electronic components as well as to educate engineering students about such systems. The modeling of the major power electronic components of the NASA Space Station Freedom Electric Power System is described along with ElectroMagnetic Transients Program (EMTP) and it is demonstrated that EMTP can serve as a very useful tool for teaching, design, analysis, and research in the area of power systems with power electronic components. EMTP modeling of power electronic circuits is described and simulation results are presented.

  4. Low-energy electron irradiation induced top-surface nanocrystallization of amorphous carbon film

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Cheng [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China); Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Fan, Xue, E-mail: fanx@szu.edu.cn [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China); Diao, Dongfeng, E-mail: dfdiao@szu.edu.cn [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China)

    2016-10-30

    Graphical abstract: Low-energy electron irradiation was proposed to nanocrystallize the top-surface of the as-deposited amorphous carbon film, and sp{sup 2} nanocrystallites formed in the film top-surface within 4 nm thickness. Display Omitted - Abstract: We report a low-energy electron irradiation method to nanocrystallize the top-surface of amorphous carbon film in electron cyclotron resonance plasma system. The nanostructure evolution of the carbon film as a function of electron irradiation density and time was examined by transmission electron microscope (TEM) and Raman spectroscopy. The results showed that the electron irradiation gave rise to the formation of sp{sup 2} nanocrystallites in the film top-surface within 4 nm thickness. The formation of sp{sup 2} nanocrystallite was ascribed to the inelastic electron scattering in the top-surface of carbon film. The frictional property of low-energy electron irradiated film was measured by a pin-on-disk tribometer. The sp{sup 2} nanocrystallized top-surface induced a lower friction coefficient than that of the original pure amorphous film. This method enables a convenient nanocrystallization of amorphous surface.

  5. Scanning Electron Microscope Analysis System

    Data.gov (United States)

    Federal Laboratory Consortium — This facility provides the capability to examine surfaces microscopically with high resolution (5 nanometers), perform micro chemical analyses of these surfaces, and...

  6. Scanning electron microscopy of human cortical bone failure surfaces.

    Science.gov (United States)

    Braidotti, P; Branca, F P; Stagni, L

    1997-02-01

    Undecalcified samples extracted from human femoral shafts are fractured by bending and the fracture surfaces are examined with a scanning electron microscope (SEM). The investigation is performed on both dry and wet (hydrated with a saline solution) specimens. SEM micrographs show patterns in many respects similar to those observed in fractography studies of laminated fiber-reinforced synthetic composites. In particular, dry and wet samples behave like brittle and ductile matrix laminates, respectively. An analysis carried out on the basis of the mechanisms that dominate the fracture process of laminates shows that a reasonable cortical bone model is that of a laminated composite material whose matrix is composed of extracellular noncollagenous calcified proteins, and the reinforcement is constituted by the calcified collagen fiber system.

  7. A surface-electrode quadrupole guide for electrons

    Energy Technology Data Exchange (ETDEWEB)

    Hoffrogge, Johannes Philipp

    2012-12-19

    This thesis reports on the design and first experimental realization of a surface-electrode quadrupole guide for free electrons. The guide is based on a miniaturized, planar electrode layout and is driven at microwave frequencies. It confines electrons in the near-field of the microwave excitation, where strong electric field gradients can be generated without resorting to resonating structures or exceptionally high drive powers. The use of chip-based electrode geometries allows the realization of versatile, microstructured potentials with the perspective of novel quantum experiments with guided electrons. I present the design, construction and operation of an experiment that demonstrates electron confinement in a planar quadrupole guide for the first time. To this end, electrons with kinetic energies from one to ten electron-volts are guided along a curved electrode geometry. The stability of electron guiding as a function of drive parameters and electron energy has been studied. A comparison with numerical particle tracking simulations yields good qualitative agreement and provides a deeper understanding of the electron dynamics in the guiding potential. Furthermore, this thesis gives a detailed description of the design of the surface-electrode layout. This includes the development of an optimized coupling structure to inject electrons into the guide with minimum transverse excitation. I also discuss the extension of the current setup to longitudinal guide dimensions that are comparable to or larger than the wavelength of the drive signal. This is possible with a modified electrode layout featuring elevated signal conductors. Electron guiding in the field of a planar, microfabricated electrode layout allows the generation of versatile and finely structured guiding potentials. One example would be the realization of junctions that split and recombine a guided electron beam. Furthermore, it should be possible to prepare electrons in low-lying quantum mechanical

  8. Guide on the use of low energy electron beams for microbiological decontamination of surfaces

    DEFF Research Database (Denmark)

    Miller, Arne; Helt-Hansen, Jakob; Gondim, Ondina

    This Guide describes the validation and routine monitoring of microbiological decontamination of surfaces by low energy electron beams (100-200 keV). The Guide is mainly based on experience gained in connection with installation of electron beam systems for surface decontamination of pre-steriliz......This Guide describes the validation and routine monitoring of microbiological decontamination of surfaces by low energy electron beams (100-200 keV). The Guide is mainly based on experience gained in connection with installation of electron beam systems for surface decontamination of pre......-sterilized containers at several aseptic filling lines at pharmaceutical manufacturers. Its main emphasis is on the dosimetric measurements that should be carried out for the validation of the decontamination process and on establishing the appropriate effective dose. Other aspects such as use of measurement...... uncertainties and formation of radiation induced by-products are also addressed....

  9. Diffuse Surface Scattering in the Plasmonic Resonances of Ultra-Low Electron Density Nanospheres

    CERN Document Server

    Monreal, R Carmina; Apell, S Peter

    2015-01-01

    Localized surface plasmon resonances (LSPRs) have recently been identified in extremely diluted electron systems obtained by doping semiconductor quantum dots. Here we investigate the role that different surface effects, namely electronic spill-out and diffuse surface scattering, play in the optical properties of these ultra-low electron density nanosystems. Diffuse scattering originates from imperfections or roughness at a microscopic scale on the surface. Using an electromagnetic theory that describes this mechanism in conjunction with a dielectric function including the quantum size effect, we find that the LSPRs show an oscillatory behavior both in position and width for large particles and a strong blueshift in energy and an increased width for smaller radii, consistent with recent experimental results for photodoped ZnO nanocrystals. We thus show that the commonly ignored process of diffuse surface scattering is a more important mechanism affecting the plasmonic properties of ultra-low electron density ...

  10. Structure of a bacterial cell surface decaheme electron conduit.

    Science.gov (United States)

    Clarke, Thomas A; Edwards, Marcus J; Gates, Andrew J; Hall, Andrea; White, Gaye F; Bradley, Justin; Reardon, Catherine L; Shi, Liang; Beliaev, Alexander S; Marshall, Matthew J; Wang, Zheming; Watmough, Nicholas J; Fredrickson, James K; Zachara, John M; Butt, Julea N; Richardson, David J

    2011-06-07

    Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of trans-outer-membrane electron transfer conduits. The cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or participating in extracellular intercytochrome electron exchange along "nanowire" appendages. We present a 3.2-Å crystal structure of one of these decaheme cytochromes, MtrF, that allows the spatial organization of the 10 hemes to be visualized for the first time. The hemes are organized across four domains in a unique crossed conformation, in which a staggered 65-Å octaheme chain transects the length of the protein and is bisected by a planar 45-Å tetraheme chain that connects two extended Greek key split β-barrel domains. The structure provides molecular insight into how reduction of insoluble substrate (e.g., minerals), soluble substrates (e.g., flavins), and cytochrome redox partners might be possible in tandem at different termini of a trifurcated electron transport chain on the cell surface.

  11. Plasmonics—the interaction of light with metal surface electrons

    Science.gov (United States)

    Kroó, Norbert; Rácz, Péter

    2016-08-01

    The realization of light amplification by stimulated emission of radiation opened up an enormous wealth of potential new research and technologies in a broad wavelength range of electromagnetic waves. One of the new fields is plasmonics, based on the special properties of some materials with negative refractive index. In this case surface electromagnetic waves, coupled to surface electrons, the so-called surface plasmons can be generated. These waves among others represent a large enhancement of the EM field near the surface of the materials. The present paper illustrates some of the consequences of this phenomenon for a broad range of phenomena from ‘lasing’ to electron pairing. The latter is the basic condition for superconductivity, in our case found at room temperature. Measurements with a scanning tunneling microscope, furthermore electron and photon emission studies are the source of the presented experimental data.

  12. Secondary Electron Yield on Cryogenic Surfaces as a Function of Physisorbed Gases

    CERN Document Server

    Kuzucan, Asena; Taborelli, Mauro

    2011-01-01

    In LHC the electron cloud induced by photoelectrons, gas ionization and secondary electrons emitted from the beam pipe walls could be a limitation of the performance. The electron cloud induce heat load on the cryogenic system, cause pressure rise, emittance growth and beam instabilities, which in the end will limit the beam’s lifetime. Beam- induced multipacting, which can arise through oscillatory motion of photoelectrons and low-energy secondary electrons bouncing back and forth between opposite walls of the vacuum chamber during successive passage of proton bunches, represent therefore a potential problem for the machine. The secondary electron yield (SEY) is one of the key parameters for the electron cloud build up and multipacting phenomenon. An electron cloud occurs if the metal surface secondary electron yield is high enough for electron multiplication. This parameter has been extensively studied on room temperature samples but uncertainties remain for samples at cryogenic temperature. Indeed, at l...

  13. Cognitive systems in electronic warfare

    Science.gov (United States)

    Kulpa, Krzysztof; Szczepankiewicz, Michał; Żywek, Marcin; Malanowski, Mateusz; Misiurewicz, Jacek; Samczyński, Piotr

    2017-04-01

    Electronic warfare (EW) techniques were invented 70 years ago and are still being developed, all the time with a key role played by their operators. However, a human operator responds far too slowly for the on-going needs since to be adequate to current threats the EW system reaction should be within 1 ms or less. Too slow reaction defers an achievement of the objectives, and generally may lead to disclosure of the applied strategy and to waste of resources. Developing the adequate response to the threat is a multifaceted matter that requires considerable experience and knowledge on the one hand, and thorough observation of outcomes of the applied strategy on the other hand. Such action requires the use of not only intelligence but also more complex algorithms for automatic control than the classical ones, and it heavily builds on the experience. It is therefore a cognitive task in its nature, and a human operator acts naturally this way. Consequently, a proper training and experience gained are what really matters. As a result of tests and actions in EW the operator builds his own knowledge base, thus, gains a capability of responding to the known threats in a balanced way. New threats, however, are much more challenging since they should be handled as fast as possible but in a fresh and creative manner. To this end, adapting the algorithms of radar jamming protection for the new conditions of the battlefield is an example of such challenging tasks. At present, such adjustments are done in a long feedback loop when the operator, after recognizing the problem, notifies the equipment manufacturers, and then, their engineers work on required solutions accordingly. Thus, the reaction time is counted in years, not a single milliseconds or seconds. Speeding up the response time is therefore the key issue, and a solution to it would be feasible only when cognitive systems were used. A concept of such cognitive system is presented in this paper.

  14. MODIFICATION OF SURFACE LAYERS FOR SILICATE GLASSES BY ELECTRON IRRADIATION

    Directory of Open Access Journals (Sweden)

    V. S. Brunov

    2014-05-01

    Full Text Available Experimental research results of silicate glass surface layers modification by the influence of electron beams with 5-50 keV energies and 20-50 mC/cm2 doses are presented. It is shown that during the glasses exposure to an electron beam with 20-50 keV electron energies, a gradient optical waveguide with increased refractive index on waveguide axis Δn = 0.01-0.04 is formed in the surface layer. Сhemical etching rate is increased in the exposed area by up to two times which is related to glass grid destruction. Depending on irradiation dose thin film or silver nanoparticles with the size less than 20nm are formed on the surface of the silver containing glasses for electron energies less than 10 keV. Silver films drawn on the surface of the glass are dissolved into the glass bulk for electron energies 20-50 keV and 20-50 mC/cm2 dose. Basic mechanisms causing these effects are: chemical bonds breaking of spatial glass grid by high energy electrons, formation of negative volume charge inside the glass and field migration of positive metal ions into the volume charge region. Achieved results can be used in photonics, integral optics and nanoplasmonics device fabrication.

  15. Surface and Core Electronic Structure of Oxidized Silicon Nanocrystals

    Directory of Open Access Journals (Sweden)

    Noor A. Nama

    2010-01-01

    Full Text Available Ab initio restricted Hartree-Fock method within the framework of large unit cell formalism is used to simulate silicon nanocrystals between 216 and 1000 atoms (1.6–2.65 nm in diameter that include Bravais and primitive cell multiples. The investigated properties include core and oxidized surface properties. Results revealed that electronic properties converge to some limit as the size of the nanocrystal increases. Increasing the size of the core of a nanocrystal resulted in an increase of the energy gap, valence band width, and cohesive energy. The lattice constant of the core and oxidized surface parts shows a decreasing trend as the nanocrystal increases in a size that converges to 5.28 Ǻ in a good agreement with the experiment. Surface and core convergence to the same lattice constant reflects good adherence of oxide layer at the surface. The core density of states shows highly degenerate states that split at the oxygenated (001-(1×1 surface due to symmetry breaking. The nanocrystal surface shows smaller gap and higher valence and conduction bands when compared to the core part, due to oxygen surface atoms and reduced structural symmetry. The smaller surface energy gap shows that energy gap of the nanocrystal is controlled by the surface part. Unlike the core part, the surface part shows a descending energy gap that proves its obedience to quantum confinement effects. Nanocrystal geometry proved to have some influence on all electronic properties including the energy gap.

  16. X2000 power system electronics development

    Science.gov (United States)

    Carr, Greg; Deligiannis, Frank; Franco, Lauro; Jones, Loren; Lam, Barbara; Nelson, Ron; Pantaleon, Jose; Ruiz, Ian; Treichler, John; Wester, Gene; Sauers, Jim; Giampoli, Paul; Haskell, Russ; Mulvey, Jim; Repp, John

    2005-01-01

    The X2000 Power System Electronics (PSE) is a Jet Propulsion Laboratory (JPL) task to develop a new generation of power system building blocks for potential use on future deep space missions. The effort includes the development of electronic components and modules that can be used as building blocks in the design of generic spacecraft power systems.

  17. Survey of Electronic Payment Methods and Systems

    NARCIS (Netherlands)

    Havinga, Paul J.M.; Smit, Gerard J.M.; Helme, Arne

    1996-01-01

    In this paper an overview of electronic payment methods and systems is given. This survey is done as part of the Moby Dick project. Electronic payment systems can be grouped into three broad classes: traditional money transactions, digital currency and creditdebit payments. Such payment systems have

  18. Electronic Noses for Composites Surface Contamination Detection in Aerospace Industry.

    Science.gov (United States)

    Vito, Saverio De; Miglietta, Maria Lucia; Massera, Ettore; Fattoruso, Grazia; Formisano, Fabrizio; Polichetti, Tiziana; Salvato, Maria; Alfano, Brigida; Esposito, Elena; Francia, Girolamo Di

    2017-04-02

    The full exploitation of Composite Fiber Reinforced Polymers (CFRP) in so-called green aircrafts design is still limited by the lack of adequate quality assurance procedures for checking the adhesive bonding assembly, especially in load-critical primary structures. In this respect, contamination of the CFRP panel surface is of significant concern since it may severely affect the bonding and the mechanical properties of the joint. During the last years, the authors have developed and tested an electronic nose as a non-destructive tool for pre-bonding surface inspection for contaminants detection, identification and quantification. Several sensors and sampling architectures have been screened in view of the high Technology Readiness Level (TRL) scenarios requirements. Ad-hoc pattern recognition systems have also been devised to ensure a fast and reliable assessment of the contamination status, by combining real time classifiers and the implementation of a suitable rejection option. Results show that e-noses could be used as first line low cost Non Destructive Test (NDT) tool in aerospace CFRP assembly and maintenance scenarios.

  19. Electronic and electrochemical doping of graphene by surface adsorbates

    Directory of Open Access Journals (Sweden)

    Hugo Pinto

    2014-10-01

    Full Text Available Many potential applications of graphene require its precise and controllable doping with charge carriers. Being a two-dimensional material graphene is extremely sensitive to surface adsorbates, so its electronic properties can be effectively modified by deposition of different atoms and molecules. In this paper, we review two mechanisms of graphene doping by surface adsorbates, namely electronic and electrochemical doping. Although, electronic doping has been extensively studied and discussed in the literature, much less attention has been paid to electrochemical doping. This mechanism can, however, explain the doping of graphene by adsorbates for which no charge transfer is expected within the electronic doping model. In addition, electrochemical doping is in the origin of the hysteresis effects often observed in graphene-based field effect transistors when operating in the atmospheric environment.

  20. Mobile surface water filtration system

    Directory of Open Access Journals (Sweden)

    Aashish Vatsyayan

    2012-09-01

    Full Text Available To design a mobile system for surface water filtrationMethodology: the filtration of surface impurities begins with their retraction to concentrated thickness using non ionising surfactants, then isolation using surface tension property and sedimentation of impurities in process chamber using electrocoagulation. Result:following studies done to determine the rate of spreading of crude oil on water a method for retraction of spread crude oil to concentrated volumes is developed involving addition of non -ionising surfactants in contrast to use of dispersants. Electrocoagulation process involves multiple processes taking place to lead to depositionof impurities such as oil, grease, metals. Studies of experiments conducted reveals parameters necessary for design of electrocoagulation process chamber though a holistic approach towards system designing is still required. Propeller theory is used in determining the required design of propeller and the desired thrust, the overall structure will finally contribute in deciding the choice of propeller.

  1. Multipurpose Platform for Electronic Currency System

    Directory of Open Access Journals (Sweden)

    Andreea Magdalena Dae

    2014-12-01

    Full Text Available Nowadays, there are multiple solutions for exchanging electronic currencies which will most probably replace physical money. This paper presents a platform for electronic currency system implemented within a Java smart card for accessing different types of products or services. The user interacts with an “electronic currency bank” and with a merchant through a secure protocol.

  2. Electronic Official Personnel Folder System

    Data.gov (United States)

    US Agency for International Development — The eOPF is a digital recreation of paper personnel folder that stores electronic personnel data spanning an individual's Federal career. eOPF allows employees to...

  3. Multifunctionalized cantilever systems for electronic nose applications.

    Science.gov (United States)

    Yoo, Yong Kyoung; Chae, Myung-Sic; Kang, Ji Yoon; Kim, Tae Song; Hwang, Kyo Seon; Lee, Jeong Hoon

    2012-10-02

    Multiple target detection using a cantilever is essential for biosensor, chemical sensor, and electronic nose systems. We report a novel microcantilever array chip that includes four microreaction chambers in a chip, which consequently contains four different functionalized surfaces for multitarget detection. For model tests, we designed microcantilever chips and demonstrated the ability of binding of 2,4-dinitrotoluene (DNT) targets onto four different surfaces. We used peptide receptors that are known to have highly selective binding. By simply using four microreaction chambers, we immobilized DNT specific peptide (HPNFSKYILHQRC; SP), DNT nonspecific peptide (TSMLLMSPKHQAC; NSP), and self-assembled monolayer (SAM) as well as a bare cantilever. After flowing DNT gases through the cantilever chip, we could monitor the four different binding signals simultaneously. The shifts in NSP provided information as a negative control because it contained information of temperature fluctuations and mechanical vibration from gas flow. By utilizing the differential signal of the SP and NSP, we acquired 7.5 Hz in resonant responses that corresponds with 160 part per billion (ppb) DNT concentration, showing the exact binding response by eliminating the inevitable thermal noise, vibration noise, as well as humidity effects on the peptide surface.

  4. Surface band-gap narrowing in quantized electron accumulation layers.

    Science.gov (United States)

    King, P D C; Veal, T D; McConville, C F; Zúñiga-Pérez, J; Muñoz-Sanjosé, V; Hopkinson, M; Rienks, E D L; Jensen, M Fuglsang; Hofmann, Ph

    2010-06-25

    An energy gap between the valence and the conduction band is the defining property of a semiconductor, and the gap size plays a crucial role in the design of semiconductor devices. We show that the presence of a two-dimensional electron gas near to the surface of a semiconductor can significantly alter the size of its band gap through many-body effects caused by its high electron density, resulting in a surface band gap that is much smaller than that in the bulk. Apart from reconciling a number of disparate previous experimental findings, the results suggest an entirely new route to spatially inhomogeneous band-gap engineering.

  5. Weissenberg reflection high-energy electron diffraction for surface crystallography.

    Science.gov (United States)

    Abukawa, Tadashi; Yamazaki, Tomoyuki; Yajima, Kentaro; Yoshimura, Koji

    2006-12-15

    The principle of a Weissenberg camera is applied to surface crystallographic analysis by reflection high-energy electron diffraction. By removing inelastic electrons and measuring hundreds of patterns as a function of sample rotation angle phi, kinematical analysis can be performed over a large volume of reciprocal space. The data set is equivalent to a three-dimensional stack of Weissenberg photographs. The method is applied to analysis of an Si(111)-square root of 3 x square root of 3-Ag surface, and the structural data obtained are in excellent agreement with the known atomic structure.

  6. A simple electron-beam lithography system

    DEFF Research Database (Denmark)

    Mølhave, Kristian; Madsen, Dorte Nørgaard; Bøggild, Peter

    2005-01-01

    A large number of applications of electron-beam lithography (EBL) systems in nanotechnology have been demonstrated in recent years. In this paper we present a simple and general-purpose EBL system constructed by insertion of an electrostatic deflector plate system at the electron-beam exit...... of the column of a scanning electron microscope (SEM). The system can easily be mounted on most standard SEM systems. The tested setup allows an area of up to about 50 x 50 pm to be scanned, if the upper limit for acceptable reduction of the SEM resolution is set to 10 run. We demonstrate how the EBL system can...

  7. Ab-initio tensorial electronic friction for molecules on metal surfaces: nonadiabatic vibrational relaxation

    CERN Document Server

    Maurer, Reinhard J; Batista, Victor S; Tully, John C

    2016-01-01

    Molecular adsorbates on metal surfaces exchange energy with substrate phonons and low-lying electron-hole pair excitations. In the limit of weak coupling, electron-hole pair excitations can be seen as exerting frictional forces on adsorbates that enhance energy transfer and facilitate vibrational relaxation or hot-electron mediated chemistry. We have recently reported on the relevance of tensorial properties of electronic friction [Phys. Rev. Lett. 116, 217601 (2016)] in dynamics at surfaces. Here we present the underlying implementation of tensorial electronic friction based on Kohn-Sham Density Functional Theory for condensed phase and cluster systems. Using local atomic-orbital basis sets, we calculate nonadiabatic coupling matrix elements and evaluate the full electronic friction tensor in the classical limit. Our approach is numerically stable and robust as shown by a detailed convergence analysis. We furthermore benchmark the accuracy of our approach by calculation of vibrational relaxation rates and li...

  8. Features of Ion-Electronic Emission from Surface of Semiconductors

    Directory of Open Access Journals (Sweden)

    A. Kurochka

    2013-12-01

    Full Text Available The results of the research value of the current of the secondary electrons in the ion-beam etching of various semiconductors. Shows the setup and electrical circuit of the experiment. An experimental study to determine the dependence of the current of the secondary electrons from the band gap Eg and the height of the potential barrier (electron affinity eχ. It is shown that in the conditions of ion-beam etching of the semiconductor is the penetration of the electric field, which leads to a shift of the energy levels of electrons in the surface layer. Found that the ion-electronic signal emission silicon n-type is higher than the p-type silicon.

  9. Electron Scattering at Surfaces and Interfaces of Transition Metals

    Science.gov (United States)

    Zheng, Pengyuan

    The effect of surfaces on the electron transport at reduced scales is attracting continuous interest due to its broad impact on both the understanding of materials properties and their application for nanoelectronics. The size dependence of for conductor's electrical resistivity rho due to electron surface scattering is most commonly described within the framework of Fuchs and Sondheimer (FS) and their various extensions, which uses a phenomenological scattering parameter p to define the probability of electrons being elastically (i.e. specularly) scattered by the surface without causing an increase of rho at reduced size. However, a basic understanding of what surface chemistry and structure parameters determine the specularity p is still lacking. In addition, the assumption of a spherical Fermi surface in the FS model is too simple for transition metals to give accurate account of the actual surface scattering effect. The goal of this study is to develop an understanding of the physics governing electron surface/interface scattering in transition metals and to study the significance of their Fermi surface shape on surface scattering. The advancement of the scientific knowledge in electron surface and interface scattering of transition metals can provide insights into how to design high-conductivity nanowires that will facilitate the viable development of advanced integrated circuits, thermoelectric power generation and spintronics. Sequential in situ and ex situ transport measurements as a function of surface chemistry demonstrate that electron surface/interface scattering can be engineered by surface doping, causing a decrease in the rho. For instance, the rho of 9.3-nm-thick epitaxial and polycrystalline Cu is reduced by 11--13% when coated with 0.75 nm Ni. This is due to electron surface scattering which exhibits a specularity p = 0.7 for the Cu-vacuum interface that transitions to completely diffuse (p = 0) when exposed to air. In contrast, Ni-coated surfaces

  10. Surface modification of pure titanium by pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.D. [Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Laboratoired' Etude des Microstructures et de Mecanique des Materiaux (LEM3), CNRS UMR 7239, Universite Paul Verlaine - Metz, Ile du Saulcy, 57045 Metz (France); Hao, S.Z., E-mail: ebeam@dlut.edu.cn [Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Li, X.N. [Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Dong, C., E-mail: dong@dlut.edu.cn [Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Grosdidier, T., E-mail: Thierry.grosdidier@univ-metz.fr [Laboratoired' Etude des Microstructures et de Mecanique des Materiaux (LEM3), CNRS UMR 7239, Universite Paul Verlaine - Metz, Ile du Saulcy, 57045 Metz (France)

    2011-04-15

    The microstructure, hardness and corrosion resistance of commercially pure Ti treated by low energy high current pulsed electron beam (LEHCPEB) have been investigated. The thin near-surface melted layer rapidly solidified into {beta} and subsequently transformed into ultrafine {alpha}' martensite. This has led to a drastic improvement of the corrosion properties and a significant increase (more than 60%) in hardness of the top surface.

  11. Positron studies of surfaces, structure and electronic properties of nanocrystals

    OpenAIRE

    Eijt, S. W. H.; Barbiellini, B.; Houtepen, A.J.; Vanmaekelbergh, D.; Mijnarends, P. E.; Bansil, A.

    2007-01-01

    A brief review is given of recent positron studies of metal and semiconductor nanocrystals. The prospects offered by positron annihilation as a sensitive method to access nanocrystal (NC) properties are described and compared with other experimental methods. The tunability of the electronic structure of nanocrystals underlies their great potential for application in many areas. Owing to their large surface-to-volume ratio, the surfaces and interfaces of NCs play a crucial role in determining ...

  12. Electron density and electron temperature measurements in nanosecond pulse discharges over liquid water surface

    Science.gov (United States)

    Simeni Simeni, M.; Roettgen, A.; Petrishchev, V.; Frederickson, K.; Adamovich, I. V.

    2016-12-01

    Time-resolved electron density, electron temperature, and gas temperature in nanosecond pulse discharges in helium and O2-He mixtures near liquid water surface are measured using Thomson/pure rotational Raman scattering, in two different geometries, (a) ‘diffuse filament’ discharge between a spherical high-voltage electrode and a grounded pin electrode placed in a reservoir filled with distilled water, with the tip exposed, and (b) dielectric barrier discharge between the high-voltage electrode and the liquid water surface. A diffuse plasma filament generated between the electrodes in helium during the primary discharge pulse exhibits noticeable constriction during the secondary discharge pulse several hundred ns later. Adding oxygen to the mixture reduces the plasma filament diameter and enhances constriction during the secondary pulse. In the dielectric barrier discharge, diffuse volumetric plasma occupies nearly the entire space between the high voltage electrode and the liquid surface, and extends radially along the surface. In the filament discharge in helium, adding water to the container results in considerable reduction of plasma lifetime compared to the discharge in dry helium, by about an order of magnitude, indicating rapid electron recombination with water cluster ions. Peak electron density during the pulse is also reduced, by about a factor of two, likely due to dissociative attachment to water vapor during the discharge pulse. These trends become more pronounced as oxygen is added to the mixture, which increases net rate of dissociative attachment. Gas temperature during the primary discharge pulse remains near room temperature, after which it increases up to T ~ 500 K over 5 µs and decays back to near room temperature before the next discharge pulse several tens of ms later. As expected, electron density and electron temperature in diffuse DBD plasmas are considerably lower compared to peak values in the filament discharge. Use of Thomson

  13. Multielectron bubbles in helium as a paradigm for studying electrons on surfaces with curvature

    Energy Technology Data Exchange (ETDEWEB)

    Tempere, J. [Lyman Laboratory of Physics, Harvard University, Cambridge MA 02138 (United States); TFVS, Universiteit Antwerpen, Groenenborgerlaan 171, B2020 Antwerpen (Belgium); Silvera, I.F. [Lyman Laboratory of Physics, Harvard University, Cambridge MA 02138 (United States); Devreese, J.T. [TFVS, Universiteit Antwerpen, Groenenborgerlaan 171, B2020 Antwerpen (Belgium)

    2007-05-31

    The study of two-dimensional electronic systems has revealed a host of new and startling phenomena, such as the quantum Hall effect. Although effort has gone into studying the effects of confinement in two-dimensional systems, the effects of surface curvature remain relatively unexplored. Nevertheless, curvature and surface topology are expected to have a profound influence: for example, on a sphere it is not possible to have a non-trivial current field that has no vortex structure in it. The spherical geometry also influences lattices in that topological lattice defects are always present. In this report, we present results and recent insights into the physics of electrons on spherical surfaces. In particular, we investigate the case of multielectron bubbles. Multielectron bubbles are (micron sized) cavities inside liquid helium, containing electrons that collect in a nanometer thin film on the surface of the bubble and form a spherical two-dimensional electronic system. Different phases are identified and investigated: the electron fluid, the Wigner lattice, and the pair-correlated 'superconducting' state. Uniaxial external magnetic fields (normal to the surface at the poles of the sphere, and tangential to the surface at the equator) influence the different phases and give rise to textures on the surface. In discussing the properties of the spherical electron system under various conditions, we identify the differences between flat surfaces and spherical surfaces. The theoretical framework presented here is focused on the case of electrons on the spherical surface of a bubble in helium. We discuss how the theory can straightforwardly be generalized to investigate the case of (finite thickness) metallic nanoshells. Nanoshells consist of a non-conducting nanograin covered by a few atomic layers of metal. The physiologically compatible size and unique optical properties of these objects have led to applications in diagnostics and directed therapeutics of

  14. Multielectron bubbles in helium as a paradigm for studying electrons on surfaces with curvature

    Science.gov (United States)

    Tempere, J.; Silvera, I. F.; Devreese, J. T.

    2007-05-01

    The study of two-dimensional electronic systems has revealed a host of new and startling phenomena, such as the quantum Hall effect. Although effort has gone into studying the effects of confinement in two-dimensional systems, the effects of surface curvature remain relatively unexplored. Nevertheless, curvature and surface topology are expected to have a profound influence: for example, on a sphere it is not possible to have a non-trivial current field that has no vortex structure in it. The spherical geometry also influences lattices in that topological lattice defects are always present. In this report, we present results and recent insights into the physics of electrons on spherical surfaces. In particular, we investigate the case of multielectron bubbles. Multielectron bubbles are (micron sized) cavities inside liquid helium, containing electrons that collect in a nanometer thin film on the surface of the bubble and form a spherical two-dimensional electronic system. Different phases are identified and investigated: the electron fluid, the Wigner lattice, and the pair-correlated "superconducting" state. Uniaxial external magnetic fields (normal to the surface at the poles of the sphere, and tangential to the surface at the equator) influence the different phases and give rise to textures on the surface. In discussing the properties of the spherical electron system under various conditions, we identify the differences between flat surfaces and spherical surfaces. The theoretical framework presented here is focused on the case of electrons on the spherical surface of a bubble in helium. We discuss how the theory can straightforwardly be generalized to investigate the case of (finite thickness) metallic nanoshells. Nanoshells consist of a non-conducting nanograin covered by a few atomic layers of metal. The physiologically compatible size and unique optical properties of these objects have led to applications in diagnostics and directed therapeutics of cancer and

  15. Observation of Hot Electrons in Surface-Wave Plasmas Excited by Surface Plasmon Polaritons

    Institute of Scientific and Technical Information of China (English)

    HU Ye-Lin; CHEN Zhao-Quan; LIU Ming-Hai; HONG Ling-Li; LI Ping; ZHENG Xiao-Liang; XIA Guang-Qing; HU Xi-Wei

    2011-01-01

    The electron energy distribution functions (EEDFs) are studied in the planar-type surface-wave plasma (SWP)caused by resonant excitation of surface plasmon polaritons (SPPs) using a single cylindrical probe.Sustained plasma characteristics can be considered as a bi-Maxwellian EEDF,which correspond to a superposition of the bulk low-temperature electron and the high-energy electron beam-like part.The beam component energy is pronounced at about 10eV but the bulk part is lower than 3.5eV.The hot electrons included in the proposed plasmas play a significant role in plasma heating and further affect the discharge chemistry.During the past several years,in the fabrication ofamorphous or crystalline silicon films,diamond film synthesis and carbon nanotube growth,the large-area overdense plasma source has been useful.In electronic device fabrication techniques such as etching,ashing or plasma chemical vapor deposition,overdense electrons and radicals are required,especially hot electrons.Among the various plasma devices,the planar-type surface-wave plasma (SWP) source is an advanced plasma source,which is a type of promising plasma source satisfying the above rigorous requirements for large-area plasma processing.%The electron energy distribution functions (EEDFs) are studied in the planar-type surface-wave plasma (SWP) caused by resonant excitation of surface plasmon polaritons (SPPs) using a single cylindrical probe. Sustained plasma characteristics can be considered as a bi-Maxwellian EEDF, which correspond to a superposition of the bulk low-temperature electron and the high-energy electron beam-like part. The beam component energy is pronounced at about 10 eV but the bulk part is lower than 3.5 eV. The hot electrons included in the proposed plasmas play a significant role in plasma heating and further affect the discharge chemistry.

  16. Reliability of power electronic converter systems

    CERN Document Server

    Chung, Henry Shu-hung; Blaabjerg, Frede; Pecht, Michael

    2016-01-01

    This book outlines current research into the scientific modeling, experimentation, and remedial measures for advancing the reliability, availability, system robustness, and maintainability of Power Electronic Converter Systems (PECS) at different levels of complexity.

  17. High perveance electron gun for the electron cooling system

    CERN Document Server

    Korotaev, Yu V; Petrov, A; Sidorin, A; Smirnov, A; Syresin, E M; Titkova, I

    2000-01-01

    The cooling time in the electron cooling system is inversely proportional to the beam current. To obtain high current of the electron beam the control electrode of the gun is provided with a positive potential and an electrostatic trap for secondary electrons appears inside the electron gun. This leads to a decrease in the gun perveance. To avoid this problem, the adiabatic high perveance electron gun with the clearing control electrode is designed in JINR (J. Bosser, Y. Korotaev, I. Meshkov, E. Syresin et al., Nucl. Instr. and Meth. A 391 (1996) 103. Yu. Korotaev, I. Meshkov, A. Sidorin, A. Smirnov, E. Syresin, The generation of electron beams with perveance of 3-6 mu A/V sup 3 sup / sup 2 , Proceedings of SCHEF'99). The clearing control electrode has a transverse electric field, which clears secondary electrons. Computer simulations of the potential map were made with RELAX3D computer code (C.J. Kost, F.W. Jones, RELAX3D User's Guide and References Manual).

  18. Anonymity control in electronic check systems

    Institute of Scientific and Technical Information of China (English)

    Ma Chunguang; Yang Yixian; Hu Zhengming

    2005-01-01

    Electronic check systems, as one of electronic payment systems, are more desirable than other electronic cash systems. In the system, only a single check is used to pay any price that is not more than the face value. The main problem in check systems is to design an efficient refund mechanism that makes refund checks undistinguished from initial checks during payment and deposit. The problem of anonymity control also called fairness is also an important issue in check systems. All check systems yet are unconditional anonymity that opens the door to misuse for crime such as laundering and blackmailing. In this paper, the notion of anonymity revocation is introduced to electronic check system for the first time, and a model of fair electronic check system is proposed. An efficient fair online electronic check system with reusable refund is presented. In the system, a passive trustee is employed to revoke the anonymity of un-honest users. Moreover, the system solves the reusability problem of refunds thanks to the RSA-based partially signature. The system is efficient and meets all basic security requirements.

  19. Peptide-functionalized semiconductor surfaces: strong surface electronic effects from minor alterations to backbone composition.

    Science.gov (United States)

    Matmor, Maayan; Lengyel, George A; Horne, W Seth; Ashkenasy, Nurit

    2017-02-22

    The use of non-canonical amino acids is a powerful way to control protein structure. Here, we show that subtle changes to backbone composition affect the ability of a dipeptide to modify solid surface electronic properties. The extreme sensitivity of the interactions to the peptide structure suggests potential applications in improving the performance of electronic devices.

  20. Extremely confined gap surface-plasmon modes excited by electrons

    DEFF Research Database (Denmark)

    Raza, Søren; Stenger, Nicolas; Pors, Anders Lambertus

    2014-01-01

    High-spatial and energy resolution electron energy-loss spectroscopy (EELS) can be used for detailed characterization of localized and propagating surface-plasmon excitations in metal nanostructures, giving insight into fundamental physical phenomena and various plasmonic effects. Here, applying...

  1. A micromachined surface stress sensor with electronic readout

    NARCIS (Netherlands)

    Carlen, E.T.; Weinberg, M.S.; Zapata, A.M.; Borenstein, J.T.

    2008-01-01

    A micromachined surface stress sensor has been fabricated and integrated off chip with a low-noise, differential capacitance, electronic readout circuit. The differential capacitance signal is modulated with a high frequency carrier signal, and the output signal is synchronously demodulated and filt

  2. Nonlinear identification of power electronic systems

    OpenAIRE

    Chau, KT; Chan, CC

    1995-01-01

    This paper presents a new approach to modelling power electronic systems using nonlinear system identification. By employing the nonlinear autoregressive moving average with exogenous input (NARMAX) technique, the parametric model of power electronic systems can be derived from the time-domain data. This approach possesses some advantages over available circuit-oriented modelling approaches, such as no small-signal approximation, no circuit idealization and no detailed knowledge of system ope...

  3. Electron capture by highly charged ions from surfaces and gases

    Energy Technology Data Exchange (ETDEWEB)

    Allen, F.

    2008-01-11

    In this study highly charged ions produced in Electron Beam Ion Traps are used to investigate electron capture from surfaces and gases. The experiments with gas targets focus on spectroscopic measurements of the K-shell x-rays emitted at the end of radiative cascades following electron capture into Rydberg states of Ar{sup 17+} and Ar{sup 18+} ions as a function of collision energy. The ions are extracted from an Electron Beam Ion Trap at an energy of 2 keVu{sup -1}, charge-selected and then decelerated down to 5 eVu{sup -1} for interaction with an argon gas target. For decreasing collision energies a shift to electron capture into low orbital angular momentum capture states is observed. Comparative measurements of the K-shell x-ray emission following electron capture by Ar{sup 17+} and Ar{sup 18+} ions from background gas in the trap are made and a discrepancy in the results compared with those from the extraction experiments is found. Possible explanations are discussed. For the investigation of electron capture from surfaces, highly charged ions are extracted from an Electron Beam Ion Trap at energies of 2 to 3 keVu{sup -1}, charge-selected and directed onto targets comprising arrays of nanoscale apertures in silicon nitride membranes. The highly charged ions implemented are Ar{sup 16+} and Xe{sup 44+} and the aperture targets are formed by focused ion beam drilling in combination with ion beam assisted thin film deposition, achieving hole diameters of 50 to 300 nm and aspect ratios of 1:5 to 3:2. After transport through the nanoscale apertures the ions pass through an electrostatic charge state analyzer and are detected. The percentage of electron capture from the aperture walls is found to be much lower than model predictions and the results are discussed in terms of a capillary guiding mechanism. (orig.)

  4. Microscopic theory of electron absorption by plasma-facing surfaces

    Science.gov (United States)

    Bronold, F. X.; Fehske, H.

    2017-01-01

    We describe a method for calculating the probability with which the wall of a plasma absorbs an electron at low energy. The method, based on an invariant embedding principle, expresses the electron absorption probability as the probability for transmission through the wall’s long-range surface potential times the probability to stay inside the wall despite of internal backscattering. To illustrate the approach we apply it to a SiO2 surface. Besides emission of optical phonons inside the wall we take elastic scattering at imperfections of the plasma-wall interface into account and obtain absorption probabilities significantly less than unity in accordance with available electron-beam scattering data but in disagreement with the widely used perfect absorber model.

  5. Studies on electronic structure of GaN(0001) surface

    CERN Document Server

    Xie Chang Kun; Xu Fa Qiang; Deng Rui; Liu Feng; Yibulaxin, K

    2002-01-01

    An electronic structure investigation on GaN(0001) is reported. The authors employ a full-potential linearized augmented plane-wave (FPLAPW) approach to calculate the partial density of state, which is in agreement with previous experimental results. The effects of the Ga3d semi-core levels on the electronic structure of GaN are discussed. The valence-electronic structure of the wurtzite GaN(0001) surface is investigated using synchrotron radiation excited angle-resolved photoemission spectroscopy. The bulk bands dispersion along GAMMA A direction in the Brillouin zones is measured using normal-emission spectra by changing photon-energy. The band structure derived from authors' experimental data is compared well with the results of authors' FPLAPW calculation. Furthermore, off-normal emission spectra are also measured along the GAMMA K and GAMMA M directions. Two surface states are identified, and their dispersions are characterized

  6. Microscopic theory of electron absorption by plasma-facing surfaces

    CERN Document Server

    Bronold, Franz X

    2016-01-01

    We describe a method for calculating the probability with which the wall of a plasma absorbs an electron at low energy. The method, based on an invariant embedding principle, expresses the electron absorption probability as the probability for transmission through the wall's long-range surface potential times the probability to stay inside the wall despite of internal backscattering. To illustrate the approach we apply it to a \\SiOTwo\\ surface. Besides emission of optical phonons inside the wall we take elastic scattering at imperfections of the plasma-wall interface into account and obtain absorption probabilities significantly less than unity in accordance with available electron-beam scattering data but in disagreement with the widely used perfect absorber model.

  7. The Helium Field Effect Transistor (I): Storing Surface State Electrons on Helium Films

    Science.gov (United States)

    Ashari, M.; Rees, D. G.; Kono, K.; Scheer, E.; Leiderer, P.

    2012-04-01

    We present investigations of surface state electrons on liquid helium films in confined geometry, using a suitable substrate structure microfabricated on a silicon wafer, similar to a Field Effect Transistor (FET). The sample has a source and drain region, separated by a gate structure, which consists of two gold electrodes with a narrow gap (channel) through which the transport of the surface state electrons takes place. The sample is illuminated to provide a sufficient number of free carriers in the silicon substrate, such that a well-defined potential distribution is achieved. The eventual goal of these experiments is to study the electron transport through a narrow channel in the various states of the phase diagram of the 2D electron system. In the present work we focus on storing the electrons in the source area of the FET, and investigate the spatial distribution of these electrons. It is shown that under the influence of a potential gradient in the silicon substrate the electrons accumulate in front of the potential barrier of the gate. The electron distribution, governed by Coulomb repulsion and by the substrate potential, is determined experimentally. The result is found to be in good agreement with a parallel-plate capacitor model of the system, developed with the aid of a finite element calculation of the surface potential profile of the device.

  8. Calculation of surface dose in rotational total skin electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pla, C.; Heese, R.; Pla, M.; Podgorsak, E.B.

    1984-07-01

    A single-field rotational total skin electron irradiation technique has recently been developed at the McGill University for treatment of skin malignancies. The dose received by a given surface point during rotation in a uniform large electron field depends on the radius of rotation of the surface point, on the local radius of curvature of the contour in the vicinity of the point of interest, and on the shadows cast by limbs (arms upon trunk or head and neck, and legs upon each other). A method for calculating the surface dose distribution on a patient is presented accounting for the various parameters affecting the dose. A series of measurements were performed with polystyrene and a humanoid phantom, and an excellent agreement between measured and calculated dose distributions was obtained.

  9. Secondary electron yield of Cu technical surfaces: Dependence on electron irradiation

    Science.gov (United States)

    Larciprete, R.; Grosso, D. R.; Commisso, M.; Flammini, R.; Cimino, R.

