One- and zero-dimensional electron systems over liquid helium (Review article)

CERN Document Server

Kovdrya, Y Z

2003-01-01

Experimental and theoretical investigations of one-dimensional and zero-dimensional electron systems near the liquid helium surface are surveyed. The properties of electron states over the plane surface of liquid helium including thin layers of helium are considered. The methods of realization of one- and zero-dimensional electron systems are discussed, and the results of experimental and theoretical investigations of their properties are given. The experiments with localization processes in a quasi-one-dimensional electron systems on liquid helium are described. The collective effects in one-dimensional and quasi-one-dimensional electron systems are considered, and the point of possible application of low-dimensional electron systems on liquid helium in electron devices and quantum computers is discussed.

One- and two-electron processes in collisions of heavy ions with H2 and He

International Nuclear Information System (INIS)

Richard, P.; Hall, J.; Shinpaugh, J.L.; Sanders, J.M.; Tipping, T.N.; Zouros, T.J.M.; Lee, D.H.; Schmidt-Boecking, H.

1987-01-01

In this paper we present a description of the apparatus and results for experiments involving one- and two-electron processes in collisions of heavy ions with H 2 and He. The experiments were performed using one-electron and bare projectiles. In the first section we describe the measurement of pure ionization of one-electron projectiles by H 2 targets and compare with previous results for He targets. We also present the results for one-electron capture by the projectile from H 2 targets. The energy dependence of the cross sections is compared to theoretical predictions for atomic and molecular hydrogen targets. Both experiments were performed by measuring only the final charge state of the projectile. In the second section we describe the measurement of partial cross sections for the same collisions by measuring the target recoil charge state in coincidence with the projectile charge state. By this method we can measure pure single- and double-ionization of the target, pure single-electron transfer and transfer ionization, and pure double-electron transfer. This experiment is presently being performed for bare flourine on He; however, absolute cross sections are not available at the time of this conference. (orig.)

De Haas-Van Alphen measurements of one-electron and many-body effects in transition metals and intermetallic compounds

International Nuclear Information System (INIS)

Crabtree, G.W.; Johanson, W.R.; Campbell, S.A.; Dye, D.H.; Karim, D.P.; Ketterson, J.B.

1980-01-01

Examples are given which demonstrate the power and versatility of the dHvA effect in studying electronic behavior in metals. In transition metals the parametrization schemes give a very complete and consistent picture of the k-dependent and surface averaged electronic properties. Because the one-electron behavior is fairly well known, the many body contribution to the Fermi velocity can be isolated and its detailed anisotropy can be displayed. This kind of information is directly relevant to the calculation of electron-phonon interaction effects and cannot be derived by any other means

One-electron theory of metals

International Nuclear Information System (INIS)

Skriver, H.L.

1984-12-01

The work described in the report and the 16 accompanying publications is based upon a one-electron theory obtained within the local approximation to density-functional theory, and deals with the ground state of metals as obtained from self-consistent electronic-structure calculations performed by means of the Linear Muffin-Tin Orbital (LMTO) method. It has been the goal of the work to establish how well this one-electron approach describes physical properties such as the crystal structures of the transition metals, the structural phase transitions in the alkali, alkaline earth, and rare earth metals, and the localization of 3d, 4f, and 5f electrons in the 3d metal monoxides, the light lanthanides, and the actinides, respectively, as well as the cohesive properties of metals in general. (orig.)

Modeling Incoherent Electron Cloud Effects

International Nuclear Information System (INIS)

Vay, Jean-Luc; Benedetto, E.; Fischer, W.; Franchetti, G.; Ohmi, K.; Schulte, D.; Sonnad, K.; Tomas, R.; Vay, J.-L.; Zimmermann, F.; Rumolo, G.; Pivi, M.; Raubenheimer, T.

2007-01-01

Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and present results for a toy model of the SPS. In addition, we present evidence that for positron beams the interplay of incoherent electron-cloud effects and synchrotron radiation can lead to a significant increase in vertical equilibrium emittance. The magnitude of a few incoherent e+e- scattering processes is also estimated. Options for future code development are reviewed

Modal description of longitudinal space-charge fields in pulse-driven free-electron devices

Directory of Open Access Journals (Sweden)

Yu. Lurie

2010-05-01

Full Text Available In pulsed-beam free-electron devices, longitudinal space-charge fields result in collective effects leading to an expansion of short electron bunches along their trajectory. This effect restricts an application of intense ultrashort electron pulses in free-electron radiation sources. A careful theoretical treatment is required in order to achieve an accurate description of the self-fields and the resulted electron beam dynamics. In this paper, longitudinal space-charge fields are considered in the framework of a three-dimensional, space-frequency approach. The model is based on the expansion of the total electromagnetic field (including self-fields in terms of transverse eigenmodes of the (cold cavity, in which the field is excited and propagates. The electromagnetic field, originally obtained in the model as a solution of the wave equation, is shown to satisfy also Gauss’s law. We applied the theory to derive an analytical expression for the longitudinal electric field of a pointlike charge, moving along a waveguide at a constant velocity. This enables consideration and study of the role played by different terms of the resulted expressions, such as components arising from forward and backward waves, propagating waves, and under cutoff frequencies, and so on. Possible simplifications in evaluation of longitudinal space-charge fields are discussed.

The KAERI 10 MeV Electron Linac - Description and Operational Manual

Energy Technology Data Exchange (ETDEWEB)

Lee, Byung Cheol; Park, Seong Hee; Jung, Young Uk; Han, Young Hwan; Kang, Hee Young

2005-06-15

The objective of this technical report is to guide the right operation and maintenance of the KAERI electron linac system. The KAERI electron linac system consists of 2 MeV injector based on 176 MHz Normal conducting RF (Radio Frequency)cavity and 10 MeV main accelerator based on 352 MHz Superconducting RF cavity, electron beamlines (injection and extraction). Since a electron accelerator generates hazard radiation, this system is located at the shielded room in basement and we can operate the system using the remote control system. It includes the description and the operational manual as well as the detailed technical direction for trouble shooting.

The KAERI 10 MeV Electron Linac - Description and Operational Manual

International Nuclear Information System (INIS)

Lee, Byung Cheol; Park, Seong Hee; Jung, Young Uk; Han, Young Hwan; Kang, Hee Young

2005-06-01

The objective of this technical report is to guide the right operation and maintenance of the KAERI electron linac system. The KAERI electron linac system consists of 2 MeV injector based on 176 MHz Normal conducting RF (Radio Frequency)cavity and 10 MeV main accelerator based on 352 MHz Superconducting RF cavity, electron beamlines (injection and extraction). Since a electron accelerator generates hazard radiation, this system is located at the shielded room in basement and we can operate the system using the remote control system. It includes the description and the operational manual as well as the detailed technical direction for trouble shooting

One-electron transfer reactions of the couple NAD./NADH

International Nuclear Information System (INIS)

Grodkowski, J.; Neta, P.; Carlson, B.W.; Miller, L.

1983-01-01

One-electron transfer reactions involving nicotinamide-adenine dinucleotide in its oxidized and reducd forms (NAD./NADH) were studied by pulse radiolysis in aqueous solutions. One-electron oxidation of NADH by various phenoxyl radicals and phenothiazine cation radicals was found to take place with rate constants in the range of 10 5 to 10 8 M -1 s -1 , depending on the redox potential of the oxidizing species. In all cases, NAD. is formed quantitatively with no indication for the existence of the protonated form (NADH + .). The spectrum of NAD., as well as the rates of oxidation of NADH by phenoxyl and by (chlorpromazine) + . were independent of pH between pH 4.5 and 13.5. Reaction of deuterated NADH indicated only a small kinetic isotope effect. All these findings point to an electron transfer mechanism. On the other hand, attempts to observe the reverse electron transfer, i.e., one-electron reduction of NAD. to NADH by radicals such as semiquinones, showed that k was less than 10 4 to 10 5 M -1 s -1 , so that it was unobservable. Consequently, it was not possible to achieve equilibrium conditions which would have permitted the direct measurement of the redox potential for NAD./NADH. One-electron reduction of NAD. appears to be an unlikely process. 1 table