    2013-01-01

    The secondary emission yield (SEY) properties of colaminated Cu samples for LHC beam screens are correlated to the surface chemical composition determined by x-ray photoelectron spectroscopy. The surface of the as-received samples is characterized by the presence of significant quantities of contaminating adsorbates and by the maximum of the SEY curve (δmax⁡) being as high as 2.1. After extended electron scrubbing at kinetic energy of 10 and 500 eV, the δmax⁡ value drops to the ultimate values of 1.35 and 1.1, respectively. In both cases the surface oxidized phases are significantly reduced, whereas only in the sample scrubbed at 500 eV the formation of a graphitic-like C layer is observed. We find that the electron scrubbing of technical Cu surfaces can be described as occurring in two steps: the first step consists in the electron-induced desorption of weakly bound contaminants that occurs indifferently at 10 and at 500 eV and corresponds to a partial decrease of δmax⁡; the second step, activated by more energetic electrons and becoming evident at high doses, increases the number of graphitic-like C-C bonds via the dissociation of adsorbates already contaminating the as-received surface or accumulating on this surface during irradiation. Our results demonstrate how the kinetic energy of impinging electrons is a crucial parameter when conditioning the surfaces of Cu and other metals by means of electron-induced chemical processing.

  10. SiGe Based Low Temperature Electronics for Lunar Surface Applications

    Science.gov (United States)

    Mojarradi, Mohammad M.; Kolawa, Elizabeth; Blalock, Benjamin; Cressler, John

    2012-01-01

    The temperature at the permanently shadowed regions of the moon's surface is approximately -240 C. Other areas of the lunar surface experience temperatures that vary between 120 C and -180 C during the day and night respectively. To protect against the large temperature variations of the moon surface, traditional electronics used in lunar robotics systems are placed inside a thermally controlled housing which is bulky, consumes power and adds complexity to the integration and test. SiGe Based electronics have the capability to operate over wide temperature range like that of the lunar surface. Deploying low temperature SiGe electronics in a lander platform can minimize the need for the central thermal protection system and enable the development of a new generation of landers and mobility platforms with highly efficient distributed architecture. For the past five years a team consisting of NASA, university and industry researchers has been examining the low temperature and wide temperature characteristic of SiGe based transistors for developing electronics for wide temperature needs of NASA environments such as the Moon, Titan, Mars and Europa. This presentation reports on the status of the development of wide temperature SiGe based electronics for the landers and lunar surface mobility systems.

  11. Surface topology and electronic structure of layered strontium ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Bienert, Robert; Klinke, Melanie; Waelsch, Michael; Mietke, Sebastian; Matzdorf, Rene [Experimentalphysik II, Universitaet Kassel (Germany); Peng, Jin; Mao, Zhiqiang [Department of Physics, Tulane University, New Orleans (United States)

    2012-07-01

    In complex materials the interplay of properties like crystal structure, electronic structure and magnetism results in very interesting physical phenomena. The Ruddlesden-Popper series of layered Strontium Ruthenates Sr{sub n+1}Ru{sub n}O{sub 3n+1} describes one class of these materials. The double and triple layer systems behave like a Fermi liquid up to the transition temperature of 15 K and 24 K, respectively. In both compounds the local density of states (LDOS) shows a peak within the dip-like feature around the Fermi energy E{sub F}. Using low-temperature (LT) STM and STS we studied the temperature dependence of the LDOS in the range from 4.7 to 35 K. By increasing the temperature the peak within the dip in the LDOS at E{sub F} is only affected by thermal broadening. The surface unit cell of the Strontium Ruthenates exhibits a c(2 x 2) super structure, which is stable from 4.7 K up to room temperature as shown by our atomically resolved LT STM images and room temperature LEED experiments.

  12. Visualizing Surface Plasmons with Photons, Photoelectrons, and Electrons

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Abellan Baeza, Patricia; Gong, Yu; Hage, F. S.; Cottom, J.; Joly, Alan G.; Brydson, R.; Ramasse, Q. M.; Hess, Wayne P.

    2016-06-21

    Both photons and electrons may be used to excite surface plasmon polaritons, the collective charge density fluctuations at the surface of metal nanostructures. By virtue of their nanoscopic and dissipative nature, a detailed characterization of surface plasmon (SP) eigenmodes in real space-time ultimately requires joint sub-nanometer spatial and sub-femtosecond temporal resolution. The latter realization has driven significant developments in the past few years, aimed at interrogating both localized and propagating SP modes over the relevant length and time scales. In this mini-review, we briefly highlight different techniques we employ to visualize the enhanced electric fields associated with SPs. Specifically, we discuss recent hyperspectral optical microscopy, tip-enhanced Raman nano-spectroscopy, nonlinear photoemission electron microscopy, as well as correlated scanning transmission electron microscopy-electron energy loss spectroscopy measurements targeting prototypical plasmonic nanostructures and constructs. Through selected practical examples, we examine the information content in multidimensional images recorded by taking advantage of each of the aforementioned techniques. In effect, we illustrate how SPs can be visualized at the ultimate limits of space and time.

  13. An electronic voting system supporting vote weights

    OpenAIRE

    Eliasson, C.; Zúquete, A.

    2006-01-01

    Typically each voter contributes with one vote for an election. But there are some elections where voters can have different weights associated with their vote. In this paper we provide a solution for allowing an arbitrary number of weights and weight values to be used in an electronic voting system. We chose REVS, Robust Electronic Voting System, a voting system designed to support Internet voting processes, as the start point for studying the introduction of vote weights. To the best of our...

  14. 76 FR 9265 - Special Conditions: Gulfstream Model GVI Airplane; Electronic Flight Control System: Control...

    Science.gov (United States)

    2011-02-17

    ... Model GVI Airplane; Electronic Flight Control System: Control Surface Position Awareness AGENCY: Federal... transport category airplanes. These design features include an electronic flight control system. The... The GVI has an electronic flight control system and no direct coupling from the cockpit controller to...

  15. Corrosion Reliability of Electronic Systems

    DEFF Research Database (Denmark)

    Ambat, Rajan; Jensen, Stine G.; Møller, Per

    2008-01-01

    Inherently two factors namely multi-material usage and potential bias makes electronic devices susceptible to corrosion if exposed to humid conditions. The problem is compounded today due to miniaturization and contamination effects. The reduction in size of the components and close spacing...... on a Printed Circuit Board (PCB) for high density packing has greatly increased the risk of corrosion under humid conditions. An important issue is the failures due to electrolytic metal migration. This paper describes an investigation of the electrolytic migration of Sn-Pb solder lines on PCBs in humid...

  16. Electron beam heating effects during environmental scanning electron microscopy imaging of water condensation on superhydrophobic surfaces

    Science.gov (United States)

    Rykaczewski, K.; Scott, J. H. J.; Fedorov, A. G.

    2011-02-01

    Superhydrophobic surfaces (SHSs) show promise as promoters of dropwise condensation. Droplets with diameters below ˜10 μm account for the majority of the heat transferred during dropwise condensation but their growth dynamics on SHS have not been systematically studied. Due to the complex topography of the surface environmental scanning electron microscopy is the preferred method for observing the growth dynamics of droplets in this size regime. By studying electron beam heating effects on condensed water droplets we establish a magnification limit below which the heating effects are negligible and use this insight to study the mechanism of individual drop growth.

  17. Harvesting the loss: surface plasmon-based hot electron photodetection

    Directory of Open Access Journals (Sweden)

    Li Wei

    2016-11-01

    Full Text Available Although the nonradiative decay of surface plasmons was once thought to be only a parasitic process within the plasmonic and metamaterial communities, hot carriers generated from nonradiative plasmon decay offer new opportunities for harnessing absorption loss. Hot carriers can be harnessed for applications ranging from chemical catalysis, photothermal heating, photovoltaics, and photodetection. Here, we present a review on the recent developments concerning photodetection based on hot electrons. The basic principles and recent progress on hot electron photodetectors are summarized. The challenges and potential future directions are also discussed.

  18. Low-energy electron scattering from molecules, biomolecules and surfaces

    CERN Document Server

    Carsky, Petr

    2011-01-01

    Since the turn of the 21st century, the field of electron molecule collisions has undergone a renaissance. The importance of such collisions in applications from radiation chemistry to astrochemistry has flowered, and their role in industrial processes such as plasma technology and lighting are vital to the advancement of next generation devices. Furthermore, the development of the scanning tunneling microscope highlights the role of such collisions in the condensed phase, in surface processing, and in the development of nanotechnology.Low-Energy Electron Scattering from Molecules, Biomolecule

  19. Standardization of surface contamination analysis systems

    Science.gov (United States)

    Boothe, Richard E.

    1995-01-01

    Corrosion products, oils and greases can potentially degrade material bonding properties. The Marshall Space Flight Center (MSFC) Surface Contamination Analysis Team (SCAT) utilizes a variety of analytical equipment to detect identify and quantify contamination on metallic and non-metallic substrates. Analysis techniques include FT-IR Microscopy (FT-IR), Near Infrared Optical Fiber Spectrometry (NIR), Optically Stimulated Electron Emission (OSEE), Ultraviolet Fluorescence (UVF) and Ellipsometry. To insure that consistent qualitative and quantitative information are obtained, standards are required to develop analysis techniques, to establish instrument sensitivity to potential contaminants, and to develop calibration curves. This paper describes techniques for preparing and preserving contamination standards. Calibration of surface contamination analysis systems is discussed, and methods are presented for evaluating the effects of potential contaminants on bonding properties.

  20. Advanced Space Surface Systems Operations

    Science.gov (United States)

    Huffaker, Zachary Lynn; Mueller, Robert P.

    2014-01-01

    The importance of advanced surface systems is becoming increasingly relevant in the modern age of space technology. Specifically, projects pursued by the Granular Mechanics and Regolith Operations (GMRO) Lab are unparalleled in the field of planetary resourcefulness. This internship opportunity involved projects that support properly utilizing natural resources from other celestial bodies. Beginning with the tele-robotic workstation, mechanical upgrades were necessary to consider for specific portions of the workstation consoles and successfully designed in concept. This would provide more means for innovation and creativity concerning advanced robotic operations. Project RASSOR is a regolith excavator robot whose primary objective is to mine, store, and dump regolith efficiently on other planetary surfaces. Mechanical adjustments were made to improve this robot's functionality, although there were some minor system changes left to perform before the opportunity ended. On the topic of excavator robots, the notes taken by the GMRO staff during the 2013 and 2014 Robotic Mining Competitions were effectively organized and analyzed for logistical purposes. Lessons learned from these annual competitions at Kennedy Space Center are greatly influential to the GMRO engineers and roboticists. Another project that GMRO staff support is Project Morpheus. Support for this project included successfully producing mathematical models of the eroded landing pad surface for the vertical testbed vehicle to predict a timeline for pad reparation. And finally, the last project this opportunity made contribution to was Project Neo, a project exterior to GMRO Lab projects, which focuses on rocket propulsion systems. Additions were successfully installed to the support structure of an original vertical testbed rocket engine, thus making progress towards futuristic test firings in which data will be analyzed by students affiliated with Rocket University. Each project will be explained in

  1. Advaced Spatio-Temporal Thermal Analysis of Electronic Systems

    Directory of Open Access Journals (Sweden)

    Miroslav Hrianka

    2003-01-01

    Full Text Available The article gives a brief review the of diagnostics and analysis possibilities by a spatio-temporal approach into electronic system in infrared bandwidth. The two dimensional image grabbed by the thermo vision camera provides information about the surface temperature distribution of an electronic system. The main idea is based on the analysis of the object which consists of a temporal sequence of a spatial thermal images. Advanced analysis is achieved by morphological image gradient spatio-temporal model: The mentioned method provides a total temperature system evaluation as well as it allows separate analysis in the chosen determined temperature area.

  2. Electronic Dental Records System Adoption.

    Science.gov (United States)

    Abramovicz-Finkelsztain, Renata; Barsottini, Claudia G N; Marin, Heimar Fatima

    2015-01-01

    The use of Electronic Dental Records (EDRs) and management software has become more frequent, following the increase in prevelance of new technologies and computers in dental offices. The purpose of this study is to identify and evaluate the use of EDRs by the dental community in the São Paulo city area. A quantitative case study was performed using a survey on the phone. A total of 54 offices were contacted and only one declinedparticipation in this study. Only one office did not have a computer. EDRs were used in 28 offices and only four were paperless. The lack of studies in this area suggests the need for more usability and implementation studies on EDRs so that we can improve EDR adoption by the dental community.

  3. New aspects of electronic excitations at the bismuth surface: Topology, thermalization and coupling to coherent phonons

    Energy Technology Data Exchange (ETDEWEB)

    Perfetti, L., E-mail: luca.perfetti@polytechnique.edu [Laboratoire des Solides Irradiés, Ecole Polytechnique – CEA/DSM – CNRS UMR 7642, 91128 Palaiseau (France); Faure, J. [Laboratoire d’Optique Appliquée, Ecole Polytechnique – ENSTA – CNRS UMR 7639, 91761 Palaiseau (France); Papalazarou, E.; Mauchain, J.; Marsi, M.; Goerbig, M.O. [Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud, F-91405 Orsay (France); Taleb-Ibrahimi, A.; Ohtsubo, Y. [Synchrotron SOLEIL, Saint-Aubin-BP 48, F-91192 Gif sur Yvette (France)

    2015-05-15

    We review measurements of angle and time resolved photoelectron spectroscopy on the surface states of the Bi(1 1 1) surface. The work covers several aspects of these surface states, discussing the topological properties, the strong anisotropy of the spin–orbit splitting and the dynamical relaxation of photoexcited electrons. Since time resolved experiments disentagle interaction processes in real time, the reported data offer a novel perspective on the motion of charge carriers in surface states and will serve as an unuseful reference for other systems with strong spin–orbit coupling.

  4. Characteristics of surface sterilization using electron cyclotron resonance plasma

    Science.gov (United States)

    Yonesu, Akira; Hara, Kazufumi; Nishikawa, Tatsuya; Hayashi, Nobuya

    2016-07-01

    The characteristics of surface sterilization using electron cyclotron resonance (ECR) plasma were investigated. High-energy electrons and oxygen radicals were observed in the ECR zone using electric probe and optical emission spectroscopic methods. A biological indicator (BI), Geobacillus stearothermophilus, containing 1 × 106 spores was sterilized in 120 s by exposure to oxygen discharges while maintaining a temperature of approximately 55 °C at the BI installation position. Oxygen radicals and high-energy electrons were found to be the sterilizing species in the ECR region. It was demonstrated that the ECR plasma could be produced in narrow tubes with an inner diameter of 5 mm. Moreover, sterilization tests confirmed that the spores present inside the narrow tube were successfully inactivated by ECR plasma irradiation.

  5. Direct first-principles simulation of a high-performance electron emitter: Lithium-oxide-coated diamond surface

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Yoshiyuki, E-mail: yoshi-miyamoto@aist.go.jp; Miyazaki, Takehide [Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Takeuchi, Daisuke; Yamasaki, Satoshi [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); JST, ALCA, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2014-09-28

    We examined the field emission properties of lithium(Li)/oxygen(O)-co-terminated diamond (001) surface [C(001)-LiO] through real-time electron dynamics simulation under an applied field. The current emitted from this surface was found to be more than four-fold that emitted by an H-terminated (001) surface, the latter being a typical negative electron affinity system. This high performance is attributed to the Li layer, which bends the potential wall of O-induced electron pockets down in the direction of vacuum, thus facilitating electron emission. Detailed analysis of the emitted electrons and the profile of the self-consistent potential elucidated that the role of O atoms changes from an electron barrier on OH-terminated diamond surfaces to an outlet for electron emission on C(001)-LiO.

  6. Hot electron mediated desorption rates calculated from excited state potential energy surfaces

    CERN Document Server

    Olsen, Thomas; Schiøtz, Jakob

    2008-01-01

    We present a model for Desorption Induce by (Multiple) Electronic Transitions (DIET/DIMET) based on potential energy surfaces calculated with the Delta Self-Consistent Field extension of Density Functional Theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on various transition metal surfaces, and show that classical nuclear dynamics does not suffice for propagation in the excited state. We present a simple Hamiltonian describing the system, with parameters obtained from the excited state potential energy surface, and show that this model can describe desorption dynamics in both the DIET and DIMET regime, and reproduce the power law behavior observed experimentally. We observe that the internal stretch degree of freedom in the molecules is crucial for the energy transfer between the hot electrons and the molecule when the coupling to the surface is strong.

  7. Microscopic theory of the residual surface resistivity of Rashba electrons

    Science.gov (United States)

    Bouaziz, Juba; Lounis, Samir; Blügel, Stefan; Ishida, Hiroshi

    2016-07-01

    A microscopic expression of the residual electrical resistivity tensor is derived in linear response theory for Rashba electrons scattering at a magnetic impurity with cylindrical or noncylindrical potential. The behavior of the longitudinal and transversal residual resistivity is obtained analytically and computed for an Fe impurity at the Au(111) surface. We studied the evolution of the resistivity tensor elements as a function of the Rashba spin-orbit strength and the magnetization direction of the impurity. We found that the absolute values of longitudinal resistivity reduce with increasing spin-orbit strength of the substrate and that the scattering of the conduction electrons at magnetic impurities with magnetic moments pointing in directions not perpendicular to the surface plane produce a planar Hall effect and an anisotropic magnetoresistance even if the impurity carries no spin-orbit interaction. Functional forms are provided describing the anisotropy of the planar Hall effect and the anisotropic magnetoresistance with respect to the direction of the impurity moment. In the limit of no spin-orbit interaction and a nonmagnetic impurity of cylindrical symmetry, the expression of the residual resistivity of a two-dimensional electron gas has the same simplicity and form as for the three-dimensional electron gas [J. Friedel, J. Nuovo. Cim. 7, 287 (1958), 10.1007/BF02751483] and can also be expressed in terms of scattering phase shifts.

  8. Electron acceleration and high harmonic generation by relativistic surface plasmons

    Science.gov (United States)

    Cantono, Giada; Luca Fedeli Team; Andrea Sgattoni Team; Andrea Macchi Team; Tiberio Ceccotti Team

    2016-10-01

    Intense, short laser pulses with ultra-high contrast allow resonant surface plasmons (SPs) excitation on solid wavelength-scale grating targets, opening the way to the extension of Plasmonics in the relativistic regime and the manipulation of intense electromagnetic fields to develop new short, energetic, laser-synchronized radiation sources. Recent theoretical and experimental studies have explored the role of SP excitation in increasing the laser-target coupling and enhancing ion acceleration, high-order harmonic generation and surface electron acceleration. Here we present our results on SP driven electron acceleration from grating targets at ultra-high laser intensities (I = 5 ×1019 W/cm2, τ = 25 fs). When the resonant condition for SP excitation is fulfilled, electrons are emitted in a narrow cone along the target surface, with a total charge of about 100 pC and energy spectra peaked around 5 MeV. Distinguishing features of the resonant process were investigated by varying the incidence angle, grating type and with the support of 3D PIC simulations, which closely reproduced the experimental data. Open challenges and further measurements on high-order harmonic generation in presence of a relativistic SP will also be discussed.

  9. Electronic structure tuning via surface modification in semimetallic nanowires

    Science.gov (United States)

    Sanchez-Soares, Alfonso; O'Donnell, Conor; Greer, James C.

    2016-12-01

    Electronic structure properties of nanowires (NWs) with diameters of 1.5 and 3 nm based on semimetallic α -Sn are investigated by employing density functional theory and perturbative GW methods. We explore the dependence of electron affinity, band structure, and band-gap values with crystallographic orientation, NW cross-sectional size, and surface passivants of varying electronegativity. We consider four chemical terminations in our study: methyl (CH3), hydrogen (H ), hydroxyl (OH ), and fluorine (F ). Results suggest a high degree of elasticity of Sn-Sn bonds within the Sn NWs' cores with no significant structural variations for nanowires with different surface passivants. Direct band gaps at Brillouin-zone centers are found for most studied structures with quasiparticle corrected band-gap magnitudes ranging from 0.25 to 3.54 eV in 1.5-nm-diameter structures, indicating an exceptional range of properties for semimetal NWs below the semimetal-to-semiconductor transition. Band-gap variations induced by changes in surface passivants indicate the possibility of realizing semimetal-semiconductor interfaces in NWs with constant cross-section and crystallographic orientation, allowing the design of novel dopant-free NW-based electronic devices.

  10. Surface cleanliness of fluid systems, specification for

    Science.gov (United States)

    1995-01-01

    This specification establishes surface cleanliness levels, test methods, cleaning and packaging requirements, and protection and inspection procedures for determining surface cleanliness. These surfaces pertain to aerospace parts, components, assemblies, subsystems, and systems in contact with any fluid medium.

  11. Electron emission from MOS electron emitters with clean and cesium covered gold surface

    DEFF Research Database (Denmark)

    Nielsen, Gunver; Thomsen, Lasse Bjørchmar; Johansson, Martin;

    2009-01-01

    MOS (metal-oxide-semiconductor) electron emitters consisting of a Si substrate, a SiO2 tunnel barrier and a Ti (1 nm)/Au(7 nm) top-electrode, with an active area of 1 cm(2) have been produced and studied with surface science techniques under UHV (ultra high vacuum) conditions and their emission c...

  12. Wet-electron Enhanced Surface Dissociative Electron Attachment Chemistry of Halocarbons

    Science.gov (United States)

    2011-03-14

    photocatalysis , TiO2, decontamination, electron spectroscopy Hrvoje Petek, Xuefeng Cui, Chungwei Lin, and Jin Zhao University of Pittsburgh 123 University...reduction processes on TiO2 surfaces. Therefore it is relevant to the mechanism of photocatalytic decontamination with TiO2 photocatalysis . (a... photocatalysis  with H2O and CH3OH  overlayers.    For a clean TiO2 surface at 90 K O2 molecules do not adsorb on  stoichiometric TiO2 surfaces; they

  13. Design for Reliability of Power Electronic Systems

    DEFF Research Database (Denmark)

    Wang, Huai; Ma, Ke; Blaabjerg, Frede

    2012-01-01

    Advances in power electronics enable efficient and flexible processing of electric power in the application of renewable energy sources, electric vehicles, adjustable-speed drives, etc. More and more efforts are devoted to better power electronic systems in terms of reliability to ensure high...... on a 2.3 MW wind power converter is discussed with emphasis on the reliability critical components IGBTs. Different aspects of improving the reliability of the power converter are mapped. Finally, the challenges and opportunities to achieve more reliable power electronic systems are addressed....

  14. Data base systems in electronic design engineering

    Science.gov (United States)

    Williams, D.

    1980-01-01

    The concepts of an integrated design data base system (DBMS) as it might apply to an electronic design company are discussed. Data elements of documentation, project specifications, project tracking, firmware, software, electronic and mechanical design can be integrated and managed through a single DBMS. Combining the attributes of a DBMS data handler with specialized systems and functional data can provide users with maximum flexibility, reduced redundancy, and increased overall systems performance. Although some system overhead is lost due to redundancy in transitory data, it is believed the combination of the two data types is advisable rather than trying to do all data handling through a single DBMS.

  15. Data base systems in electronic design engineering

    Science.gov (United States)

    Williams, D.

    1980-01-01

    The concepts of an integrated design data base system (DBMS) as it might apply to an electronic design company are discussed. Data elements of documentation, project specifications, project tracking, firmware, software, electronic and mechanical design can be integrated and managed through a single DBMS. Combining the attributes of a DBMS data handler with specialized systems and functional data can provide users with maximum flexibility, reduced redundancy, and increased overall systems performance. Although some system overhead is lost due to redundancy in transitory data, it is believed the combination of the two data types is advisable rather than trying to do all data handling through a single DBMS.

  16. An Internet Based Anonymous Electronic Cash System

    Directory of Open Access Journals (Sweden)

    Israt Jahan

    2015-04-01

    Full Text Available There is an increase activity in research to improve the current electronic payment system which is parallel with the progress of internet. Electronic cash system is a cryptographic payment system which offers anonymity during withdrawal and purchase. Electronic cash displays serial numbers which can be recorded to allow further tracing. Contrary to their physical counterparts, e-cash have an inherent limitation; they are easy to copy and reuse (double-spending. An observer is a tamper-resistant device, issued by the Internet bank, which is incorporated with the Internet user’s computer that prevents double-spending physically, i.e., the user has no access to her e-cash and therefore he cannot copy them. In this paper, we shall present an anonymous electronic cash scheme on the internet which incorporates tamper-resistant device with user-module.

  17. Surface spin-electron acoustic waves in magnetically ordered metals

    CERN Document Server

    Andreev, Pavel A

    2015-01-01

    Degenerate plasmas with motionless ions show existence of three surface waves: the Langmuir wave, the electromagnetic wave, and the zeroth sound. Applying the separated spin evolution quantum hydrodynamics to half-space plasma we demonstrate the existence of the surface spin-electron acoustic wave (SSEAW). We study dispersion of the SSEAW. We show that there is hybridization between the surface Langmuir wave and the SSEAW at rather small spin polarization. In the hybridization area the dispersion branches are located close to each other. In this area there is a strong interaction between these waves leading to the energy exchange. Consequently, generating the Langmuir waves with the frequencies close to hybridization area we can generate the SSEAWs. Thus, we report a method of creation of the SEAWs.

  18. Atomic and electronic structure of surfaces theoretical foundations

    CERN Document Server

    Lannoo, Michel

    1991-01-01

    Surfaces and interfaces play an increasingly important role in today's solid state devices. In this book the reader is introduced, in a didactic manner, to the essential theoretical aspects of the atomic and electronic structure of surfaces and interfaces. The book does not pretend to give a complete overview of contemporary problems and methods. Instead, the authors strive to provide simple but qualitatively useful arguments that apply to a wide variety of cases. The emphasis of the book is on semiconductor surfaces and interfaces but it also includes a thorough treatment of transition metals, a general discussion of phonon dispersion curves, and examples of large computational calculations. The exercises accompanying every chapter will be of great benefit to the student.

  19. Electron backscatter diffraction characterization of laser-induced periodic surface structures on nickel surface

    Energy Technology Data Exchange (ETDEWEB)

    Sedao, Xxx, E-mail: sedao.xxx@gmail.com [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Maurice, Claire [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Quey, Romain; Blanc, Gilles [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Pigeon, Florent [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France)

    2014-05-01

    Graphical abstract: -- Highlight: •Lattice rotation and its distribution in laser-induced periodic surface structures (LIPSS) and the subsurface region on a nickel substrate are revealed using electron backscatter diffraction (EBSD). -- Abstract: We report on the structural investigation of laser-induced periodic surface structures (LIPSS) generated in polycrystalline nickel target after multi-shot irradiation by femtosecond laser pulses. Electron backscatter diffraction (EBSD) is used to reveal lattice rotation caused by dislocation storage during LIPSS formation. Localized crystallographic damages in the LIPSS are detected from both surface and cross-sectional EBSD studies. A surface region (up to 200 nm) with 1–3° grain disorientation is observed in localized areas from the cross-section of the LIPSS. The distribution of the local disorientation is inhomogeneous across the LIPSS and the subsurface region.

  20. Power System for Venus Surface Exploration

    Science.gov (United States)

    Landis, Geoffrey A.; Mellott, Kenneth

    2002-01-01

    A radioisotope power and cooling system is designed to provide electrical power for a probe operating on the surface of Venus. Most foreseeable electronics devices and sensors cannot operate at the 450 C ambient surface temperature of Venus. Because the mission duration is substantially long and the use of thermal mass to maintain an operable temperature range is likely impractical, some type of active refrigeration may be required to keep electronic components at a temperature below ambient. The fundamental cooling parameters are the cold sink temperature, the hot sink temperature, and the amount of heat to be removed. In this instance, it is anticipated that electronics would have a nominal operating temperature of 300 C. Due to the highly thermal convective nature of the high-density (90 bar CO2) atmosphere, the hot sink temperature was assumed to be 50 C, which provided a 500 C temperature of the cooler's heat rejecter to the ambient atmosphere. The majority of the heat load on the cooler is from the high temperature ambient surface environment on Venus, with a small contribution of heat generation from electronics and sensors. Both thermoelectric (RTG) and dynamic power conversion systems were analyzed, based on use of a standard isotope (General-purpose heat source, or GPHS) brick. For the radioisotope Stirling power converter configuration designed, the Sage model predicts a thermodynamic power output capacity of 478.1 watts, which slightly exceeds the required 469.1 watts. The hot sink temperature is 1200 C, and the cold sink temperature is 500 C. The required heat input is 1740 watts. This gives a thermodynamic efficiency of 27.48 %. It is estimated that the mechanical efficiency of the power converter design is on the order of 85 %, based on experimental measurements taken from 500-watt power class, laboratory-tested Stirling engines. The overall efficiency is calculated to be 23.36 %. The mass of the power converter is estimated at approximately 21.6 kg

  1. Tuning the electronic properties at the surface of BaBiO3 thin films

    Science.gov (United States)

    Ferreyra, C.; Guller, F.; Marchini, F.; Lüders, U.; Albornoz, C.; Leyva, A. G.; Williams, F. J.; Llois, A. M.; Vildosola, V.; Rubi, D.

    2016-06-01

    The presence of 2D electron gases at surfaces or interfaces in oxide thin films remains a hot topic in condensed matter physics. In particular, BaBiO3 appears as a very interesting system as it was theoretically proposed that its (001) surface should become metallic if a Bi-termination is achieved (Vildosola et al., PRL 110, 206805 (2013)). Here we report on the preparation by pulsed laser deposition and characterization of BaBiO3 thin films on silicon. We show that the texture of the films can be tuned by controlling the growth conditions, being possible to stabilize strongly (100)-textured films. We find significant differences on the spectroscopic and transport properties between (100)-textured and non-textured films. We rationalize these experimental results by performing first principles calculations, which indicate the existence of electron doping at the (100) surface. This stabilizes Bi ions in a 3+ state, shortens Bi-O bonds and reduces the electronic band gap, increasing the surface conductivity. Our results emphasize the importance of surface effects on the electronic properties of perovskites, and provide strategies to design novel oxide heterostructures with potential interface-related 2D electron gases.

  2. Tuning the electronic properties at the surface of BaBiO3 thin films

    Directory of Open Access Journals (Sweden)

    C. Ferreyra

    2016-06-01

    Full Text Available The presence of 2D electron gases at surfaces or interfaces in oxide thin films remains a hot topic in condensed matter physics. In particular, BaBiO3 appears as a very interesting system as it was theoretically proposed that its (001 surface should become metallic if a Bi-termination is achieved (Vildosola et al., PRL 110, 206805 (2013. Here we report on the preparation by pulsed laser deposition and characterization of BaBiO3 thin films on silicon. We show that the texture of the films can be tuned by controlling the growth conditions, being possible to stabilize strongly (100-textured films. We find significant differences on the spectroscopic and transport properties between (100-textured and non-textured films. We rationalize these experimental results by performing first principles calculations, which indicate the existence of electron doping at the (100 surface. This stabilizes Bi ions in a 3+ state, shortens Bi-O bonds and reduces the electronic band gap, increasing the surface conductivity. Our results emphasize the importance of surface effects on the electronic properties of perovskites, and provide strategies to design novel oxide heterostructures with potential interface-related 2D electron gases.

  3. Tuning the electronic properties at the surface of BaBiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ferreyra, C. [GIyA y INN, CNEA, Av.Gral Paz 1499, (1650), San Martín, Buenos Aires (Argentina); Departamento de Física, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Guller, F.; Llois, A. M.; Vildosola, V. [GIyA y INN, CNEA, Av.Gral Paz 1499, (1650), San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Marchini, F.; Williams, F. J. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Departamento de Química Inorgánica, Analítica y Química-Física, INQUIMAE-CONICET, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, Buenos Aires (Argentina); Lüders, U. [CRISMAT, CNRS UMR 6508, ENSICAEN, 6 Boulevard Maréchal Juin, 14050 Caen Cedex 4 (France); Albornoz, C. [GIyA y INN, CNEA, Av.Gral Paz 1499, (1650), San Martín, Buenos Aires (Argentina); Leyva, A. G. [GIyA y INN, CNEA, Av.Gral Paz 1499, (1650), San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología, UNSAM, Campus Miguelete, (1650), San Martín, Buenos Aires (Argentina); and others

    2016-06-15

    The presence of 2D electron gases at surfaces or interfaces in oxide thin films remains a hot topic in condensed matter physics. In particular, BaBiO{sub 3} appears as a very interesting system as it was theoretically proposed that its (001) surface should become metallic if a Bi-termination is achieved (Vildosola et al., PRL 110, 206805 (2013)). Here we report on the preparation by pulsed laser deposition and characterization of BaBiO{sub 3} thin films on silicon. We show that the texture of the films can be tuned by controlling the growth conditions, being possible to stabilize strongly (100)-textured films. We find significant differences on the spectroscopic and transport properties between (100)-textured and non-textured films. We rationalize these experimental results by performing first principles calculations, which indicate the existence of electron doping at the (100) surface. This stabilizes Bi ions in a 3+ state, shortens Bi-O bonds and reduces the electronic band gap, increasing the surface conductivity. Our results emphasize the importance of surface effects on the electronic properties of perovskites, and provide strategies to design novel oxide heterostructures with potential interface-related 2D electron gases.

  4. Security in Electronic Payment Systems

    Directory of Open Access Journals (Sweden)

    Roxana Turcu

    2014-12-01

    Full Text Available The payment security becomes fundamental in our days. Based on this statement I have decided to deepen this subject and to study the online payment systems and the connection between them. I have observed that this area becomes the hackers’ attraction and I have realized how important the security of the ecommerce is. Also I have done a research of the possible attacks and I have searched for the countermeasures of this attacks. The result of my research is my payment gateway solution presented in the following lines.

  5. Disordered strongly correlated electronic systems

    Science.gov (United States)

    Javan Mard, Hossein

    Disorder can have a vast variety of consequences for the physics of phase transitions. Some transitions remain unchanged in the presence of disorder while others are completely destroyed. In this dissertation we study the effects of quenched disorder on electronic systmens at zero temperature. First, we perform variational studies of the interaction-localization problem to describe the interaction-induced renormalizations of the effective (screened) random potential seen by quasiparticles. Here we present results of careful finite-size scaling studies for the conductance of disordered Hubbard chains at half-filling and zero temperature. While our results indicate that quasiparticle wave functions remain exponentially localized even in the presence of moderate to strong repulsive interactions, we show that interactions produce a strong decrease of the characteristic conductance scale g* signaling the crossover to strong localization. This effect, which cannot be captured by a simple renormalization of the disorder strength, instead reflects a peculiar non-Gaussian form of the spatial correlations of the screened disordered potential, a hitherto neglected mechanism to dramatically reduce the impact of Anderson localization (interference) effects. Second, we formulate a strong-disorder renormalization-group (SDRG) approach to study the beta function of the tight-binding model in one dimension with both diagonal and off-diagonal disorder for states at the band center. We show that the SDRG method, when used to compute transport properties, yields exact results since it is identical to the transfer matrix method. The beta function is shown to be universal when only off-diagonal disorder is present even though single-parameter scaling is known to be violated. A different single-parameter scaling theory is formulated for this particular (particle-hole symmetric) case. Upon breaking particle-hole symmetry (by adding diagonal disorder), the beta function is shown to

  6. The Intelligent Technologies of Electronic Information System

    Science.gov (United States)

    Li, Xianyu

    2017-08-01

    Based upon the synopsis of system intelligence and information services, this paper puts forward the attributes and the logic structure of information service, sets forth intelligent technology framework of electronic information system, and presents a series of measures, such as optimizing business information flow, advancing data decision capability, improving information fusion precision, strengthening deep learning application and enhancing prognostic and health management, and demonstrates system operation effectiveness. This will benefit the enhancement of system intelligence.

  7. Weight Estimation of Electronic Power Conversion Systems

    OpenAIRE

    Wen, Bo

    2011-01-01

    Electronic power conversion systems with large number of power converters have a variety of applications, such as data center, electric vehicles and future smart â nanogridâ in residential home. Those systems could have very different architectures. For example, one system could be based on ac, dc or hybrid power distribution bus, and the bus voltage could be different. Also those systems have great need to develop low-cost architectures which reduce weight, increase efficiency and improve...

  8. Zeeman shift of an electron trapped near a surface

    Science.gov (United States)

    Bennett, Robert; Eberlein, Claudia

    2014-04-01

    Boundary-dependent corrections to the spin energy eigenvalues of an electron in a weak magnetic field and confined by a harmonic trapping potential are investigated. The electromagnetic field is quantized through a normal-mode expansion obeying the Maxwell boundary conditions at the material surface. We couple the electron to this photon field and a classical magnetic field in the Dirac equation, to which we apply the unitary Foldy-Wouthuysen transformation in order to generate a nonrelativistic approximation of the Hamiltonian to the desired order. We obtain the Schrödinger eigenstates of an electron subject to double confinement by a harmonic potential and a classical magnetic field, and then use these within second-order perturbation theory to calculate the spin energy shift that is attributable to the surface-modified quantized field. We find that a pole at the eigenfrequency of a set of generalized Landau transitions gives dominant oscillatory contributions to the energy shift in the limit of tight harmonic confinement in a weak magnetic field, which also make the energy shift preferable to the magnetic moment for a physically meaningful interpretation.

  9. Power Electronics in Wind Turbine Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Chen, Zhe; Teodorescu, Remus

    2006-01-01

    the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power systems, power production and end-user application. This paper discuss the most emerging renewable energy source, wind energy, which by means of power...... electronics is changing from being a minor energy source to be acting as an important power source in the energy system. By that wind power is also getting an added value in the power system operation....

  10. Symmetry of many-electron systems

    CERN Document Server

    Kaplan, I G

    2013-01-01

    Symmetry of Many-Electron Systems discusses the group-theoretical methods applied to physical and chemical problems. Group theory allows an individual to analyze qualitatively the elements of a certain system in scope. The text evaluates the characteristics of the Schrodinger equations. It is proved that some groups of continuous transformation from the Lie groups are useful in identifying conditions and in developing wavefunctions. A section of the book is devoted to the utilization of group-theoretical methods in quantal calculations on many-electron systems. The focus is on the use of group

  11. Sensor Arrays and Electronic Tongue Systems

    Directory of Open Access Journals (Sweden)

    Manel del Valle

    2012-01-01

    Full Text Available This paper describes recent work performed with electronic tongue systems utilizing electrochemical sensors. The electronic tongues concept is a new trend in sensors that uses arrays of sensors together with chemometric tools to unravel the complex information generated. Initial contributions and also the most used variant employ conventional ion selective electrodes, in which it is named potentiometric electronic tongue. The second important variant is the one that employs voltammetry for its operation. As chemometric processing tool, the use of artificial neural networks as the preferred data processing variant will be described. The use of the sensor arrays inserted in flow injection or sequential injection systems will exemplify attempts made to automate the operation of electronic tongues. Significant use of biosensors, mainly enzyme-based, to form what is already named bioelectronic tongue will be also presented. Application examples will be illustrated with selected study cases from the Sensors and Biosensors Group at the Autonomous University of Barcelona.

  12. Blind Signatures in Electronic Voting Systems

    Science.gov (United States)

    Kucharczyk, Marcin

    Electronic voting systems are created to facilitate the election, accelerate voting and counting votes and increase turnout for the election. The main problems of the electronic systems are related with the assurance of system security (cryptographic security and protection against frauds) and a guarantee that the voters are anonymous. The authorization of voters and the anonymity of them seem to be contradictory, but it is possible to create such a system where the both requirements are met. Some solutions, the most common e-voting systems, are presented in the paper. These models are adjusted to the demands and implemented in the polls system for quality of teaching evaluation where anonymity is very important. The blind signature protocol, model directed to user's anonymity, is a very good solution of the authorization and anonymity problem in the polls system with remote access only, as it was described in the paper.

  13. Application of Electron Beam Surface Technologies in the Automotive Industry

    Institute of Scientific and Technical Information of China (English)

    Rolf Zenker; Anja Buchwalder

    2004-01-01

    Progress in the beam deflection technique opens up new possibilities for the application of electron beam (EB)surface and welding technologies in the automotive industry. This development is based on three-dimensional high-speed beam deflection and fully automatic online process control. So, in the EB surface treatment three-dimensional energy transfer fields can be realised which take into account the contour of a component, the conditions of heat conduction and the load conditions. High flexibility, precision and reproducibility are typical characteristics. High productivity is achieved by the simultaneous interaction of the EB in several processing areas or by carrying out several processes simultaneously. EB surface treatment is becoming more and more attractive and important especially in the automotive industry, and also in comparison to laser technologies. This paper deals with different EB surface technologies, for example hardening,remelting, surface alloying, dispersing or cladding of different materials such as steel, cast iron and different alloys of Al,Mg and Ti. Examples of applications in the automotive industry, especially engine components, will be discussed.

  14. Electron backscatter diffraction characterization of laser-induced periodic surface structures on nickel surface

    Science.gov (United States)

    Sedao, Xxx; Maurice, Claire; Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie; Quey, Romain; Blanc, Gilles; Pigeon, Florent

    2014-05-01

    We report on the structural investigation of laser-induced periodic surface structures (LIPSS) generated in polycrystalline nickel target after multi-shot irradiation by femtosecond laser pulses. Electron backscatter diffraction (EBSD) is used to reveal lattice rotation caused by dislocation storage during LIPSS formation. Localized crystallographic damages in the LIPSS are detected from both surface and cross-sectional EBSD studies. A surface region (up to 200 nm) with 1-3° grain disorientation is observed in localized areas from the cross-section of the LIPSS. The distribution of the local disorientation is inhomogeneous across the LIPSS and the subsurface region.

  15. Power electronics for renewable energy systems

    DEFF Research Database (Denmark)

    Iov, Florin; Blaabjerg, Frede

    2009-01-01

    sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss some of the most emerging renewable energy sources......, wind energy and photovoltaics, which by means of power electronics are changing from being minor energy sources to be acting as important power sources in the energy system....

  16. VHDL Model of Electronic-Lock System

    Directory of Open Access Journals (Sweden)

    J. Noga

    2000-04-01

    Full Text Available The paper describes the design of an electronic-lock system which wascompleted as part of the Basic VHDL course in the Department of Controland Measurement Faculty of Electrical Engineering and Informatics,Technical University of Ostrava, Czech Republic in co-operation withthe Department if Electronic Engineering, University of Hull, GreatBritain in the frame of TEMPUS project no. S_JEP/09468-95.

  17. Cooled electronic system with thermal spreaders coupling electronics cards to cold rails

    Science.gov (United States)

    Chainer, Timothy J; Gaynes, Michael A; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Schultz, Mark D; Simco, Daniel P; Steinke, Mark E

    2013-07-23

    Liquid-cooled electronic systems are provided which include an electronic assembly having an electronics card and a socket with a latch at one end. The latch facilitates securing of the card within the socket or removal of the card from the socket. A liquid-cooled cold rail is disposed at the one end of the socket, and a thermal spreader couples the electronics card to the cold rail. The thermal spreader includes first and second thermal transfer plates coupled to first and second surfaces on opposite sides of the card, and thermally conductive extensions extending from end edges of the plates, which couple the respective transfer plates to the liquid-cooled cold rail. The thermally conductive extensions are disposed to the sides of the latch, and the card is securable within or removable from the socket using the latch without removing the cold rail or the thermal spreader.

  18. Nanoscale electron transport at the surface of a topological insulator

    Science.gov (United States)

    Bauer, Sebastian; Bobisch, Christian A.

    2016-01-01

    The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless transport of electrons at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the electronic transport. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role. PMID:27098939

  19. Nanoscale electron transport at the surface of a topological insulator

    Science.gov (United States)

    Bauer, Sebastian; Bobisch, Christian A.

    2016-04-01

    The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless transport of electrons at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the electronic transport. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role.

  20. Power electronics system modeling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Jih-Sheng

    1994-12-31

    This paper introduces control system design based softwares, SIMNON and MATLAB/SIMULINK, for power electronics system simulation. A complete power electronics system typically consists of a rectifier bridge along with its smoothing capacitor, an inverter, and a motor. The system components, featuring discrete or continuous, linear or nonlinear, are modeled in mathematical equations. Inverter control methods,such as pulse-width-modulation and hysteresis current control, are expressed in either computer algorithms or digital circuits. After describing component models and control methods, computer programs are then developed for complete systems simulation. Simulation results are mainly used for studying system performances, such as input and output current harmonics, torque ripples, and speed responses. Key computer programs and simulation results are demonstrated for educational purposes.

  1. A Flexible Electronic Commerce Recommendation System

    Science.gov (United States)

    Gong, Songjie

    Recommendation systems have become very popular in E-commerce websites. Many of the largest commerce websites are already using recommender technologies to help their customers find products to purchase. An electronic commerce recommendation system learns from a customer and recommends products that the customer will find most valuable from among the available products. But most recommendation methods are hard-wired into the system and they support only fixed recommendations. This paper presented a framework of flexible electronic commerce recommendation system. The framework is composed by user model interface, recommendation engine, recommendation strategy model, recommendation technology group, user interest model and database interface. In the recommender strategy model, the method can be collaborative filtering, content-based filtering, mining associate rules method, knowledge-based filtering method or the mixed method. The system mapped the implementation and demand through strategy model, and the whole system would be design as standard parts to adapt to the change of the recommendation strategy.

  2. Improvement of carbon fiber surface properties using electron beam irradiation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Carbon fiber-reinforced advance composites have been used for struetural applications, mainly on account of their mechanical properties. The main factor for a good mechanical performance of carbon fiber-reinforced composite is the interfacial interaction between its components, which are carbon fiber and polymeric matrix. The aim of this study is to improve the surface properties of the carbon fiber using ionizing radiation from an electron beam to obtain better adhesion properties in the resultant composite. EB radiation was applied on the carbon fiber itself before preparing test specimens for the mechanical tests. Experimental results showed that EB irradiation improved the tensile strength of carbon fiber samples. The maximum value in tensile strength was reached using doses of about 250kGy. After breakage, the morphology aspect of the tensile specimens prepared with irradiated and non-irradiated carbon fibers were evaluated. SEM micrographs showed modifications on the carbon fiber surface.

  3. Electronic Resources Management System: Recommendation Report 2017

    KAUST Repository

    Ramli, Rindra M.

    2017-05-01

    This recommendation report provides an overview of the selection process for the new Electronic Resources Management System. The library has decided to move away from Innovative Interfaces Millennium ERM module. The library reviewed 3 system as potential replacements namely: Proquest 360 Resource Manager, Ex Libris Alma and Open Source CORAL ERMS. After comparing and trialling the systems, it was decided to go for Proquest 360 Resource Manager.

  4. Hot-electron-assisted femtochemistry at surfaces: A time-dependent density functional theory approach

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Rubio, Angel; Olsen, Thomas;

    2009-01-01

    Using time-evolution time-dependent density functional theory (TDDFT) within the adiabatic local-density approximation, we study the interactions between single electrons and molecular resonances at surfaces. Our system is a nitrogen molecule adsorbed on a ruthenium surface. The surface is modeled...... resonance and the lowering of the resonance energy due to an image charge effect. Finally we apply the TDDFT procedure to only consider the decay of molecular excitations and find that it agrees quite well with the width of the projected density of Kohn-Sham states....

  5. Ab initio tensorial electronic friction for molecules on metal surfaces: Nonadiabatic vibrational relaxation

    Science.gov (United States)

    Maurer, Reinhard J.; Askerka, Mikhail; Batista, Victor S.; Tully, John C.

    2016-09-01

    Molecular adsorbates on metal surfaces exchange energy with substrate phonons and low-lying electron-hole pair excitations. In the limit of weak coupling, electron-hole pair excitations can be seen as exerting frictional forces on adsorbates that enhance energy transfer and facilitate vibrational relaxation or hot-electron-mediated chemistry. We have recently reported on the relevance of tensorial properties of electronic friction [M. Askerka et al., Phys. Rev. Lett. 116, 217601 (2016), 10.1103/PhysRevLett.116.217601] in dynamics at surfaces. Here we present the underlying implementation of tensorial electronic friction based on Kohn-Sham density functional theory for condensed phase and cluster systems. Using local atomic-orbital basis sets, we calculate nonadiabatic coupling matrix elements and evaluate the full electronic friction tensor in the Markov limit. Our approach is numerically stable and robust, as shown by a detailed convergence analysis. We furthermore benchmark the accuracy of our approach by calculation of vibrational relaxation rates and lifetimes for a number of diatomic molecules at metal surfaces. We find friction-induced mode-coupling between neighboring CO adsorbates on Cu(100) in a c (2 ×2 ) overlayer to be important for understanding experimental findings.

  6. Demonstration of a Passive Thermal Management System for Cooling Electronics in Extreme Environments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Extended operation of exploratory systems on the surface of planets like Venus, means that techniques to cool system electronics to essentially room temperature...

  7. Power Electronics for Renewable Energy Systems

    DEFF Research Database (Denmark)

    Choi, U. M.; Lee, K. B.; Blaabjerg, Frede

    2012-01-01

    The use of renewable energy sources are increased because of the depletion of natural resources and the increasing pollution level from energy production. The wind energy and the solar energy are most widely used among the renewable energy sources. Power electronics is needed in almost all kinds...... of renewable energy system. It controls the renewable source and interfaces with the load effectively, which can be grid-connected or van work in stand-alone mode. In this presentation, overview of wind and photovoltaic energy systems are introduced. Next, the power electronic circuits behind the most common...

  8. Effective action for strongly correlated electron systems

    Energy Technology Data Exchange (ETDEWEB)

    Ferraz, A., E-mail: aferraz.iccmp@gmail.com [International Institute of Physics - UFRN, Department of Experimental and Theoretical Physics - UFRN, Natal (Brazil); Kochetov, E.A. [International Institute of Physics - UFRN, Natal (Brazil); Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

    2011-12-21

    The su(2|1) coherent-state path-integral representation of the partition function of the t-J model of strongly correlated electrons is derived at finite doping. The emergent effective action is compared to the one proposed earlier on phenomenological grounds by Shankar to describe holes in an antiferromagnet [R. Shankar, Nucl. Phys. B 330 (1990) 433]. The t-J model effective action is found to have an important 'extra' factor with no analogue in Shankar's action. It represents the local constraint of no double electron occupancy and reflects the rearrangement of the underlying phase-space manifold due to the presence of strong electron correlation. This important ingredient is shown to be essential to describe the physics of strongly correlated electron systems.

  9. Electronic warfare receivers and receiving systems

    CERN Document Server

    Poisel, Richard A

    2014-01-01

    Receivers systems are considered the core of electronic warfare (EW) intercept systems. Without them, the fundamental purpose of such systems is null and void. This book considers the major elements that make up receiver systems and the receivers that go in them.This resource provides system design engineers with techniques for design and development of EW receivers for modern modulations (spread spectrum) in addition to receivers for older, common modulation formats. Each major module in these receivers is considered in detail. Design information is included as well as performance tradeoffs o

  10. Designing artificial two dimensional electron lattice on metal surface: a Kagome-like lattice as an example.

    Science.gov (United States)

    Li, Shuai; Qiu, Wen-Xuan; Gao, Jin-Hua

    2016-07-07

    Recently, a new kind of artificial two dimensional (2D) electron lattice on the nanoscale, i.e. molecular graphene, has drawn a lot of interest, where the metal surface electrons are transformed into a honeycomb lattice via absorbing a molecular lattice on the metal surface [Gomes et al., Nature, 2012, 438, 306; Wang et al., Phys. Rev. Lett., 2014, 113, 196803]. In this work, we theoretically demonstrate that this technique can be readily used to build other complex 2D electron lattices on a metal surface, which are of high interest in the field of condensed matter physics. The main challenge to build a complex 2D electron lattice is that this is a quantum antidot system, where the absorbed molecule normally exerts a repulsive potential on the surface electrons. Thus, there is no straightforward corresponding relation between the molecular lattice pattern and the desired 2D lattice of surface electrons. Here, we give an interesting example about the Kagome lattice, which has exotic correlated electronic states. We design a special molecular pattern and show that this molecular lattice can transform the surface electrons into a Kagome-like lattice. The numerical simulation is conducted using a Cu(111) surface and CO molecules. We first estimate the effective parameters of the Cu/CO system by fitting experimental data of the molecular graphene. Then, we calculate the corresponding energy bands and LDOS of the surface electrons in the presence of the proposed molecular lattice. Finally, we interpret the numerical results by the tight binding model of the Kagome lattice. We hope that our work can stimulate further theoretical and experimental interest in this novel artificial 2D electron lattice system.

  11. Self-consistent many-electron theory of electron work functions and surface potential characteristics for selected metals

    Science.gov (United States)

    Smith, J. R.

    1969-01-01

    Electron work functions, surface potentials, and electron number density distributions and electric fields in the surface region of 26 metals were calculated from first principles within the free electron model. Calculation proceeded from an expression of the total energy as a functional of the electron number density, including exchange and correlation energies, as well as a first inhomogeneity term. The self-consistent solution was obtained via a variational procedure. Surface barriers were due principally to many-body effects; dipole barriers were small only for some alkali metals, becoming quite large for the transition metals. Surface energies were inadequately described by this model, which neglects atomistic effects. Reasonable results were obtained for electron work functions and surface potential characteristics, maximum electron densities varying by a factor of over 60.

  12. Hot electron dynamics at semiconductor surfaces: Implications for quantum dot photovoltaics

    Science.gov (United States)

    Tisdale, William A., III

    Finding a viable supply of clean, renewable energy is one of the most daunting challenges facing the world today. Solar cells have had limited impact in meeting this challenge because of their high cost and low power conversion efficiencies. Semiconductor nanocrystals, or quantum dots, are promising materials for use in novel solar cells because they can be processed with potentially inexpensive solution-based techniques and because they are predicted to have novel optoelectronic properties that could enable the realization of ultra-efficient solar power converters. However, there is a lack of fundamental understanding regarding the behavior of highly-excited, or "hot," charge carriers near quantum-dot and semiconductor interfaces, which is of paramount importance to the rational design of high-efficiency devices. The elucidation of these ultrafast hot electron dynamics is the central aim of this Dissertation. I present a theoretical framework for treating the electronic interactions between quantum dots and bulk semiconductor surfaces and propose a novel experimental technique, time-resolved surface second harmonic generation (TR-SHG), for probing these interactions. I then describe a series of experimental investigations into hot electron dynamics in specific quantum-dot/semiconductor systems. A two-photon photoelectron spectroscopy (2PPE) study of the technologically-relevant ZnO(1010) surface reveals ultrafast (sub-30fs) cooling of hot electrons in the bulk conduction band, which is due to strong electron-phonon coupling in this highly polar material. The presence of a continuum of defect states near the conduction band edge results in Fermi-level pinning and upward (n-type) band-bending at the (1010) surface and provides an alternate route for electronic relaxation. In monolayer films of colloidal PbSe quantum dots, chemical treatment with either hydrazine or 1,2-ethanedithiol results in strong and tunable electronic coupling between neighboring quantum dots

  13. Design for Reliability of Power Electronic Systems

    DEFF Research Database (Denmark)

    Wang, Huai; Ma, Ke; Blaabjerg, Frede

    2012-01-01

    availability, long lifetime, sufficient robustness, low maintenance cost and low cost of energy. However, the reliability predictions are still dominantly according to outdated models and terms, such as MIL-HDBK-217F handbook models, Mean-Time-To-Failure (MTTF), and Mean-Time-Between-Failures (MTBF......Advances in power electronics enable efficient and flexible processing of electric power in the application of renewable energy sources, electric vehicles, adjustable-speed drives, etc. More and more efforts are devoted to better power electronic systems in terms of reliability to ensure high......). A collection of methodologies based on Physics-of-Failure (PoF) approach and mission profile analysis are presented in this paper to perform reliability-oriented design of power electronic systems. The corresponding design procedures and reliability prediction models are provided. Further on, a case study...

  14. Thermodynamics of GaN(s)-NH3(v)+N2(v)+H2(v) system - Electronic aspects of the processes at GaN(0001) surface

    Science.gov (United States)

    Kempisty, Pawel; Strak, Pawel; Sakowski, Konrad; Krukowski, Stanislaw

    2017-08-01

    Comprehensive analysis of GaN(0001) surface in equilibrium with ammonia/hydrogen mixture was undertaken using results of ab initio calculations. Adsorption energies of the species derived from ammonia and molecular hydrogen and their stable sites were obtained. It was shown that the adsorption process type and energy depend on the position of Fermi level at the surface. Hydrogen decomposes into two separate H atoms, always adsorbed in the positions on top of the surface Ga atoms (On-top). Ammonia adsorption at GaN(0001) surface proceeds molecularly to ammonia in the On-top position or dissociatively into NH2 radicals in bridge (NH2-bridge) or On-top positions or into NH radicals in H3 (NH-H3) site. Presence of these species affects Fermi level pinning at the surface due to creation of new surface states. The Fermi level pinning in function of the surface attached species concentration was determined using extended electron counting rule (EECR). Results of ab initio calculations fully proved validity of the EECR predictions. Thermodynamic analysis of the surface in equilibrium with molecular hydrogen and ammonia vapor mixture is made giving the range of ammonia and hydrogen pressures, corresponding to Fermi level pinned at Ga-broken bond state for NH-H3&H and NH3&H and NH2-bridge&H coverage and at VBM for NH3 & H coverage. As the region of Fermi level pinned at Ga broken bond state corresponds to very low pressures, at pressures close to normal, GaN(0001) surface is almost totally covered by H, NH3 and NH2 located in On-top positions. It is also shown however that dominant portion of the hydrogen and ammonia pressures corresponds to Fermi level not pinned. Among them are these corresponding to MOVPE and HVPE growth conditions in which the surface is almost fully covered by NH3, NH2 and H species in On-top positions.

  15. Venus Surface Power and Cooling System Design

    Science.gov (United States)

    Landis, Geoffrey A.; Mellott, Kenneth D.

    2004-01-01

    A radioisotope power and cooling system is designed to provide electrical power for the a probe operating on the surface of Venus. Most foreseeable electronics devices and sensors simply cannot operate at the 450 C ambient surface temperature of Venus. Because the mission duration is substantially long and the use of thermal mass to maintain an operable temperature range is likely impractical, some type of active refrigeration may be required to keep certain components at a temperature below ambient. The fundamental cooling requirements are comprised of the cold sink temperature, the hot sink temperature, and the amount of heat to be removed. In this instance, it is anticipated that electronics would have a nominal operating temperature of 300 C. Due to the highly thermal convective nature of the high-density atmosphere, the hot sink temperature was assumed to be 50 C, which provided a 500 C temperature of the cooler's heat rejecter to the ambient atmosphere. The majority of the heat load on the cooler is from the high temperature ambient surface environment on Venus. Assuming 5 cm radial thickness of ceramic blanket insulation, the ambient heat load was estimated at approximately 77 watts. With an estimated quantity of 10 watts of heat generation from electronics and sensors, and to accommodate some level of uncertainty, the total heat load requirement was rounded up to an even 100 watts. For the radioisotope Stirling power converter configuration designed, the Sage model predicts a thermodynamic power output capacity of 478.1 watts, which slightly exceeds the required 469.1 watts. The hot sink temperature is 1200 C, and the cold sink temperature is 500 C. The required heat input is 1740 watts. This gives a thermodynamic efficiency of 27.48 %. The maximum theoretically obtainable efficiency is 47.52 %. It is estimated that the mechanical efficiency of the power converter design is on the order of 85 %, based on experimental measurements taken from 500 watt power

  16. Negative plasma potential relative to electron-emitting surfaces.

    Science.gov (United States)

    Campanell, M D

    2013-09-01

    Most works on plasma-wall interaction predict that with strong electron emission, a nonmonotonic "space-charge-limited" (SCL) sheath forms where the plasma potential is positive relative to the wall. We show that a fundamentally different sheath structure is possible where the potential monotonically increases toward a positively charged wall that is shielded by a single layer of negative charge. No ion-accelerating presheath exists in the plasma and the ion wall flux is zero. An analytical solution of the "inverse sheath" regime is demonstrated for a general plasma-wall system where the plasma electrons and emitted electrons are Maxwellian with different temperatures. Implications of the inverse sheath effect are that (a) the plasma potential is negative, (b) ion sputtering vanishes, (c) no charge is lost at the wall, and (d) the electron energy flux is thermal. To test empirically what type of sheath structure forms under strong emission, a full plasma bounded by strongly emitting walls is simulated. It is found that inverse sheaths form at the walls and ions are confined in the plasma. This result differs from past particle-in-cell simulation studies of emission which contain an artificial "source sheath" that accelerates ions to the wall, leading to a SCL sheath at high emission intensity.

  17. Electronic Chart Display and Information System

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper introduces the most advanced form of electronic chart display and information systems (ECDIS) which complies with the Performance Standards for ECDIS established by the International Maritime Organization (IMO) and the International Hydrographic Organization (IHO).It also describes the key features and the important functions of ECDIS.Then the future development of ECDIS in marine is discussed.

  18. Chemistry of SOFC Cathode Surfaces: Fundamental Investigation and Tailoring of Electronic Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, Bilge; Heski, Clemens

    2013-08-31

    1) Electron tunneling characteristics on La0.7Sr0.3MnO3 (LSM) thin-film surfaces were studied up to 580oC in 10-3mbar oxygen pressure, using scanning tunneling microscopy/ spectroscopy (STM/STS). A threshold-like drop in the tunneling current was observed at positive bias in STS, which is interpreted as a unique indicator for the activation polarization in cation oxygen bonding on LSM cathodes. Sr-enrichment was found on the surface at high temperature using Auger electron spectroscopy, and was accompanied by a decrease in tunneling conductance in STS. This suggests that Sr-terminated surfaces are less active for electron transfer in oxygen reduction compared to Mn-terminated surfaces on LSM. 2) Effects of strain on the surface cation chemistry and the electronic structure are important to understand and control for attaining fast oxygen reduction kinetics on transition metal oxides. Here, we demonstrate and mechanistically interpret the strain coupling to Sr segregation, oxygen vacancy formation, and electronic structure on the surface of La0.7Sr0.3MnO3 (LSM) thin films as a model system. Our experimental results from x-ray photoelectron spectroscopy and scanning tunneling spectroscopy are discussed in light of our first principles-based calculations. A stronger Sr enrichment tendency and a more facile oxygen vacancy formation prevail for the tensile strained LSM surface. The electronic structure of the tensile strained LSM surface exhibits a larger band gap at room temperature, however, a higher tunneling conductance near the Fermi level than the compressively strained LSM at elevated temperatures in oxygen. Our findings suggest lattice strain as a key parameter to tune the reactivity of perovskite transition metal oxides with oxygen in solid oxide fuel cell cathodes. 3) Cation segregation on perovskite oxide surfaces affects vastly the oxygen reduction activity and stability of solid oxide fuel cell (SOFC) cathodes. A unified theory that explains the physical

  19. Chemistry of SOFC Cathode Surfaces: Fundamental Investigation and Tailoring of Electronic Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, Bilge; Heski, Clemens

    2013-08-31

    1) Electron tunneling characteristics on La0.7Sr0.3MnO3 (LSM) thin-film surfaces were studied up to 580oC in 10-3mbar oxygen pressure, using scanning tunneling microscopy/ spectroscopy (STM/STS). A threshold-like drop in the tunneling current was observed at positive bias in STS, which is interpreted as a unique indicator for the activation polarization in cation oxygen bonding on LSM cathodes. Sr-enrichment was found on the surface at high temperature using Auger electron spectroscopy, and was accompanied by a decrease in tunneling conductance in STS. This suggests that Sr-terminated surfaces are less active for electron transfer in oxygen reduction compared to Mn-terminated surfaces on LSM. 2) Effects of strain on the surface cation chemistry and the electronic structure are important to understand and control for attaining fast oxygen reduction kinetics on transition metal oxides. Here, we demonstrate and mechanistically interpret the strain coupling to Sr segregation, oxygen vacancy formation, and electronic structure on the surface of La0.7Sr0.3MnO3 (LSM) thin films as a model system. Our experimental results from x-ray photoelectron spectroscopy and scanning tunneling spectroscopy are discussed in light of our first principles-based calculations. A stronger Sr enrichment tendency and a more facile oxygen vacancy formation prevail for the tensile strained LSM surface. The electronic structure of the tensile strained LSM surface exhibits a larger band gap at room temperature, however, a higher tunneling conductance near the Fermi level than the compressively strained LSM at elevated temperatures in oxygen. Our findings suggest lattice strain as a key parameter to tune the reactivity of perovskite transition metal oxides with oxygen in solid oxide fuel cell cathodes. 3) Cation segregation on perovskite oxide surfaces affects vastly the oxygen reduction activity and stability of solid oxide fuel cell (SOFC) cathodes. A unified theory that explains the physical

  20. Emission of correlated electron pairs from Au(111) and Cu(111) surfaces under low-energy electron impact: Contribution of surface states, d-states and spin effects

    Energy Technology Data Exchange (ETDEWEB)

    Samarin, S., E-mail: samar@physics.uwa.edu.au [Centre for Atomic, Molecular and Surface Physics, University of Western Australia, Perth, WA 6009 (Australia); Research Institute of Physics, St. Petersburg University, St. Petersburg (Russian Federation); Artamonov, O.M. [Research Institute of Physics, St. Petersburg University, St. Petersburg (Russian Federation); Guagliardo, P. [Centre for Microscopy, Characterisation and Analysis, UWA, Perth (Australia); Pravica, L. [Centre for Atomic, Molecular and Surface Physics, University of Western Australia, Perth, WA 6009 (Australia); Baraban, A. [Research Institute of Physics, St. Petersburg University, St. Petersburg (Russian Federation); Schumann, F.O. [Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany); Williams, J.F. [Centre for Atomic, Molecular and Surface Physics, University of Western Australia, Perth, WA 6009 (Australia)

    2015-01-15

    Highlights: • Spin-polarized two-electron spectroscopy (e,2e) was applied for studying surface states on Cu(111) and Au(111). • Relative (to d-states) contribution of surface states in the (e,2e) spectrum decreases exponentially when primary electron energy increases from 14 to 30 eV. • Spin asymmetry is readily observed in the spectra of Au(111) whereas in the spectra of Cu(111) the spin effect is negligible. - Abstract: The emission of correlated electron pairs excited from surfaces of Au(111) and Cu(111) by low-energy electrons is measured and analyzed. Energy and momentum conservation allows identification of electron pairs involving excitation of electrons from Shockley surface states and from valence d-states. The relative contributions of surface and d-states to the measured spectra of correlated electron pairs is shown to depend on the primary electron energy and is larger from surface states at relatively small primary energies. The use of a spin-polarized incident electron beam highlights the spin effects in producing an electron pair. Measurements show that spin effects are larger for the pair excitation from the valence d-states than for pairs excited from the surface states.

  1. Soft errors in modern electronic systems

    CERN Document Server

    Nicolaidis, Michael

    2010-01-01

    This book provides a comprehensive presentation of the most advanced research results and technological developments enabling understanding, qualifying and mitigating the soft errors effect in advanced electronics, including the fundamental physical mechanisms of radiation induced soft errors, the various steps that lead to a system failure, the modelling and simulation of soft error at various levels (including physical, electrical, netlist, event driven, RTL, and system level modelling and simulation), hardware fault injection, accelerated radiation testing and natural environment testing, s

  2. Electronic system for optical shutter control

    Science.gov (United States)

    Viljoen, H. C.; Gaylord, T. K.

    1976-01-01

    The paper describes a precise and versatile electronic system for shutter control in light beam experiments. Digital and analog circuitry is used to provide automatic timing, exposure control, manual operation, and remote programmability. A block diagram of the system is presented and the individual circuits - the timer control circuit, the clock control circuit, the comparator circuit, the exposure (integrator) circuit, and the shutter drive circuit are discussed in detail and diagrams are provided.

  3. Electronic emulator of linear dynamic systems

    OpenAIRE

    Garan, Maryna; Kovalenko, Iaroslav; Moučka, Michal; Vagaská, Alena

    2015-01-01

    The aim of this article is development and realization of electronic emulator of dynamic systems with setting of parameters from PC. This emulator is the first prototype, which is meant to prove the possibility of emulating the behavior of dynamic systems by microprocessor. The main goal of research is creating of equipment, which can emulate a behavior of pneumatic muscle with sufficient accuracy. Dynamic of pneumatic muscles is significantly non-linear and changeable in the dependence on...

  4. Graphene surface plasmon polaritons with opposite in-plane electron oscillations along its two surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Huawei; Ruan, Shuangchen, E-mail: scruan@szu.edu.cn; Zhang, Min; Su, Hong; Li, Irene Ling [Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060 (China)

    2015-08-31

    We predict the existence of a surface plasmon polariton (SPP) mode that can be guided by a graphene monolayer, regardless of the sign of the imaginary part of its conductivity. In this mode, in-plane electron oscillations along two surfaces of graphene are of opposite directions, which is very different from conventional SPPs on graphene. Significantly, coating graphene with dielectric films yields a way to guide the SPPs with both sub-wavelength mode widths and ultra-long propagation distances. In particular, the mode characteristics are very sensitive to the chemical potential of graphene, so the graphene-based waveguide can find applications in many optoelectronic devices.

  5. 600-GHz Electronically Tunable Vector Measurement System

    Science.gov (United States)

    Dengler, Robert; Maiwald, Frank; Siegel, Peter

    2007-01-01

    A compact, high-dynamic-range, electronically tunable vector measurement system that operates in the frequency range from approximately 560 to approximately 635 GHz has been developed as a prototype of vector measurement systems that would be suitable for use in nearly-real-time active submillimeter-wave imaging. As used here, 'vector measurement system" signifies an instrumentation system that applies a radio-frequency (RF) excitation to an object of interest and measures the resulting amplitude and phase response, relative to either the applied excitatory signal or another reference signal related in a known way to applied excitatory signal.

  6. Epidermal electronic systems for sensing and therapy

    Science.gov (United States)

    Lu, Nanshu; Ameri, Shideh K.; Ha, Taewoo; Nicolini, Luke; Stier, Andrew; Wang, Pulin

    2017-04-01

    Epidermal electronic system is a class of hair thin, skin soft, stretchable sensors and electronics capable of continuous and long-term physiological sensing and clinical therapy when applied on human skin. The high cost of manpower, materials, and photolithographic facilities associated with its manufacture limit the availability of disposable epidermal electronics. We have invented a cost and time effective, completely dry, benchtop "cut-and-paste" method for the green, freeform and portable manufacture of epidermal electronics within minutes. We have applied the "cut-and-paste" method to manufacture epidermal electrodes, hydration and temperature sensors, conformable power-efficient heaters, as well as cuffless continuous blood pressure monitors out of metal thin films, two-dimensional (2D) materials, and piezoelectric polymer sheets. For demonstration purpose, we will discuss three examples of "cut-and-pasted" epidermal electronic systems in this paper. The first will be submicron thick, transparent epidermal graphene electrodes that can be directly transferred to human skin like a temporary transfer tattoo and can measure electrocardiogram (ECG) with signal-to-noise ratio and motion artifacts on par with conventional gel electrodes. The second will be a chest patch which houses both electrodes and pressure sensors for the synchronous measurements of ECG and seismocardiogram (SCG) such that beat-to-beat blood pressure can be inferred from the time interval between the R peak of the ECG and the AC peak of the SCG. The last example will be a highly conformable, low power consumption epidermal heater for thermal therapy.

  7. Resistive Memory for Harsh Electronics: Immunity to Surface Effect and High Corrosion Resistance via Surface Modification

    Science.gov (United States)

    Huang, Teng-Han; Yang, Po-Kang; Lien, Der-Hsien; Kang, Chen-Fang; Tsai, Meng-Lin; Chueh, Yu-Lun; He-Hau, Jr.

    2014-03-01

    The tolerance/resistance of the electronic devices to extremely harsh environments is of supreme interest. Surface effects and chemical corrosion adversely affect stability and operation uniformity of metal oxide resistive memories. To achieve the surrounding-independent behavior, the surface modification is introduced into the ZnO memristors via incorporating fluorine to replace the oxygen sites. F-Zn bonds is formed to prevent oxygen chemisorption and ZnO dissolution upon corrosive atmospheric exposure, which effectively improves switching characteristics against harmful surroundings. In addition, the fluorine doping stabilizes the cycling endurance and narrows the distribution of switching parameters. The outcomes provide valuable insights for future nonvolatile memory developments in harsh electronics.

  8. Surface science analysis of GaAs photocathodes following sustained electron beam delivery

    Energy Technology Data Exchange (ETDEWEB)

    Carlos Hernandez-Garcia, Fay Hannon, Marcy Stutzman, V. Shutthanandan, Z. Zhu, M. Nandasri, S. V. Kuchibhatla, S. Thevuthasan, W. P. Hess

    2012-06-01

    Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power Free Electron Lasers (FEL). Photocathode quantum efficiency (QE) degradation is due to residual gasses in the electron source vacuum system being ionized and accelerated back to the photocathode. These investigations are a first attempt to characterize the nature of the photocathode degradation, and employ multiple surface and bulk analysis techniques to investigate damage mechanisms including sputtering of the Cs-oxidant surface monolayer, other surface chemistry effects, and ion implantation. Surface and bulk analysis studies were conducted on two GaAs photocathodes, which were removed from the JLab FEL DC photoemission gun after delivering electron beam, and two control samples. The analysis techniques include Helium Ion Microscopy (HIM), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Secondary Ion Mass Spectrometry (SIMS). In addition, two high-polarization strained superlattice GaAs photocathode samples, one removed from the Continuous Electron Beam Accelerator Facility (CEBAF) photoinjector and one unused, were also analyzed using Transmission Electron Microscopy (TEM) and SIMS. It was found that heat cleaning the FEL GaAs wafer introduces surface roughness, which seems to be reduced by prolonged use. The bulk GaAs samples retained a fairly well organized crystalline structure after delivering beam but shows evidence of Cs depletion on the surface. Within the precision of the SIMS and RBS measurements the data showed no indication of hydrogen implantation or lattice damage from ion back bombardment in the bulk GaAs wafers. In contrast, SIMS and TEM measurements of the strained superlattice photocathode show clear crystal damage in the wafer from ion back bombardment.

  9. Surface science analysis of GaAs photocathodes following sustained electron beam delivery

    Directory of Open Access Journals (Sweden)

    V. Shutthanandan

    2012-06-01

    Full Text Available Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power free electron lasers (FEL. Photocathode quantum efficiency degradation is due to residual gases in the electron source vacuum system being ionized and accelerated back to the photocathode. These investigations are a first attempt to characterize the nature of the photocathode degradation, and employ multiple surface and bulk analysis techniques to investigate damage mechanisms including sputtering of the Cs-oxidant surface monolayer, other surface chemistry effects, and ion implantation. Surface and bulk analysis studies were conducted on two GaAs photocathodes, which were removed from the JLab FEL DC photoemission gun after delivering electron beam, and two control samples. The analysis techniques include helium ion microscopy, Rutherford backscattering spectrometry (RBS, atomic force microscopy, and secondary ion mass spectrometry (SIMS. In addition, two high-polarization strained superlattice GaAs photocathode samples, one removed from the continuous electron beam accelerator facility (CEBAF photoinjector and one unused, were also analyzed using transmission electron microscopy (TEM and SIMS. It was found that heat cleaning the FEL GaAs wafer introduces surface roughness, which seems to be reduced by prolonged use. The bulk GaAs samples retained a fairly well organized crystalline structure after delivering beam but show evidence of Cs depletion on the surface. Within the precision of the SIMS and RBS measurements, the data showed no indication of hydrogen implantation or lattice damage from ion back bombardment in the bulk GaAs wafers. In contrast, SIMS and TEM measurements of the strained superlattice photocathode show clear crystal damage in the wafer from ion back bombardment.

  10. Surface science analysis of GaAs photocathodes following sustained electron beam delivery

    Energy Technology Data Exchange (ETDEWEB)

    Carlos Hernandez-Garcia, Fay Hannon, Marcy Stutzman, V. Shutthanandan, Z. Zhu, M. Nandasri, S. V. Kuchibhatla, S. Thevuthasan, W. P. Hess

    2012-06-01

    Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power Free Electron Lasers (FEL). Photocathode quantum efficiency (QE) degradation is due to residual gasses in the electron source vacuum system being ionized and accelerated back to the photocathode. These investigations are a first attempt to characterize the nature of the photocathode degradation, and employ multiple surface and bulk analysis techniques to investigate damage mechanisms including sputtering of the Cs-oxidant surface monolayer, other surface chemistry effects, and ion implantation. Surface and bulk analysis studies were conducted on two GaAs photocathodes, which were removed from the JLab FEL DC photoemission gun after delivering electron beam, and two control samples. The analysis techniques include Helium Ion Microscopy (HIM), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Secondary Ion Mass Spectrometry (SIMS). In addition, two high-polarization strained superlattice GaAs photocathode samples, one removed from the Continuous Electron Beam Accelerator Facility (CEBAF) photoinjector and one unused, were also analyzed using Transmission Electron Microscopy (TEM) and SIMS. It was found that heat cleaning the FEL GaAs wafer introduces surface roughness, which seems to be reduced by prolonged use. The bulk GaAs samples retained a fairly well organized crystalline structure after delivering beam but shows evidence of Cs depletion on the surface. Within the precision of the SIMS and RBS measurements the data showed no indication of hydrogen implantation or lattice damage from ion back bombardment in the bulk GaAs wafers. In contrast, SIMS and TEM measurements of the strained superlattice photocathode show clear crystal damage in the wafer from ion back bombardment.

  11. Preparation of cluster states with trapped electrons on a liquid helium surface

    Institute of Scientific and Technical Information of China (English)

    Ai Ling-Yan; Shi Yan-Li; Zhang Zhi-Ming

    2011-01-01

    We present a scheme for the preparation of one-dimensional (1D) and two-dimensional (2D) cluster states with electrons trapped on a liquid helium surface and driven by a classical laser beam.The two lowest levels of the vertical motion of the electron act as a two-level system,and the quantized vibration of the electron along one of the parallel directions (the x direction) serves as the bosonic mode.The degrees of freedom of the vertical and parallel motions of the trapped electron can be coupled together by a classical laser field.With the proper frequency of the laser field,the cluster states can be realized.

  12. Band structure and Fermi surface of electron-doped C60 monolayers.

    Science.gov (United States)

    Yang, W L; Brouet, V; Zhou, X J; Choi, Hyoung J; Louie, Steven G; Cohen, Marvin L; Kellar, S A; Bogdanov, P V; Lanzara, A; Goldoni, A; Parmigiani, F; Hussain, Z; Shen, Z-X

    2003-04-11

    C60 fullerides are challenging systems because both the electron-phonon and electron-electron interactions are large on the energy scale of the expected narrow band width. We report angle-resolved photoemission data on the band dispersion for an alkali-doped C60 monolayer and a detailed comparison with theory. Compared to the maximum bare theoretical band width of 170 meV, the observed 100-meV dispersion is within the range of renormalization by electron-phonon coupling. This dispersion is only a fraction of the integrated peak width, revealing the importance of many-body effects. Additionally, measurements on the Fermi surface indicate the robustness of the Luttinger theorem even for materials with strong interactions.

  13. Double ionization of two-electron systems

    Energy Technology Data Exchange (ETDEWEB)

    Ancarani, L U; Cappello, C Dal [Laboratoire de Physique Moleculaire et des Collisions, Universite Paul Verlaine - Metz, 57078 Metz (France); Gasaneo, G, E-mail: ancarani@univ-metz.f [Departamento de Fisica, Universidad Nacional del Sur and Consejo Nacional de Investigaciones CientIficas y Tecnicas, 8000 BahIa Blanca, Buenos Aires (Argentina)

    2010-02-01

    We address various issues related to the double ionization by electron impact of two-electron systems. The emphasis will be put on the theoretical description of high incident energy (e,3e) processes, for which the first Born approximation should be suitable. In the case of helium, absolute experimental data for fivefold differential cross sections are available in coplanar geometry. We will review and discuss the divergencies existing between the results obtained with different theoretical models, and those appearing when compared to the experiments in particular with respect to the absolute scale. We will then discuss some results obtained in a recently proposed out of plane geometry.

  14. The Small Explorer power system electronics

    Science.gov (United States)

    Dakermanji, G.; Carlsson, U.; Temkin, D.; Culver, H.; Rodriguez, G. E.; Ahmad, A.

    1991-01-01

    The power system electronics for the NASA Goddard Space Flight Center Small Explorer Satellites are intended to satisfy various planned missions. The selected topology is a direct energy transfer (DET) system with the battery connected directly to the bus. The shunt control technique is a linear sequential full shunt which provides a simple solar array interface and can support both 3 axis stabilized and spinner satellites. In addition, it can meet stringent electromagnetic interference requirements which are expected on some Small Explorer Missions. The Power Systems Electronics (PSE) performs battery charge control using both temperature compensated charge/discharge ratio ampere hour integration and voltage-temperature control. The PSE includes all the circuits needed to perform telemetry and command functions using an optical MIL-STD-1773 interface.

  15. Tutorial: Radiation Effects in Electronic Systems

    Science.gov (United States)

    Pellish, Jonathan A.

    2017-01-01

    This tutorial presentation will give an overview of radiation effects in electrical, electronic, and electromechanical (EEE) components as it applies to civilian space systems of varying size and complexity. The natural space environment presents many unique threats to electronic systems regardless of where the systems operate from low-Earth orbit to interplanetary space. The presentation will cover several topics, including: an overview and introduction to the applicable space radiation environments common to a broad range of mission designs; definitions and impacts of effects due to impinging particles in the space environment e.g., total ionizing dose (TID), total non-ionizing dose (TNID), and single-event effects (SEE); and, testing for and evaluation of TID, TNID, and SEE in EEE components.

  16. 42 CFR 456.722 - Electronic claims management system.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Electronic claims management system. 456.722... Electronic Claims Management System for Outpatient Drug Claims § 456.722 Electronic claims management system... electronic claims management (ECM) system to perform on-line, real-time (that is, immediate)...

  17. The Helium Field Effect Transistor (II): Gated Transport of Surface-State Electrons Through Micro-constrictions

    Science.gov (United States)

    Shaban, F.; Ashari, M.; Lorenz, T.; Rau, R.; Scheer, E.; Kono, K.; Rees, D. G.; Leiderer, P.

    2016-11-01

    We present transport measurements of surface-state electrons on liquid helium films in confined geometry. The measurements are taken using split-gate devices similar to a field effect transistor. The number of electrons passing between the source and drain areas of the device can be precisely controlled by changing the length of the voltage pulse applied to the gate electrode. We find evidence that the effective driving potential depends on electron-electron interactions, as well as the electric field applied to the substrate. Our measurements indicate that the mobility of electrons on helium films can be high and that microfabricated transistor devices allow electron manipulation on length scales close to the interelectron separation. Our experiment is an important step toward investigations of surface-state electron properties at much higher densities, for which the quantum melting of the system to a degenerate Fermi gas should be observed.

  18. Electronic structure, molecular bonding and potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ruedenberg, K. [Ames Laboratory, IA (United States)

    1993-12-01

    By virtue of the universal validity of the generalized Born-Oppenheimer separation, potential energy surfaces (PES`) represent the central conceptual as well as quantitative entities of chemical physics and provide the basis for the understanding of most physicochemical phenomena in many diverse fields. The research in this group deals with the elucidation of general properties of PES` as well as with the quantitative determination of PES` for concrete systems, in particular pertaining to reactions involving carbon, oxygen, nitrogen and hydrogen molecules.

  19. Surface magnetism Correlation of structural, electronic and chemical properties with magnetic behavior

    CERN Document Server

    Getzlaff, Mathias

    2010-01-01

    This volume reviews on selected aspects related to surface magnetism, a field of extraordinary interest during the last decade. The special emphasis is set to the correlation of structural, electronic and magnetic properties in rare earth metal systems and ferromagnetic transition metals. This is made possible by the combination of electron emission techniques (spin polarized photoelectron spectroscopy, magnetic dichroism in photoemission and spin polarized metastable deexcitation spectroscopy) and local probes with high lateral resolution down to the atomic scale (spin polarized scanning tunneling microscopy / spectroscopy).

  20. Fabrication and electronic transport studies of single nanocrystal systems

    Energy Technology Data Exchange (ETDEWEB)

    Klein, David Louis [Univ. of California, Berkeley, CA (United States). Dept. of Physics

    1997-05-01

    Semiconductor and metallic nanocrystals exhibit interesting electronic transport behavior as a result of electrostatic and quantum mechanical confinement effects. These effects can be studied to learn about the nature of electronic states in these systems. This thesis describes several techniques for the electronic study of nanocrystals. The primary focus is the development of novel methods to attach leads to prefabricated nanocrystals. This is because, while nanocrystals can be readily synthesized from a variety of materials with excellent size control, means to make electrical contact to these nanocrystals are limited. The first approach that will be described uses scanning probe microscopy to first image and then electrically probe surfaces. It is found that electronic investigations of nanocrystals by this technique are complicated by tip-sample interactions and environmental factors such as salvation and capillary forces. Next, an atomic force microscope technique for the catalytic patterning of the surface of a self assembled monolayer is described. In principle, this nano-fabrication technique can be used to create electronic devices which are based upon complex arrangements of nanocrystals. Finally, the fabrication and electrical characterization of a nanocrystal-based single electron transistor is presented. This device is fabricated using a hybrid scheme which combines electron beam lithography and wet chemistry to bind single nanocrystals in tunneling contact between closely spaced metallic leads. In these devices, both Au and CdSe nanocrystals show Coulomb blockade effects with characteristic energies of several tens of meV. Additional structure is seen the transport behavior of CdSe nanocrystals as a result of its electronic structure.

  1. Ultrafast time-resolved electron diffraction on adsorbate systems on silicon surfaces. Vibrational excitation in monllayers and dynamics of phase transitions; Ultraschnelle zeitaufgeloeste Elektronenbeugung an Adsorbatsystemen auf Siliziumoberflaechen. Vibrationsanregung in Monolagen und Dynamik von Phasenuebergaengen

    Energy Technology Data Exchange (ETDEWEB)

    Moellenbeck, Simone

    2011-04-11

    surface phase transitions was analysed for the first time with TR-RHEED. As a first modell system, the Si(0 0 1) c(4 x 2)-(2 x 1) order disorder phase transition was analyzed. The dynamics of this phase transition can be observed with TR-RHEED, as the Laue rings on which the c(4 x 2)-spots are located vanishes almost completely in the temporal overlap. The observed intensity decrease of the (2 x 1)-reflexes is however quiet small. Due to the direct bandgap of Silicon, a direct absorption of the photons in the Silicon substrate can be excluded. Instead, the excitation of the phase transition is explained by absorption in the surface state of the tilted dimer. Furthermore, the Peierls like phase transition of In/Si(1 1 1) (4 x 1)-(8 x ''2'') was analyzed in detail. This phase transition can be observed excellently in TR-RHEED: the diffraction spots of the (8 x ''2'')-reconstruction vanish whereas the intensity of the (4 x 1)-spots increases simultaneously. The intensity increase cannot be explained with a simple Debye-Waller effect. A real structural transiton at the surface takes place. Fluence and base temperature dependent measurements are presented to confirm, that the electronic excitation instead of thermal excitation destroys the low temperature phase. Furthermore, a complete structural formation of the (8 x ''2'')-reconstruction (time constant of approx. 500 ps) and growth from seeds around adsorbates (down to 50 ps) can be distinguished. In addition, the thermal cooling before the structural change can be observed when the surface is heated above the phase transition temperature (time constant up to 2000 ps). (orig.)

  2. Electronic stopping of keV nitrogen ions interacting with a Pt(110) (1 x 2) surface - a tool to characterize electronic surfaces

    NARCIS (Netherlands)

    Robin, A; Postnikov, AV; Heiland, W

    2005-01-01

    Ion channeling is used to investigate the electronic density corrugation at surfaces by analysing the electronic stopping behaviour of ions scattering grazingly off a clean single crystalline Pt(110)(1 x 2) surface. We use the fact that under these conditions the elastic contribution can be separate

  3. Surface trap mediated electronic transport in biofunctionalized silicon nanowires

    Science.gov (United States)

    Puppo, F.; Traversa, F. L.; Di Ventra, M.; De Micheli, G.; Carrara, S.

    2016-08-01

    Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with biological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs, featuring memristive-like behavior in bare conditions, show, in the presence of biomarkers, modified hysteresis and, more importantly, a voltage memory component, namely a voltage gap. The voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its high-resolution dependence on charges in proximity of the wire. This unique approach of sensing has never been studied and adopted before. Here, we propose a physical model of the surface electronic transport in Schottky barrier SiNW biosensors, aiming at reproducing and understanding the voltage gap based behavior. The implemented model describes well the experimental I-V characteristics of the device. It also links the modification of the voltage gap to the changing concentration of antigens by showing the decrease of this parameter in response to increasing concentrations of the molecules that are detected with femtomolar resolution in real human samples. Both experiments and simulations highlight the predominant role of the dynamic recombination of the nanowire surface states, with the incoming external charges from bio-species, in the appearance and modification of the voltage gap. Finally, thanks to its compactness, and strict correlation with the physics of the nanodevice, this model can be used to describe and predict the I-V characteristics in other nanostructured devices, for different than antibody-based sensing as well as electronic applications.

  4. Recent perspectives of electronic medical record systems.

    Science.gov (United States)

    Zhang, Xiao-Ying; Zhang, Peiying

    2016-06-01

    Implementation of electronic medical record (EMR) systems within developing contexts as part of efforts to monitor and facilitate the attainment of health-related aims has been on the increase. However, these efforts have been concentrated on urban hospitals. Recent findings showed that development processes of EMR systems are associated with various discrepancies between protocols and work practices. These discrepancies were mainly caused by factors including high workload, lack of medical resources, misunderstanding of the protocols by health workers, and client/patient practices. The present review focused on the effects of EMRs on patient care work, and on appropriate EMR designs principles and strategies to ameliorate these systems.