Hyperpolarizabilities of one and two electron ions under strongly coupled plasma

International Nuclear Information System (INIS)

Sen, Subhrangsu; Mandal, Puspajit; Kumar Mukherjee, Prasanta; Fricke, Burkhard

2013-01-01

Systematic investigations on the hyperpolarizabilities of hydrogen and helium like ions up to nuclear charge Z = 7 under strongly coupled plasma environment have been performed. Variation perturbation theory has been adopted to evaluate such properties for the one and two electron systems. For the two electron systems coupled Hartree-Fock theory, which takes care of partial electron correlation effects, has been utilised. Ion sphere model of the strongly coupled plasma, valid for ionic systems only, has been adopted for estimating the effect of plasma environment on the hyperpolarizability. The calculated free ion hyperpolarizability for all the systems is in good agreement with the existing data. Under confinement hyperpolarizabilities of one and two electron ions show interesting trend with respect to plasma coupling strength.

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

Developing a model for the adequate description of electronic communication in hospitals.

Science.gov (United States)

Saboor, Samrend; Ammenwerth, Elske

2011-01-01

Adequate information and communication systems (ICT) can help to improve the communication in hospitals. Changes to the ICT-infrastructure of hospitals must be planed carefully. In order to support a comprehensive planning, we presented a classification of 81 common errors of the electronic communication on the MIE 2008 congress. Our objective now was to develop a data model that defines specific requirements for an adequate description of electronic communication processes We first applied the method of explicating qualitative content analysis on the error categorization in order to determine the essential process details. After this, we applied the method of subsuming qualitative content analysis on the results of the first step. A data model for the adequate description of electronic communication. This model comprises 61 entities and 91 relationships. The data model comprises and organizes all details that are necessary for the detection of the respective errors. It can be for either used to extend the capabilities of existing modeling methods or as a basis for the development of a new approach.

Electrons, pseudoparticles, and quasiparticles in the one-dimensional many-electron problem

International Nuclear Information System (INIS)

Carmelo, J.M.; Castro Neto, A.H.

1996-01-01

We generalize the concept of quasiparticle for one-dimensional (1D) interacting electronic systems. The ↑ and ↓ quasiparticles recombine the pseudoparticle colors c and s (charge and spin at zero-magnetic field) and are constituted by one many-pseudoparticle topological-momentum shift and one or two pseudoparticles. These excitations cannot be separated. We consider the case of the Hubbard chain. We show that the low-energy electron-quasiparticle transformation has a singular character which justifies the perturbative and nonperturbative nature of the quantum problem in the pseudoparticle and electronic basis, respectively. This follows from the absence of zero-energy electron-quasiparticle overlap in 1D. The existence of Fermi-surface quasiparticles both in 1D and three dimensional (3D) many-electron systems suggests their existence in quantum liquids in dimensions 1 1 or whether it becomes finite as soon as we leave 1D remains an unsolved question. copyright 1996 The American Physical Society

Visualizing One-Dimensional Electronic States and their Scattering in Semi-conducting Nanowires

Science.gov (United States)

Beidenkopf, Haim; Reiner, Jonathan; Norris, Andrew; Nayak, Abhay Kumar; Avraham, Nurit; Shtrikman, Hadas

One-dimensional electronic systems constitute a fascinating playground for the emergence of exotic electronic effects and phases, within and beyond the Tomonaga-Luttinger liquid paradigm. More recently topological superconductivity and Majorana modes were added to that long list of phenomena. We report scanning tunneling microscopy and spectroscopy measurements conducted on pristine, epitaxialy grown InAs nanowires. We resolve the 1D electronic band structure manifested both via Van-Hove singularities in the local density-of-states, as well as by the quasi-particle interference patterns, induced by scattering from surface impurities. By studying the scattering of the one-dimensional electronic states off various scatterers, including crystallographic defects and the nanowire end, we identify new one-dimensional relaxation regimes and yet unexplored effects of interactions. Some of these may bear implications on the topological superconducting state and Majorana modes therein. The authors acknowledge support from the Israeli Science Foundation (ISF).