  5. NASA Electronic Library System (NELS) optimization

    Science.gov (United States)

    Pribyl, William L.

    1993-01-01

    This is a compilation of NELS (NASA Electronic Library System) Optimization progress/problem, interim, and final reports for all phases. The NELS database was examined, particularly in the memory, disk contention, and CPU, to discover bottlenecks. Methods to increase the speed of NELS code were investigated. The tasks included restructuring the existing code to interact with others more effectively. An error reporting code to help detect and remove bugs in the NELS was added. Report writing tools were recommended to integrate with the ASV3 system. The Oracle database management system and tools were to be installed on a Sun workstation, intended for demonstration purposes.

  6. Surface treatment of 0.20% C carbon steel by high-current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    XU Guo-cheng; FU Shi-you; GUAN Qing-feng

    2006-01-01

    A high-current pulsed electron beam(HCPEB) generated on the system of Nadezhda-2 was applied to improve the microstructure and performance of 0.20% C low carbon steel. Surface layers of the samples bombarded by explosive electron beam at different pulses was observed by using electron microscopy. The physical model of the thermal-stress process and related modification mechanism as a result of HCPEB irradiation was also investigated. After HCPEB post treatments, obvious changes in microstructure and significant hardening occur in the depth of 200-250 μm from the surface after HCPEB irradiation. Rapid heating and subsequent rapid solidification induce heavy plastic deformation, which results in that the laminated structure of pearlite is substituted by dispersive rounded-like cementites in the near-surface. The effect of HCPEB treatment can reach more than 500 m depth from the surface. The original crystalline structure is changed to a different degree that grows with the numbers of bombardment, and in the surface layer amorphous states and nanocrystaline structures consisting of grains of γ-phase and cementite are found. The violent stress induced by HCPEB irradiation is the origin of the nanostructured and amorphous structure formation.

  7. Cryofree Toploading Rotator System for High-Throughput Study of Novel Low-Dimensional Electron Systems

    Science.gov (United States)

    2015-01-30

    Composite fermions and broken symmetries in graphene , Nature Communications, (02 2014): 5838. doi: 10.1038/ncomms6838 TOTAL: 1 Received Paper...Watanabe, Takashi Taniguchi, David Goldhaber-Gordon. A high-mobility electronic system at an electrolyte -gated oxide surface, arXiv:1410.3034 (10 2014...detailed information about electronic behavior can be extracted. Secondly, we are in the process of integrating onto one of the probes a cryogenic two

  8. Metastable and spin-polarized states in electron systems with localized electron-electron interaction

    Science.gov (United States)

    Sablikov, Vladimir A.; Shchamkhalova, Bagun S.

    2014-05-01

    We study the formation of spontaneous spin polarization in inhomogeneous electron systems with pair interaction localized in a small region that is not separated by a barrier from surrounding gas of non-interacting electrons. Such a system is interesting as a minimal model of a quantum point contact in which the electron-electron interaction is strong in a small constriction coupled to electron reservoirs without barriers. Based on the analysis of the grand potential within the self-consistent field approximation, we find that the formation of the polarized state strongly differs from the Bloch or Stoner transition in homogeneous interacting systems. The main difference is that a metastable state appears in the critical point in addition to the globally stable state, so that when the interaction parameter exceeds a critical value, two states coexist. One state has spin polarization and the other is unpolarized. Another feature is that the spin polarization increases continuously with the interaction parameter and has a square-root singularity in the critical point. We study the critical conditions and the grand potentials of the polarized and unpolarized states for one-dimensional and two-dimensional models in the case of extremely small size of the interaction region.

  9. Electron-hole interaction and optical excitations in solids, surfaces, and polymers

    OpenAIRE

    Louie, S. G.

    2001-01-01

    The optical properties of a variety of materials have been calculated using a recently developed ab initio method based on solving the Bethe-Salpeter equation of the two-particle Green's functions. Relevant self-energy and electron-hole interaction effects are included from first-principles. Results on selected semiconductors, insulators, surfaces, and conjugated polymers are discussed. In many of these systems, excitonic effects are shown to dramatically alter the excitation energies a...

  10. Electron-hole interaction and optical excitations in solids, surfaces, and polymers

    OpenAIRE

    Louie, S. G.

    2001-01-01

    The optical properties of a variety of materials have been calculated using a recently developed ab initio method based on solving the Bethe-Salpeter equation of the two-particle Green's functions. Relevant self-energy and electron-hole interaction effects are included from first-principles. Results on selected semiconductors, insulators, surfaces, and conjugated polymers are discussed. In many of these systems, excitonic effects are shown to dramatically alter the excitation energies a...

  11. Database for Simulation of Electron Spectra for Surface Analysis (SESSA)Database for Simulation of Electron Spectra for Surface Analysis (SESSA)

    Science.gov (United States)

    SRD 100 Database for Simulation of Electron Spectra for Surface Analysis (SESSA)Database for Simulation of Electron Spectra for Surface Analysis (SESSA) (PC database for purchase)   This database has been designed to facilitate quantitative interpretation of Auger-electron and X-ray photoelectron spectra and to improve the accuracy of quantitation in routine analysis. The database contains all physical data needed to perform quantitative interpretation of an electron spectrum for a thin-film specimen of given composition. A simulation module provides an estimate of peak intensities as well as the energy and angular distributions of the emitted electron flux.

  12. Microfluidic system for transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ring, Elisabeth A [ORNL; De Jonge, Niels [ORNL

    2010-01-01

    We present a microfluidic system that maintains liquid flow in a specimen chamber for (scanning) transmission electron microscope ((S)TEM) imaging. The specimen chamber consists of two ultra-thin silicon nitride windows supported by silicon microchips. They are placed in a specimen holder that seals the sample from the vacuum in the electron microscope, and incorporates tubing to and from the sample connected to a syringe pump outside the microscope. Using results obtained from fluorescence microscopy of microspheres flowing through the system, an equation to characterize the liquid flow through the system was calibrated. Gold nanoparticles of diameters of 30 and 100 nm moving in liquid were imaged with a 200 kV STEM. It was concluded that despite strong influences from Brownian motion, and sensitivity to small changes in the depth of the bypass channel, the electron microscopy flow data matched the calculated flow speed within an order of magnitude. The system allows for rapid (within a minute) liquid exchange, which can potentially be used, for example, to investigate the response of specimens, e.g., eukaryotic-, or bacterial cells, to certain stimuli.

  13. Quantum frustrated and correlated electron systems

    Directory of Open Access Journals (Sweden)

    P Thalmeier

    2008-06-01

    Full Text Available  Quantum phases and fluctuations in correlated electron systems with frustration and competing interactions are reviewed. In the localized moment case the S=1/2 J1 - J2 - model on a square lattice exhibits a rich phase diagram with magnetic as well as exotic hidden order phases due to the interplay of frustration and quantum fluctuations. Their signature in magnetocaloric quantities and the high field magnetization are surveyed. The possible quantum phase transitions are discussed and applied to layered vanadium oxides. In itinerant electron systems frustration is an emergent property caused by electron correlations. It leads to enhanced spin fluctuations in a very large region of momentum space and therefore may cause heavy fermion type low temperature anomalies as in the 3d spinel compound LiV2O4 . Competing on-site and inter-site electronic interactions in Kondo compounds are responsible for the quantum phase transition between nonmagnetic Kondo singlet phase and magnetic phase such as observed in many 4f compounds. They may be described by Kondo lattice and simplified Kondo necklace type models. Their quantum phase transitions are investigated by numerical exact diagonalization and analytical bond operator methods respectively.

  14. Oxide/Water Interfaces: How the Surface Chemistry Modifies the Electronic Energy Alignment

    Science.gov (United States)

    Sprik, Michiel

    2014-03-01

    The minimum of the d-electron conduction band of an aqueous transition metal oxide electrode is typically no more than a few 100 mV away from the standard hydrogen electrode (SHE). Because of this favourable alignment of the electronic energy levels (near) metallic transition metal oxides with partly filled d bands can be used as electrocatalysts while the compounds with finite electronic gap can be used as photocatalysts. However, because of their ionic character, transition metal-oxide surfaces also show amphiphilic acid-base activity. At low pH the basic sites are protonated and at high pH the acidic sites deprotonated creating an electrical double layer with corresponding surface potential. The alignment of the electronic energy levels, and by implication their redox activity, is therefore pH dependent. In fact, even in absence of protonic surface charge, the coordination with water molecules is already capable of shifting the electronic energy levels of the oxide by 1 eV or more. Computation of the electronic energies in transition metal oxide electrodes requires therefore a detailed modeling of their aqueous surface chemistry. The solvation energy of the proton is the common energy reference for both redox potentials on the SHE scale and acidity constants (pKa). Computation of the H+ solvation energy is therefore a key component in a unified treatment of redox and acid-base chemistry. In this talk we outline the Density Functional Theory based Molecular Dynamics (DFTMD) method we have developed for this purpose. The central tool of our approach is a method for reversible insertion of protons in the aqueous part of the DFTMD model system. As an illustration we discuss the application to the rutile TiO2/water and MnO2/water interface.

  15. The near-surface electron radiation environment of Saturn's moon Mimas

    Science.gov (United States)

    Nordheim, Tom; Hand, Kevin P.; Paranicas, Christopher; Howett, Carly; Hendrix, Amanda R.; Jones, Geraint H.; Coates, Andrew

    2016-10-01

    Introduction: Saturn's inner mid-size moons are exposed to a number of external weathering processes, including charged particle bombardment and UV photolysis, as well as deposition of E ring grains and interplanetary dust. While optical remote sensing observations by several instruments onboard the Cassini spacecraft have revealed a number of weathering patterns across the surfaces of these moons, it is currently not entirely clear which external process is responsible for which observed weathering pattern. Here we focus on Saturn's moon Mimas and model the effect of energetic electron bombardment across its surface. Our results are discussed in the context of previously reported Cassini remote sensing observations of Mimas.Methods: To model the access of energetic electrons to different surface locations we used a guiding center, bounce-averaged approach which has previously been employed for the Jovian and Saturnian moons. The electron spectrum at the orbit of Mimas was implemented according to the fit functions provided by, which are based on averaged measurements from the Cassini Magnetospheric Imaging Instrument (MIMI) Low Energy Magnetospheric Measurement System (LEMMS) at a narrow corridor near the orbit of Mimas (~3.08 Rs) during the period 2004-2013. The interaction of electrons with the surface of Mimas was implemented using the PLANETOCOSMICS code, which is based on the Geant4 toolkit.Results: We predict a lens-shaped electron energy deposition pattern which extends down to ~cm depths at low latitudes near the center of the leading hemisphere. These results are consistent with previous remote sensing observations of a lens-shaped color anomaly [4] as well as a thermal inertia anomaly at this location. At the trailing hemisphere, we predict a similar lens-shaped electron energy deposition pattern, which to date has not been observed by the Cassini optical remote sensing instruments. We suggest that no corresponding lens-shaped weathering pattern has been

  16. Electronic tunneling through a potential barrier on the surface of a topological insulator

    Science.gov (United States)

    Zhou, Benliang; Zhou, Benhu; Zhou, Guanghui

    2016-12-01

    We investigate the tunneling transport for electrons on the surface of a topological insulator (TI) through an electrostatic potential barrier. By using the Dirac equation with the continuity conditions for all segments of wave functions at the interfaces between regions inside and outside the barrier, we calculate analytically the transmission probability and conductance for the system. It is demonstrated that, the Klein paradox can also been observed in the system same as in graphene system. Interestingly, the conductance reaches the minimum value when the incident electron energy is equal to the barrier strength. Moreover, with increasing barrier width, the conductance turns up some tunneling oscillation peaks, and larger barrier strength can cause lower conductance, shorter period but larger oscillation amplitude. The oscillation amplitude decreases as the barrier width increases, which is similar as that of the system consisting of the compressive uniaxial strain applied on a TI, but somewhat different from that of graphene system where the oscillation amplitude is a constant. The findings here imply that an electrostatic barrier can greatly influence the electron tunneling transport of the system, and may provide a new way to realize directional filtering of electrons.

  17. High-energy photoemission spectroscopy for investigating bulk electronic structures of strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Sekiyama, Akira, E-mail: sekiyama@mp.es.osaka-u.ac.jp [Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka (Japan); SPring-8/RIKEN, Sayo 679-5148, Hyogo (Japan)

    2016-04-15

    Progress of high-energy photoemission spectroscopy for investigating the bulk electronic structures of strongly correlated electron systems is reviewed. High-resolution soft X-ray photoemission has opened the door for revealing the bulk strongly correlated spectral functions overcoming the surface contributions. More bulk-sensitive hard X-ray photoemission spectroscopy (HAXPES) enables us to study the electronic structure with negligible surface contribution. The recent development of the polarization-dependent HAXPES is also described in this short review.

  18. Excitation of surface plasmon polaritons by electron beam with graphene ribbon arrays

    Science.gov (United States)

    Liu, Yong-Qiang; Liu, Pu-Kun

    2017-03-01

    Graphene has emerged as an alternative material to support surface plasmon polaritons (SPPs) with its excellent properties such as the tight electromagnetic field localization, low dissipative loss, and versatile tunability. Thus, graphene surface plasmon polaritons (GSPs) provide an exciting platform to develop a series of novel devices and systems from the optical band to the terahertz (THz) band. In this paper, theoretical and simulated studies about the excitation of SPPs by an injected electron beam with periodic graphene ribbon arrays deposited on a dielectric medium are presented. The analytical dispersion expression of the GSP mode on the graphene ribbon arrays is obtained by using a modal expansion method along with periodic boundary conditions in the structure. With this result, the dispersion relation, propagation loss, and field pattern of the propagating GSPs for both periodic graphene microribbon arrays and the complete graphene sheet are investigated and analyzed in the THz band. It is shown that the electromagnetic field with a better concentration on the interface can be realized with graphene ribbon arrays compared with the graphene sheet for a given frequency. Besides, the excitation of GSPs by an injected electron beam with graphene ribbon arrays is modeled and implemented by the particle-in-cell simulation based on the finite difference time domain algorithm. GSPs can be excited effectively when the dispersion line of the electron beam and SPPs on the graphene ribbon arrays is matched with each other well. Besides, the dependences of output power on electron beam parameters such as the distance of the electron beam above the graphene ribbon surface and beam voltage are studied and analyzed. Finally, the tunability of graphene conductivity via biased voltage with a ground metal is considered and the tunable excitation of GSPs on the structure with biased drive voltage by the injected electron beam is also realized. The present work can find a

  19. Decal Electronics: Printable Packaged with 3D Printing High-Performance Flexible CMOS Electronic Systems

    KAUST Repository

    Sevilla, Galo T.

    2016-10-14

    High-performance complementary metal oxide semiconductor electronics are flexed, packaged using 3D printing as decal electronics, and then printed in roll-to-roll fashion for highly manufacturable printed flexible high-performance electronic systems.

  20. Electronic Document Management Using Inverted Files System

    Science.gov (United States)

    Suhartono, Derwin; Setiawan, Erwin; Irwanto, Djon

    2014-03-01

    The amount of documents increases so fast. Those documents exist not only in a paper based but also in an electronic based. It can be seen from the data sample taken by the SpringerLink publisher in 2010, which showed an increase in the number of digital document collections from 2003 to mid of 2010. Then, how to manage them well becomes an important need. This paper describes a new method in managing documents called as inverted files system. Related with the electronic based document, the inverted files system will closely used in term of its usage to document so that it can be searched over the Internet using the Search Engine. It can improve document search mechanism and document save mechanism.

  1. Electronic Document Management Using Inverted Files System

    Directory of Open Access Journals (Sweden)

    Suhartono Derwin

    2014-03-01

    Full Text Available The amount of documents increases so fast. Those documents exist not only in a paper based but also in an electronic based. It can be seen from the data sample taken by the SpringerLink publisher in 2010, which showed an increase in the number of digital document collections from 2003 to mid of 2010. Then, how to manage them well becomes an important need. This paper describes a new method in managing documents called as inverted files system. Related with the electronic based document, the inverted files system will closely used in term of its usage to document so that it can be searched over the Internet using the Search Engine. It can improve document search mechanism and document save mechanism.

  2. Surface plasmon modes of a single silver nanorod: An electron energy loss study

    DEFF Research Database (Denmark)

    Nicoletti, Olivia; Wubs, Martijn; Mortensen, N. Asger;

    2011-01-01

    We present an electron energy loss study using energy filtered TEM of spatially resolved surface plasmon excitations on a silver nanorod of aspect ratio 14.2 resting on a 30 nm thick silicon nitride membrane. Our results show that the excitation is quantized as resonant modes whose intensity maxima...... vary along the nanorod's length and whose wavelength becomes compressed towards the ends of the nanorod. Theoretical calculations modelling the surface plasmon response of the silver nanorodsilicon nitride system show the importance of including retardation and substrate effects in order to describe...

  3. Electronic circuits for communications systems: A compilation

    Science.gov (United States)

    1972-01-01

    The compilation of electronic circuits for communications systems is divided into thirteen basic categories, each representing an area of circuit design and application. The compilation items are moderately complex and, as such, would appeal to the applications engineer. However, the rationale for the selection criteria was tailored so that the circuits would reflect fundamental design principles and applications, with an additional requirement for simplicity whenever possible.

  4. Rapid electron exchange between surface-exposed bacterial cytochromes and Fe(III) minerals

    Science.gov (United States)

    White, Gaye F.; Shi, Zhi; Shi, Liang; Wang, Zheming; Dohnalkova, Alice C.; Marshall, Matthew J.; Fredrickson, James K.; Zachara, John M.; Butt, Julea N.; Richardson, David J.; Clarke, Thomas A.

    2013-04-01

    The mineral-respiring bacterium Shewanella oneidensis uses a protein complex, MtrCAB, composed of two decaheme cytochromes, MtrC and MtrA, brought together inside a transmembrane porin, MtrB, to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. A proteoliposome system containing a pool of internalized electron carriers was used to investigate how the topology of the MtrCAB complex relates to its ability to transport electrons across a lipid bilayer to externally located Fe(III) oxides. With MtrA facing the interior and MtrC exposed on the outer surface of the phospholipid bilayer, the established in vivo orientation, electron transfer from the interior electron carrier pool through MtrCAB to solid-phase Fe(III) oxides was demonstrated. The rates were 103 times higher than those reported for reduction of goethite, hematite, and lepidocrocite by S. oneidensis, and the order of the reaction rates was consistent with those observed in S. oneidensis cultures. In contrast, established rates for single turnover reactions between purified MtrC and Fe(III) oxides were 103 times lower. By providing a continuous flow of electrons, the proteoliposome experiments demonstrate that conduction through MtrCAB directly to Fe(III) oxides is sufficient to support in vivo, anaerobic, solid-phase iron respiration.

  5. Electron dynamics in the normal state of cuprates: Spectral function, Fermi surface and ARPES data

    Science.gov (United States)

    Zubov, E. E.

    2016-11-01

    An influence of the electron-phonon interaction on excitation spectrum and damping in a narrow band electron subsystem of cuprates has been investigated. Within the framework of the t-J model an approach to solving a problem of account of both strong electron correlations and local electron-phonon binding with characteristic Einstein mode ω0 in the normal state has been presented. In approximation Hubbard-I it was found an exact solution for the polaron bands. We established that in the low-dimensional system with a pure kinematic part of Hamiltonian a complicated excitation spectrum is realized. It is determined mainly by peculiarities of the lattice Green's function. In the definite area of the electron concentration and hopping integrals a correlation gap may be possible on the Fermi level. Also, in specific cases it is observed a doping evolution of the Fermi surface. We found that the strong electron-phonon binding enforces a degree of coherence of electron-polaron excitations near the Fermi level and spectrum along the nodal direction depends on wave vector module weakly. It corresponds to ARPES data. A possible origin of the experimentally observed kink in the nodal direction of cuprates is explained by fine structure of the polaron band to be formed near the mode -ω0.

  6. Automatic Checkout System for Ground Electronics of a Weapon System (Short Communication

    Directory of Open Access Journals (Sweden)

    V. Ashok Kumar

    1997-04-01

    Full Text Available An automatic checkout system (ACOS designed and developed for a surface-to-air missile system is described. The system has a built-in self-check and has been extensively used for checking faults in the subsystems of ground electronics. It has resulted in saving a lot of effort in quickly diagnosing and rectifying faults. The salient features of the ACOS have been described and the scope for further work in this area has been outline.

  7. Atomic and electronic structure of molybdenum carbide phases: bulk and low Miller-index surfaces.

    Science.gov (United States)

    Politi, José Roberto dos Santos; Viñes, Francesc; Rodriguez, Jose A; Illas, Francesc

    2013-08-14

    The geometric and electronic structure of catalytically relevant molybdenum carbide phases (cubic δ-MoC, hexagonal α-MoC, and orthorhombic β-Mo2C) and their low Miller-index surfaces have been investigated by means of periodic density functional theory (DFT) based calculations with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional. Comparison to available experimental data indicates that this functional is particularly well suited to study these materials. The calculations reveal that β-Mo2C has a stronger metallic character than the other two polymorphs, both β-Mo2C and δ-MoC have a large ionic contribution, and δ- and α-MoC exhibit the strongest covalent character. Among the various surfaces explored, the calculations reveal the high stability of the δ-MoC(001) nonpolar surface, Mo- and C-terminated (001) polar surfaces of α-MoC, and the nonpolar (011) surface of β-Mo2C. A substantially low work function of only 3.4 eV is predicted for β-Mo2C(011), suggesting that this system is particularly well suited for (electro)catalytic processes where surface → adsorbate electron transfer is essential. The overall implications for heterogeneously catalysed reactions by these molybdenum carbide nanoparticles are also discussed.

  8. Plasma Modes of the Three-Chain Electron System Over Liquid Helium

    Science.gov (United States)

    Sokolov, S. S.; Syvokon, V. E.

    2016-12-01

    We simulate the surface electron system over liquid helium subjected to a confinement potential in the electron layer plane. In the solid phase, the two-dimensional system is observed to transform first into a multi-chain system and, finally, into a three chain, a zigzag structure and a single chain. Both longitudinal and transversal plasma oscillations of the three-chain electron system are determined. One of the longitudinal oscillation modes is acoustic, whereas the other two are optical. On turn, all transversal oscillations branches are optical. The theoretical results obtained can be used to identify experimentally the configurations of the low-dimensional electron system over helium under confinement potential.

  9. Mapping the surface adsorption forces of nanomaterials in biological systems.

    Science.gov (United States)

    Xia, Xin R; Monteiro-Riviere, Nancy A; Mathur, Sanjay; Song, Xuefeng; Xiao, Lisong; Oldenberg, Steven J; Fadeel, Bengt; Riviere, Jim E

    2011-11-22

    The biological surface adsorption index (BSAI) is a novel approach to characterize surface adsorption energy of nanomaterials that is the primary force behind nanoparticle aggregation, protein corona formation, and other complex interactions of nanomaterials within biological systems. Five quantitative nanodescriptors were obtained to represent the surface adsorption forces (hydrophobicity, hydrogen bond, polarity/polarizability, and lone-pair electrons) of the nanomaterial interaction with biological components. We have mapped the surface adsorption forces over 16 different nanomaterials. When the five-dimensional information of the nanodescriptors was reduced to two dimensions, the 16 nanomaterials were classified into distinct clusters according their surface adsorption properties. BSAI nanodescriptors are intrinsic properties of nanomaterials useful for quantitative structure-activity relationship (QSAR) model development. This is the first success in quantitative characterization of the surface adsorption forces of nanomaterials in biological conditions, which could open a quantitative avenue in predictive nanomedicine development, risk assessment, and safety evaluation of nanomaterials. © 2011 American Chemical Society

  10. New electronics for the surface detectors of the Pierre Auger Observatory

    Science.gov (United States)

    Kleifges, M.; Pierre Auger Collaboration

    2016-07-01

    The Pierre Auger Observatory is the largest installation worldwide for the investigation of ultra-high energy cosmic rays. Air showers are detected using a hybrid technique with 27 fluorescence telescopes and 1660 water-Cherenkov detectors (WCD) distributed over about 3000 km2. The Auger Collaboration has decided to upgrade the electronics of the WCD and complement the surface detector with scintillators (SSD). The objective is to improve the separation between the muonic and the electron/photon shower component for better mass composition determination during an extended operation period of 8-10 years. The surface detector electronics records data locally and generates time stamps based on the GPS timing. The performance of the detectors is significantly improved with a higher sampling rate, an increased dynamic range, new generation of GPS receivers, and FPGA integrated CPU power. The number of analog channels will be increased to integrate the new SSD, but the power consumption needs to stay below 10 W to be able to use the existing photovoltaic system. In this paper, the concept of the additional SSD is presented with a focus on the design and performance of the new surface detector electronics.

  11. New electronics for the surface detectors of the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Kleifges, M., E-mail: Matthias.Kleifges@kit.edu [Karlsruhe Institute of Technology – Institute for Data Processing and Electronics, Karlsruhe (Germany)

    2016-07-11

    The Pierre Auger Observatory is the largest installation worldwide for the investigation of ultra-high energy cosmic rays. Air showers are detected using a hybrid technique with 27 fluorescence telescopes and 1660 water-Cherenkov detectors (WCD) distributed over about 3000 km{sup 2}. The Auger Collaboration has decided to upgrade the electronics of the WCD and complement the surface detector with scintillators (SSD). The objective is to improve the separation between the muonic and the electron/photon shower component for better mass composition determination during an extended operation period of 8–10 years. The surface detector electronics records data locally and generates time stamps based on the GPS timing. The performance of the detectors is significantly improved with a higher sampling rate, an increased dynamic range, new generation of GPS receivers, and FPGA integrated CPU power. The number of analog channels will be increased to integrate the new SSD, but the power consumption needs to stay below 10 W to be able to use the existing photovoltaic system. In this paper, the concept of the additional SSD is presented with a focus on the design and performance of the new surface detector electronics.

  12. Ultrafast Electron Transfer Between Dye and Catalyst on a Mesoporous NiO Surface.

    Science.gov (United States)

    Brown, Allison M; Antila, Liisa J; Mirmohades, Mohammad; Pullen, Sonja; Ott, Sascha; Hammarström, Leif

    2016-07-01

    The combination of molecular dyes and catalysts with semiconductors into dye-sensitized solar fuel devices (DSSFDs) requires control of efficient interfacial and surface charge transfer between the components. The present study reports on the light-induced electron transfer processes of p-type NiO films cosensitized with coumarin C343 and a bioinspired proton reduction catalyst, [FeFe](mcbdt)(CO)6 (mcbdt = 3-carboxybenzene-1,2-dithiolate). By transient optical spectroscopy we find that ultrafast interfacial electron transfer (τ ≈ 200 fs) from NiO to the excited C343 ("hole injection") is followed by rapid (t1/2 ≈ 10 ps) and efficient surface electron transfer from C343(-) to the coadsorbed [FeFe](mcbdt)(CO)6. The reduced catalyst has a clear spectroscopic signature that persists for several tens of microseconds, before charge recombination with NiO holes occurs. The demonstration of rapid surface electron transfer from dye to catalyst on NiO, and the relatively long lifetime of the resulting charge separated state, suggests the possibility to use these systems for photocathodes on DSSFDs.

  13. Gutzwiller approximation in strongly correlated electron systems

    Science.gov (United States)

    Li, Chunhua

    Gutzwiller wave function is an important theoretical technique for treating local electron-electron correlations nonperturbatively in condensed matter and materials physics. It is concerned with calculating variationally the ground state wave function by projecting out multi-occupation configurations that are energetically costly. The projection can be carried out analytically in the Gutzwiller approximation that offers an approximate way of calculating expectation values in the Gutzwiller projected wave function. This approach has proven to be very successful in strongly correlated systems such as the high temperature cuprate superconductors, the sodium cobaltates, and the heavy fermion compounds. In recent years, it has become increasingly evident that strongly correlated systems have a strong propensity towards forming inhomogeneous electronic states with spatially periodic superstrutural modulations. A good example is the commonly observed stripes and checkerboard states in high- Tc superconductors under a variety of conditions where superconductivity is weakened. There exists currently a real challenge and demand for new theoretical ideas and approaches that treats strongly correlated inhomogeneous electronic states, which is the subject matter of this thesis. This thesis contains four parts. In the first part of the thesis, the Gutzwiller approach is formulated in the grand canonical ensemble where, for the first time, a spatially (and spin) unrestricted Gutzwiller approximation (SUGA) is developed for studying inhomogeneous (both ordered and disordered) quantum electronic states in strongly correlated electron systems. The second part of the thesis applies the SUGA to the t-J model for doped Mott insulators which led to the discovery of checkerboard-like inhomogeneous electronic states competing with d-wave superconductivity, consistent with experimental observations made on several families of high-Tc superconductors. In the third part of the thesis, new

  14. Fabrication of surface micro- and nanostructures for superhydrophobic surfaces in electric and electronic applications

    Science.gov (United States)

    Xiu, Yonghao

    In our study, the superhydrophobic surface based on biomimetic lotus leave is explored to maintain the desired properties for self-cleaning. Parameters in controlling bead-up and roll-off characteristics of water droplets were investigated on different model surfaces. The governing equations were proposed. Heuristic study is performed. First, the fundamental understanding of the effect of roughness on superhydrophobicity is performed. The effect of hierarchical roughness, i.e., two scale roughness effect on roughness is investigated using systems of (1) monodisperse colloidal silica sphere (submicron) arrays and Au nanoparticle on top and (2) Si micrometer pyramids and Si nanostructures on top from KOH etching and metal assisted etching of Si. The relation between the contact area fraction and water droplet contact angles are derived based on Wenzel and Cassie-Baxter equation for the systems and the two scale effect is explained regarding the synergistic combination of two scales. Previously the microscopic three-phase-contact line is thought to be the key factor in determining contact angles and hystereses. In our study, Laplace pressure was brought up and related to the three-phase-contact line and taken as a key figure of merit in determining superhydrophobicity. In addition, we are one of the first to study the effect of tapered structures (wall inclination). Combining with a second scale roughness on the tapered structures, stable Cassie state for both water and low surface energy oil may be achieved. This is of great significance for designing both superhydrophobicity and superoleophobicity. Regarding the origin of contact angle hysteresis, study of superhydrophobicity on micrometer Si pillars was performed. The relation between the interface work of function and contact angle hysteresis was proposed and derived mathematically based on the Young-Dupre equation. The three-phase-contact line was further related to a secondary scale roughness induced. Based on

  15. Possible correlation effects of surface state electrons on a solid hydrogen film

    NARCIS (Netherlands)

    Mugele, Friedrich Gunther; Albrecht, Uwe; Leiderer, Paul; Kono, Kimitoshi

    1992-01-01

    We have investigated the transport properties of surface state electrons on thin quench-condensed hydrogen films for various electron densities. The surface state electron mobility showed a continuous dependence on the plasma parameter Gamma in the range from 20 to 130, indicating a strong influence

  16. Relaxation between electrons and surface phonons of a homogeneously photoexcited metal film

    Indian Academy of Sciences (India)

    Navinder Singh

    2004-11-01

    The energy relaxation between the hot degenerate electrons of a homogeneously photoexcited metal film and the surface phonons (phonon wave vectors in two dimensions) is considered under Debye approximation. The state of electrons and phonons is described by equilibrium Fermi and Bose functions with different temperatures. Two cases for electron scattering by the metal surface, namely specular and diffuse scattering, are considered.

  17. 77 FR 57039 - Special Conditions: Embraer S.A., Model EMB-550 Airplane; Electronic Flight Control System...

    Science.gov (United States)

    2012-09-17

    ...; Electronic Flight Control System: Control Surface Awareness and Mode Annunciation AGENCY: Federal Aviation... control system. The applicable airworthiness regulations do not contain adequate or appropriate safety... electronic flight control system and no direct coupling from the flightdeck controller to the control surface...

  18. The lowest-lying electronic singlet and triplet potential energy surfaces for the HNO-NOH system: energetics, unimolecular rate constants, tunneling and kinetic isotope effects for the isomerization and dissociation reactions.

    Science.gov (United States)

    Bozkaya, Uğur; Turney, Justin M; Yamaguchi, Yukio; Schaefer, Henry F

    2012-04-28

    The lowest-lying electronic singlet and triplet potential energy surfaces (PES) for the HNO-NOH system have been investigated employing high level ab initio quantum chemical methods. The reaction energies and barriers have been predicted for two isomerization and four dissociation reactions. Total energies are extrapolated to the complete basis set limit applying focal point analyses. Anharmonic zero-point vibrational energies, diagonal Born-Oppenheimer corrections, relativistic effects, and core correlation corrections are also taken into account. On the singlet PES, the (1)HNO → (1)NOH endothermicity including all corrections is predicted to be 42.23 ± 0.2 kcal mol(-1). For the barrierless decomposition of (1)HNO to H + NO, the dissociation energy is estimated to be 47.48 ± 0.2 kcal mol(-1). For (1)NOH → H + NO, the reaction endothermicity and barrier are 5.25 ± 0.2 and 7.88 ± 0.2 kcal mol(-1). On the triplet PES the reaction energy and barrier including all corrections are predicted to be 7.73 ± 0.2 and 39.31 ± 0.2 kcal mol(-1) for the isomerization reaction (3)HNO → (3)NOH. For the triplet dissociation reaction (to H + NO) the corresponding results are 29.03 ± 0.2 and 32.41 ± 0.2 kcal mol(-1). Analogous results are 21.30 ± 0.2 and 33.67 ± 0.2 kcal mol(-1) for the dissociation reaction of (3)NOH (to H + NO). Unimolecular rate constants for the isomerization and dissociation reactions were obtained utilizing kinetic modeling methods. The tunneling and kinetic isotope effects are also investigated for these reactions. The adiabatic singlet-triplet energy splittings are predicted to be 18.45 ± 0.2 and 16.05 ± 0.2 kcal mol(-1) for HNO and NOH, respectively. Kinetic analyses based on solution of simultaneous first-order ordinary-differential rate equations demonstrate that the singlet NOH molecule will be difficult to prepare at room temperature, while the triplet NOH molecule is viable with respect to isomerization and dissociation reactions up to

  19. Electronic integrated disease surveillance system and pathogen asset control system.

    Science.gov (United States)

    Wahl, Tom G; Burdakov, Aleksey V; Oukharov, Andrey O; Zhilokov, Azamat K

    2012-06-20

    Electronic Integrated Disease Surveillance System (EIDSS) has been used to strengthen and support monitoring and prevention of dangerous diseases within One Health concept by integrating veterinary and human surveillance, passive and active approaches, case-based records including disease-specific clinical data based on standardised case definitions and aggregated data, laboratory data including sample tracking linked to each case and event with test results and epidemiological investigations. Information was collected and shared in secure way by different means: through the distributed nodes which are continuously synchronised amongst each other, through the web service, through the handheld devices. Electronic Integrated Disease Surveillance System provided near real time information flow that has been then disseminated to the appropriate organisations in a timely manner. It has been used for comprehensive analysis and visualisation capabilities including real time mapping of case events as these unfold enhancing decision making. Electronic Integrated Disease Surveillance System facilitated countries to comply with the IHR 2005 requirements through a data transfer module reporting diseases electronically to the World Health Organisation (WHO) data center as well as establish authorised data exchange with other electronic system using Open Architecture approach. Pathogen Asset Control System (PACS) has been used for accounting, management and control of biological agent stocks. Information on samples and strains of any kind throughout their entire lifecycle has been tracked in a comprehensive and flexible solution PACS.Both systems have been used in a combination and individually. Electronic Integrated Disease Surveillance System and PACS are currently deployed in the Republics of Kazakhstan, Georgia and Azerbaijan as a part of the Cooperative Biological Engagement Program (CBEP) sponsored by the US Defense Threat Reduction Agency (DTRA).

  20. Electronic Integrated Disease Surveillance System and Pathogen Asset Control System

    Directory of Open Access Journals (Sweden)

    Tom G. Wahl

    2012-06-01

    Full Text Available Electronic Integrated Disease Surveillance System (EIDSS has been used to strengthen and support monitoring and prevention of dangerous diseases within One Health concept by integrating veterinary and human surveillance, passive and active approaches, case-based records including disease-specific clinical data based on standardised case definitions and aggregated data, laboratory data including sample tracking linked to each case and event with test results and epidemiological investigations. Information was collected and shared in secure way by different means: through the distributed nodes which are continuously synchronised amongst each other, through the web service, through the handheld devices. Electronic Integrated Disease Surveillance System provided near real time information flow that has been then disseminated to the appropriate organisations in a timely manner. It has been used for comprehensive analysis and visualisation capabilities including real time mapping of case events as these unfold enhancing decision making. Electronic Integrated Disease Surveillance System facilitated countries to comply with the IHR 2005 requirements through a data transfer module reporting diseases electronically to the World Health Organisation (WHO data center as well as establish authorised data exchange with other electronic system using Open Architecture approach. Pathogen Asset Control System (PACS has been used for accounting, management and control of biological agent stocks. Information on samples and strains of any kind throughout their entire lifecycle has been tracked in a comprehensive and flexible solution PACS.Both systems have been used in a combination and individually. Electronic Integrated Disease Surveillance System and PACS are currently deployed in the Republics of Kazakhstan, Georgia and Azerbaijan as a part of the Cooperative Biological Engagement Program (CBEP sponsored by the US Defense Threat Reduction Agency (DTRA.

  1. Electron energy-loss spectroscopy of coupled plasmonic systems: beyond the standard electron perspective

    Science.gov (United States)

    Bernasconi, G. D.; Flauraud, V.; Alexander, D. T. L.; Brugger, J.; Martin, O. J. F.; Butet, J.

    2016-09-01

    Electron energy-loss spectroscopy (EELS) has become an experimental method of choice for the investigation of localized surface plasmon resonances, allowing the simultaneous mapping of the associated field distributions and their resonant energies with a nanoscale spatial resolution. The experimental observations have been well-supported by numerical models based on the computation of the Lorentz force acting on the impinging electrons by the scattered field. However, in this framework, the influence of the intrinsic properties of the plasmonic nanostructures studied with the electron energy-loss (EEL) measurements is somehow hidden in the global response. To overcome this limitation, we propose to go beyond this standard, and well-established, electron perspective and instead to interpret the EELS data using directly the intrinsic properties of the nanostructures, without regard to the force acting on the electron. The proposed method is particularly well-suited for the description of coupled plasmonic systems, because the role played by each individual nanoparticle in the observed EEL spectrum can be clearly disentangled, enabling a more subtle understanding of the underlying physical processes. As examples, we consider different plasmonic geometries in order to emphasize the benefits of this new conceptual approach for interpreting experimental EELS data. In particular, we use it to describe results from samples made by traditional thin film patterning and by arranging colloidal nanostructures.

  2. Emergent behavior in strongly correlated electron systems

    Science.gov (United States)

    Pines, David

    2016-09-01

    I describe early work on strongly correlated electron systems (SCES) from the perspective of a theoretical physicist who, while a participant in their reductionist top-down beginnings, is now part of the paradigm change to a bottom-up ‘emergent’ approach with its focus on using phenomenology to find the organizing principles responsible for their emergent behavior disclosed by experiment—and only then constructing microscopic models that incorporate these. After considering the organizing principles responsible for the emergence of plasmons, quasiparticles, and conventional superconductivity in SCES, I consider their application to three of SCES’s sister systems, the helium liquids, nuclei, and the nuclear matter found in neutron stars. I note some recent applications of the random phase approximation and examine briefly the role that paradigm change is playing in two central problems in our field: understanding the emergence and subsequent behavior of heavy electrons in Kondo lattice materials; and finding the mechanism for the unconventional superconductivity found in heavy electron, organic, cuprate, and iron-based materials.

  3. Final Report Theoretical Studies of Surface Reactions on Metals and Electronic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jerry L. Whitten

    2012-04-23

    This proposal describes the proposed renewal of a theoretical research program on the structure and reactivity of molecules adsorbed on transition metal surfaces. A new direction of the work extends investigations to interfaces between solid surfaces, adsorbates and aqueous solutions and includes fundamental work on photoinduced electron transport into chemisorbed species and into solution. The goal is to discover practical ways to reduce water to hydrogen and oxygen using radiation comparable to that available in the solar spectrum. The work relates to two broad subject areas: photocatalytic processes and production of hydrogen from water. The objective is to obtain high quality solutions of the electronic structure of adsorbate-metal-surface-solution systems so as to allow activation barriers to be calculated and reaction mechanisms to be determined. An ab initio embedding formalism provides a route to the required accuracy. New theoretical methods developed during the previous grant period will be implemented in order to solve the large systems involved in this work. Included is the formulation of a correlation operator that is used to treat localized electron distributions such as ionic or regionally localized distributions. The correlation operator which is expressed as a two-particle projector is used in conjunction with configuration interaction.

  4. Final Report Theoretical Studies of Surface Reactions on Metals and Electronic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jerry L. Whitten

    2012-04-23

    This proposal describes the proposed renewal of a theoretical research program on the structure and reactivity of molecules adsorbed on transition metal surfaces. A new direction of the work extends investigations to interfaces between solid surfaces, adsorbates and aqueous solutions and includes fundamental work on photoinduced electron transport into chemisorbed species and into solution. The goal is to discover practical ways to reduce water to hydrogen and oxygen using radiation comparable to that available in the solar spectrum. The work relates to two broad subject areas: photocatalytic processes and production of hydrogen from water. The objective is to obtain high quality solutions of the electronic structure of adsorbate-metal-surface-solution systems so as to allow activation barriers to be calculated and reaction mechanisms to be determined. An ab initio embedding formalism provides a route to the required accuracy. New theoretical methods developed during the previous grant period will be implemented in order to solve the large systems involved in this work. Included is the formulation of a correlation operator that is used to treat localized electron distributions such as ionic or regionally localized distributions. The correlation operator which is expressed as a two-particle projector is used in conjunction with configuration interaction.

  5. Electron transport system activity of microfouling material: Relationships with biomass parameters

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Tulaskar, A.; Wagh, A.B.

    Microfouling material developed on aluminium panels immersed in surface waters of the Dona Paula Bay, Goa India was analysed for biomass (measured as dry weight, organic crabon, protein and chlorophyll @ia@@) and electron transport system actitity...

  6. Electronic Structure of the Perylene / Zinc Oxide Interface: A Computational Study of Photoinduced Electron Transfer and Impact of Surface Defects

    KAUST Repository

    Li, Jingrui

    2015-07-29

    The electronic properties of dye-sensitized semiconductor surfaces consisting of pery- lene chromophores chemisorbed on zinc oxide via different spacer-anchor groups, have been studied at the density-functional-theory level. The energy distributions of the donor states and the rates of photoinduced electron transfer from dye to surface are predicted. We evaluate in particular the impact of saturated versus unsaturated aliphatic spacer groups inserted between the perylene chromophore and the semiconductor as well as the influence of surface defects on the electron-injection rates.

  7. Electron impact ionization of helium isoelectronic systems

    Energy Technology Data Exchange (ETDEWEB)

    Talukder, M.R. [Rajshahi Univ., Dept. of Applied Physics and Electronic Engineering (Bangladesh)

    2008-09-15

    The electron impact single ionization cross sections, on the helium isoelectronic He, Li{sup 1+}, B{sup 3+}, C{sup 4+} N{sup 5+} O{sup 6+} Ne{sup 8+}, Na{sup 9+}. Ar{sup +16}, Fe{sup 24+}, Mo{sup 41+} Ag{sup 45+}, and U{sup 90+} targets, are calculated modifying the simplified Bell (SBELL) model [Eur. Phys. J. D 46, 281 (2008)]. The results of the present analysis are compared with the available experimental and theoretical data. The modified SBELL (MSBELL) model, incorporating the ionic correction factor in it, produces excellent agreement with the experimental data and theoretical calculations for all the two-electron systems, neutral or ions. This model may be a prudent choice in plasma modeling due to its simple inherent structure. (authors)

  8. XUV free-electron laser-based projection lithography systems

    Energy Technology Data Exchange (ETDEWEB)

    Newnam, B.E.

    1990-01-01

    Free-electron laser sources, driven by rf-linear accelerators, have the potential to operate in the extreme ultraviolet (XUV) spectral range with more than sufficient average power for high-volume projection lithography. For XUV wavelengths from 100 nm to 4 nm, such sources will enable the resolution limit of optical projection lithography to be extended from 0.25 {mu}m to 0.05{mu}m and with an adequate total depth of focus (1 to 2 {mu}m). Recent developments of a photoinjector of very bright electron beams, high-precision magnetic undulators, and ring-resonator cavities raise our confidence that FEL operation below 100 nm is ready for prototype demonstration. We address the motivation for an XUV FEL source for commercial microcircuit production and its integration into a lithographic system, include reflecting reduction masks, reflecting XUV projection optics and alignment systems, and surface-imaging photoresists. 52 refs., 7 figs.

  9. Earthing: Health Implications of Reconnecting the Human Body to the Earth's Surface Electrons

    Directory of Open Access Journals (Sweden)

    Gaétan Chevalier

    2012-01-01

    Full Text Available Environmental medicine generally addresses environmental factors with a negative impact on human health. However, emerging scientific research has revealed a surprisingly positive and overlooked environmental factor on health: direct physical contact with the vast supply of electrons on the surface of the Earth. Modern lifestyle separates humans from such contact. The research suggests that this disconnect may be a major contributor to physiological dysfunction and unwellness. Reconnection with the Earth's electrons has been found to promote intriguing physiological changes and subjective reports of well-being. Earthing (or grounding refers to the discovery of benefits—including better sleep and reduced pain—from walking barefoot outside or sitting, working, or sleeping indoors connected to conductive systems that transfer the Earth's electrons from the ground into the body. This paper reviews the earthing research and the potential of earthing as a simple and easily accessed global modality of significant clinical importance.

  10. 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.

  11. New Electron Gun System for BEPCII

    CERN Document Server

    Liu, Bo; Long Chi, Yun; Zhang, Chuang

    2005-01-01

    The new electron gun system for BEPCII has been put into operation since Nov. 2004. The article describes the design, experiment and operation of this new system. The design current of the gun is 10 A for the pulse lengths of 1 ns, 2.5 ns and 1 μs with repetition rate of 50 Hz. The gun is operated with a pulsed high voltage power supply which can provide up to 200 kV high voltage. Computer simulations have been carried out in the design stage, including simulation of the gun geometry and beam transportation. Some important relation curves are obtained during the experiment. Two-bunch operation is available and some elementary tests have been performed. New scheme of the gun control system based on EPICS is also presented. The real operation shows that the design and manufacturing is basically successful.

  12. Rapid electron exchange between surface-exposed bacterial cytochromes and Fe(III) minerals

    Energy Technology Data Exchange (ETDEWEB)

    White, Gaye F.; Shi, Zhi; Shi, Liang; Wang, Zheming; Dohnalkova, Alice; Marshall, Matthew J.; Fredrickson, Jim K.; Zachara, John M.; Butt, Julea N.; Richardson, David; Clarke, Thomas A.

    2013-04-16

    The mineral respiring bacterium Shewanella oneidensis uses a protein complex, MtrCAB, composed of two decaheme cytochromes brought together inside a transmembrane porin to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. A proteoliposome system that contains methyl viologen as an internalised electron carrier has been used to investigate how the topology of the MtrCAB complex relates to its ability to transport electrons across a lipid bilayer to externally-located Fe(III) oxides. With MtrA facing the interior and MtrC exposed on the outer surface of the phospholipid bilayer, direct electron transfer from the interior through MtrCAB to solid-phase Fe(III) oxides was demonstrated. The observed rates of conduction through the protein complex were 2 to 3 orders of magnitude higher than that observed in whole cells, demonstrating that direct electron exchange between MtrCAB and Fe(III) oxides is efficient enough to support in-vivo, anaerobic, solid phase iron respiration.

  13. Electronic Wiring of a Multi-Redox Site Membrane Protein in a Biomimetic Surface Architecture

    Science.gov (United States)

    Friedrich, Marcel G.; Robertson, Joseph W. F.; Walz, Dieter; Knoll, Wolfgang; Naumann, Renate L. C.

    2008-01-01

    Bioelectronic coupling of multi-redox-site membrane proteins was accomplished with cytochrome c oxidase (CcO) as an example. A biomimetic membrane system was used for the oriented immobilization of the CcO oxidase on a metal electrode. When the protein is immobilized with the CcO binding side directed toward the electrode and reconstituted in situ into a lipid bilayer, it is addressable by direct electron transfer to the redox centers. Electron transfer to the enzyme via the spacer, referred to as electronic wiring, shows an exceptionally high rate constant. This allows a kinetic analysis of all four consecutive electron transfer steps within the enzyme to be carried out. Electron transfer followed by rapid scan cyclic voltametry in combination with surface-enhanced resonance Raman spectroscopy provides mechanistic and structural information about the heme centers. Probing the enzyme under turnover conditions showed mechanistic insights into proton translocation coupled to electron transfer. This bioelectronic approach opens a new field of activity to investigate complex processes in a wide variety of membrane proteins. PMID:18222995

  14. Electron surface layer at the interface of a plasma and a dielectric wall

    CERN Document Server

    Heinisch, Rafael L; Fehske, Holger

    2011-01-01

    We study the potential and the charge distribution across the interface of a plasma and a dielectric wall. For this purpose, the charge bound to the wall is modelled as a quasi-stationary electron surface layer which satisfies Poisson's equation and minimizes the grand canonical potential of the wall-thermalized excess electrons constituting the wall charge. Based on an effective model for a graded interface taking into account the image potential and the offset of the conduction band to the potential just outside the dielectric, we specifically calculate the potential and the electron distribution for magnesium oxide, silicon dioxide and sapphire surfaces in contact with a helium discharge. Depending on the electron affinity of the surface, we find two vastly different behaviors. For negative electron affinity, electrons do not penetrate into the wall and an external surface charge is formed in the image potential, while for positive electron affinity, electrons penetrate into the wall and a space charge lay...

  15. Electronic journal management systems experiences from the field

    CERN Document Server

    Ives, Gary W

    2013-01-01

    Discover how to manage your library's electronic journals?with tips from those who've already met the challenge!The explosive growth of electronic journals presents unique challenges for libraries. Electronic Journal Management Systems: Experiences from the Field comprehensively examines these complex topics, including explanations of the automated systems libraries have developed or adopted, licensing issues, and the provision of access to electronic journals. Respected library professionals discuss their own experiences in the implementation and use of electronic journal management systems,

  16. SURFACES OF HARD-SPHERE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Dietrich Stoyan

    2014-07-01

    Full Text Available In various situations surfaces appear that are formed by systems of hard spheres. Examples are porous layers as surfaces of sand heaps and biofilms or fracture surfaces of concrete. The present paper considers models where a statistically homogeneous system of hard spheres with random radii is intersected by a plane and the surface is formed by the spheres with centers close to this plane. Formulae are derived for various characteristics of such surfaces: for the porosity profile, i.e. the local porosity in dependence on the distance from the section plane and for the geometry of the sphere caps that look above the section plane.It turns out that these characteristics only depend on the first-order characteristics of the sphere system, its sphere density and the sphere radius distribution.Comparison with empirically studied biofilms shows that the model is realistic.

  17. Electronic resource management systems a workflow approach

    CERN Document Server

    Anderson, Elsa K

    2014-01-01

    To get to the bottom of a successful approach to Electronic Resource Management (ERM), Anderson interviewed staff at 11 institutions about their ERM implementations. Among her conclusions, presented in this issue of Library Technology Reports, is that grasping the intricacies of your workflow-analyzing each step to reveal the gaps and problems-at the beginning is crucial to selecting and implementing an ERM. Whether the system will be used to fill a gap, aggregate critical data, or replace a tedious manual process, the best solution for your library depends on factors such as your current soft

  18. Structural dynamics of electronic and photonic systems

    CERN Document Server

    Suhir, Ephraim; Steinberg, David S

    2011-01-01

    The proposed book will offer comprehensive and versatile methodologies and recommendations on how to determine dynamic characteristics of typical micro- and opto-electronic structural elements (printed circuit boards, solder joints, heavy devices, etc.) and how to design a viable and reliable structure that would be able to withstand high-level dynamic loading. Particular attention will be given to portable devices and systems designed for operation in harsh environments (such as automotive, aerospace, military, etc.)  In-depth discussion from a mechanical engineer's viewpoint will be conducte

  19. Controlling Underwater Robots with Electronic Nervous Systems

    Directory of Open Access Journals (Sweden)

    Joseph Ayers

    2010-01-01

    Full Text Available We are developing robot controllers based on biomimetic design principles. The goal is to realise the adaptive capabilities of the animal models in natural environments. We report feasibility studies of a hybrid architecture that instantiates a command and coordinating level with computed discrete-time map-based (DTM neuronal networks and the central pattern generators with analogue VLSI (Very Large Scale Integration electronic neuron (aVLSI networks. DTM networks are realised using neurons based on a 1-D or 2-D Map with two additional parameters that define silent, spiking and bursting regimes. Electronic neurons (ENs based on Hindmarsh–Rose (HR dynamics can be instantiated in analogue VLSI and exhibit similar behaviour to those based on discrete components. We have constructed locomotor central pattern generators (CPGs with aVLSI networks that can be modulated to select different behaviours on the basis of selective command input. The two technologies can be fused by interfacing the signals from the DTM circuits directly to the aVLSI CPGs. Using DTMs, we have been able to simulate complex sensory fusion for rheotaxic behaviour based on both hydrodynamic and optical flow senses. We will illustrate aspects of controllers for ambulatory biomimetic robots. These studies indicate that it is feasible to fabricate an electronic nervous system controller integrating both aVLSI CPGs and layered DTM exteroceptive reflexes.

  20. On the Convergence of the Electronic Structure Properties of the FCC Americium (001) Surface

    OpenAIRE

    Gao, Da; Ray, Asok K.

    2006-01-01

    Electronic and magnetic properties of the fcc Americium (001) surface have been investigated via full-potential all-electron density-functional electronic structure calculations at both scalar and fully relativistic levels. Effects of various theoretical approximations on the fcc Am (001) surface properties have been thoroughly examined. The ground state of fcc Am (001) surface is found to be anti-ferromagnetic with spin-orbit coupling included (AFM-SO). At the ground state, the magnetic mome...

  1. SYSTEM IDENTIFICATION OF SURFACE SHIP DYNAMICS.

    Science.gov (United States)

    The feasibility of applying a Newtonian system identification technique to a nonlinear three degree of freedom system of equations describing the...steering and maneuvering of a surface ship is investigated. The input to the system identification program is provided by both analog and digital

  2. HIGH IMPEDANCE SURFACES FOR FLEXIBLE AND CONFORMAL WIRELESS SYSTEMS

    Directory of Open Access Journals (Sweden)

    Haider R. Khaleel

    2014-01-01

    Full Text Available Recent years have witnessed a great deal of interest from both scientific and academic communities in the field of flexible electronic systems. Most flexible electronic systems require the integration of flexible antennas operating in specific frequency bands to provide wireless connectivity which is highly demanded by today’s network oriented society. On the other hand, High Impedance Surfaces have become very popular in the design of contemporary antenna and micro-wave devices due to their wide range of applications derived from their unique electromagnetic properties which significantly enhance the performance of antennas and RF systems. Accordingly, the integration of HIS structures within flexible wireless systems is very beneficial in this growing field of research. In this paper, a systematic review of flexible HIS structures reported in the literature is conducted, which provides the reader with a thorough description and a complete list of state of the art designs intended for flexible wireless systems.

  3. Surface Waters Information Management System (SWIMS)

    Data.gov (United States)

    Kansas Data Access and Support Center — The Surface Waters Information Management System (SWIMS) has been designed to meet multi-agency hydrologic database needs for Kansas. The SWIMS project was supported...

  4. Enhanced surface acceleration of fast electrons by using sub-wavelength grating targets

    CERN Document Server

    Hu, Guang-yue; Wang, Wen-tao; Wang, Jing-wei; Huang, Lin-gen; Wang, Xin; Xu, Yi; Liu, Jian-sheng; Shen, Bai-fei; Yu, Wei; Li, Ru-xin; Xu, Zhi-zhan

    2010-01-01

    Surface acceleration of fast electrons in intense laser-plasma interaction is improved by using sub-wavelength grating targets. The fast electron beam emitted along the target surface was enhanced by more than three times relative to that by using planar target. The total number of the fast electrons ejected from the front side of target was also increased by about one time. The method to enhance the surface acceleration of fast electron is effective for various targets with sub-wavelength structured surface, and can be applied widely in the cone-guided fast ignition, energetic ion acceleration, plasma device, and other high energy density physics experiments.

  5. Electron cyclotron resonance breakdown studies in a linear plasma system

    Indian Academy of Sciences (India)

    Vipin K Yadav; K Sathyanarayana; D Bora

    2008-03-01

    Electron cyclotron resonance (ECR) plasma breakdown is studied in a small linear cylindrical system with four different gases - hydrogen, helium, argon and nitrogen. Microwave power in the experimental system is delivered by a magnetron at 2.45 ± 0.02 GHz in TE10 mode and launched radially to have extra-ordinary (X) wave in plasma. The axial magnetic field required for ECR in the system is such that the fundamental ECR surface ( = 875.0 G) resides at the geometrical centre of the plasma system. ECR breakdown parameters such as plasma delay time and plasma decay time from plasma density measurements are carried out at the centre using a Langmuir probe. The operating parameters such as working gas pressure (1 × 10-5 -1 × 10-2 mbar) and input microwave power (160{800 W) are varied and the corresponding effect on the breakdown parameters is studied. The experimental results obtained are presented in this paper.

  6. Complexity in electronic negotiation support systems.

    Science.gov (United States)

    Griessmair, Michele; Strunk, Guido; Vetschera, Rudolf; Koeszegi, Sabine T

    2011-10-01

    It is generally acknowledged that the medium influences the way we communicate and negotiation research directs considerable attention to the impact of different electronic communication modes on the negotiation process and outcomes. Complexity theories offer models and methods that allow the investigation of how pattern and temporal sequences unfold over time in negotiation interactions. By focusing on the dynamic and interactive quality of negotiations as well as the information, choice, and uncertainty contained in the negotiation process, the complexity perspective addresses several issues of central interest in classical negotiation research. In the present study we compare the complexity of the negotiation communication process among synchronous and asynchronous negotiations (IM vs. e-mail) as well as an electronic negotiation support system including a decision support system (DSS). For this purpose, transcripts of 145 negotiations have been coded and analyzed with the Shannon entropy and the grammar complexity. Our results show that negotiating asynchronically via e-mail as well as including a DSS significantly reduces the complexity of the negotiation process. Furthermore, a reduction of the complexity increases the probability of reaching an agreement.

  7. Radiation Risks and Mitigation in Electronic Systems

    CERN Document Server

    Todd, B

    2015-01-01

    Electrical and electronic systems can be disturbed by radiation-induced effects. In some cases, radiation-induced effects are of a low probability and can be ignored; however, radiation effects must be considered when designing systems that have a high mean time to failure requirement, an impact on protection, and/or higher exposure to radiat ion. High-energy physics power systems suffer from a combination of these effects: a high mean time to failure is required, failure can impact on protection, and the proximity of systems to accelerators increases the likelihood of radiation-induced events. This paper presents the principal radiation-induced effects, and radiation environments typical to high-energy physics. It outlines a procedure for designing and validating radiation-tolerant systems using commercial off-the-shelf components. The paper ends with a worked example of radiation-tolerant power converter controls that are being developed for the Large Hadron Collider and High Luminosity-Large Hadron Colli...

  8. Note: Ion-induced secondary electron emission from oxidized metal surfaces measured in a particle beam reactor

    Science.gov (United States)

    Marcak, Adrian; Corbella, Carles; de los Arcos, Teresa; von Keudell, Achim

    2015-10-01

    The secondary electron emission of metals induced by slow ions is characterized in a beam chamber by means of two coaxial semi-cylindrical electrodes with different apertures. The voltages of the outer electrode (screening), inner electrode (collector), and sample holder (target) were set independently in order to measure the effective yield of potential and kinetic electron emissions during ion bombardment. Aluminum samples were exposed to quantified beams of argon ions up to 2000 eV and to oxygen atoms and molecules in order to mimic the plasma-surface interactions on metallic targets during reactive sputtering. The variation of electron emission yield was correlated to the ion energy and to the oxidation state of Al surfaces. This system provides reliable measurements of the electron yields in real time and is of great utility to explore the fundamental surface processes during target poisoning occurring in reactive magnetron sputtering applications.

  9. Note: Ion-induced secondary electron emission from oxidized metal surfaces measured in a particle beam reactor

    Energy Technology Data Exchange (ETDEWEB)

    Marcak, Adrian; Corbella, Carles, E-mail: carles.corbella@rub.de; Keudell, Achim von [Research Group Reactive Plasmas, Ruhr-University Bochum, 44801 Bochum (Germany); Arcos, Teresa de los [Technical and Macromolecular Chemistry, Paderborn University, 33098 Paderborn (Germany)

    2015-10-15

    The secondary electron emission of metals induced by slow ions is characterized in a beam chamber by means of two coaxial semi-cylindrical electrodes with different apertures. The voltages of the outer electrode (screening), inner electrode (collector), and sample holder (target) were set independently in order to measure the effective yield of potential and kinetic electron emissions during ion bombardment. Aluminum samples were exposed to quantified beams of argon ions up to 2000 eV and to oxygen atoms and molecules in order to mimic the plasma-surface interactions on metallic targets during reactive sputtering. The variation of electron emission yield was correlated to the ion energy and to the oxidation state of Al surfaces. This system provides reliable measurements of the electron yields in real time and is of great utility to explore the fundamental surface processes during target poisoning occurring in reactive magnetron sputtering applications.

  10. Electron spectroscopic study of electronic and morphological modifications of the WSe{sub 2} surface induced by Rb adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Jens

    2010-07-20

    The rubidium-covered surface of the semiconducting transition metal dichalcogenide tungsten diselenide (WSe{sub 2}) is examined using photoelectron spectroscopy (PES) and photoemission electron microscopy (PEEM). Adsorbed Rb is known to induce a variety of effects in this system concerning electronic, structural, and mechanical properties. In this work, the surface potential created by charge transfer upon Rb deposition is examined in thermal equilibrium (band bending) and stationary non-equilibrium (surface photovoltage (SPV) effect), which is induced by the absorption of light. It is shown that combined measurements and numerical simulations of the SPV effect as a function of the photon flux can be exploited for the estimation of many material parameters of the system, especially of the unoccupied adsorbate state. Issues of extending a conventional photoelectron spectrometer setup by a secondary light source will be discussed in the context of simulations and calibration measurements. The customization of an existing theoretical model of the SPV effect for the WSe{sub 2}: Rb system is introduced, and a comprehensive validation of the obtained predictions is given in the context of experimental data. In addition, the self-organized formation of Rb domains at room temperature was examined by application of spatially resolved XPS spectroscopy using the PEEM setup at the end station of beamline UE49/PGMa at the BESSY II synchrotron facility. From the obtained results, the arrangement of Rb in surface lattices can be concluded. Furthermore, an X-Ray absorption study of self-organized nanostructure networks, aiming at the chemical characterization, is presented. Based on the interpretation of the examined structures as tension-induced cracks, a statistical approach to analyzing large-scale features was pursued. First accordance with the predictions made by a primitive, mechanical model of crack creation developed here gives gives some evidence for the validity of the

  11. Educational Systems Design Implications of Electronic Publishing.

    Science.gov (United States)

    Romiszowski, Alexander J.

    1994-01-01

    Discussion of electronic publishing focuses on the four main purposes of media in general: communication, entertainment, motivation, and education. Highlights include electronic journals and books; hypertext; user control; computer graphics and animation; electronic games; virtual reality; multimedia; electronic performance support;…

  12. Educational Systems Design Implications of Electronic Publishing.

    Science.gov (United States)

    Romiszowski, Alexander J.

    1994-01-01

    Discussion of electronic publishing focuses on the four main purposes of media in general: communication, entertainment, motivation, and education. Highlights include electronic journals and books; hypertext; user control; computer graphics and animation; electronic games; virtual reality; multimedia; electronic performance support;…

  13. Extracellular Electron Uptake: Among Autotrophs and Mediated by Surfaces

    DEFF Research Database (Denmark)

    Tremblay, Pier-Luc; Angenent, Largus T.; Zhang, Tian

    2017-01-01

    Autotrophic microbes can acquire electrons from solid donors such as steel, other microbial cells, or electrodes. Based on this feature, bioprocesses are being developed for the microbial electrosynthesis (MES) of useful products from the greenhouse gas CO2. Extracellular electron-transfer mechan......Autotrophic microbes can acquire electrons from solid donors such as steel, other microbial cells, or electrodes. Based on this feature, bioprocesses are being developed for the microbial electrosynthesis (MES) of useful products from the greenhouse gas CO2. Extracellular electron...

  14. A Novel Contactless Method for Characterization of Semiconductors: Surface Electron Beam Induced Voltage in Scanning Electron Microscopy

    Institute of Scientific and Technical Information of China (English)

    朱世秋; E.I.RAU; 杨富华; 郑厚植

    2002-01-01

    We present a novel contactless and nondestructive method called the surface electron beam induced voltage (SEBIV) method for characterizing semiconductor materials and devices. The SEBIV method is based on the detection of the surface potential induced by electron beams of scanning electron microscopy (SEM). The core part of the SEBIV detection set-up is a circular metal detector placed above the sample surface. The capacitance between the circular detector and whole surface of the sample is estimated to be about 0.64pf. It is large enough for the detection of the induced surface potential. The irradiation mode of electron beam (e-beam) influences the signal generation. When the e-beam irradiates on the surface of semiconductors continuously, a differential signal is obtained. The real distribution of surface potentials can be obtained when a pulsed e-beam with a fixed frequency is used for irradiation and a lock-in amplifier is employed for detection. The polarity of induced potential depends on the structure of potential barriers and surface states of samples. The contrast of SEBIV images in SEM changes with irradiation time and e-beam intensity.

  15. Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Joel Glenn [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

  16. Effect of surface mechanical finishes on charging ability of electron irradiated PMMA in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Rondot, Sebastien, E-mail: sebastien.rondot@univ-reims.fr [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France); Jbara, Omar [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France); Fakhfakh, Slim [LaMaCop, Faculte des Sciences de SFAX, Route Soukra Km 3, BP 1171, C.P 3000 Sfax (Tunisia); Belkorissat, Redouane; Patat, Jean Marc [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France)

    2011-10-01

    Charging of Polymethyl Methacrylate insulators (PMMA), in a scanning electron microscope (SEM) is studied owing to a time resolved current method. This method allows the evolution of trapped charge versus time and the charging time constant to be deduced. The effect of surface roughness change on the ability of PMMA to trapped charge is highlighted. The results show that the trapped charge at the steady state decreases when the roughness increases in the micrometer range while the time constant of charging increases with surface roughness. This behaviour is due to the increase of leakage current and/or enhanced secondary electron emission (SEE). On the one hand, surface mechanical finishes allows, the build up charge in insulators submitted to an electron bombardment to be lowered. On the other hand this treatment allows the secondary electron emission to be raised for some specific applications.

  17. Surface modification of the patterned Al6061/SUS304 metal plates using the large electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Min; Kim, Jisu; Park, Sung Soo [School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, UNIST-gil 50, Eonyang-eup, Ulju-gun, Ulsan Metropolitan City 689-798 (Korea, Republic of); Park, Hyung Wook, E-mail: hwpark@unist.ac.kr [School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, UNIST-gil 50, Eonyang-eup, Ulju-gun, Ulsan Metropolitan City 689-798 (Korea, Republic of); Ki, Hyungson [School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, UNIST-gil 50, Eonyang-eup, Ulju-gun, Ulsan Metropolitan City 689-798 (Korea, Republic of)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer We performed the large-electron-beam polishing of the patterned metal plates. Black-Right-Pointing-Pointer We observed its effect on surface hardness, surface roughness, and water repellency. Black-Right-Pointing-Pointer The contact angle for Al6061 and SUS304 increased after the electron-beam irradiation. Black-Right-Pointing-Pointer We observed the microstructure after the electron beam irradiation. - Abstract: Polishing is a finishing process used to improve surface integrity by reducing surface roughness and residual stress caused by other machining processes. The recently developed electron beam polishing method was used in this study to improve surface quality. In this process, an electron beam with a maximum diameter of 60 mm was applied for a few microseconds to melt and evaporate a metal surface. Al6061 and SUS304 metal plates were prepared with different geometric patterns and subjected to electron beam polishing. The surface roughness of the patterned SUS304 metal plate was significantly improved. However, the surface roughness of the patterned Al6061 metal plate became worse. Although the surface hardness decreased by approximately 10% on the re-solidified layers on both types of plates, the contact angle increased due to changes in surface morphology. The microstructure variation after the electron beam irradiation was also examined and compared with the thickness prediction of the re-solidified layer for Al6061 and SUS304 metal plates.

  18. Electron beam deposition for nanofabrication : Insights from surface science

    NARCIS (Netherlands)

    Wnuk, J. D.; Rosenberg, S. G.; Gorham, J. M.; van Dorp, W. F.; Hagen, C. W.; Fairbrother, D. H.

    2011-01-01

    Electron beam induced deposition (EBID) is a direct-write lithographic technique that utilizes the dissociation of volatile precursors by a focused electron beam in a low vacuum environment to create nanostructures. Notable advantages of EBID over competing lithographic techniques are that it is a s

  19. JCMT active surface control system: implementation

    Science.gov (United States)

    Smith, Ian A.

    1998-05-01

    The James Clerk Maxwell Telescope on the summit of Mauna Kea in Hawaii is a 15 meter sub-millimeter telescope which operates in the 350 microns to 2 millimeter region. The primary antenna surface consists of 276 panels, each of which is positioned by 3 stepper motors. In order to achieve the highest possible surface accuracy we are embarking upon a project to actively control the position of the panels adjuster system is based on a 6809 micro connected to the control computer by a GPIB interface. This system is slow and inflexible and it would prove difficult to build an active surface control system with it. Part of the upgrade project is to replace the existing micro with a 68060 VME micro. The poster paper will describe how the temperature of the antenna is monitored with the new system, how a Finite Element Analyses package transforms temperature changes into a series of panel adjuster moves, and how these moves are then applied to the surface. The FEA package will run on a high end Sun workstation. A series of DRAMA tasks distributed between the workstation and the Baja 68060 VxWorks Active Surface Control System micro will control the temperature monitoring, FEA and panel adjustment activities. Users can interact with the system via a Tcl/TK based GUI.

  20. Electronic Structure of Single-Crystal Monolayer Graphene on Hydrogen-Terminated Germanium Surface

    Science.gov (United States)

    Ahn, Sung Joon; Lee, Jae-Hyun; Ahn, Joung Real; Whang, Dongmok

    2015-03-01

    Graphene, atomically flat 2-Dimensional layered nano material, has a lot of interesting characteristics from its unusual electronic structure. Almost properties of graphene are influenced by its crystallinity, therefore the uniform growth of single crystal graphene and layer control over the wafer scale areas remains a challenge in the fields of electronic, photonic and other devices based on graphene. Here, we report the method to make wafer scale single crystal monolayer graphene on hydrogen terminated germanium(110) surface and properties and electronic band structure of the graphene by using the tool of scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, electron transport measurement, electron diffraction and angle-resolved photoemission spectroscopy.

  1. 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

  2. CERN Sells its Electronic Document Handling System

    CERN Multimedia

    2001-01-01

    The EDH team. Left to right: Derek Mathieson, Rotislav Titov, Per Gunnar Jonsson, Ivica Dobrovicova, James Purvis. Missing from the photo is Jurgen De Jonghe. In a 1 MCHF deal announced this week, the British company Transacsys bought the rights to CERN's Electronic Document Handling (EDH) system, which has revolutionised the Laboratory's administrative procedures over the last decade. Under the deal, CERN and Transacsys will collaborate on developing EDH over the coming 12 months. CERN will provide manpower and expertise and will retain the rights to use EDH, which will also be available freely to other particle physics laboratories. This development is an excellent example of the active technology transfer policy CERN is currently pursuing. The negotiations were carried out through a fruitful collaboration between AS and ETT Divisions, following the recommendations of the Technology Advisory Board, and with the help of SPL Division. EDH was born in 1991 when John Ferguson and Achille Petrilli of AS Divisi...

  3. Electron cyclotron resonance heating in a short cylindrical plasma system

    Indian Academy of Sciences (India)

    Vipin K Yadav; D Bora

    2004-09-01

    Electron cyclotron resonance (ECR) plasma is produced and studied in a small cylindrical system. Microwave power is delivered by a CW magnetron at 2.45 GHz in TE10 mode and launched radially to have extraordinary (X) wave in plasma. The axial magnetic field required for ECR in the system is such that the first two ECR surfaces ( = 875.0 G and = 437.5 G) reside in the system. ECR plasma is produced with hydrogen with typical plasma density e as 3.2 × 1010 cm-3 and plasma temperature e between 9 and 15 eV. Various cut-off and resonance positions are identified in the plasma system. ECR heating (ECRH) of the plasma is observed experimentally. This heating is because of the mode conversion of X-wave to electron Bernstein wave (EBW) at the upper hybrid resonance (UHR) layer. The power mode conversion efficiency is estimated to be 0.85 for this system. The experimental results are presented in this paper.

  4. Aspects of Metal Surface Glowing Mechanisms with Intensive Electron Beam Bombardment

    Directory of Open Access Journals (Sweden)

    I.V. Barsuk

    2012-06-01

    Full Text Available The paper gives a brief description and analysis of the main physical processes which can have an effect on the glowing nature of metal element surfaces in different electric vacuum devices when they are bombarded by electron beams. It has been found that the electron glowing effects on metal surfaces according to the electron energy can be explained with the help of the transition scattering on plasma waves or just with the classical transition radiation effect. This fact is rather important in terms of classical physics interpretation of the observed glowing effects on metal surface elements and techniques optimization of metal and electron beams diagnostics as well.

  5. Modeling of Reduced Effective Secondary Electron Emission Yield from a Velvet Surface

    CERN Document Server

    Swanson, Charles

    2016-01-01

    Complex structures on a material surface can significantly reduce total secondary electron emission from that surface. A velvet is a surface that consists of an array of vertically standing whiskers. The reduction occurs due to the capture of low-energy, true secondary electrons emitted at the bottom of the structure and on the sides of the velvet whiskers. We performed numerical simulations and developed an approximate analytical model that calculates the net secondary electron emission yield from a velvet surface as a function of the velvet whisker length and packing density, and the angle of incidence of primary electrons. The values of optimal velvet whisker packing density that maximally suppresses secondary electron emission yield are determined as a function of velvet aspect ratio and electron angle of incidence.

  6. The Role of Substrate Electrons in the Wetting of a Metal Surface

    Energy Technology Data Exchange (ETDEWEB)

    Schiros, T.; Takahashi, O.; Andersson, K.J.; Ostrom, H.; Pettersson, L.G.M.; Nilsson, A.; Ogasawara, H.; /SLAC

    2012-04-18

    We address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution of charge that enables surface wetting. On open d-shell Pt(111), the ligand field of water alters the distribution of metal d-electrons to reduce the repulsion. The closed-shell Cu d{sup 10} configuration of isostructural Cu(111), however, does not afford this mechanism, resulting in a hydrophobic surface and three-dimensional ice cluster formation. On the geometrically corrugated Cu(110) surface, however, charge depletion involving the mobile sp-electrons at atomic rows reduces the exchange repulsion sufficiently such that formation of a two-dimensional wetting layer is still favored in spite of the d{sup 10} electronic configuration.

  7. Parallel data acquisition system for electron momentum spectrometer

    CERN Document Server

    Pang, W N

    1999-01-01

    A parallel data acquisition system has been developed for the study of electron impact ionization of atoms and molecules. The system has a large data storage capacity providing good experimental resolution and system flexibility. The system is used to collect and analyze data from electron momentum spectroscopy experiment. Results from electron momentum spectroscopy experiments on C sub 4 H sub 1 sub 0 molecules, at an incident energy of 1200 eV, are presented to demonstrate the performance of the system. (author)

  8. Nonadiabaticity and single-electron transport driven by surface acoustic waves

    DEFF Research Database (Denmark)

    Flensberg, Karsten; Niu, Q.; Pustilnik, M.

    1999-01-01

    Single-electron transport driven by surface acoustic waves (SAW) through a narrow constriction, formed in a two-dimensional electron gas, is studied theoretically. Due to long-range Coulomb interaction, the tunneling coupling between the electron gas and the moving minimum of the SAW...

  9. The role of substrate electrons in the wetting of a metal surface

    DEFF Research Database (Denmark)

    Schiros, T.; Takahashi, O.; Andersson, Klas Jerker;

    2010-01-01

    We address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution of...

  10. The effect of hot electrons and surface plasmons on heterogeneous catalysis

    Science.gov (United States)

    Kim, Sun Mi; Lee, Si Woo; Moon, Song Yi; Park, Jeong Young

    2016-06-01

    Hot electrons and surface-plasmon-driven chemistry are amongst the most actively studied research subjects because they are deeply associated with energy dissipation and the conversion processes at the surface and interfaces, which are still open questions and key issues in the surface science community. In this topical review, we give an overview of the concept of hot electrons or surface-plasmon-mediated hot electrons generated under various structural schemes (i.e. metals, metal-semiconductor, and metal-insulator-metal) and their role affecting catalytic activity in chemical reactions. We highlight recent studies on the relation between hot electrons and catalytic activity on metallic surfaces. We discuss possible mechanisms for how hot electrons participate in chemical reactions. We also introduce controlled chemistry to describe specific pathways for selectivity control in catalysis on metal nanoparticles.

  11. Investigations on electronic, Fermi surface, Curie temperature and optical properties of Zr2CoAl

    Science.gov (United States)

    Wei, Xiao-Ping; Sun, Weiwei; Zhang, Ya-Ling; Sun, Xiao-Wei; Song, Ting; Wang, Ting; Zhang, Jia-Liang; Su, Hao; Deng, Jian-Bo; Zhu, Xing-Feng

    2017-03-01

    Using full-potential local-orbital minimum-basis along with spin-polarized relativistic Korringa-Kohn-Rostoker methods, we study the electronic, Fermi surface, Curie temperature and optical properties of Zr2CoAl alloy. The alloy with Li2AgSb and Cu2MnAl structures are compared in terms of magnetic properties, and the electronic structures in two structures are also discussed. According to the calculated electronic states, it finds that the Zr2CoAl with Li2AgSb structure is half-metallic ferromagnet with an integral magnetic moment of 2.00μB , meanwhile we also notice the d-d and p-d hybridizations are responsible for the formation of minority-spin gap, furthermore, the fat-bands are applied to discuss the mixture between d and p electrons in the vicinity of the Fermi level. The Fermi surfaces related to the valence bands are constructed, and it is found that the spin-up valence bands 26, 27 and 28 across the Fermi energy dominate the nature of electrons. By mapping the system onto a Heisenberg Hamiltonian, we obtain the exchange coupling parameters, and observe that the Zr(A)-Co(C) and Zr(A)-Zr(B) interactions provide a major contribution for exchange interactions. Based on the calculated exchange coupling parameters, the Curie temperature is estimated to be 287.86 K at equilibrium, and also the dependence of Curie temperature on lattice constant related to the tunable Curie temperature in Zr2CoAl alloy is studied. Finally, we report the optical properties of Zr2CoAl alloy, and present the photon energy dependence of the absorption, the optical conductivity and the loss function.

  12. Electron-hole pair contributions to scattering, sticking, and surface diffusion: CO on Cu(100)

    Energy Technology Data Exchange (ETDEWEB)

    Kindt, J.T.; Tully, J.C. [Department of Chemistry, Yale University, New Haven, Connecticut 06511 (United States); Head-Gordon, M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Gomez, M.A. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-09-01

    To assess the importance of coupling to electron-hole pair (ehp) excitations for molecular sticking, scattering, and diffusion dynamics at metal surfaces, simulations of the CO/Cu(100) system were performed using the {open_quotes}molecular dynamics with electronic frictions{close_quotes} method. Over a range of incident translational energies, energy losses to ehp excitations produce a moderate increase in sticking probability and account for 5{percent}{endash}10{percent} of initial translational energy in scattered molecules, significantly less than phonon losses. Vibrational excitation and deexcitation of scattered molecules, while remaining a minor pathway for energy flow, is strongly affected by the inclusion of ehp excitations. Finally, although equilibrium diffusion constants are unaffected by the inclusion of coupling to ehp, it causes a significant quenching of transient mobility following adsorption of translationally hot molecules. {copyright} {ital 1998 American Institute of Physics.}

  13. Electronic Structure of Solids and Their Surfaces and Interfaces.

    Science.gov (United States)

    1981-06-30

    point and several articles relating to these studies are being prepared for publication. I. ~ -- ~ i n’J This irnvest.gf.gation has the iur-Pose of...the ideal terminated cubic ,- cristobalite ) surface. Using an admittedly crude model for the surface, they found no states in the band gap. The purpose...this level is an E’ center at or near the surface ( ). The method of sample preparation which they have used (grinding) could easily have caused

  14. Realistic theory of electronic correlations in nanoscopic systems

    Science.gov (United States)

    Schüler, Malte; Barthel, Stefan; Wehling, Tim; Karolak, Michael; Valli, Angelo; Sangiovanni, Giorgio

    2017-07-01

    Nanostructures with open shell transition metal or molecular constituents host often strong electronic correlations and are highly sensitive to atomistic material details. This tutorial review discusses method developments and applications of theoretical approaches for the realistic description of the electronic and magnetic properties of nanostructures with correlated electrons. First, the implementation of a flexible interface between density functional theory and a variant of dynamical mean field theory (DMFT) highly suitable for the simulation of complex correlated structures is explained and illustrated. On the DMFT side, this interface is largely based on recent developments of quantum Monte Carlo and exact diagonalization techniques allowing for efficient descriptions of general four fermion Coulomb interactions, reduced symmetries and spin-orbit coupling, which are explained here. With the examples of the Cr (001) surfaces, magnetic adatoms, and molecular systems it is shown how the interplay of Hubbard U and Hund's J determines charge and spin fluctuations and how these interactions drive different sorts of correlation effects in nanosystems. Non-local interactions and correlations present a particular challenge for the theory of low dimensional systems. We present our method developments addressing these two challenges, i.e., advancements of the dynamical vertex approximation and a combination of the constrained random phase approximation with continuum medium theories. We demonstrate how non-local interaction and correlation phenomena are controlled not only by dimensionality but also by coupling to the environment which is typically important for determining the physics of nanosystems.

  15. Electron beam induced oxidation of Ni3Al surfaces : electron flux effects

    NARCIS (Netherlands)

    Koch, S.A.; Palasantzas, G.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2002-01-01

    Electron beam irradiation of polycrystalline boron doped Ni3Al (at 300 K and under ultrahigh vacuum conditions) induces fast oxidation. The rate and depth of oxidation initially increase with increasing electron flux as indicated by results from Auger electron spectroscopy. Curves of oxygen developm

  16. Electron Conditioning of Technical Aluminium Surfaces: Effect on the Secondary Electron Yield

    Energy Technology Data Exchange (ETDEWEB)

    Le Pimpec, F.

    2004-12-13

    The effect of electron conditioning on commercially aluminium alloys 1100 and 6063 were investigated. Contrary to the assumption that electron conditioning, if performed long enough, can reduce and stabilize the SEY to low values (< 1.3, value of many pure elements [1] ), the SEY of aluminium did not go lower than 1.8. In fact, it reincreases with continued electron exposure dose.

  17. Reference Avionics Architecture for Lunar Surface Systems

    Science.gov (United States)

    Somervill, Kevin M.; Lapin, Jonathan C.; Schmidt, Oron L.

    2010-01-01

    Developing and delivering infrastructure capable of supporting long-term manned operations to the lunar surface has been a primary objective of the Constellation Program in the Exploration Systems Mission Directorate. Several concepts have been developed related to development and deployment lunar exploration vehicles and assets that provide critical functionality such as transportation, habitation, and communication, to name a few. Together, these systems perform complex safety-critical functions, largely dependent on avionics for control and behavior of system functions. These functions are implemented using interchangeable, modular avionics designed for lunar transit and lunar surface deployment. Systems are optimized towards reuse and commonality of form and interface and can be configured via software or component integration for special purpose applications. There are two core concepts in the reference avionics architecture described in this report. The first concept uses distributed, smart systems to manage complexity, simplify integration, and facilitate commonality. The second core concept is to employ extensive commonality between elements and subsystems. These two concepts are used in the context of developing reference designs for many lunar surface exploration vehicles and elements. These concepts are repeated constantly as architectural patterns in a conceptual architectural framework. This report describes the use of these architectural patterns in a reference avionics architecture for Lunar surface systems elements.

  18. Electrostatic discharge and field effects of electronics systems

    Science.gov (United States)

    Dicks, L. R.; Morin, G.

    1988-04-01

    The effects of static electricity on modern electronics are discussed, as well as a comprehensive approach to electrostatic discharge (ESD) protection measures in all phases of the life cycle of an electronic system. Static electricity has become a potential source of damage to electronic systems used in most applications, including aircraft, ground and shipboard installations.

  19. One nanosecond pulsed electron gun systems

    Energy Technology Data Exchange (ETDEWEB)

    Koontz, R.F.

    1979-02-01

    At SLAC there has been a continuous need for the injection of very short bunches of electrons into the accelerator. Several time-of-flight experiments have used bursts of short pulses during a normal 1.6 micro-second rf acceleration period. Single bunch beam loading experiments made use of a short pulse injection system which included high power transverse beam chopping equipment. Until the equipment described in this paper came on line, the basic grid-controlled gun pulse was limited to a rise time of 7 nanoseconds and a pulse width of 10 nanoseconds. The system described here has a grid-controlled rise time of less than 500 pico-seconds, and a minimum pulse width of less than 1 nanosecond. Pulse burst repetition rate has been demonstrated above 20 MHz during a 1.6 microsecond rf accelerating period. The order-of-magnitude increase in gun grid switching speed comes from a new gun design which minimizes lead inductance and stray capacitance, and also increases gun grid transconductance. These gun improvements coupled with a newly designed fast pulser mounted directly within the gun envelope make possible subnanosecond pulsing of the gun.

  20. Tangible display systems: bringing virtual surfaces into the real world

    Science.gov (United States)

    Ferwerda, James A.

    2012-03-01

    We are developing tangible display systems that enable natural interaction with virtual surfaces. Tangible display systems are based on modern mobile devices that incorporate electronic image displays, graphics hardware, tracking systems, and digital cameras. Custom software allows the orientation of a device and the position of the observer to be tracked in real-time. Using this information, realistic images of surfaces with complex textures and material properties illuminated by environment-mapped lighting, can be rendered to the screen at interactive rates. Tilting or moving in front of the device produces realistic changes in surface lighting and material appearance. In this way, tangible displays allow virtual surfaces to be observed and manipulated as naturally as real ones, with the added benefit that surface geometry and material properties can be modified in real-time. We demonstrate the utility of tangible display systems in four application areas: material appearance research; computer-aided appearance design; enhanced access to digital library and museum collections; and new tools for digital artists.

  1. Linear in-plane magnetoconductance and spin susceptibility of a 2D electron gas on a vicinal silicon surface

    OpenAIRE

    Proskuryakov, Y. Y.; Kvon, Z. D.; Savchenko, A. K.

    2003-01-01

    In this work we have studied the parallel magnetoresistance of a 2DEG near a vicinal silicon surface. An unusual, linear magnetoconductance is observed in the fields up to $B = 15$ T, which we explain by the effect of spin olarization on impurity scattering. This linear magnetoresistance shows strong anomalies near the boundaries of the minigap in the electron spectrum of the vicinal system.

  2. One-dimensional electron liquid at a surface. Gold nanowires on Ge(001)

    Energy Technology Data Exchange (ETDEWEB)

    Blumenstein, Christian

    2012-09-11

    Self-organized nanowires at semiconductor surfaces offer the unique opportunity to study electrons in reduced dimensions. Notably the dimensionality of the system determines it's electronic properties, beyond the quasiparticle description. In the quasi-one-dimensional (1D) regime with weak lateral coupling between the chains, a Peierls instability can be realized. A nesting condition in the Fermi surface leads to a backfolding of the 1D electron band and thus to an insulating state. It is accompanied by a charge density wave (CDW) in real space that corresponds to the nesting vector. This effect has been claimed to occur in many surface-defined nanowire systems, such as the In chains on Si(111) or the Au reconstructions on the terraced Si(553) and Si(557) surfaces. Therefore a weak coupling between the nanowires in these systems has to be concluded. However theory proposes another state in the perfect 1D limit, which is completely destroyed upon slight coupling to higher dimensions. In this so-called Tomonaga-Luttinger liquid (TLL) state, the quasiparticle description of the Fermi liquid breaks down. Since the interaction between the electrons is enhanced due to the strong confinement, only collective excitations are allowed. This leads to novel effects like spin charge separation, where spin and charge degrees of freedom are decoupled and allowed to travel independently along the 1D-chain. Such rare state has not been realized at a surface until today. This thesis uses a novel approach to realize nanowires with improved confinement by studying the Au reconstructed Ge(001) surface. A new cleaning procedure using piranha solution is presented, in order to prepare a clean and long-range ordered substrate. To ensure optimal growth of the Au nanowires the phase diagram is extensively studied by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The structural elements of the chains are revealed and described in high detail. Remarkably

  3. Duke Electronic Mail Post Office A Practical Mail Linking System*

    Science.gov (United States)

    Dryfoos, James D.; Hammond, William E.; Spero, Laurence A.; Rabold, Jean S.; Straube, Mark J.; Stead, William W.

    1988-01-01

    This paper describes a system designed to integrate the many different electronic mail systems in use throughout Duke University. The Duke Electronic Mail Post Office project is part of Duke University Medical Center's model for Achieving an Integrated Academic Information Management System (IAIMS). Main features of the systems, problems encountered during implementation, and future directions are presented and discussed.

  4. Power electronic converters and systems frontiers and applications

    CERN Document Server

    Trzynadlowski, Andrzej M

    2016-01-01

    Power electronics is a branch of electrical engineering dealing with conversion and control of electric power using semiconductor power switches. This book provides an overview of modern power electronic converters and systems, and their applications.

  5. Analysis of surface insulation resistance related failures in electronics by circuit simulation

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Joshy, Salil; Jellesen, Morten Stendahl

    2017-01-01

    Purpose-The purpose of this study is to show that the humidity levels for surface insulation resistance (SIR)-related failures are dependent on the type of activators used in no-clean flux systems and to demonstrate the possibility of simulating the effects of humidity and contamination on printed...... for the circuit analysis. The SIR data were compared to the surface resistance values observable on a real device printed circuit board assembly. SIR issues at the component and circuit levels were analysed on the basis of parasitic circuit effects owing to the formation of a water layer as an electrical...... conduction medium. Findings-This paper provides a summary of the effects of contamination with various weak organic acids representing the active components in no-clean solder flux residue, and demonstrates the effect of humidity and contamination on the possible malfunctions and errors in electronic...

  6. An ultrafast nanotip electron gun triggered by grating-coupled surface plasmons

    Science.gov (United States)

    Schröder, Benjamin; Sivis, Murat; Bormann, Reiner; Schäfer, Sascha; Ropers, Claus

    2015-12-01

    We demonstrate multiphoton photoelectron emission from gold nanotips induced by nanofocusing surface plasmons, resonantly excited on the tip shaft by a grating coupler. The tip is integrated into an electron gun assembly, which facilitates control over the spatial emission sites and allows us to disentangle direct grating emission from plasmon-triggered apex emission. The nanoscale source size of this electron gun concept enables highly coherent electron pulses with applications in ultrafast electron imaging and diffraction.

  7. An ultrafast nanotip electron gun triggered by grating-coupled surface plasmons

    Energy Technology Data Exchange (ETDEWEB)

    Schröder, Benjamin; Sivis, Murat; Bormann, Reiner; Schäfer, Sascha; Ropers, Claus, E-mail: cropers@gwdg.de [4th Physical Institute - Solids and Nanostructures, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2015-12-07

    We demonstrate multiphoton photoelectron emission from gold nanotips induced by nanofocusing surface plasmons, resonantly excited on the tip shaft by a grating coupler. The tip is integrated into an electron gun assembly, which facilitates control over the spatial emission sites and allows us to disentangle direct grating emission from plasmon-triggered apex emission. The nanoscale source size of this electron gun concept enables highly coherent electron pulses with applications in ultrafast electron imaging and diffraction.

  8. Electronic structures of the oxygenated diamond (100)surfaces

    Institute of Scientific and Technical Information of China (English)

    LIU Fengbin; WANG Jiadao; LIU Bing; LI Xuemin; CHEN Darong

    2006-01-01

    By means of first principles method on the basis of density functional theory (DFT), the equilibrium geometries and density of states (DOS) of the two oxygenated diamond (100) surfaces, bridging model and on-top model are calculated. The results indicate that there are no surface states located in the band gap of the bridging model of oxygenated diamond (100) surface, and the occupied surface states in the valence band are attributed to the non-bonded O 2p orbital, O 2p and C 2p bonding orbitals, and C 2p and H1s bonding orbitals. By contrast, for the on-top model of oxygenated diamond (100) surface,the unoccupied surface states exist in the band gap,which originate from non-bonded C 2p and O 2p orbitals. In addition, the occupied surface states in the valence band are induced by non-bonded O 2p orbital and the C=O π bond.

  9. Electronic and structural properties of the (1010) and (1120) ZnO surfaces.

    Science.gov (United States)

    Marana, N L; Longo, V M; Longo, E; Martins, J B L; Sambrano, J R

    2008-09-25

    The structural and electronic properties of ZnO (1010) and (1120) surfaces were investigated by means of density functional theory applied to periodic calculations at B3LYP level. The stability and relaxation effects for both surfaces were analyzed. The electronic and energy band properties were discussed on the basis of band structure as well as density of states. There is a significant relaxation in the (1010) as compared to the (1120) terminated surfaces. The calculated direct gap is 3.09, 2.85, and 3.09 eV for bulk, (1010), and (1120) surfaces, respectively. The band structures for both surfaces are very similar.

  10. Low energy high current pulsed electron beam treatment for improving surface microstructure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J; Allain-Bonasso, N; Zhang, X D; Hao, S Z; Grosdider, T; Dong, C [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, UMR-CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Zou, J X, E-mail: jiang.wu@univ-metz.fr, E-mail: thierry.grosdidier@univ-metz.fr [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-06-15

    Low energy high current pulsed electron beam (LEHCPEB) is a fairly new technique for surface modifications authorizing improvement in wear and corrosion properties as well as texture changes and hardening. This contribution highlights some microstructure modifications encountered at the surface of HCPEB treated steels and bulk metallic glasses taking into account the effects of surface melting and the effects of the induced stress.

  11. Primary role of electron work function for evaluation of nanostructured titania implant surface against bacterial infection.

    Science.gov (United States)

    Golda-Cepa, M; Syrek, K; Brzychczy-Wloch, M; Sulka, G D; Kotarba, A

    2016-09-01

    The electron work function as an essential descriptor for the evaluation of metal implant surfaces against bacterial infection is identified for the first time. Its validity is demonstrated on Staphylococcus aureus adhesion to nanostructured titania surfaces. The established correlation: work function-bacteria adhesion is of general importance since it can be used for direct evaluation of any electrically conductive implant surfaces.

  12. Electronic Resource Management System. Vernetzung von Lizenzinformationen

    Directory of Open Access Journals (Sweden)

    Michaela Selbach

    2014-12-01

    collections efficiently. Not only libraries, but also the negotiators of Alliance and National Licences need a software application which helps them to handle these complex licences efficiently. The project presented in this paper aims at developing a national Electronic Resource Management System (ERMS. It is funded by the German Research Foundation/Deutsche Forschungsgemeinschaft (DFG. The project partners are the North Rhine-Westphalian Library Service Centre (hbz, the University Library Johann Christian Senckenberg Frankfurt, the Head Office of the Gemeinsamer Bibliotheksverbund (GBV and the Freiburg University Library. The projected ERMS  will provide a software system with a central knowledge base which supports a unified overview of licence data with a local, regional and national scope. In the current state of development, the focus is on data and function modelling and on designing concepts for rights management, cooperative data management, implementation of interface standards and the intended services such as statistical analyses.

  13. Development of High Power Electron Beam Measuring and Analyzing System for Microwave Vacuum Electron Devices

    Science.gov (United States)

    Ruan, C. J.; Wu, X. L.; Li, Q. S.; Li, C. S.

    The measurement and analysis of high power electron beam during its formation and transmission are the basic scientific problems and key techniques for the development of high performance microwave vacuum electron devices, which are widely used in the fields of military weapon, microwave system and scientific instruments. In this paper, the dynamic parameters measurement and analysis system being built in Institute of Electronics, Chinese Academy of Sciences (IECAS) recently are introduced. The instrument are designed to determine the cross-section, the current density, and the energy resolution of the high power electron beam during its formation and transmission process, which are available both for the electron gun and the electron optics system respectively. Then the three dimension trajectory images of the electron beam can be rebuilt and display with computer controlled data acquisition and processing system easily. Thus, much more complicated structures are considered and solved completely to achieve its detection and analysis, such as big chamber with 10-6 Pa high vacuum system, the controlled detector movement system in axis direction with distance of 600 mm inside the vacuum chamber, the electron beam energy analysis system with high resolution of 0.5%, and the electron beam cross-section and density detector using the YAG: Ce crystal and CCD imaging system et al. At present, the key parts of the instrument have been finished, the cross-section experiment of the electron beam have been performed successfully. Hereafter, the instrument will be used to measure and analyze the electron beam with the electron gun and electron optics system for the single beam and multiple beam klystron, gyrotron, sheet beam device, and traveling wave tube etc. thoroughly.

  14. Monitoring System for ALICE Surface Areas

    CERN Document Server

    Demirbasci, Oguz

    2016-01-01

    I have been at CERN for 12 weeks within the scope of Summer Student Programme working on a monitoring system project for surface areas of the ALICE experiment during this period of time. The development and implementation of a monitoring system for environmental parameters in the accessible areas where a cheap hardware setup can be deployed were aim of this project. This report explains how it was developed by using Arduino, Raspberry PI, WinCC OA and DIM protocol.

  15. Electron mean free path dependence of the vortex surface impedance

    Science.gov (United States)

    Checchin, M.; Martinello, M.; Grassellino, A.; Romanenko, A.; Zasadzinski, J. F.

    2017-03-01

    In the present study the radio-frequency complex response of trapped vortices in superconductors is calculated and compared to experimental data previously published. The motion equation for a magnetic flux line is solved assuming a bi-dimensional and mean-free-path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the unprecedented bell-shaped trend as a function of the mean-free-path observed in our previous experimental work. We demonstrate that such bell-shaped trend of the surface resistance as a function of the mean-free-path may be described as the interplay of the two limiting regimes of the surface resistance, for low and large mean-free-path values: pinning and flux-flow regimes respectively. Since the possibility of defining the pinning potential at different locations from the surface and with different strengths, we discuss how the surface resistance is affected by different configurations of pinning sites. By tackling the frequency dependence of the surface resistance, we also demonstrate that the separation between pinning- and flux-flow-dominated regimes cannot be determined only by the depinning frequency. The dissipation regime can be tuned either by acting on the frequency or on the mean-free-path value.

  16. Photoelectron spectroscopy and Auger electron spectroscopy of solids and surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kowalczyk, S.P.

    1976-01-01

    The use of photoelectron spectroscopy, primarily x-ray photoelectron spectroscopy, to obtain information on the electronic structure of a wide variety of solids (especially the bulk electronic structure of solids) is covered. Both valence band and core-level spectra, as well as a few cases of photon excited Auger electron spectroscopy, are employed in the investigations to derive information on N(E). The effect of several modulations inherent in the measured I(E)'s, such as final state band structure, cross section, and relaxation, is discussed. Examples of many-electron interactions in PES are given. Some experimental aspects of PES and AES studies are given with emphasis on sample preparation techniques. Multiple splitting of core levels is examined using the Mn levels in MnF/sub 2/ as a detailed case study. Core level splittings in transition metals, rare earth metals, transition metal halides and several alloys are also reported. The application of PES to the study of the chemical bond in some crystalline semiconductors and insulators, A/sup N/B/sup 8-N/ and A/sup N/B/sup 10-N/ compounds is treated, and a spectroscopic scale of ionicity for these compounds is developed from the measured ''s-band'' splitting in the valence band density of states. (GHT)

  17. ARM Surface Meteorology Systems Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Ritsche, MT

    2011-03-08

    The ARM Surface Meteorology Systems consist mainly of conventional in situ sensors that obtain a defined “core” set of measurements. The core set of measurements is: Barometric Pressure (kPa), Temperature (°C), Relative Humidity (%), Arithmetic-Averaged Wind Speed (m/s), Vector-Averaged Wind Speed (m/s), and Vector-Averaged Wind Direction (deg).

  18. Advanced Photonic and Electronic Systems WILGA 2010

    CERN Document Server

    Romaniuk, R S

    2010-01-01

    SPIE – PSP WILGA Symposium gathers two times a year in January and in May new adepts of advanced photonic and electronic systems. The event is oriented on components and applications. WILGA Symposium on Photonics and Web Engineering is well known on the web for its devotion to “young research” promotion under the eminent sponsorship of international engineering associations like SPIE and IEEE and their Poland Sections or Counterparts. WILGA is supported by the most important national professional organizations like KEiT PAN and PSP-Photonics Society of Poland. The Symposium is organized since 1998 twice a year. It has gathered over 4000 young researchers and published over 2000 papers mainly internationally, including more than 900 in 10 published so far volumes of Proc. SPIE. This paper is a digest of WILGA Symposium Series and WILGA 2010 summary. Introductory part treats WILGA Photonics Applications characteristics over the period 1998-2010. Following part presents a short report on the XXVth and XXVI...

  19. Surface plasmon enhanced interfacial electron transfer and resonance Raman, surface-enhanced resonance Raman studies of cytochrome C mutants

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Junwei

    1999-11-08

    Surface plasmon resonance was utilized to enhance the electron transfer at silver/solution interfaces. Photoelectrochemical reductions of nitrite, nitrate, and CO{sub 2} were studied on electrochemically roughened silver electrode surfaces. The dependence of the photocurrent on photon energy, applied potential and concentration of nitrite demonstrates that the photoelectrochemical reduction proceeds via photoemission process followed by the capture of hydrated electrons. The excitation of plasmon resonances in nanosized metal structures resulted in the enhancement of the photoemission process. In the case of photoelectrocatalytic reduction of CO{sub 2}, large photoelectrocatalytic effect for the reduction of CO{sub 2} was observed in the presence of surface adsorbed methylviologen, which functions as a mediator for the photoexcited electron transfer from silver metal to CO{sub 2} in solution. Photoinduced reduction of microperoxidase-11 adsorbed on roughened silver electrode was also observed and attributed to the direct photoejection of free electrons of silver metal. Surface plasmon assisted electron transfer at nanostructured silver particle surfaces was further determined by EPR method.

  20. Surface plasmon enhanced interfacial electron transfer and resonance Raman, surface-enhanced resonance Raman studies of cytochrome C mutants

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Junwei [Iowa State Univ., Ames, IA (United States)

    1999-11-08

    Surface plasmon resonance was utilized to enhance the electron transfer at silver/solution interfaces. Photoelectrochemical reductions of nitrite, nitrate, and CO2 were studied on electrochemically roughened silver electrode surfaces. The dependence of the photocurrent on photon energy, applied potential and concentration of nitrite demonstrates that the photoelectrochemical reduction proceeds via photoemission process followed by the capture of hydrated electrons. The excitation of plasmon resonances in nanosized metal structures resulted in the enhancement of the photoemission process. In the case of photoelectrocatalytic reduction of CO2, large photoelectrocatalytic effect for the reduction of CO2 was observed in the presence of surface adsorbed methylviologen, which functions as a mediator for the photoexcited electron transfer from silver metal to CO2 in solution. Photoinduced reduction of microperoxidase-11 adsorbed on roughened silver electrode was also observed and attributed to the direct photoejection of free electrons of silver metal. Surface plasmon assisted electron transfer at nanostructured silver particle surfaces was further determined by EPR method.

  1. Power electronic converter systems for direct drive renewable energy applications

    DEFF Research Database (Denmark)

    Chen, Zhe

    2013-01-01

    This chapter presents power electronic conversion systems for wind and marine energy generation applications, in particular, direct drive generator energy conversion systems. Various topologies are presented and system design optimization and reliability are briefly discussed....

  2. Glass for parenteral products: a surface view using the scanning electron microscope.

    Science.gov (United States)

    Roseman, T J; Brown, J A; Scothorn, W W

    1976-01-01

    The scanning electron microscope was utilized to explore the internal surface of glass ampuls and vials used in parenteral products. The surface topography of USP Type I borosilicate glass containers was viewed after exposure to "sulfur," ammonium bifluoride, and sulfuric acid treatments. The scanning electron micrographs showed startling differences in the appearance of the surface regions. "Sulfur treatment" of ampuls was associated with a pitting of the surface and the presence of sodium sulfate crystals. The sulfur treatment of vials altered the glass surface in a characteristically different manner. The dissimilarity between the surface appearances was attributed to the method of sulfur treatment. Ampuls exposed to sulfuric acid solutions at room temperature did not show the pitting associated with the sulfur treatment. Scanning electron micrographs of ammonium bifluoride-treated ampuls showed a relief effect, suggesting that the glass was affected by the bifluoride solution but that sufficient stripping of the surface layer did not occur to remove the pits associated with the sulfur treatment. Flakes emanating from the glass were identified with the aid of the electron microprobe. Scanning electron micrographs showed that these vitreous flakes resulted from a delamination of a thin layer of the glass surface. It is concluded that the scanning electron microscope, in conjunction with other analytical techniques, is a valuable tool in assessing the quality of glass used for parenteral products. The techniques studied should be of particular importance to the pharmaceutical industry where efforts are being made to reduce the levels of particulate matter in parenteral dosage forms.

  3. Effect of electron-electron interactions on Rashba-like and spin-split systems

    Science.gov (United States)

    Alexandradinata, A.; Hirsch, J. E.

    2010-11-01

    The role of electron-electron interactions is analyzed for Rashba-like and spin-split systems within a tight-binding single-band Hubbard model with on-site and all nearest-neighbor matrix elements of the Coulomb interaction. By Rashba-like systems we refer to the Dresselhaus and Rashba spin-orbit-coupled phases while spin-split systems have spin-up and spin-down Fermi surfaces shifted relative to each other. Both systems break parity but preserve time-reversal symmetry. They belong to a class of symmetry-breaking ground states that satisfy: (i) electron crystal momentum is a good quantum number, (ii) these states have no net magnetic moment, and (iii) their distribution of “polarized spin” in momentum space breaks the lattice symmetry. For all members of this class, the relevant Coulomb matrix elements are found to be nearest-neighbor exchange J , pair hopping J' , and nearest-neighbor repulsion V . These ground states lower their energy most effectively through J , hence we name them class J states. The competing effects of V-J' on the direct and exchange energies determine the relative stability of class J states. We show that the spin-split and Rashba-like phases are the most favored ground states within class J because they have the minimum anisotropy in polarized spin. We analyze these two states on a square lattice and find that the spin-split phase is always favored for near-empty bands; above a critical filling, we predict a transition from the paramagnetic to the Rashba-like phase at a critical J(Jc1) and a second transition from the Rashba-like to the spin-split state at Jc2>Jc1 . An energetic comparison with ferromagnetism highlights the importance of the role of V in the stability of class J states. We discuss the relevance of our results to (i) the α and β phases proposed by Wu and Zhang in the Fermi-liquid formalism and (ii) experimental observations of spin-orbit splitting in Au(111) surface states.

  4. Implementing CORAL: An Electronic Resource Management System

    Science.gov (United States)

    Whitfield, Sharon

    2011-01-01

    A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

  5. Implementing CORAL: An Electronic Resource Management System

    Science.gov (United States)

    Whitfield, Sharon

    2011-01-01

    A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

  6. 78 FR 11553 - Special Conditions: Embraer S.A., Model EMB-550 Airplane; Electronic Flight Control System...

    Science.gov (United States)

    2013-02-19

    ... Airplane; Electronic Flight Control System: Control Surface Awareness and Mode Annunciation AGENCY: Federal... control system. The applicable airworthiness regulations do not contain adequate or appropriate safety... a fly-by-wire electronic flight control system and no direct coupling from the flightdeck controller...

  7. Electron emission induced by resonant coherent ion-surface interaction at grazing incidence

    Energy Technology Data Exchange (ETDEWEB)

    Garcia de Abajo, F.J. (Departamento de Ciencias de la Computacion e Inteligencia Artificial, Facultad de Informatica, Universidad del Pais Vasco, Apartado 649, 20080 San Sebastian (Spain)); Ponce, V.H. (Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 San Carlos de Bariloche, Rio Negro (Argentina)); Echenique, P.M. (Departamento de Fisica de Materiales, Facultad de Quimica, Universidad del Pais Vasco, Apartado 1072, 20080 San Sebastian (Spain))

    1992-10-19

    A new spectroscopy based on the resonant coherently induced electron loss to the continuum in ion-surface scattering under grazing incidence is proposed. A series of peaks, corresponding to the energy differences determined by the resonant interaction with the rows of atoms in the surface, is predicted to appear in the energy distribution of electrons emitted from electronic states bound to the probe. Calculations for MeV He{sup +} ions scattered at a W(001) surface along the {l angle}100{r angle} direction with a glancing angle of 0--2 mrad show a total yield close to 1.

  8. Field-Emission from Chemically Functionalized Diamond Surfaces: Does Electron Affinity Picture Work?

    Science.gov (United States)

    Miyamoto, Yoshiyuki; Miyazaki, Takehide; Takeuchi, Daisuke; Okushi, Hideyo; Yamasaki, Satoshi

    2014-03-01

    By means of the time-dependent density functional electron dynamics, we have revisited the field-emission efficiency of chemically functionalized diamond (100) surfaces. In order to achieve high efficiency and high (chemical) stability, proper chemical species are needed to terminate diamond surfaces. Hydrogen (H) termination is well known to achieve the negative electron affinity (NEA) of diamond surface which indeed enhances field emission performance than that of clean surface with positive electron affinity (PEA). Yet, the durability of H-terminated diamond surface was concerned for long-time operation of the field-emission. Meantime, oxidation, or hydroxyl (OH) termination was considered to achieve chemical stability of the surface but presence of oxygen (O) atom should reduce the emission efficiency. Recently, H- OH-co-terminated surface is reported as NEA and was expected to achieve both emission efficiency and chemical stability. However, our simulation showed that emission efficiency of the H- OH- co-terminated surface is much lower than clean surface with PEA, thus we note that the electron affinity cannot be a unique measure to determine the emission efficiency. In this talk, we introduce necessity of new concept to understand the emission efficiency which needs to know detailed potential profile from bulk to vacuum through surface, which is strongly dependent on the surface chemical functionalization. This work was supported by ALCA project conducted by Japan Science and Technology Agency.

  9. NASA Electronic Library System (NELS): The system impact of security

    Science.gov (United States)

    Mcgregor, Terry L.

    1993-01-01

    This paper discusses security issues as they relate to the NASA Electronic Library System which is currently in use as the repository system for AdaNET System Version 3 (ASV3) being operated by MountainNET, Inc. NELS was originally designed to provide for public, development, and secure collections and objects. The secure feature for collections and objects was deferred in the initial system for implementation at a later date. The NELS system is now 9 months old and many lessons have been learned about the use and maintenance of library systems. MountainNET has 9 months of experience in operating the system and gathering feedback from the ASV3 user community. The user community has expressed an interest in seeing security features implemented in the current system. The time has come to take another look at the whole issue of security for the NELS system. Two requirements involving security have been put forth by MountainNET for the ASV3 system. The first is to incorporate at the collection level a security scheme to allow restricted access to collections. This should be invisible to end users and be controlled by librarians. The second is to allow inclusion of applications which can be executed only by a controlled group of users; for example, an application which can be executed by librarians only. The requirements provide a broad framework in which to work. These requirements raise more questions than answers. To explore the impact of these requirements a top down approach will be used.

  10. 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

  11. Local electronic properties of graphene flakes on noble metal surfaces

    OpenAIRE

    Leicht, Philipp

    2015-01-01

    This thesis examines possible routes for the preparation of graphene nanostructures on metal substrates and performs structural and electronic characterizations using scanning tunneling microcopy and spectroscopy. Investigations of graphene nanostructures necessitate the use of a suitable graphene-substrate combination, which allows for a controlled in situ preparation of small and well-shaped graphene nanostructures. The choice of a graphene-substrate combination with weak interaction in or...

  12. Electronic structure of reconstructed InAs(001) surfaces - identification of bulk and surface bands based on their symmetries

    Science.gov (United States)

    Olszowska, Natalia; Kolodziej, Jacek J.

    2016-02-01

    Using angle-resolved photoelectron spectroscopy (ARPES) band structures of indium- and arsenic-terminated InAs(001) surfaces are investigated. These surfaces are highly reconstructed, elementary cells of their lattices contain many atoms in different chemical configurations, and moreover, they are composed of domains having related but different reconstructions. These domain-type surface reconstructions result in the reciprocal spaces containing regions with well-defined k→∥-vector and regions with not-well-defined one. In the ARPES spectra most of the surface related features appear as straight lines in the indeterminate k→∥-vector space. It is shown that, thanks to differences in crystal and surface symmetries, the single photon energy ARPES may be successfully used for classification of surface and bulk bands of electronic states on complex, highly reconstructed surfaces instead of the most often used variable photon energy studies.

  13. Controlled cooling of an electronic system for reduced energy consumption

    Science.gov (United States)

    David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

    2016-08-09

    Energy efficient control of a cooling system cooling an electronic system is provided. The control includes automatically determining at least one adjusted control setting for at least one adjustable cooling component of a cooling system cooling the electronic system. The automatically determining is based, at least in part, on power being consumed by the cooling system and temperature of a heat sink to which heat extracted by the cooling system is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on one or more experimentally obtained models relating the targeted temperature and power consumption of the one or more adjustable cooling components of the cooling system.

  14. Spatial filtering with surface plasmon resonance systems

    Science.gov (United States)

    Ghosh, A. K.; Siddharth, V.; Bhagat, M.; Aggarwal, S.; Anurag, P.; Jain, M.

    2007-09-01

    Surface plasmon resonance based sensors are most useful in measuring the refractive indices of biochemicals. In such sensors a beam of light obliquely incident at an interface of glass and metallic thin film excites resonant plasmon waves in the metal if the angle of incidence or the wavelength is selected properly. The resonance conditions are changed by the refractive indices of any material in contact with the metal film. When resonance occurs the light beam is absorbed strongly. We can easily show that the phenomenon of surface plasmon resonance in such a system acts as a high quality spatial notch or band rejection filter.

  15. Magnetite Fe3O4 (111) Surfaces: Impact of Defects on Structure, Stability, and Electronic Properties

    KAUST Repository

    Noh, Junghyun

    2015-08-04

    We present a comprehensive investigation, via first-principles density functional theory (DFT) calculations, of various surface terminations of magnetite, Fe3O4 (111), a major iron oxide which has also a number of applications in electronics and spintronics. We compare the thermodynamic stability and electronic structure among the different surfaces terminations. Interestingly, we find that surfaces modified with point defects and adatoms can be more stable than bulk-like terminations. These surfaces show different surface chemistry, electronic structures and distinctive spin polarization features near the Fermi level from those previously considered in the literature. Our studies provide an atomic level insight for magnetite surfaces, which is a necessary step to understanding their interfaces with organic layers in OLED and spintronic devices.

  16. Atomic and Electronic Structures of Cd0.96Zn0.04Te(110) Surface

    Institute of Scientific and Technical Information of China (English)

    ZHA Gang-Qiang; JIE Wan-Qi; ZHANG Wen-Hua; LI Qiang; XU Fa-Qiang

    2005-01-01

    @@ X-Ray diffraction is used to analyse the lattice structure of Cd0.96Zn0.04Te (CZT), and the lattice constant is measured to be 0.647nm. The atomic structure of the clean CZT(110) surface obtained by Ar+ etching in vacuum is observed by low-energy electron diffraction, where no surface reconstruction is discovered. Angleresolved photoemission spectroscopy was used to characterize the surface state of the clean CZT (110) surface,by which we find a 1.5-eV-wide surface band with the peak at 0.9eV below the Fermi energy containing about6.9 × 1014 electrons/cm2, approximately one electron per surface atom.

  17. Electronic structure of the surface unoccupied band of Ge(001)-c (4 ×2 ) : Direct imaging of surface electron relaxation pathways

    Science.gov (United States)

    Kanasaki, J.; Yamamoto, I.; Azuma, J.; Fukatsu, S.

    2017-09-01

    We have studied the electronic structure of the surface unoccupied band (SUB) of clean Ge(001)-c (4 ×2 ) , with high energy and momentum resolution, by means of time- and angle-resolved two-photon photoelectron spectroscopy. The time evolution of photoelectron intensity images, measured as functions of energy and emission angle after photoexcitation with laser pulses (1.5 eV, 200 fs), provides a momentum space view of the relaxation pathways of surface excited electrons toward the bottom of the SUB. Surface excited electrons relax in several picoseconds along the strongly dispersive directions (Γ ¯J'¯ and Γ ¯J2 '¯ ) and then accumulate near the band bottom. Taking into account the ultrafast change of surface potential, possibly due to the spatial redistribution of nonthermal carriers generated by photoexcitation, an energy width of 0.22 eV was determined as the surface band gap, as well as the surface dispersion properties along three high-symmetry directions.

  18. Radiation Hard Electronics for Advanced Communication Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced reconfigurable/reprogrammable communication systems will require use of commercial sub 100 nm electronics. Legacy radiation tolerant circuits fail to...

  19. VISA Final Report: Fully Integrated Power Electronic Systems in Automotive Electronics

    NARCIS (Netherlands)

    Waffenschmidt, E.

    2011-01-01

    This report summarizes the activities related to the public funded project “Vollintegrierte leistungselektronische Systeme in der Automobilelektronik – VISA” (Fully Integrated Power Electronic Systems in Automotive Electronics). Aim of the project is to investigate the integration of components into

  20. Quantifying electron transfer reactions in biological systems

    DEFF Research Database (Denmark)

    Sjulstok, Emil Sjulstok; Olsen, Jógvan Magnus Haugaard; Solov'yov, Ilia A

    2015-01-01

    Various biological processes involve the conversion of energy into forms that are usable for chemical transformations and are quantum mechanical in nature. Such processes involve light absorption, excited electronic states formation, excitation energy transfer, electrons and protons tunnelling...... which for example occur in photosynthesis, cellular respiration, DNA repair, and possibly magnetic field sensing. Quantum biology uses computation to model biological interactions in light of quantum mechanical effects and has primarily developed over the past decade as a result of convergence between...... quantum physics and biology. In this paper we consider electron transfer in biological processes, from a theoretical view-point; namely in terms of quantum mechanical and semi-classical models. We systematically characterize the interactions between the moving electron and its biological environment...

  1. Coupling a Surface Acoustic Wave to an Electron Spin in Diamond via a Dark State

    Directory of Open Access Journals (Sweden)

    D. Andrew Golter

    2016-12-01

    Full Text Available The emerging field of quantum acoustics explores interactions between acoustic waves and artificial atoms and their applications in quantum information processing. In this experimental study, we demonstrate the coupling between a surface acoustic wave (SAW and an electron spin in diamond by taking advantage of the strong strain coupling of the excited states of a nitrogen vacancy center while avoiding the short lifetime of these states. The SAW-spin coupling takes place through a Λ-type three-level system where two ground spin states couple to a common excited state through a phonon-assisted as well as a direct dipole optical transition. Both coherent population trapping and optically driven spin transitions have been realized. The coherent population trapping demonstrates the coupling between a SAW and an electron spin coherence through a dark state. The optically driven spin transitions, which resemble the sideband transitions in a trapped-ion system, can enable the quantum control of both spin and mechanical degrees of freedom and potentially a trapped-ion-like solid-state system for applications in quantum computing. These results establish an experimental platform for spin-based quantum acoustics, bridging the gap between spintronics and quantum acoustics.

  2. Electronic structure and dynamics of ordered clusters with ME or RE ions on oxide surface

    Energy Technology Data Exchange (ETDEWEB)

    Kulagin, N.A., E-mail: nkulagin@bestnet.kharkov.u [Kharkiv National University for Radio Electronics, Avenue Shakespeare 6-48, 61045 Kharkiv (Ukraine)

    2011-03-15

    Selected data of ab initio simulation of the electronic structure and spectral properties of either cluster with ions of iron, rare earth or actinium group elements have been presented here. Appearance of doped Cr{sup +4} ions in oxides, Cu{sup +2} in HTSC, Nd{sup +2} in solids has been discussed. Analysis of experimental data for plasma created ordered structures of crystallites with size of about 10{sup -9} m on surface of separate oxides are given, too. Change in the spectroscopic properties of clusters and nano-structures on surface of strontium titanate crystals discussed shortly using the X-ray line spectroscopy experimental results. - Research highlights: External influence and variation of technology induce changes in valence of nl ions in compounds. Wave function of cluster presented as anti-symmetrical set of ions wave functions. The main equation describes the self-consistent field depending on state of all electrons of cluster. Level scheme of Cr{sup 4+} ions in octo- and tetra-site corresponds to doped oxides spectra after treatment. Plasma treatment effects in appearance of systems of unit crystallites with size of about 10{sup -6}-10{sup -9} m.

  3. [Construction of Lactobacillus rhamnosus GG particles surface display system].

    Science.gov (United States)

    Su, Runyu; Nie, Boyao; Yuan, Shengling; Tao, Haoxia; Liu, Chunjie; Yang, Bailiang; Wang, Yanchun

    2017-01-25

    To describe a novel particles surface display system which is consisted of gram-positive enhancer matrix (GEM) particles and anchor proteins for bacteria-like particles vaccines, we treated Lactobacillus rhamnosus GG bacteria with 10% heated-TCA for preparing GEM particles, and then identified the harvested GEM particles by electron microscopy, RT-PCR and SDS-PAGE. Meanwhile, Escherichia coli was induced to express hybrid proteins PA3-EGFP and P60-EGFP, and GEM particles were incubated with them. Then binding of anchor proteins were determined by Western blotting, transmission electron microscopy, fluorescence microscopy and spectrofluorometry. GEM particles preserved original size and shape, and proteins and DNA contents of GEM particles were released substantially. The two anchor proteins both had efficiently immobilized on the surface of GEM. GEM particles that were bounded by anchor proteins were brushy. The fluorescence of GEM particles anchoring PA3 was slightly brighter than P60, but the difference was not significant (P>0.05). GEM particles prepared from L. rhamnosus GG have a good binding efficiency with anchor proteins PA3-EGFP and P60-EGFP. Therefore, this novel foreign protein surface display system could be used for bacteria-like particle vaccines.

  4. Electrically induced spontaneous emission in open electronic system

    Science.gov (United States)

    Wang, Rulin; Zhang, Yu; Yam, Chiyung; Computation Algorithms Division (CSRC) Team; Theoretical; Computational Chemistry (HKU) Collaboration

    A quantum mechanical approach is formulated for simulation of electroluminescence process in open electronic system. Based on nonequilibrium Green's function quantum transport equations and combining with photon-electron interaction, this method is used to describe electrically induced spontaneous emission caused by electron-hole recombination. The accuracy and reliability of simulation depends critically on correct description of the electronic band structure and the electron occupancy in the system. In this work, instead of considering electron-hole recombination in discrete states in the previous work, we take continuous states into account to simulate the spontaneous emission in open electronic system, and discover that the polarization of emitted photon is closely related to its propagation direction. Numerical studies have been performed to silicon nanowire-based P-N junction with different bias voltage.

  5. Optical manipulation of ultrafast electron and nuclear motion on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Petek, Hrvoje

    2009-12-02

    We study the unoccupied electronic structure and dynamics of chemisorbed atoms and molecules on metal surfaces by time resolved two-photon photoemission (TR-2PP). spectroscopy, low temperature scanning tunneling microscopy (LT-STM), and theory. Our research concerns simple atomic adsorbates such as alkali and alkaline earth atoms, which provide fundamentally important models for adsorbate-surface interactions, and more complex adsorbates such as fullerenes on noble metals, which illustrate emergent interfacial properties that derive from intrinsic molecular attributes, and moleculemolecule and molecule-surface interactions. Our goal is to understand how these interactions contribute to formation of the interfacial electronic structure, and how thus formed electronic properties affect interfacial phenomena of importance to energy transduction and storage. Moreover, we explore how the interfacial electronic excitation drives dynamical phenomena such as charge transfer and surface femtochemistry.

  6. High resolution electron energy loss spectroscopy of narrow gap III-V semiconductor surfaces and interfaces

    CERN Document Server

    Veal, T D

    2002-01-01

    The electronic properties of n-type narrow gap III-V semiconductor surfaces and interfaces are investigated using high-resolution electron-energy-loss spectroscopy (HREELS). Changing the incident electron energy, alters the wave-vector transfer parallel to the surface, allowing the probing depth to be varied over typical space-charge layer widths (100 - 2000 A). Semi-classical dielectric theory simulations of the HREEL spectra are performed to extract quantitative information from the probing energy-dependence of the surface plasmon and phonon peaks. The plasma frequency used in the simulations is related to the electron concentration and effective mass using the Kane model of the non-parabolic conduction band. Space-charge layer parameters are obtained by comparing calculated smooth charge profiles with the histogram profiles that are used in the simulations. Complementary experimental techniques are employed to correlate the reconstruction, chemical composition and morphology of the surface with the electro...

  7. Probing the electronic transport on the reconstructed Au/Ge(001 surface

    Directory of Open Access Journals (Sweden)

    Franciszek Krok

    2014-09-01

    Full Text Available By using scanning tunnelling potentiometry we characterized the lateral variation of the electrochemical potential µec on the gold-induced Ge(001-c(8 × 2-Au surface reconstruction while a lateral current flows through the sample. On the reconstruction and across domain boundaries we find that µec shows a constant gradient as a function of the position between the contacts. In addition, nanoscale Au clusters on the surface do not show an electronic coupling to the gold-induced surface reconstruction. In combination with high resolution scanning electron microscopy and transmission electron microscopy, we conclude that an additional transport channel buried about 2 nm underneath the surface represents a major transport channel for electrons.

  8. Surface electronic and structural properties of nanostructured titanium oxide grown by pulsed laser deposition

    NARCIS (Netherlands)

    Fusi, M.; Maccallini, E.; Caruso, T.; Casari, C. S.; Bassi, A. Li; Bottani, C. E.; Rudolf, P.; Prince, K. C.; Agostino, R. G.

    2011-01-01

    Titanium oxide nanostructured thin films synthesized by pulsed laser deposition (PLD) were here characterized with a multi-technique approach to investigate the relation between surface electronic, structural and morphological properties. Depending on the growth parameters, these films present chara

  9. Microstructure evolution during surface alloying of ductile iron and austempered ductile iron by electron beam melting

    Science.gov (United States)

    Gulzar, A.; Akhter, J. I.; Ahmad, M.; Ali, G.; Mahmood, M.; Ajmal, M.

    2009-07-01

    Alloying and microstructural modification of surfaces by electron beam has become popular to tailor the surface properties of materials. Surface modification of as-received ductile iron, Ni-plated ductile iron and Ni-plated austempered ductile iron was carried out by electron beam melting to improve the surface properties. Martensitic structure evolved in the heat affected zone and ledeburite structure was produced in the molten zone of the ductile iron. Microhardness of the melted specimens enhanced considerably as compared to the as-received samples. However the microhardness of melted Ni-plated samples is lower than that of the unplated specimens. X-ray diffraction clearly revealed the formation of an austenite and Fe 3C phases in the electron beam molten zone. The broadening of peaks suggests refinement of the microstructure as well as internal stresses generated during electron beam melting.

  10. Microstructure evolution during surface alloying of ductile iron and austempered ductile iron by electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Gulzar, A. [Materials Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Akhter, J.I. [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Ahmad, M., E-mail: maqomer@yahoo.com [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Ali, G. [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Mahmood, M. [Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan); Ajmal, M. [Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore (Pakistan)

    2009-07-30

    Alloying and microstructural modification of surfaces by electron beam has become popular to tailor the surface properties of materials. Surface modification of as-received ductile iron, Ni-plated ductile iron and Ni-plated austempered ductile iron was carried out by electron beam melting to improve the surface properties. Martensitic structure evolved in the heat affected zone and ledeburite structure was produced in the molten zone of the ductile iron. Microhardness of the melted specimens enhanced considerably as compared to the as-received samples. However the microhardness of melted Ni-plated samples is lower than that of the unplated specimens. X-ray diffraction clearly revealed the formation of an austenite and Fe{sub 3}C phases in the electron beam molten zone. The broadening of peaks suggests refinement of the microstructure as well as internal stresses generated during electron beam melting.

  11. Quantum Nuclear Extension of Electron Nuclear Dynamics on Folded Effective-Potential Surfaces

    DEFF Research Database (Denmark)

    Hall, B.; Deumens, E.; Ohrn, Y.;

    2014-01-01

    A perennial problem in quantum scattering calculations is accurate theoretical treatment of low energy collisions. We propose a method of extracting a folded, nonadiabatic, effective potential energy surface from electron nuclear dynamics (END) trajectories; we then perform nuclear wave packet...

  12. Surface electronic transport measurements: A micro multi-point probe approach

    DEFF Research Database (Denmark)

    Barreto, Lucas

    2014-01-01

    setup, but the terminology used and data analysis were also ameliorated in order to simplify the interpretation of the results. We used the mentioned technique in the following projects: • The electronic transport dimensionality of epitaxial grahene grown on SiC is detected and important physical......This work is mostly focused on the study of electronic transport properties of two-dimensional materials, in particular graphene and topological insulators. To study these, we have improved a unique micro multi-point probe instrument used to perform transport measurements. Not only the experimental...... a direct measurement of the surface electronic transport on a bulk topological insulator. The surface state conductivity and mobility are obtained. Apart from transport properties, we also investigate the atomic structure of the Bi2Se3(111) surface via surface x-ray diraction and low-energy electron...

  13. Computational studies of model disordered and strongly correlated electronic systems

    Science.gov (United States)

    Johri, Sonika

    cannot be achieved perfectly in experiments. A chapter of this thesis is devoted to studying signatures of incomplete localization in a disordered system with interacting particles which is coupled to a bath. . Strongly interacting particles can also give rise to topological phases of matter that have exotic emergent properties, such as quasiparticles with fractional charges and anyonic, or perhaps even non-Abelian statistics. In addition to their intrinsic novelty, these particles (e.g. Majorana fermions) may be the building blocks of future quantum computers. The third part of my thesis focuses on the best experimentally known realizations of such systems - the fractional quantum Hall effect (FQHE) which occurs in two-dimensional electron gases in a strong perpendicular magnetic field. It has been observed in systems such as semiconductor heterostructures and, more recently, graphene. I have developed software for exact diagonalization of the many-body FQHE problem on the surface of a cylinder, a hitherto unstudied type of geometry. This geometry turns out to be optimal for the DMRG algorithm. Using this new geometry, I have studied properties of various fractionally-filled states, computing the overlap between exact ground states and model wavefunctions, their edge excitations, and entanglement spectra. I have calculated the sizes and tunneling amplitudes of quasiparticles, information which is needed to design the interferometers used to experimentally measure their Aharanov-Bohm phase. I have also designed numerical probes of the recently discovered geometric degree of freedom of FQHE states.

  14. Modification of Fluoropolymer Surfaces with Electronically Conductive Polymers

    Science.gov (United States)

    1993-06-01

    CI0 4)3. Polyaniline was synthesized by mixing equal volumes of a solution that was 0.25 M in ammonium persulfate and a solution that was 0.5 M in...31 Conductive polymers, polypyrrole , lithography 16. PRICE CODE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION...surface. Fortunately, conductive polymers such as polypyrrole adhere quite well to many substrates, including nylon, polycarbonate, cellulosics

  15. Functional Risk Modeling for Lunar Surface Systems

    Science.gov (United States)

    Thomson, Fraser; Mathias, Donovan; Go, Susie; Nejad, Hamed

    2010-01-01

    We introduce an approach to risk modeling that we call functional modeling , which we have developed to estimate the capabilities of a lunar base. The functional model tracks the availability of functions provided by systems, in addition to the operational state of those systems constituent strings. By tracking functions, we are able to identify cases where identical functions are provided by elements (rovers, habitats, etc.) that are connected together on the lunar surface. We credit functional diversity in those cases, and in doing so compute more realistic estimates of operational mode availabilities. The functional modeling approach yields more realistic estimates of the availability of the various operational modes provided to astronauts by the ensemble of surface elements included in a lunar base architecture. By tracking functional availability the effects of diverse backup, which often exists when two or more independent elements are connected together, is properly accounted for.

  16. Two-dimensional simulation research of secondary electron emission avalanche discharge on vacuum insulator surface

    Science.gov (United States)

    Cai, Libing; Wang, Jianguo; Zhu, Xiangqin; Wang, Yue; Zhang, Dianhui

    2015-01-01

    Based on the secondary electron emission avalanche (SEEA) model, the SEEA discharge on the vacuum insulator surface is simulated by using a 2D PIC-MCC code developed by ourselves. The evolutions of the number of discharge electrons, insulator surface charge, current, and 2D particle distribution are obtained. The effects of the strength of the applied electric field, secondary electron yield coefficient, rise time of the pulse, length of the insulator on the discharge are investigated. The results show that the number of the SEEA electrons presents a quadratic dependence upon the applied field strength. The SEEA current, which is on the order of Ampere, is directly proportional to the field strength and secondary electron yield coefficient. Finally, the electron-stimulated outgassing is included in the simulation code, and a three-phase discharge curve is presented by the simulation, which agrees with the experimental data.

  17. Interaction of a Surface Acoustic Wave with a Two-dimensional Electron Gas

    Institute of Scientific and Technical Information of China (English)

    YANG Shi-Jie; ZHAO Hu; YU Yue

    2005-01-01

    When a surface acoustic wave (SAW) propagates on the surface of a GaAs semiconductor, coupling between electrons in the two-dimensional electron gas beneath the interface and the elastic host crystal through piezoelectric interaction will attenuate the SAW. The coupling coefficient is calculated for the SAW propagating along an arbitrary direction. It is found that the coupling strength is strongly dependent on the propagating direction. When the SAW propagates along the [011] direction, the coupling becomes quite weak.

  18. Controlled cooling of an electronic system based on projected conditions

    Science.gov (United States)

    David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

    2016-05-17

    Energy efficient control of a cooling system cooling an electronic system is provided based, in part, on projected conditions. The control includes automatically determining an adjusted control setting(s) for an adjustable cooling component(s) of the cooling system. The automatically determining is based, at least in part, on projected power consumed by the electronic system at a future time and projected temperature at the future time of a heat sink to which heat extracted is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on an experimentally obtained model(s) relating the targeted temperature and power consumption of the adjustable cooling component(s) of the cooling system.

  19. Controlled cooling of an electronic system based on projected conditions

    Energy Technology Data Exchange (ETDEWEB)

    David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

    2015-08-18

    Energy efficient control of a cooling system cooling an electronic system is provided based, in part, on projected conditions. The control includes automatically determining an adjusted control setting(s) for an adjustable cooling component(s) of the cooling system. The automatically determining is based, at least in part, on projected power consumed by the electronic system at a future time and projected temperature at the future time of a heat sink to which heat extracted is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on an experimentally obtained model(s) relating the targeted temperature and power consumption of the adjustable cooling component(s) of the cooling system.

  20. Freeform Compliant CMOS Electronic Systems for Internet of Everything Applications

    KAUST Repository

    Shaikh, Sohail F.

    2017-01-17

    The state-of-the-art electronics technology has been an integral part of modern advances. The prevalent rise of the mobile device and computational technology in the age of information technology offers exciting applications that are attributed to sophisticated, enormously reliable, and most mature CMOS-based electronics. We are accustomed to high performance, cost-effective, multifunctional, and energy-efficient scaled electronics. However, they are rigid, bulky, and brittle. The convolution of flexibility and stretchability in electronics for emerging Internet of Everything application can unleash smart application horizon in unexplored areas, such as robotics, healthcare, smart cities, transport, and entertainment systems. While flexible and stretchable device themes are being remarkably chased, the realization of the fully compliant electronic system is unaddressed. Integration of data processing, storage, communication, and energy management devices complements a compliant system. Here, a comprehensive review is presented on necessity and design criteria for freeform (physically flexible and stretchable) compliant high-performance CMOS electronic systems.

  1. Electron band bending and surface sensitivity: X-ray photoelectron spectroscopy of polar GaN surfaces

    Science.gov (United States)

    Bartoš, I.; Romanyuk, O.; Paskova, T.; Jiříček, P.

    2017-10-01

    The role of electron band bending and surface sensitivity in determining the core level binding energies by X-ray photoelectron spectroscopy is investigated. A dominating contribution of surface atomic layers to photoemission intensity is confirmed for normal photoemission. The energy of the photoelectron core level peak does not deviate from core level peak energies of electrons photoemitted from the surface atomic layers of the crystal. The higher surface sensitivity regime, achieved e.g. at off-normal photoelectron detection angle, can be used to study the surface potential barrier in just a few topmost atomic layers. In addition, it is demonstrated that core level binding energy measured by angle-resolved X-ray photoelectron spectroscopy reflect the electron attenuation anisotropy. In particular, core level binding energy changes with emission angle and correlates with the forward focusing directions in a crystal. This effect is demonstrated by measuring the polar angle dependence of Ga 3d core levels on clean GaN(0001) and GaN(000 1 bar) surfaces with a higher and a lower band bending, respectively. The effect is explained by variation of emission depth in a crystal for normal and off-normal photoelectron emission angles.

  2. Hot Electron Photoemission from Plasmonic Nanostructures: The Role of Surface Photoemission and Transition Absorption

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Ikhsanov, Renat Sh;

    2015-01-01

    We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of "transition absorption", i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate photoemis...

  3. Secondary electron yield from stainless steel surface coated with titanium nitride

    Science.gov (United States)

    Orlov, O. S.; Meshkov, I. N.; Rudakov, A. Yu.; Philippov, A. V.

    2014-09-01

    The experiment on measurement of secondary electron yield from surface of a stainless steel Kh189 sample covered with titanium nitride is performed at stand "Recuperator". This work is related to known problem of electron clouds formation in a vacuum chamber by a propagating charge particle beam. An original method of secondary electron yield measurement was developed in this experiment. The obtained results allow one to estimate efficiency of coating nitride titanium.

  4. Reduced Heat Flux Through Preferential Surface Reactions Leading to Vibrationally and Electronically Excited Product States

    Science.gov (United States)

    2016-03-04

    AFRL-AFOSR-VA-TR-2016-0124 Reduced Heat Flux Through Preferential Surface Reactions Leading to Vibrationally and Electronically Excited Product...Reactions Leading to Vibrationally and Electronically Excited Product States 5a. CONTRACT NUMBER FA9550-12-1-0486 5b. GRANT NUMBER 5c. PROGRAM... Leading to Vibrationally and Electronically Excited Product States FINAL TECHNICAL REPORT: Grant #FA9550-12-1-0486 2013 Basic Research Initiative (BRI

  5. The surface magnetization study of Cr2O3 by spin polarized low energy electron microscopy

    Science.gov (United States)

    Cao, Shi; Wu, Ning; Zhang, Xin; N'diaye, Alpha; Chen, Gong; Schmid, Andreas; Echtenkamp, Will; Lauter, Valeria; Binek, Christian; Dowben, Peter

    2014-03-01

    The boundary magnetization at the surface of a Cr2O3 single crystal has been demonstrated by using spin-polarized low-energy electron microscopy (SPLEEM), indicating net surface spin polarization. This work shows that the placement of Cr2O3 single crystal in the single domain state, will result in net Cr2O3 spin polarization at the boundary, even in the presence of a gold overlayer. There are indications that the spin-polarized low-energy electron microscopy (SPLEEM) contrast for the two polarizations states is different. In addition, the boundary magnetization protected by the symmetry exists despite of the surface roughness/softness which was studied by the non-spin neutron reflectometry and low energy electron diffraction. Unoccupied surface oxygen sites and chromium sites are possible mechanism contributing to the surface ``softness,'' which will be discussed.

  6. Electronic transport at semiconductor surfaces - from point-contact transistor to micro-four-point probes

    DEFF Research Database (Denmark)

    Hasegawa, S.; Grey, Francois

    2002-01-01

    show that this type of conduction is measurable using new types of experimental probes, such as the multi-tip scanning tunnelling microscope and the micro-four-point probe. The resulting electronic transport properties are intriguing, and suggest that semiconductor surfaces should be considered......The electrical properties of semiconductor surfaces have played a decisive role in one of the most important discoveries of the last century, transistors. In the 1940s, the concept of surface states-new electron energy levels characteristic of the surface atoms-was instrumental in the fabrication...... of the first point-contact transistors, and led to the successful fabrication of field-effect transistors. However, to this day, one property of semiconductor surface states remains poorly understood, both theoretically and experimentally. That is the conduction of electrons or holes directly through...

  7. MONTE CARLO SIMULATION STUDY OF SURFACE ELECTRONIC EXCITATION OF NOBLE METALS

    Institute of Scientific and Technical Information of China (English)

    H.M. Li; Z.J. Ding; Q.R. Pu; Z.M. Zhang

    2002-01-01

    In this work we present a numerical simulation of REELS-spectrum for noble metals,Au and Ag. The calculation is based on an electron-surface inelastic scattering modelpreviously developed. The differential inelastic cross section is obtained fron an inho-mogeneous electron self-energy in the surface region, which provides full informationof the dependency of the total and differential cross section on the kinetic energy,the distance from the surface and the moving direction of electrons, accommodatingthe formulation to the practical situation in surface electron spectroscopes. A novelMonte Carlo simulation code of electron interaction with a surface incorporating thelocal scattering mean free path has been developed. The comparison of the simulatedREELS-spectra with the experimental measurements shows a remarkable agreement onthe spectrum shape, which then confirms that the present model for electron-surfaceinelastic .scattering is quite reasonable. The simulation has further shown the compo.nent to surface excitation due to the individual scattering processes along trajectorypart, i.e., the loss in vacuum before reflection, the loss in vacuum after reflection andloss in metal events.

  8. The system of RF beam control for electron gun

    Science.gov (United States)

    Barnyakov, A. M.; Chernousov, Yu. D.; Ivannikov, V. I.; Levichev, A. E.; Shebolaev, I. V.

    2015-06-01

    The system of RF control of three-electrode electron gun current is described. It consists of a source of microwave signal, coaxial line, coaxial RF switch and RF antenna lead. The system allows one to get the electron beam in the form of bunches with the frequency of the accelerating section to achieve the capture of particles in the acceleration mode close to 100%. The results of calculation and analysis of the elements of the system are presented. Characteristics of the devices are obtained experimentally. The results of using RF control in three-electrode electron gun at electron linear accelerator are described.

  9. Tuning the surface electronic structure of a Pt3Ti(111) electro catalyst

    Science.gov (United States)

    Paßens, M.; Caciuc, V.; Atodiresei, N.; Moors, M.; Blügel, S.; Waser, R.; Karthäuser, S.

    2016-07-01

    Increasing the efficiency and stability of bimetallic electro catalysts is particularly important for future clean energy technologies. However, the relationship between the surface termination of these alloys and their catalytic activity is poorly understood. Therefore, we report on fundamental UHV-SPM, LEED, and DFT calculations of the Pt3Ti(111) single crystal surface. Using voltage dependent imaging the surface termination of Pt3Ti(111) was studied with atomic resolution. Combining these images with simulated STM maps based on ab initio DFT calculations allowed us to identify the three upper layers of the Pt3Ti(111) single crystal and their influence upon the surface electronic structure. Our results show that small changes in the composition of the second and third atomic layer are of significant influence upon the surface electronic structure of the Pt3Ti electro catalyst. Furthermore, we provide relevant insights into the dependence of the surface termination on the preparation conditions.Increasing the efficiency and stability of bimetallic electro catalysts is particularly important for future clean energy technologies. However, the relationship between the surface termination of these alloys and their catalytic activity is poorly understood. Therefore, we report on fundamental UHV-SPM, LEED, and DFT calculations of the Pt3Ti(111) single crystal surface. Using voltage dependent imaging the surface termination of Pt3Ti(111) was studied with atomic resolution. Combining these images with simulated STM maps based on ab initio DFT calculations allowed us to identify the three upper layers of the Pt3Ti(111) single crystal and their influence upon the surface electronic structure. Our results show that small changes in the composition of the second and third atomic layer are of significant influence upon the surface electronic structure of the Pt3Ti electro catalyst. Furthermore, we provide relevant insights into the dependence of the surface termination on the

  10. Evaluation of the benefits of high temperature electronics for lunar power systems

    Science.gov (United States)

    Fay, Edgar H.

    A comparative evaluation is conducted of several approaches to the cooling of a lunar power system's power electronics, in view of the 400 K temperature of the 354-hour lunar day and lunar dust accumulation, which can contaminate power components and radiator surfaces. It is noted that, by raising the power electronics' baseplate temperature to 480 K, no thermal control system is required; the surface of the baseplate acts as its own, waste-heat-rejecting radiator, but the baseplate must be kept clean of lunar dust contamination.

  11. Evaluation of the Benefits of High Temperature Electronics for Lunar Power Systems

    Science.gov (United States)

    Fay, Edgar H.

    1992-01-01

    A comparative evaluation is conducted of several approaches to the cooling of a lunar power system's power electronics, in view of the 400 K temperature of the 354-hour lunar day and lunar dust accumulation, which can contaminate power components and radiator surfaces. It is noted that, by raising the power electronics' baseplate temperature to 480 K, no thermal control system is required; the surface of the baseplate acts as its own, waste-heat-rejecting radiator, but the baseplate must be kept clean of lunar dust contamination.

  12. Ionic liquids influence on the surface properties of electron beam irradiated wood

    Energy Technology Data Exchange (ETDEWEB)

    Croitoru, Catalin [“Transilvania” University of Brasov, Product Design and Environment Department, 29 Eroilor Str., 500036, Brasov (Romania); Patachia, Silvia, E-mail: st.patachia@unitbv.ro [“Transilvania” University of Brasov, Product Design and Environment Department, 29 Eroilor Str., 500036, Brasov (Romania); Doroftei, Florica; Parparita, Elena; Vasile, Cornelia [“Petru Poni” Institute of Macromolecular Chemistry, Physical Chemistry of Polymers Department, 41A Gr. Ghica Voda Alley, Iasi (Romania)

    2014-09-30

    Highlights: • Wood veneers impregnated with three imidazolium-based ionic liquids and irradiated with electron beam were studied by FTIR-ATR, SEM/EDX, AFM, contact angle and image analysis. • ILs preserve the surface properties of the wood (surface energy, roughness, color) upon irradiation, in comparison with the reference wood, but the surface composition is changed by treatment with IL-s, mainly with 1-butyl-3-methylimidazolium tetrafluoroborate. • Under electron beam irradiation covalent bonding of the imidazolium moiety to wood determines a higher resistance to water penetration and spreading on the surface. - Abstract: In this paper, the influence of three imidazolium-based ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-hexyl-3-methylimidazolium chloride) on the structure and surface properties of sycamore maple (Acer pseudoplatanus) veneers submitted to electron beam irradiation with a dose of 50 kGy has been studied by using Fourier transform infrared spectroscopy, as well as image, scanning electron microscopy/SEM/EDX, atomic force microscopy and contact angle analysis. The experimental results have proven that the studied ionic liquids determine a better preservation of the structural features of wood (cellulose crystallinity index and lignin concentration on the surface) as well as some of surface properties such as surface energy, roughness, color upon irradiation with electron beam, in comparison with the reference wood, but surface composition is changed by treatment with imidazolium-based ionic liquids mainly with 1-butyl-3-methylimidazolium tetrafluoroborate. Also, under electron beam irradiation covalent bonding of the imidazolium moiety to wood determines a higher resistance to water penetration and spreading on the surface.

  13. MIS hot electron devices for enhancement of surface reactivity by hot electrons

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar

    to be an important energy loss center for the electrons tunneling through the oxide lowering the emission e±ciency of a factor of 10 for a 1 nm Ti layer thickness. Electron emission is observed under ambient pressure conditions and in up to 2 bars of Ar. 2 bar Ar decrease the emission current by an order...... is monitored using the calibrated resistance of the metal layer. The MIS hot electron emitters are cleaned in-situ in a background pressure of 3 £ 10¡7 mbar O2. Thermal desorption experiments with labeled CO are carried out with a reproducibility of 7%. The detection limit of labeled CO for the mass...

  14. Microcomputer array processor system. [design for electronic warfare

    Science.gov (United States)

    Slezak, K. D.

    1980-01-01

    The microcomputer array system is discussed with specific attention given to its electronic warware applications. Several aspects of the system architecture are described as well as some of its distinctive characteristics.

  15. CSIR's new integrated electronic library information-system

    CSIR Research Space (South Africa)

    Michie, A

    1995-08-01

    Full Text Available The CSIR has developed a CDROM-based electronic library information system which provides the ability to reproduce and search for published information and colour brochures on the computer screen. The system integrates this information with online...

  16. Quantum-kinetic modeling of electron release in low-energy surface collisions of atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Marbach, Johannes

    2012-09-20

    In this work we present a theoretical description of electron release in the collision of atomic and molecular projectiles with metallic and especially dielectric surfaces. The associated electron yield, the secondary electron emission coefficient, is an important input parameter for numerical simulations of dielectric barrier discharges and other bounded low-temperature gas discharges. The available reference data for emission coefficients is, however, very sparse and often uncertain, especially for molecular projectiles. With the present work we aim to contribute to the filling of these gaps by providing a flexible and easy-to-use model that allows for a convenient calculation of the emission coefficient and related quantities for a wide range of projectile-surface systems and the most dominant reaction channels.

  17. Security analysis of electronic voting and online banking systems

    OpenAIRE

    2007-01-01

    The main focus of this dissertation is on security analysis of electronic voting and online banking systems. Six papers form the basis of the thesis and include the following topics: a model for analysis of voting systems, a case study where we apply the proposed model, a new scheme for remote electronic voting, and three case studies of commercial online banking solutions in Norway.

  18. Experimental investigations into secondary electron-electron emission from the surface of vacuum chambers

    Science.gov (United States)

    Meshkov, I. N.; Rudakov, A. Yu.

    2012-07-01

    An experiment on measuring the secondary electron yield (SEY) of samples coated with titanium nitride (TiN2) is in progress at the Recuperator test bench at the Dzhelepov Laboratory of Nuclear Problems, Joint Institute for Nuclear Research. This work is related the problem of electron-cloud formation in the vacuum chambers of accelerators and is of practical importance for the NICA project. The results of the experiment on the SEY measurement will make it possible to choose the most appropriate material for coating the vacuum chamber. In this experiment samples of stainless steel with titanium nitride coating and without any coating are compared.

  19. The potential surface in the ground electronic state of HCP with the isomerization process: the validity of calculating potential surface with DFT methods

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The density functional theory (DFT) provides us an effective way to calculate large cluster systems with moderate computational demands. We calculate potential energy surfaces (PES) with several different approaches of DFT. The PES in the ground electronic state are related to HCP's isomerization process. The calculated PES are compared with the “experimental” PES obtained by fitting from the experimental vibrational spectra and that given by the “accurate” quantum chemistry calculation with more expensive computations. The comparisons show that the potential surfaces calculated with DFT methods can reach the accuracy of less than 0.1 eV.

  20. Thermodynamic potential of electrons and phonons system of disordered alloy

    CERN Document Server

    Repetskij, S P

    2002-01-01

    The cluster decomposition for the delayed two-time Green functions and the disordered crystal dynamic potential is obtained with an account of the electron-phonon and electron-electron interactions. The system electron states are described within the frames of the multizone strong coupling model. The calculations are based on the diagram technique for the Green temperature functions. The coherent potential approximation is chosen as the zero mononode approximation in this cluster decomposition method. It is shown that the processes of the contributions of the elementary excitations scattering on the clusters decrease with the cluster nodes number growth in the cluster in correspondence with certain small parameters. The analytical evaluations of the electron-phonon interaction impact on the electron energy spectrum of the ordering alloy are made in the monozone model. The possibility of applying the obtained results for describing the strong electron correlations impact on the electron structure and propertie...

  1. Snell's law for surface electrons: Refraction of an electron gas imaged in real space

    OpenAIRE

    Repp, Jascha; Meyer, Gerhard; Rieder, Karl-Heinz

    2003-01-01

    On NaCl(100)/Cu(111) an interface state band is observed that descends from the surface-state band of the clean copper surface. This band exhibits a Moire-pattern-induced one-dimensional band gap, which is accompanied by strong standing-wave patterns, as revealed in low-temperature scanning tunneling microscopy images. At NaCl island step edges, one can directly see the refraction of these standing waves, which obey Snell's refraction law.

  2. Snell's law for surface electrons: refraction of an electron gas imaged in real space.

    Science.gov (United States)

    Repp, Jascha; Meyer, Gerhard; Rieder, Karl-Heinz

    2004-01-23

    On NaCl(100)/Cu(111) an interface state band is observed that descends from the surface-state band of the clean copper surface. This band exhibits a Moiré-pattern-induced one-dimensional band gap, which is accompanied by strong standing-wave patterns, as revealed in low-temperature scanning tunneling microscopy images. At NaCl island step edges, one can directly see the refraction of these standing waves, which obey Snell's refraction law.

  3. System design of electronic vehicles and components

    OpenAIRE

    Смолій, Вікторія Миколаївна

    2015-01-01

    The oscillation mechanical and thermal mathematical models of electronic vehicles that allow to take into account properties and cooperation of making model elements of replacement and design oscillation stability of PCBS and components in the conditions of technological process of their production are worked out

  4. New Project System for Undergraduate Electronic Engineering

    Science.gov (United States)

    Chiu, Dirk M.; Chiu, Shen Y.

    2005-01-01

    A new approach to projects for undergraduate electronic engineering in an Australian university has been applied successfully for over 10 years. This approach has a number of projects running over three year period. Feedback from past graduates and their managers has confirmed that these projects train the students well, giving them the ability…

  5. Micro-Shaping of Nanopatterned Surfaces by Electron Beam Irradiation

    Directory of Open Access Journals (Sweden)

    Carlos Angulo Barrios

    2016-04-01

    Full Text Available We show that planar nanopatterned thin films on standard polycarbonate (PC compact discs (CD can be micro-shaped in a non-contact manner via direct e-beam exposure. The shape of the film can be controlled by proper selection of the e-beam parameters. As an example of application, we demonstrate a two-dimensional (2D array of micro-lenses/reservoirs conformally covered by an Al 2D nanohole array (NHA film on a PC CD substrate. It is also shown that such a curvilinear Al NHA layer can be easily transferred onto a flexible polymeric support. The presented technique provides a new tool for creating lab-on-CD architectures and developing multifunctional (flexible non-planar nanostructured films and surfaces.

  6. Study of surface leakage current of AlGaN/GaN high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chen, YongHe; Zhang, Kai; Cao, MengYi; Zhao, ShengLei; Zhang, JinCheng; Hao, Yue, E-mail: yhao@xidian.edu.cn [Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Ma, XiaoHua, E-mail: xhma@xidian.edu.cn [Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); School of Advanced Materials and Nanotechnology, Xidian University, Xi' an 710071 (China)

    2014-04-14

    Temperature-dependent surface current measurements were performed to analyze the mechanism of surface conductance of AlGaN/GaN channel high-electron-mobility transistors by utilizing process-optimized double gate structures. Different temperatures and electric field dependence have been found in surface current measurements. At low electric field, the mechanism of surface conductance is considered to be two-dimensional variable range hopping. At elevated electric field, the Frenkel–Poole trap assisted emission governs the main surface electrons transportation. The extracted energy barrier height of electrons emitting from trapped state near Fermi energy level into a threading dislocations-related continuum state is 0.38 eV. SiN passivation reduces the surface leakage current by two order of magnitude and nearly 4 orders of magnitude at low and high electric fields, respectively. SiN also suppresses the Frenkel–Poole conductance at high temperature by improving the surface states of AlGaN/GaN. A surface treatment process has been introduced to further suppress the surface leakage current at high temperature and high field, which results in a decrease in surface current of almost 3 orders of magnitude at 476 K.

  7. Extraction of negative charges from an ion source: Transition from an electron repelling to an electron attracting plasma close to the extraction surface

    Science.gov (United States)

    Wimmer, Christian; Fantz, Ursel

    2016-08-01

    Large-scale sources for negative hydrogen ions, capable of delivering an extracted ion current of several ten amperes, are a key component of the neutral beam injection system of the upcoming ITER fusion device. Since the created heat load of the inevitably co-extracted electrons after magnetic separation from the extracted beam limits their tolerable amount, special care must be taken for the reduction of co-extracted electrons—in particular, in deuterium operation, where the larger amount of co-extracted electrons often limits the source performance. By biasing the plasma grid (PG, first grid of the extraction system) positively with respect to the source body, the plasma sheath in front of the PG can be changed from an electron repelling towards an electron attracting sheath. In this way, the flux of charged particles onto the PG can be varied, thus changing the bias current and inverse to it the amount of co-extracted electrons. The PG bias affects also the flux of surface-produced H - towards the plasma volume as well as the plasma symmetry in front of the plasma grid, strongly influenced by an E → × B → drift. The influence of varying PG sheath potential profile on the plasma drift, the negative hydrogen ion density, and the source performance at the prototype H - source is presented, comparing hydrogen and deuterium operation. The transition in the PG sheath profile takes place in both isotopes, with a minimum of co-extracted electrons formed in case of the electron attracting PG sheath. The co-extracted electron density in deuterium operation is higher than in hydrogen operation, which is accompanied by an increased plasma density in deuterium.

  8. Towards hot electron mediated charge exchange in hyperthermal energy ion-surface interactions

    DEFF Research Database (Denmark)

    Ray, M. P.; Lake, R. E.; Thomsen, Lasse Bjørchmar;

    2010-01-01

    electrons useful for driving chemical reactions at surfaces. Using the binary collision approximation and a nonadiabatic model that takes into account the time-varying nature of the ion–surface interaction, the energy loss of the ions is reproduced. The energy loss for Na + ions incident on the devices...

  9. Frictional and bone ingrowth properties of engineered surface topographies produced by electron beam technology

    NARCIS (Netherlands)

    Biemond, J.E.; Aquarius, R.J.M.; Verdonschot, N.J.J.; Buma, P.

    2011-01-01

    BACKGROUND: Electron beam melting (E-beam) is a new technology to produce 3-dimensional surface topographies for cementless orthopedic implants. METHODS: The friction coefficients of two newly developed E-beam produced surface topographies were in vitro compared with sandblasted E-beam and titanium

  10. Frictional and bone ingrowth properties of engineered surface topographies produced by electron beam technology

    NARCIS (Netherlands)

    Biemond, J. Elizabeth; Aquarius, Rene; Verdonschot, Nicolaas Jacobus Joseph; Buma, Pieter

    2011-01-01

    Background Electron beam melting (E-beam) is a new technology to produce 3-dimensional surface topographies for cementless orthopedic implants. Methods The friction coefficients of two newly developed E-beam produced surface topographies were in vitro compared with sandblasted E-beam and titanium

  11. Surface sensitivity effects with local probe scanning Auger–scanning electron microscopy

    NARCIS (Netherlands)

    Agterveld, D.T.L. van; Palasantzas, G.; Hosson, J.Th.M. De

    1999-01-01

    This letter concentrates on a quantitative description of surface roughness effects on Auger peak-line profiles for pure and alloyed specimens. The nanometer lateral electron probe size of the order of 10 nm yielded peak-line profiles that capture surface topology variations down to nanometer-length

  12. Preface: Special Topic Section on Advanced Electronic Structure Methods for Solids and Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Michaelides, Angelos, E-mail: angelos.michaelides@ucl.ac.uk [London Centre for Nanotechnology and Department of Chemistry, University College London, London (United Kingdom); Martinez, Todd J. [Department of Chemistry and the PULSE Institute, Stanford University, Stanford, California 94305, USA and SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Alavi, Ali [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany and Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Kresse, Georg [Faculty of Physics and Center for Computational Materials Science, Department of Physics, University of Vienna, Sensengasse 8/12, A-1090 Vienna (Austria); Manby, Frederick R. [Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)

    2015-09-14

    This Special Topic section on Advanced Electronic Structure Methods for Solids and Surfaces contains a collection of research papers that showcase recent advances in the high accuracy prediction of materials and surface properties. It provides a timely snapshot of a growing field that is of broad importance to chemistry, physics, and materials science.

  13. Direct observation of surface reconstruction and termination on a complex metal oxide catalyst by electron microscopy

    KAUST Repository

    Zhu, Yihan

    2012-03-19

    On the surface: The surface reconstruction of an MoVTeO complex metal oxide catalyst was observed directly by various electron microscopic techniques and the results explain the puzzling catalytic behavior. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Electronic interconnects and devices with topological surface states and methods for fabricating same

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, Ali; Ong, N. Phuan; Cava, Robert J.

    2017-04-04

    An interconnect is disclosed with enhanced immunity of electrical conductivity to defects. The interconnect includes a material with charge carriers having topological surface states. Also disclosed is a method for fabricating such interconnects. Also disclosed is an integrated circuit including such interconnects. Also disclosed is a gated electronic device including a material with charge carriers having topological surface states.

  15. Electronic interconnects and devices with topological surface states and methods for fabricating same

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, Ali; Ong, N. Phuan; Cava, Robert J.

    2016-05-03

    An interconnect is disclosed with enhanced immunity of electrical conductivity to defects. The interconnect includes a material with charge carriers having topological surface states. Also disclosed is a method for fabricating such interconnects. Also disclosed is an integrated circuit including such interconnects. Also disclosed is a gated electronic device including a material with charge carriers having topological surface states.

  16. Van der Waals Layered Materials: Surface Morphology, Interlayer Interaction, and Electronic Structure

    Science.gov (United States)

    Yeh, Po-Chun

    The search for new ultrathin materials as the "new silicon" has begun. In this dissertation, I examine (1) the surface structure, including the growth, the crystal quality, and thin film surface corrugation of a monolayer sample and a few layers of MoS2 and WSe2, and (2) their electronic structure. The characteristics of these electronic systems depend intimately on the morphology of the surfaces they inhabit, and their interactions with the substrate or within layers. These physical properties will be addressed in each chapter. This thesis has dedicated to the characterization of mono- and a few layers of MoS2 and WSe2 that uses surface-sensitive probes such as low-energy electron microscopy and diffraction (LEEM and LEED). Prior to our studies, the characterization of monolayer MoS2 and WSe2 has been generally limited to optical and transport probes. Furthermore, the heavy use of thick silicon oxide layer as the supporting substrate has been important in order to allow optical microscopic characterization of the 2D material. Hence, to the best of our knowledge, this has prohibited studies of this material on other surfaces, and it has precluded the discovery of potentially rich interface interactions that may exist between MoS 2 and its supporting substrate. Thus, in our study, we use a so-called SPELEEM system (Spectroscopic Photo-Emission and Low Energy Electron Microscopy) to address these imaging modalities: (1) real-space microscopy, which would allow locating of monolayer MoS2 samples, (2) spatially-resolved low-energy diffraction which would allow confirmation of the crystalline quality and domain orientation of MoS2 samples, and, (3) spatially-resolved spectroscopy, which would allow electronic structure mapping of MoS2 samples. Moreover, we have developed a preparation procedure for samples that yield, a surface-probe ready, ultra-clean, and can be transferred on an arbitrary substrate. To fully understand the physics in MoS2 such as direct

  17. Potential and Kinetic Electron Emissions from HOPG Surface Irradiated by Highly Charged Xenon and Neon Ions

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-Yu; ZHAO Yong-Tao; SUN Jian-Rong; LI De-Hui; QAYYUM Abdul; LI Jin-Yu; WANG Ping-Zhi; XIAO Guo-Qing

    2011-01-01

    Highly charged 129 Xeq+ (q =10-30) and 40Neq+ (q =4-8) ion-induced secondary electron emissions on the surface of highly oriented pyrolytic graphite (HOPG) are reported. The total secondary electron yield is measured as a function of the potential energy of incident ions. The experimental data are used to separate contributions of kinetic and potential electron yields. Our results show that about 4.5% and 13.2% of ion's potential energies are consumed in potential electron emission due to different Xeq+-HOPG and Neq+-HOPG combinations. A simple formula is introduced to estimate the fraction of ion's potential energy for potential electron emission.%@@ Highly charged 129 Xeq+(q =10-30) and 40Neq+(q =4-8) ion-induced secondary electron emissions on the surface of highly oriented pyrolytic graphite(HOPG) are reported.The total secondary electron yield is measured as a function of the potential energy of incident ions.The experimental data are used to separate contributions of kinetic and potential electron yields.Our results show that about 4.5% and 13.2% of ion's potential energies are consumed in potential electron emission due to different Xeq+-HOPG and Neq+-HOPG combinations.A simple formula is introduced to estimate the fraction of ion's potential energy for potential electron emission.

  18. Fission Surface Power System Initial Concept Definition

    Science.gov (United States)

    2010-01-01

    Under the NASA Exploration Technology Development Program (ETDP) and in partnership with the Department of Energy (DOE), NASA has embarked on a project to develop Fission Surface Power (FSP) technology. The primary goals of the project are to 1) develop FSP concepts that meet expected surface power requirements at reasonable cost with added benefits over other options, 2) establish a hardwarebased technical foundation for FSP design concepts and reduce overall development risk, 3) reduce the cost uncertainties for FSP and establish greater credibility for flight system cost estimates, and 4) generate the key products to allow NASA decision-makers to consider FSP as a preferred option for flight development. The FSP project was initiated in 2006 as the Prometheus Program and the Jupiter Icy Moons Orbiter (JIMO) mission were phased-out. As a first step, NASA Headquarters commissioned the Affordable Fission Surface Power System Study to evaluate the potential for an affordable FSP development approach. With a cost-effective FSP strategy identified, the FSP team evaluated design options and selected a Preliminary Reference Concept to guide technology development. Since then, the FSP Preliminary Reference Concept has served as a point-of-departure for several NASA mission architecture studies examining the use of nuclear power and has provided the foundation for a series of "Pathfinder" hardware tests. The long-term technology goal is a Technology Demonstration Unit (TDU) integrated system test using full-scale components and a non-nuclear reactor simulator. The FSP team consists of Glenn Research Center (GRC), Marshall Space Flight Center (MSFC) and the DOE National Laboratories at Los Alamos (LANL), Idaho (INL), Oak Ridge (ORNL), and Sandia (SNL). The project is organized into two main elements: Concept Definition and Risk Reduction. Under Concept Definition, the team performs trade studies, develops analytical tools, and formulates system concepts. Under Risk

  19. Quantum corrected Langevin dynamics for adsorbates on metal surfaces interacting with hot electrons

    DEFF Research Database (Denmark)

    Olsen, Thomas; Schiøtz, Jakob

    2010-01-01

    quantum mechanical probabilities from the classical phase space distributions resulting from the dynamics. At short time scales, classical and quasiclassical initial conditions lead to wrong results and only correctly quantized initial conditions give a close agreement with an inherently quantum......We investigate the importance of including quantized initial conditions in Langevin dynamics for adsorbates interacting with a thermal reservoir of electrons. For quadratic potentials the time evolution is exactly described by a classical Langevin equation and it is shown how to rigorously obtain...... mechanical master equation approach. With CO on Cu(100) as an example, we demonstrate the effect for a system with ab initio frictional tensor and potential energy surfaces and show that quantizing the initial conditions can have a large impact on both the desorption probability and the distribution...

  20. Assessment of root surfaces of apicected teeth: A scanning electron ...

    African Journals Online (AJOL)

    2014-05-15

    May 15, 2014 ... Many dental root canal systems have unreachable fields like isthmi, lateral ... root resection and ultrasonic root‑end preparation, when compared with root ... irrigation with 5 ml of 15% EDTA (Wizard, Rehber Kimya. San. ve Tic ...

  1. Electron attachment and ion mobility in hydrocarbons and related systems

    Energy Technology Data Exchange (ETDEWEB)

    Bakale, G.

    1988-01-01

    During the last two decades, a firm base for the emerging field of liquid state electronics (LSE) has developed through studies of the transport and reaction properties of excess electrons in a variety of liquid-phase systems. Pulse-conductivity techniques were used in many of these studies to measure the mobilities of electrons and ions in pure liquids as well as the rate constants of electron attachment to a wide variety of electron-accepting solutes. Results obtained through such studies have interdisciplinary implications that are described in the discussion that follows which includes examples of the contributions of LSE to physics, chemistry and biology. 42 refs.

  2. Electron field emission from nanostructured surfaces of GaN and AlGaN

    Energy Technology Data Exchange (ETDEWEB)

    Evtukh, A.; Litovchenko, V.; Semenenko, M.; Gorbanyuk, T.; Grygoriev, A. [Institute of Semiconductor Physics, 41 prospekt Nauki, 03028 Kiev (Ukraine); Yilmazoglu, O.; Hartnagel, H.; Pavlidis, D. [Technische Universitaet Darmstadt, Institut fuer Hochfrequenztechnik, Merckstr. 25, 64283 Darmstadt (Germany)

    2008-07-01

    The possibility of high frequency electromagnetic wave generation by field emission based devices has great interest. The wide bandgap materials GaN and AlGaN are very promising for these applications due to low electron affinity and the existence of satellite valleys in conduction band. The results of investigations of the peculiarities of electron field emission from nanostructured surfaces of GaN and AlGaN are presented. Multilayer GaN and AlGaN structures with various levels of layer doping on sapphire and bulk GaN substrates were used as initial wafers. The surface of the upper layers was nanostructured by photoelectrochemical etching in water solution of KOH. Intensive electron field emission into vacuum was observed and explained by low electron affinity and electric field enhancement on surface nanowires. A decrease of the slope in the Fowler-Nordheim characteristics was revealed. The changing slope suggests a lowering of effective work function. It is caused by electron heating and transfer into an upper satellite valley with lower electron affinity. A theory was developed for the observed phenomena and interpretation of results. It is based on electron intervalley transition upon heating and on energy band reconstruction of the surface of the nanowires due to quantum size-confinement effect. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Effective Model for Massless Dirac Electrons on a Surface of Weak Topological Insulators

    Science.gov (United States)

    Arita, Takashi; Takane, Yositake

    2014-12-01

    In a typical situation, gapless surface states of a three-dimensional (3D) weak topological insulator (WTI) appear only on the sides, leaving the top and bottom surfaces gapped. To describe massless Dirac electrons emergent on such side surfaces of a WTI, a two-dimensional (2D) model consisting of a series of one-dimensional helical channels is usually employed. However, an explicit derivation of such a model from a 3D bulk Hamiltonian has been lacking. Here, we explicitly derive an effective 2D model for the WTI surface states starting from the Wilson-Dirac Hamiltonian for the bulk WTI and establish a firm basis for the hitherto hypothesized 2D model. We show that the resulting 2D model accurately reproduces the excitation spectrum of surface Dirac electrons determined by the 3D model. We also show that the 2D model is applicable to a side surface with atomic steps.

  4. Excitation of surface and volume plasmons in metal nanocluster by fast electrons

    CERN Document Server

    Gildenburg, V B; Pavlichenko, I A

    2015-01-01

    Surface and volume plasmons excited in a metal cluster by moving electron and corresponding inelastic scattering spectra are studied based on the hydrodynamic approach. Along with the bulk losses traditionally taken into account, the surface and radiative ones are also considered as the physical mechanisms responsible for the plasmon damping. The second and third mechanisms are found to be essential for the surface plasmons and depend very differently on the multipole mode order. The differential equations are obtained which describe the temporal evolution of every particular mode as that one of a linear oscillator excited by the given external force, and the electron energy loss spectra are calculated. The changes in spectrum shape with the impact parameter and with the electron passage time are analyzed and found to be in good enough agreement with the data of scanning transmission electron microscopy (STEM) experiments. It is shown that, in the general case, a pronounced contribution to the formation of th...

  5. Effect of dielectric coating on the electron work function and the surface stress of a metal

    Science.gov (United States)

    Babich, A. V.; Pogosov, V. V.

    2009-08-01

    The electron work function, contact potential difference, and surface stress of the elastically deformed faces of the metal covered by a dielectric are calculated by using the Kohn-Sham method and stabilized jellium model. Our calculations demonstrate the opposite deformation dependencies of the work function and contact potential difference. Dielectric coating leads to a negative change in the work function and a positive change in the contact potential difference. It is shown that the measurements of the contact potential difference of a deformed face by the Kelvin method give only the change in the value of the one-electron effective potential in the plane of a virtual image behind the surface, rather than the value of the electron work function. The obtained values of the electron work function and surface stress for Al, Au, Cu, and Zn are in agreement with the results of experiments for polycrystals.

  6. Cooled electronic system with liquid-cooled cold plate and thermal spreader coupled to electronic component

    Energy Technology Data Exchange (ETDEWEB)

    Chainer, Timothy J.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2016-04-05

    Apparatus and method are provided for facilitating cooling of an electronic component. The apparatus includes a liquid-cooled cold plate and a thermal spreader associated with the cold plate. The cold plate includes multiple coolant-carrying channel sections extending within the cold plate, and a thermal conduction surface with a larger surface area than a surface area of the component to be cooled. The thermal spreader includes one or more heat pipes including multiple heat pipe sections. One or more heat pipe sections are partially aligned to a first region of the cold plate, that is, where aligned to the surface to be cooled, and partially aligned to a second region of the cold plate, which is outside the first region. The one or more heat pipes facilitate distribution of heat from the electronic component to coolant-carrying channel sections of the cold plate located in the second region of the cold plate.

  7. Cooled electronic system with liquid-cooled cold plate and thermal spreader coupled to electronic component

    Energy Technology Data Exchange (ETDEWEB)

    Chainer, Timothy J.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2016-08-09

    Apparatus and method are provided for facilitating cooling of an electronic component. The apparatus includes a liquid-cooled cold plate and a thermal spreader associated with the cold plate. The cold plate includes multiple coolant-carrying channel sections extending within the cold plate, and a thermal conduction surface with a larger surface area than a surface area of the component to be cooled. The thermal spreader includes one or more heat pipes including multiple heat pipe sections. One or more heat pipe sections are partially aligned to a first region of the cold plate, that is, where aligned to the surface to be cooled, and partially aligned to a second region of the cold plate, which is outside the first region. The one or more heat pipes facilitate distribution of heat from the electronic component to coolant-carrying channel sections of the cold plate located in the second region of the cold plate.

  8. New Electronic-Transition Laser Systems. Part 1. Electron Pumped Systems. Part 2. Chemically Pumped Systems

    Science.gov (United States)

    1976-12-01

    laser development . There has not yet been a demonstration of gain in a visible chemical laser systems, and it appears unlikely that practical lasers of this type will be developed in the near future. Substantial progress has been made

  9. Electronic Properties of Molecules and Surfaces with a Self-Consistent Interatomic van der Waals Density Functional

    Science.gov (United States)

    Ferri, Nicola; DiStasio, Robert A.; Ambrosetti, Alberto; Car, Roberto; Tkatchenko, Alexandre

    2015-05-01

    How strong is the effect of van der Waals (vdW) interactions on the electronic properties of molecules and extended systems? To answer this question, we derived a fully self-consistent implementation of the density-dependent interatomic vdW functional of Tkatchenko and Scheffler [Phys. Rev. Lett. 102, 073005 (2009)]. Not surprisingly, vdW self-consistency leads to tiny modifications of the structure, stability, and electronic properties of molecular dimers and crystals. However, unexpectedly large effects were found in the binding energies, distances, and electrostatic moments of highly polarizable alkali-metal dimers. Most importantly, vdW interactions induced complex and sizable electronic charge redistribution in the vicinity of metallic surfaces and at organic-metal interfaces. As a result, a substantial influence on the computed work functions was found, revealing a nontrivial connection between electrostatics and long-range electron correlation effects.

  10. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    Energy Technology Data Exchange (ETDEWEB)

    Lollobrigida, V. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Basso, V.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Torino (Italy); Borgatti, F. [CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), I-40129 Bologna (Italy); Torelli, P.; Panaccione, G. [CNR, Istituto Officina dei Materiali (IOM), Lab. TASC, I-34149 Trieste (Italy); Tortora, L. [Laboratorio di Analisi di Superficie, Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Ingegneria Meccanica, Università Tor Vergata, I-00133 Rome (Italy); Stefani, G.; Offi, F. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy)

    2014-05-28

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  11. Primary role of electron work function for evaluation of nanostructured titania implant surface against bacterial infection

    Energy Technology Data Exchange (ETDEWEB)

    Golda-Cepa, M., E-mail: golda@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Syrek, K. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Brzychczy-Wloch, M. [Department of Bacteriology, Microbial Ecology and Parasitology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow (Poland); Sulka, G.D. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Kotarba, A., E-mail: kotarba@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)

    2016-09-01

    The electron work function as an essential descriptor for the evaluation of metal implant surfaces against bacterial infection is identified for the first time. Its validity is demonstrated on Staphylococcus aureus adhesion to nanostructured titania surfaces. The established correlation: work function–bacteria adhesion is of general importance since it can be used for direct evaluation of any electrically conductive implant surfaces. - Highlights: • The correlation between work function and bacteria adhesion was discovered. • The discovered correlation is rationalized in terms of electrostatic bacteria–surface repulsion. • The results provide basis for the simple evaluation of implant surfaces against infection.

  12. Scanning electron microscopy study of protein immobilized on SIO2 Sol-gel surfaces

    Directory of Open Access Journals (Sweden)

    O.B.G. Assis

    2003-09-01

    Full Text Available Uniform attachment of enzymes to solid surfaces is essential in the development of bio and optical sensor devices. Immobilization by adsorption according to hydrophilic or hydrophobic nature is dependent on the charges and defects of the support surfaces. Sol-gel SiO2 densified glass surfaces, frequently used as supports for protein immobilization, are evaluated via scanning electron microscopy. The model protein is globular enzyme lysozyme, deposited by adsorption on functionalized surfaces. Formation of a protein layer is confirmed by FTIR spectroscopy, and the SEM images suggest discontinuous adsorption in areas where cracks predominate on the glass surface.

  13. Developing the Surface Chemistry of Transparent Butyl Rubber for Impermeable Stretchable Electronics.

    Science.gov (United States)

    Vohra, Akhil; Carmichael, R Stephen; Carmichael, Tricia Breen

    2016-10-11

    Transparent butyl rubber is a new elastomer that has the potential to revolutionize stretchable electronics due to its intrinsically low gas permeability. Encapsulating organic electronic materials and devices with transparent butyl rubber protects them from problematic degradation due to oxygen and moisture, preventing premature device failure and enabling the fabrication of stretchable organic electronic devices with practical lifetimes. Here, we report a methodology to alter the surface chemistry of transparent butyl rubber to advance this material from acting as a simple device encapsulant to functioning as a substrate primed for direct device fabrication on its surface. We demonstrate a combination of plasma and chemical treatment to deposit a hydrophilic silicate layer on the transparent butyl rubber surface to create a new layered composite that combines Si-OH surface chemistry with the favorable gas-barrier properties of bulk transparent butyl rubber. We demonstrate that these surface Si-OH groups react with organosilanes to form self-assembled monolayers necessary for the deposition of electronic materials, and furthermore demonstrate the fabrication of stretchable gold wires using nanotransfer printing of gold films onto transparent butyl rubber modified with a thiol-terminated self-assembled monolayer. The surface modification of transparent butyl rubber establishes this material as an important new elastomer for stretchable electronics and opens the way to robust, stretchable devices.

  14. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    OpenAIRE

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2015-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autocla...

  15. Structures, electronic properties and stability phase diagrams for copper(I/II) bromide surfaces.

    Science.gov (United States)

    Altarawneh, Mohammednoor; Marashdeh, Ali; Dlugogorski, Bogdan Z

    2015-04-14

    This study presents a comprehensive periodic slab DFT investigation into structures, electronic properties and thermodynamic stability of all plausible terminations of CuBr and CuBr2 surfaces. We first estimate lattice constants, formation and cohesive energies for the two bulk copper bromides before proceeding to analyse geometrical and electronic features of CuBr and CuBr2 configurations. Surface geometries exhibit, to a large extent, corresponding bulk structures. Nevertheless, certain CuBr2 surfaces experience a downward displacement of the topmost Cu-containing layers. We plot total and projected density of states for bulk and surface geometries of these two copper bromides and calculate their associated Bader's electronic charges. Electronic structure analysis for the bulk and surfaces of these two copper bromides show that CuBr bulk and its most stable surface (CuBr(001)_Br) do not exhibit any metallic character, whereas CuBr2 bulk and its most stable surface (CuBr2(001)_Br) both exhibit metallic characters. The formalism of the ab initio atomistic thermodynamics affords the construction of energy phase diagrams. We predict that the CuBr(001) surface, truncated with Br atoms, is the most stable structure among the considered CuBr slabs at all physically meaningful ranges of the chemical potential of bromine. This surface resembles a c(2 × 2)-bromine sheet that was characterised experimentally from initial interaction of Br2 with a Cu(100) surface. We find that surfaces terminated with the electronegative bromine atoms, if accompanied by significant relaxation, tend to be more stable. Calculated surface energies predict the shapes of CuBr and CuBr2 nanoparticles as the chemical potential of bromine changes.

  16. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    OpenAIRE

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2015-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autocla...

  17. A surface acoustic wave bio-electronic nose for detection of volatile odorant molecules.

    Science.gov (United States)

    Di Pietrantonio, F; Benetti, M; Cannatà, D; Verona, E; Palla-Papavlu, A; Fernández-Pradas, J M; Serra, P; Staiano, M; Varriale, A; D'Auria, S

    2015-05-15

    In this work, a "bio-electronic nose" for vapour phase detection of odorant molecules based on surface acoustic wave (SAW) resonators is presented. The biosensor system is composed of an array of five SAW resonators coated with three types of odorant-binding proteins (OBPs): the wild-type OBP from bovine (wtbOBP), a double-mutant of the OBP from bovine (dmbOBP), and the wild-type OBP from pig (wtpOBP). High resolution deposition of OBPs onto the active area of SAW resonators was implemented through laser-induced forward transfer (LIFT). The resonant frequency shifts of the SAW resonators after the deposition of the biomolecules confirmed the immobilisation of the proteins onto the Al/Au inter-digital transducers (IDTs). In addition, a low increase of insertion losses with a limited degradation of Q-factors is reported. The "bio-electronic nose" fabricated by LIFT is tested in nitrogen upon exposure to separated concentrations of R-(-)-1-octen-3-ol (octenol) and R-(-)-carvone (carvone) vapours. The "bio-electronic nose" showed low detection limits for the tested compounds (i.e. 0.48 ppm for the detection of octenol, and 0.74 ppm for the detection of carvone). In addition, the bio-sensing system was able to discriminate the octenol molecules from the carvone molecules, making it pertinent for the assessment of food contamination by moulds, or for the evaluation of indoor air quality in buildings. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Implementation of variable time step stochastic dynamics for electronically inelastic gas-surface collisions

    Science.gov (United States)

    Garrett, Bruce C.; Swaminathan, P. K.; Murthy, C. S.; Redmon, Michael J.

    1987-01-01

    A variable time step algorithm has been implemented for solving the stochastic equations of motion for gas-surface collisions. It has been tested for a simple model of electronically inelastic collisions with an insulator surface in which the phonon manifold acts as a heat bath and electronic states are localized. In addition to reproducing the accurate nuclear dynamics of the surface atoms, numerical calculations have shown the algorithm to yield accurate ensemble averages of physical observables such as electronic transition probabilities and total energy loss of the gas atom to the surface. This new algorithm offers a gain in efficieny of up to an order of magnitude compared to fixed time step integration.

  19. Sulfur passivation of surface electrons in highly Mg-doped InN

    Energy Technology Data Exchange (ETDEWEB)

    Linhart, W. M.; Veal, T. D. [Stephenson Institute for Renewable Energy and Department of Physics, University of Liverpool, Liverpool L69 4ZF (United Kingdom); Chai, J. [Department of Electrical and Computer Engineering, University of Canterbury, Christchurch 8140 (New Zealand); McConville, C. F. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Durbin, S. M. [Department of Electrical and Computer Engineering, University of Canterbury, Christchurch 8140 (New Zealand); Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, Michigan 49008 (United States)

    2013-09-14

    Electron accumulation with a sheet density greater than 10{sup 13} cm{sup −2} usually occurs at InN surfaces. Here, the effects of treatment with ammonium sulfide ((NH{sub 4}){sub 2}S{sub x}) on the surface electronic properties of highly Mg-doped InN (>4×10{sup 18} cm{sup −3}) have been investigated with high resolution x-ray photoemission spectroscopy. The valence band photoemission spectra show that the surface Fermi level decreases by approximately 0.08 eV with (NH{sub 4}){sub 2}S{sub x} treatment, resulting in a decrease of the downward band bending and up to a 70% reduction in the surface electron sheet density.

  20. Multi-electron beam system for high resolution electron beam induced deposition

    NARCIS (Netherlands)

    Van Bruggen, M.J.

    2008-01-01

    The development of a multi-electron beam system is described which is dedicated for electron beam induced deposition (EBID) with sub-10 nm resolution. EBID is a promising mask-less nanolithography technique which has the potential to become a viable technique for the fabrication of 20-2 nm structure

  1. Energy Transformation in Molecular Electronic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kasha, Michael

    1999-05-17

    This laboratory has developed many new ideas and methods in the electronic spectroscopy of molecules. This report covers the contract period 1993-1995. A number of the projects were completed in 1996, and those papers are included in the report. The DOE contract was terminated at the end of 1995 owing to a reorganizational change eliminating nationally the projects under the Office of Health and Environmental Research, U. S. Department of Energy.

  2. Variables Affecting Two Electron Transport System Assays

    OpenAIRE

    Burton, G. Allen; Lanza, Guy R.

    1986-01-01

    Several methodological variables were critical in two commonly used electron transport activity assays. The dehydrogenase assay based on triphenyl formazan production exhibited a nonlinear relationship between formazan production (dehydrogenase activity) and sediment dilution, and linear formazan production occurred for 1 h in sediment slurries. Activity decreased with increased time of sediment storage at 4°C. Extraction efficiencies of formazan from sediment varied with alcohol type; methan...

  3. Electronic Equipment Proposal to Improve the Photovoltaic Systems Efficiency

    Science.gov (United States)

    Flores-Mena, J. E.; Juárez Morán, L. A.; Díaz Reyes, J.

    2011-05-01

    This paper reports a new technique proposal to improve the photovoltaic systems. It was made to design and implement an electronic system that will detect, capture, and transfer the maximum power of the photovoltaic (PV) panel to optimize the supplied power of a solar panel. The electronic system works on base technical proposal of electrical sweeping of electric characteristics using capacitive impedance. The maximum power is transformed and the solar panel energy is sent to an automotive battery. This electronic system reduces the energy lost originated when the solar radiation level decreases or the PV panel temperature is increased. This electronic system tracks, captures, and stores the PV module's maximum power into a capacitor. After, a higher voltage level step-up circuit was designed to increase the voltage of the PV module's maximum power and then its current can be sent to a battery. The experimental results show that the developed electronic system has 95% efficiency. The measurement was made to 50 W, the electronic system works rightly with solar radiation rate from 100 to 1,000 W m - 2 and the PV panel temperature rate changed from 1 to 75°C. The main advantage of this electronic system compared with conventional methods is the elimination of microprocessors, computers, and sophisticated numerical approximations, and it does not need any small electrical signals to track the maximum power. The proposed method is simple, fast, and it is also cheaper.

  4. Renewable Energy Systems in the Power Electronics Curriculum

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Chen, Zhe; Teodorescu, Remus

    2005-01-01

    Power Electronics is still an emerging technology and its applications are increasing. The primary function is to convert electrical energy from one stage to another and it is used in many different applications. The power electronics curriculum is multidisciplinary covering fields like devices......, magnetics, electrical machines, power systems, analogue and digital control, materials, power converters, electronics, materials, thermal design and EMC. However, those fields may not be enough in order to give the students enough skills. It is also necessary to learn about systems and for the moment one...... of the most important area is renewable energy systems. This paper will discuss the basic courses for the power electronics curriculum. It will also discuss how to teach power electronic systems efficiently through a projectoriented and problem-based learning approach with Aalborg University in Denmark...

  5. A comparative DFT study of the structural and electronic properties of nonpolar GaN surfaces

    Energy Technology Data Exchange (ETDEWEB)

    González-Hernández, Rafael, E-mail: rhernandezj@uninorte.edu.co [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); González-García, Alvaro [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); Barragán-Yani, Daniel [Fachgebiet Material modellierung, Institut für Materialwissenschaft, Technische Universität Darmstadt, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); López-Pérez, William [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia)

    2014-09-30

    Highlights: • A comparative analysis of the geometry and the electronic characteristics of nonpolar GaN surfaces was carried out. • Surface energies are too low for LDA, but lower still for GGA and MGGA functionals, except for PBEsol. • PBEsol exhibits good lattice parameters and surface energies. • Surface intra-gap states reduce the band gap of the nonpolar GaN surfaces. • Slight changes in the dispersion of surface states were observed for the LDA, GGA, and MGGA functionals. - Abstract: A comparative analysis of the geometry and the electronic characteristics of nonpolar GaN surfaces was carried out using density-functional theory (DFT) with different approximations for the exchange-correlation energy (LDA, PBE, PBEsol, RPBE, TPSS, revTPSS, and HSE). The obtained data show that the GaN(101{sup ¯}0) (m-plane) is more energetically stable than the GaN(112{sup ¯}0) (a-plane) surface. However, these surfaces have similar surface relaxation geometry, with a Ga-N surface bond-length contraction of around 6–7% and a Ga-N surface rotational angle in the range of 6–9°. Our results show that the use of different exchange-correlation functionals does not significantly change the surface energy and surface geometry. In addition, we found the presence of surface intra-gap states that reduce the band gap of the nonpolar GaN surface with respect to the bulk value, in agreement with recent photoelectron and surface optical spectroscopy experiments.

  6. Surface structures from low energy electron diffraction: Atoms, small molecules and an ordered ice film on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Materer, N.F.

    1995-09-01

    We investigated the surface bonding of various adsorbates (0, S, C{sub 2}H{sub 3} and NO) along with the resulting relaxation of the Pt(111) surface using low energy electron diffiraction (LEED). LEED experiments have been performed on these ordered overlayers along with theoretical structural analysis using automated tensor LEED (ATLEED). The resulting surface structures of these ordered overlayers exhibit similar adsorbate-induced relaxations. In all cases the adsorbate occupies the fcc hollow site and induces an approximately 0.1 A buckling of the metal surface. The three metal atoms directly bonded to the adsorbate are ``pulled`` out of the surface and the metal atom that is not bound to the adsorbate is `pushed`` inward. In order to understand the reliability of such details, we have carried out a comprehensive study of various non-structural parameters used in a LEED computation. We also studied the adsorption of water on the Pt(lll) surface. We ordered an ultra thin ice film on this surface. The film`s surface is found to be the (0001) face of hexagonal ice. This surface is apparently terminated by a full-bilayer, in which the uppermost water molecules have large vibrational amplitudes even at temperatures as low as 90 K. We examined two other metal surfaces besides Pt(111): Ni(111) and Fe(lll). On Ni(111), we have studied the surface under a high coverage of NO. On both Ni(111) and Pt(111) NO molecules occupy the hollow sites and the N-0 bond distances are practically identical. The challenging sample preparation of an Fe(111) surface has been investigated and a successful procedure has been obtained. The small interlayer spacing found on Fe(111) required special treatment in the LEED calculations. A new ATLEED program has been developed to handle this surface.

  7. Measuring a System’s Attack Surface

    Science.gov (United States)

    2004-01-01

    fold: • In terms of a state machine model of the system, we present formal definitions of attack, attack surface, and attack class. Our definitions are...versions. The rest of this paper is organized as follows. In Section 2, we introduce our state machine model and point out the key differences from...approach in Section 6 and compare it to related work in Section 7. We conclude in Section 8. 2 State Machine Model We use a state machine to model the

  8. Secure electronic commerce communication system based on CA

    Science.gov (United States)

    Chen, Deyun; Zhang, Junfeng; Pei, Shujun

    2001-07-01

    In this paper, we introduce the situation of electronic commercial security, then we analyze the working process and security for SSL protocol. At last, we propose a secure electronic commerce communication system based on CA. The system provide secure services such as encryption, integer, peer authentication and non-repudiation for application layer communication software of browser clients' and web server. The system can implement automatic allocation and united management of key through setting up the CA in the network.

  9. Handbook of power systems engineering with power electronics applications

    CERN Document Server

    Hase, Yoshihide

    2012-01-01

    Formerly known as Handbook of Power System Engineering, this second edition provides rigorous revisions to the original treatment of systems analysis together with a substantial new four-chapter section on power electronics applications. Encompassing a whole range of equipment, phenomena, and analytical approaches, this handbook offers a complete overview of power systems and their power electronics applications, and presents a thorough examination of the fundamental principles, combining theories and technologies that are usually treated in separate specialised fields, in a single u

  10. Sequential energy and electron transfer in a three-component system aligned on a clay nanosheet.

    Science.gov (United States)

    Fujimura, Takuya; Ramasamy, Elamparuthi; Ishida, Yohei; Shimada, Tetsuya; Takagi, Shinsuke; Ramamurthy, Vaidhyanathan

    2016-02-21

    To achieve the goal of energy transfer and subsequent electron transfer across three molecules, a phenomenon often utilized in artificial light harvesting systems, we have assembled a light absorber (that also serves as an energy donor), an energy acceptor (that also serves as an electron donor) and an electron acceptor on the surface of an anionic clay nanosheet. Since neutral organic molecules have no tendency to adsorb onto the anionic surface of clay, a positively charged water-soluble organic capsule was used to hold neutral light absorbers on the above surface. A three-component assembly was prepared by the co-adsorption of a cationic bipyridinium derivative, cationic zinc porphyrin and cationic octaamine encapsulated 2-acetylanthracene on an exfoliated anionic clay surface in water. Energy and electron transfer phenomena were monitored by steady state fluorescence and picosecond time resolved fluorescence decay. The excitation of 2-acetylanthracene in the three-component system resulted in energy transfer from 2-acetylanthracene to zinc porphyrin with 71% efficiency. Very little loss due to electron transfer from 2-acetylanthracene in the cavitand to the bipyridinium derivative was noticed. Energy transfer was followed by electron transfer from the zinc porphyrin to the cationic bipyridinium derivative with 81% efficiency. Analyses of fluorescence decay profiles confirmed the occurrence of energy transfer and subsequent electron transfer. Merging the concepts of supramolecular chemistry and surface chemistry we realized sequential energy and electron transfer between three hydrophobic molecules in water. Exfoliated transparent saponite clay served as a matrix to align the three photoactive molecules at a close distance in aqueous solutions.

  11. The electronic identification, signature and security of information systems

    Directory of Open Access Journals (Sweden)

    Horovèák Pavel

    2002-12-01

    Full Text Available The contribution deals with the actual methods and technologies of information and communication systems security. It introduces the overview of electronic identification elements such as static password, dynamic password and single sign-on. Into this category belong also biometric and dynamic characteristics of verified person. Widespread is authentication based on identification elements ownership, such as various cards and authentication calculators. In the next part is specified a definition and characterization of electronic signature, its basic functions and certificate categories. Practical utilization of electronic signature consists of electronic signature acquirement, signature of outgoing email message, receiving of electronic signature and verification of electronic signature. The use of electronic signature is continuously growing and in connection with legislation development it exercises in all resorts.

  12. Surface Energy Balance System (SEBS) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, D. R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    A Surface Energy Balance System (SEBS) has been installed collocated with each deployed Eddy Correlation Flux Measurement System (ECOR) at the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Southern Great Plains (SGP) site, North Slope of Alaska (NSA) site, first ARM Mobile Facility (AMF1), second ARM Mobile Facility (AMF2), and third ARM Mobile Facility (AMF3) at Oliktok Point (OLI). A SEBS was also deployed with the Tropical Western Pacific (TWP) site, before it was decommissioned. Data from these sites, including the retired TWP, are available in the ARM Data Archive. The SEBS consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes.

  13. Excess electrons at anatase TiO2 surfaces and interfaces: insights from first principles simulations

    Science.gov (United States)

    Selçuk, Sencer; Selloni, Annabella

    2017-07-01

    TiO2 is an important technological material with widespread applications in photocatalysis, photovoltaics and self-cleaning surfaces. Excess electrons from intrinsic defects, dopants and photoexcitation play a key role in the properties of TiO2 that are relevant to its energy-related applications. The picture of excess and photoexcited electrons in TiO2 is based on the polaron model, where the electron forms a localized state that is stabilized by an accompanying lattice distortion. Here, we focus on excess and photoexcited electrons in anatase, the TiO2 polymorph most relevant to photocatalysis and solar energy conversion. For anatase, evidence of both small and large electron polarons has been reported in the literature. In addition, several studies have revealed a remarkable dependence of the photocatalytic activity of anatase on the crystal surface. After an overview of experimental studies, we briefly discuss recent progress in the theoretical description of polaronic states in TiO2, and finally present a more detailed account of our computational studies on the trapping and dynamics of excess electrons near the most common anatase surfaces and aqueous interfaces. The results of these studies provide a bridge between surface science experiments under vacuum conditions and observations of crystal-face-dependent photocatalysis on anatase, and support the idea that optimization of the ratio between different anatase facets can help enhance the photocatalytic activity of this material.

  14. Power Electronics and Controls for Wind Turbine Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Iov, Florin; Chen, Zhe

    2010-01-01

    term) based energy sources to renewable energy sources. Another is to use power electronics to achieve high efficiency in power generation, transmission/distribution and utilization. This paper discuss trends of the most promising renewable energy sources, wind energy, which ,integrated with power...... electronics, is changing the future electrical infrastructure and also contributes steadily to non-carbon based electricity production. The paper’s focus is on the power electronics technologies used in wind turbine systems....

  15. Note on Modern Trends in Heavy Vehicle Electrical Electronic systems

    Directory of Open Access Journals (Sweden)

    B. S. Sastry

    1982-04-01

    Full Text Available The paper presents an overview of some of the aerospace control systems that are being successfully adopted in the field of Armoured Fighting Vehicles. An automatic electronic transmission controller for an epicyclic gear box with a torque converter to select the forward and reverse speeds in a sequential logic has been developed. Transducers developed for monitoring various engine and transmission parameters are being used for Electronic Fuel Injection (EFI, variable valve timings and electronic governing.

  16. Modulating semiconductor surface electronic properties by inorganic peptide-binders sequence design.

    Science.gov (United States)

    Matmor, Maayan; Ashkenasy, Nurit

    2012-12-19

    The use of proteins and peptides as part of biosensors and electronic devices has been the focus of intense research in recent years. However, despite the fact that the interface between the bioorganic molecules and the inorganic matter plays a significant role in determining the properties of such devices, information on the electronic properties of such interfaces is sparse. In this work, we demonstrate that the identity and position of single amino acid in short inorganic binding protein-segments can significantly modulate the electronic properties of semiconductor surfaces on which they are bound. Specifically, we show that the introduction of tyrosine or tryptophan, both possessing an aromatic side chain which higher occupied molecular orbitals are positioned in proximity to the edge of GaAs valence band, to the sequence of a peptide that binds to GaAs (100) results in changes of both the electron affinity and surface potential of the semiconductor. These effects were found to be more pronounced than the effects induced by the same amino acids once bound on the surface in a head-tail configuration. Furthermore, the relative magnitude of each effect was found to depend on the position of the modification in the sequence. This sequence dependent behavior is induced both indirectly by changes in the peptide surface coverage, and directly, probably, due to changes in the orientation and proximity of the tyrosine/tryptophan side group with respect to the surface due to the preferred conformation the peptide adopts on the surface. These studies reveal that despite the use of short protein oligomers and aiming at a non-natural-electronic task, the well-known relations between the proteins' structure and function is preserved. Combining the ability to tune the electronic properties at the interface with the ability to direct the growth of inorganic materials makes peptides promising building blocks for the construction of novel hybrid electronic devices and biosensors.

  17. Copper plasmonics and catalysis: role of electron-phonon interactions in dephasing localized surface plasmons.

    Science.gov (United States)

    Sun, Qi-C; Ding, Yuchen; Goodman, Samuel M; Funke, Hans H; Nagpal, Prashant

    2014-11-07

    Copper metal can provide an important alternative for the development of efficient, low-cost and low-loss plasmonic nanoparticles, and selective nanocatalysts. However, poor chemical stability and lack of insight into photophysics and plasmon decay mechanisms has impeded study. Here, we use smooth conformal ALD coating on copper nanoparticles to prevent surface oxidation, and study dephasing time for localized surface plasmons on different sized copper nanoparticles. Using dephasing time as a figure of merit, we elucidate the role of electron-electron, electron-phonon, impurity, surface and grain boundary scattering on the decay of localized surface plasmon waves. Using our quantitative analysis and different temperature dependent measurements, we show that electron-phonon interactions dominate over other scattering mechanisms in dephasing plasmon waves. While interband transitions in copper metal contributes substantially to plasmon losses, tuning surface plasmon modes to infrared frequencies leads to a five-fold enhancement in the quality factor. These findings demonstrate that conformal ALD coatings can improve the chemical stability for copper nanoparticles, even at high temperatures (>300 °C) in ambient atmosphere, and nanoscaled copper is a good alternative material for many potential applications in nanophotonics, plasmonics, catalysis and nanoscale electronics.

  18. Surface charging of phosphors and its effects on cathodoluminescence at low electron energies

    Energy Technology Data Exchange (ETDEWEB)

    Seager, C.H.; Warren, W.L.; Tallant, D.R.

    1997-05-01

    Measurements of the threshold for secondary electron emission and shifts of the carbon Auger line position have been used to deduce the surface potential of several common phosphors during irradiation by electrons in the 0.5--5.0 keV range. All of the insulating phosphors display similar behavior: the surface potential is within {+-}1 V of zero at low electron energies. However, above 2--3 kV it becomes increasingly negative, reaching hundreds of volts within 1 keV of the turn-on energy. The electron energy at which this charging begins decreases dramatically after Coulomb aging at 17 {micro}A/cm{sup 2} for 30--60 min. Measurements using coincident electron beams at low and high electron energies to control the surface potential were made to investigate the dependence of the cathodoluminescence (CL) process on charging. Initially, the CL from the two beams is identical to the sum of the separate beam responses, but after Coulomb aging large deviations from this additivity are observed. These results indicate that charging has important, detrimental effects on CL efficiency after prolonged e-beam irradiation. Measurements of the electron energy dependence of the CL efficiency before and after Coulomb aging will also be presented, and the implications of these data on the physics of the low-voltage CL process will be discussed.

  19. Scanning tunneling microscopy characterization of the geometric and electronic structure of hydrogen-terminated silicon surfaces

    Science.gov (United States)

    Kaiser, W. J.; Bell, L. D.; Hecht, M. H.; Grunthaner, F. J.

    1988-01-01

    Scanning tunneling microscopy (STM) methods are used to characterize hydrogen-terminated Si surfaces prepared by a novel method. The surface preparation method is used to expose the Si-SiO2 interface. STM images directly reveal the topographic structure of the Si-SiO2 interface. The dependence of interface topography on oxide preparation conditions observed by STM is compared to the results of conventional surface characterization methods. Also, the electronic structure of the hydrogen-terminated surface is studied by STM spectroscopy. The near-ideal electronic structure of this surface enables direct tunnel spectroscopy measurements of Schottky barrier phenomena. In addition, this method enables probing of semiconductor subsurface properties by STM.

  20. Electronic states on the clean and oxygen-covered molybdenum (110) surface measured using time-of-flight momentum microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chernov, Sergii

    2016-04-20

    Recent experiments discovered a new class of materials called topological insulators and started an extensive investigation in order to find more materials of such type and to understand and explore the opening perspectives in fundamental science and application. These materials exhibit a Dirac-type (massless) electronic state, bridging the fundamental band gap. Surprisingly, a strongly spin-polarized surface state with linear dispersion resembling that of Dirac type was found on the already well-investigated W(110) surface. This rose the question of the existence of the same non-trivial electron state on other metal surfaces. The present work describes the investigation of surface electronic states on the Mo(110) surface, their dispersion and transformation upon surface oxidation. This system is isoelectronic to the case of W(110) but due to the lower atomic number the spin-orbit interaction responsible for local band gap formation is substantially decreased by a factor of 5. The Mo(110) surface was shown to exhibit a linearly dispersing state quite similar to the one on W(110), but within a smaller energy range of 120 meV, with the Dirac point lying in the center of a local band gap in k-space. The experimental investigations were performed with the help of momentum microscopy, using a Ti:sapphire laser in the lab and synchrotron radiation at BESSY II, Berlin. The results show good agreement with theoretical calculations of the band structure and photoemission patterns for clean Mo(110). The fully parallel 3D acquisition scheme allowed to visualize the full surface Brillouin zone of the sample up to few eV binding energy within a single exposure of typically less than 30 min. This opens the door to future time-resolved experiments with maximum detection efficiency.

  1. Investigation of the electron emission properties of silver: From exposed to ambient atmosphere Ag surface to ion-cleaned Ag surface

    Energy Technology Data Exchange (ETDEWEB)

    Gineste, T., E-mail: Thomas.Gineste@onera.fr [ONERA The French Aerospace Lab, 31055 Toulouse (France); Belhaj, M. [ONERA The French Aerospace Lab, 31055 Toulouse (France); Teyssedre, G. [LAPLACE - Laboratoire Plasma et Conversion d’Energie -UMR 5213, Université Paul Sabatier - 118, route de Narbonne, 31062 Toulouse Cedex (France); Puech, J. [CNES, 18 Avenue Edouard Belin 31055 Toulouse Cédex 9 (France)

    2015-12-30

    Highlights: • We investigated the electron emission yield of an air exposed Ag to a cleaned Ag. • Air exposed Ag sample was cleaned by ion Ar etching. • Surface composition was determined by AES. • Electron emission yield was related to surface composition evolution. • Natural contamination hugely influence electron properties of Ag sample. - Abstract: Electron emission properties of materials are highly dependent to the surface and the first nanometres subsurface. Technical materials, i.e. used within applications are ordinarily exposed to atmosphere, which interacts with the surface. The contamination layer building up at the surface of materials and/or oxidation layer affects dramatically the electron emission proprieties. In this paper, starting from 99.99% pure silver sample, exposed 4 years to ambient atmosphere, we monitored the variations of the electron emission properties and the surface composition during step by step ion etching procedure.

  2. INVESTIGATION OF TITANIUM BONDED GRAPHITE FOAM COMPOSITES FOR MICRO ELECTRONIC MECHANICAL SYSTEMS (MEMS) APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Menchhofer, Paul A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-04-01

    PiMEMS Inc. (Santa Barbara, CA) in collaboration with ORNL investigated the use of Titanium Bonded Graphite Foam Composites (TBGC) for thermal mitigation in Micro Electronic Mechanical Systems (MEMS) applications. Also considered were potentially new additive manufacturing routes to producing novel high surface area micro features and diverse shaped heat transfer components for numerous lightweight MEMs applications.

  3. Thermal management system for electronic devices

    Directory of Open Access Journals (Sweden)

    Tsevukh I. V.

    2016-02-01

    Full Text Available A four-channel thermal management system with low level of electromagnetic interference is proposed. The system is designed for single- and multi-core CPUs, GPUs, motherboard chipsets etc., emitting a heat flow with the density up to 200 W/cm2.

  4. Design study for electronic system for Jupiter Orbit Probe (JOP)

    Science.gov (United States)

    Elero, B. P., Jr.; Carignan, G. R.

    1978-01-01

    The conceptual design of the Jupiter probe spectrometer is presented. Block and circuit diagrams are presented along with tabulated parts lists. Problem areas are considered to be (1) the schedule, (2) weight limitations for the electronic systems, and (3) radiation hardness of the electronic devices.

  5. Thickness of the electron atmosphere in large nuclear systems

    Science.gov (United States)

    Pacheco, A. F.; Sañudo, J.

    1986-03-01

    Using the relativistic Thomas-Fermi model and the virial theorem it is found that the thickness of the electron skin outside a large nuclear system is given by S⋍6.73 n-1/3, n being the electron density inside the nucleus. On leave from Departamento de Fisica Teorica, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain.

  6. XXIII International Conference on Nonlinear Dynamics of Electronic Systems

    CERN Document Server

    Stoop, Ruedi; Stramaglia, Sebastiano

    2017-01-01

    This book collects contributions to the XXIII international conference “Nonlinear dynamics of electronic systems”. Topics range from non-linearity in electronic circuits to synchronisation effects in complex networks to biological systems, neural dynamics and the complex organisation of the brain. Resting on a solid mathematical basis, these investigations address highly interdisciplinary problems in physics, engineering, biology and biochemistry.

  7. The development of efficient coding for an electronic mail system

    Science.gov (United States)

    Rice, R. F.

    1983-01-01

    Techniques for efficiently representing scanned electronic documents were investigated. Major results include the definition and preliminary performance results of a Universal System for Efficient Electronic Mail (USEEM), offering a potential order of magnitude improvement over standard facsimile techniques for representing textual material.

  8. Surface analytical characterization of Streptavidin/poly(3-hexylthiophene) bilayers for bio-electronic applications

    Science.gov (United States)

    Sportelli, M. C.; Picca, R. A.; Manoli, K.; Re, M.; Pesce, E.; Tapfer, L.; Di Franco, C.; Cioffi, N.; Torsi, L.

    2017-10-01

    The analytical performance of bioelectronic devices is highly influenced by their fabrication methods. In particular, the final architecture of field-effect transistor biosensors combining spin-cast poly(3-hexylthiophene) (P3HT) film and a biomolecule interlayer deposited on a SiO2/Si substrate can lead to the development of highly performing sensing systems, such as for the case of streptavidin (SA) used for biotin sensing. To gain a better understanding of the quality of the interfacial area, critical is the assessment of the morphological features characteristic of the adopted biolayer deposition protocol, namely: the layer-by-layer (LbL) approach and the spin coating technique. The present study relies on a combined surface spectroscopic and morphological characterization. Specifically, X-ray photoelectron spectroscopy operated in the parallel angle-resolved mode allowed the non-destructive investigation of the in-depth chemical composition of the SA film, alone or in the presence of the P3HT overlayer. Spectroscopic data were supported and corroborated by the results obtained with a Scanning Electron and a Helium Ion microscope investigation performed on the SA layer that provided relevant information on the protein structural arrangement or on its surface morphology. Clear differences emerged between the SA layers prepared by the two approaches, with the layer-by-layer deposition resulting in a smoother and better defined bio-electronic interface. Such findings support the superior analytical performance shown by bioelectronic devices based on LbL-deposited protein layers over spin coated ones.

  9. 4D scanning ultrafast electron microscopy: visualization of materials surface dynamics.

    Science.gov (United States)

    Mohammed, Omar F; Yang, Ding-Shyue; Pal, Samir Kumar; Zewail, Ahmed H

    2011-05-25

    The continuous electron beam of conventional scanning electron microscopes (SEM) limits the temporal resolution required for the study of ultrafast dynamics of materials surfaces. Here, we report the development of scanning ultrafast electron microscopy (S-UEM) as a time-resolved method with resolutions in both space and time. The approach is demonstrated in the investigation of the dynamics of semiconducting and metallic materials visualized using secondary-electron images and backscattering electron diffraction patterns. For probing, the electron packet was photogenerated from the sharp field-emitter tip of the microscope with a very low number of electrons in order to suppress space-charge repulsion between electrons and reach the ultrashort temporal resolution, an improvement of orders of magnitude when compared to the traditional beam-blanking method. Moreover, the spatial resolution of SEM is maintained, thus enabling spatiotemporal visualization of surface dynamics following the initiation of change by femtosecond heating or excitation. We discuss capabilities and potential applications of S-UEM in materials and biological science.

  10. Nanopatterning of mobile lipid monolayers on electron-beam-sculpted Teflon AF surfaces.

    Science.gov (United States)

    Shaali, Mehrnaz; Lara-Avila, Samuel; Dommersnes, Paul; Ainla, Alar; Kubatkin, Sergey; Jesorka, Aldo

    2015-02-24

    Direct electron-beam lithography is used to fabricate nanostructured Teflon AF surfaces, which are utilized to pattern surface-supported monolayer phospholipid films with 50 nm lateral feature size. In comparison with unexposed Teflon AF coatings, e-beam-irradiated areas show reduced surface tension and surface potential. For phospholipid monolayer spreading experiments, these areas can be designed to function as barriers that enclose unexposed areas of nanometer dimensions and confine the lipid film within. We show that the effectiveness of the barrier is defined by pattern geometry and radiation dose. This surface preparation technique represents an efficient, yet simple, nanopatterning strategy supporting studies of lipid monolayer behavior in ultraconfined spaces. The generated structures are useful for imaging studies of biomimetic membranes and other specialized surface applications requiring spatially controlled formation of self-assembled, molecularly thin films on optically transparent patterned polymer surfaces with very low autofluorescence.

  11. Curved Two-Dimensional Electron Systems in Semiconductor Nanoscrolls

    Science.gov (United States)

    Peters, Karen; Mendach, Stefan; Hansen, Wolfgang

    The perfect control of strain and layer thickness in epitaxial semiconductor bilayers is employed to fabricate semiconductor nanoscrolls with precisely adjusted scroll diameter ranging between a few nanometers and several tens of microns. Furthermore, semiconductor heteroepitaxy allows us to incorporate quantum objects such as quantum wells, quantum dots, or modulation doped low-dimensional carrier systems into the nanoscrolls. In this review, we summarize techniques that we have developed to fabricate semiconductor nanoscrolls with well-defined location, orientation, geometry, and winding number. We focus on magneto-transport studies of curved two-dimensional electron systems in such nanoscrolls. An externally applied magnetic field results in a strongly modulated normal-to-surface component leading to magnetic barriers, reflection of edge channels, and local spin currents. The observations are compared to finite-element calculations and discussed on the basis of simple models taking into account the influence of a locally modulated state density on the conductivity. In particular, it is shown that the observations in high magnetic fields can be well described considering the transport in edge channels according to the Landauer-Büttiker model if additional magnetic field induced channels aligned along magnetic barriers are accounted for.

  12. Equilibrium Geometries, Reaction Pathways, and Electronic Structures of Ethanol Adsorbed on the Si (111) Surface

    CERN Document Server

    Gavrilenko, A V; Gavrilenko, V I

    2008-01-01

    Equilibrium atomic configurations and electron energy structure of ethanol adsorbed on the Si (111) surface are studied by the first-principles density functional theory. Geometry optimization is performed by the total energy minimization method. Several equilibrium atomic configurations of ethanol, both undissociated and dissociated, on the Si (111) surface are found. Reaction pathways and predicted transition states are discussed in comparison with available experimental data in terms of the feasibility of the reactions occurring. Analysis of atom and orbital resolved projected density of states indicate substantial modifications of the Si surface valence and conduction bands due to the adsorption of ethanol affecting the electrical properties of the surface.

  13. Investigation of Noise in Electronic Ultrasonic Systems

    Directory of Open Access Journals (Sweden)

    Paulius Adomavičius

    2011-03-01

    Full Text Available Noise models in ultrasonic control system have been investigated. Ultrasonic system channel consist of exciting generator, ultrasonic transducer, amplitude limiter, amplifier, low band filter and A/D converter. The ultrasonic transducers have been described as Von Hippel model, Van Dyke model or improved Van Dyke model. Advantages and disadvantages of these models are discussed in this paper. Noise models of amplitude limiter and linear operational amplifier are presented. The summary results of calculated noise spectral density of ultrasonic system channel have been presented.Article in Lithuanian

  14. Geometric and electronic structure of dysprosium thin films on tungsten surfaces Structural and magnetic properties

    CERN Document Server

    Moslemzadeh, N

    2001-01-01

    The rare earth thin films are frequently the focus of investigators due to their unusual structural and magnetic properties. Despite the potential interest of Dy/W systems to the surface/rare earth community, they have been little studied. This study is the first try of growing Dy on W(100) and W(112) and W(110) in which almost a complete set of information about film morphology and electronic structure of the surface and interface have been achieved. A set of different experiments have been done for this purpose including LEED, XPS, UPS (with synchrotron radiation) and STM. The growth modes of Dy on different W substrates (W(100), W(112) and W(110)) at RT and at elevated temperatures have been determined by XPS of Dy 3d sub 3 sub / sub 2 and W 4f intensities. Crystallographic ordering and the epitaxial relationship between adsorbate Dy and different W substrates have been studied with LEED and the effect of annealing temperature on the resultant superstructures was investigated. As a complementary study to t...

  15. Electron scattering at surfaces and grain boundaries in thin Au films

    Energy Technology Data Exchange (ETDEWEB)

    Henriquez, Ricardo [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Casilla 110-V, Valparaíso (Chile); Flores, Marcos; Moraga, Luis [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago 8370449 (Chile); Kremer, German [Bachillerato, Universidad de Chile, Las Palmeras 3425, Santiago 7800024 (Chile); González-Fuentes, Claudio [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Casilla 110-V, Valparaíso (Chile); Munoz, Raul C., E-mail: ramunoz@ing.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago 8370449 (Chile)

    2013-05-15

    The electron scattering at surfaces and grain boundaries is investigated using polycrystalline Au films deposited onto mica substrates. We vary the three length scales associated with: (i) electron scattering in the bulk, that at temperature T is characterized by the electronic mean free path in the bulk ℓ{sub 0}(T); (ii) electron-surface scattering, that is characterized by the film thickness t; (iii) electron-grain boundary scattering, that is characterized by the mean grain diameter D. We varied independently the film thickness from approximately 50 nm to about 100 nm, and the typical grain size making up the samples from 12 nm to 160 nm. We also varied the scale of length associated with electron scattering in the bulk by measuring the resistivity of each specimen at temperatures T, 4 K < T < 300 K. Cooling the samples to 4 K increases ℓ{sub 0}(T) by approximately 2 orders of magnitude. Detailed measurements of the grain size distribution as well as surface roughness of each sample were performed with a Scanning Tunnelling Microscope (STM). We compare, for the first time, theoretical predictions with resistivity data employing the two theories available that incorporate the effect of both electron-surface as well as electron-grain boundary scattering acting simultaneously: the theory of A.F. Mayadas and M. Shatzkes, Phys. Rev. 1 1382 (1970) (MS), and that of G. Palasantzas, Phys. Rev. B 58 9685 (1998). We eliminate adjustable parameters from the resistivity data analysis, by using as input the grain size distribution as well as the surface roughness measured with the STM on each sample. The outcome is that both theories provide a fair representation of both the temperature as well as the thickness dependence of the resistivity data, but yet there are marked differences between the resistivity predicted by these theories. In the case of the MS theory, when the average grain diameter D is significantly smaller than ℓ{sub 0}(300) = 37 nm, the electron mean

  16. Surface-conduction electron-emitter characteristics and fabrication based on vertically aligned carbon nanotube arrays

    Science.gov (United States)

    Shih, Yi-Ting; Li, Kuan-Wei; Honda, Shin-ichi; Lin, Pao-Hung; Huang, Ying-Sheng; Lee, Kuei-Yi

    2017-06-01

    The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. Vertically aligned CNT arrays with a delta-star arrangement were patterned and synthesized onto a quartz substrate using photolithography and thermal chemical vapor deposition. Delta-star shaped VACNT arrays with 20° tips are used as cathodes that easily emit electrons because of their high electrical field gradient. In order to improve the field emission and secondary electrons (SEs) in SCE applications, magnesium oxide (MgO) nanostructures were coated onto the VACNT arrays to promote the surface-conduction electron-emitter display (SED) efficiency (η). According to the definition of η in SCE applications, in this study, the η was stably maintained in the 75-85% range. The proposed design provides a facile new method for developing SED applications.

  17. Controlling multipolar surface plasmon excitation through the azimuthal phase structure of electron vortex beams

    Science.gov (United States)

    Ugarte, Daniel; Ducati, Caterina

    2016-05-01

    We have theoretically studied how the azimuthal phase structure of an electron vortex beam excites surface plasmons on metal particles of different geometries as observed in electron energy loss spectroscopy (EELS). We have developed a semiclassical approximation combining a ring-shaped beam and the dielectric formalism. Our results indicate that for the case of total orbital angular momentum transfer, we can manipulate surface plasmon multipole excitation and even attain an enhancement factor of several orders of magnitude. Since electron vortex beams interact with particles mostly through effects due to azimuthal symmetry, i.e., in the plane perpendicular to the electron beam, anisotropy information (longitudinal and transversal) of the sample may be derived in EELS studies by comparing nonvortex and vortex beam measurements.

  18. Core-shell nanowire based electrical surface fastener used for room-temperature electronic packaging bonding

    Science.gov (United States)

    Wang, Peng; Ju, Yang; Hosoi, Atsushi

    2014-03-01

    With the ongoing miniaturization in electronic packaging, the traditional solders suffer from severe performance degradation. In addition, the high temperature required in the traditional solder reflow process may damage electronic elements. Therefore, there is an increasing urgent need for a new kind of nontoxic solder that can afford good mechanical stress and electrical contact at low temperature. This paper presents a method of fabricating nanowire surface fastener for the application of microelectronic packaging bonding at room temperature. This surface fastener consists of copper core and polystyrene shell nanowire arrays. It showed an adhesive strength of ˜24 N/cm2 and an electrical resistance of ˜0.41 × 10-2 Ω·cm2. This kind of nanowire surface fastener may enable the exploration of wide range applications, involving assembly of components in the electronic packaging.

  19. Single-element Electron-transfer Optical Detector System

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor)

    2004-01-01

    An optical detector system includes an electrically resistive screen that is substantially transparent to radiation energy having a wavelength of interest. An electron transfer element (e.g., a low work function photoactive material or a carbon nanotube (CNT)-based element) has a first end and a second end with its first end spaced apart from the screen by an evacuated gap. When radiation energy passes through the screen with a bias voltage being applied thereto, transfer of electrons through the electron transfer element is induced from its first to its second end such that a quantity indicative of the electrons transferred can be detected.

  20. Determination of radiation resistant of electronic components in robot system

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hee Dong [Kyungpook National University, Taegu (Korea); Kim, Do Sung [Taegu University, Taegu (Korea); Woo, Hong [Kyungsan University, Kyungsan (Korea)

    1998-04-01

    We investigated the characteristic change for the electronic components of the systems which were used in radiation area, when those were exposured by gamma rays. Bipolar transistor, FET, TTL, CMOS, operational amplifier, some capacitors, and several electronic components were selected for experiment. We applied irradiated gamma ray to the electronic components in the range of 10{sup 6} rad, by {sup 6}0Co(KAERI). We made up appropriate assessment circuit for each electronic component during the performance test, and assessed the reliability and radiation-resistance of them for the each radiation irradiation. (author). 59 refs., 35 figs., 8 tabs.