Excess electrons in methanol clusters: Beyond the one-electron picture

Science.gov (United States)

Pohl, Gábor; Mones, Letif; Turi, László

2016-10-01

We performed a series of comparative quantum chemical calculations on various size negatively charged methanol clusters, ("separators=" CH 3 OH ) n - . The clusters are examined in their optimized geometries (n = 2-4), and in geometries taken from mixed quantum-classical molecular dynamics simulations at finite temperature (n = 2-128). These latter structures model potential electron binding sites in methanol clusters and in bulk methanol. In particular, we compute the vertical detachment energy (VDE) of an excess electron from increasing size methanol cluster anions using quantum chemical computations at various levels of theory including a one-electron pseudopotential model, several density functional theory (DFT) based methods, MP2 and coupled-cluster CCSD(T) calculations. The results suggest that at least four methanol molecules are needed to bind an excess electron on a hydrogen bonded methanol chain in a dipole bound state. Larger methanol clusters are able to form stronger interactions with an excess electron. The two simulated excess electron binding motifs in methanol clusters, interior and surface states, correlate well with distinct, experimentally found VDE tendencies with size. Interior states in a solvent cavity are stabilized significantly stronger than electron states on cluster surfaces. Although we find that all the examined quantum chemistry methods more or less overestimate the strength of the experimental excess electron stabilization, MP2, LC-BLYP, and BHandHLYP methods with diffuse basis sets provide a significantly better estimate of the VDE than traditional DFT methods (BLYP, B3LYP, X3LYP, PBE0). A comparison to the better performing many electron methods indicates that the examined one-electron pseudopotential can be reasonably used in simulations for systems of larger size.

Emergent Gauge Fields and Their Nonperturbative Effects in Correlated Electrons

Science.gov (United States)

Kim, Ki-Seok; Tanaka, Akihiro

The history of modern condensed matter physics may be regarded as the competition and reconciliation between Stoner's and Anderson's physical pictures, where the former is based on momentum-space descriptions focusing on long wave-length fluctuations while the latter is based on real-space physics emphasizing emergent localized excitations. In particular, these two view points compete with each other in various nonperturbative phenomena, which range from the problem of high Tc superconductivity, quantum spin liquids in organic materials and frustrated spin systems, heavy-fermion quantum criticality, metal-insulator transitions in correlated electron systems such as doped silicons and two-dimensional electron systems, the fractional quantum Hall effect, to the recently discussed Fe-based superconductors. An approach to reconcile these competing frameworks is to introduce topologically nontrivial excitations into the Stoner's description, which appear to be localized in either space or time and sometimes both, where scattering between itinerant electrons and topological excitations such as skyrmions, vortices, various forms of instantons, emergent magnetic monopoles, and etc. may catch nonperturbative local physics beyond the Stoner's paradigm. In this review article we discuss nonperturbative effects of topological excitations on dynamics of correlated electrons. First, we focus on the problem of scattering between itinerant fermions and topological excitations in antiferromagnetic doped Mott insulators, expected to be relevant for the pseudogap phase of high Tc cuprates. We propose that nonperturbative effects of topological excitations can be incorporated within the perturbative framework, where an enhanced global symmetry with a topological term plays an essential role. In the second part, we go on to discuss the subject of symmetry protected topological states in a largely similar light. While we do not introduce itinerant fermions here, the nonperturbative

On one peculiarity of the model describing the interaction of the electron beam with the semiconductor surface

Science.gov (United States)

Stepovich, M. A.; Amrastanov, A. N.; Seregina, E. V.; Filippov, M. N.

2018-01-01

The problem of heat distribution in semiconductor materials irradiated with sharply focused electron beams in the absence of heat exchange between the target and the external medium is considered by mathematical modeling methods. For a quantitative description of energy losses by probe electrons a model based on a separate description of the contributions of absorbed in the target and backscattered electrons and applicable to a wide class of solids and a range of primary electron energies is used. Using the features of this approach, the nonmonotonic dependence of the temperature of the maximum heating in the target on the energy of the primary electrons is explained. Some modeling results are illustrated for semiconductor materials of electronic engineering.

Effective temperature of an ultracold electron source based on near-threshold photoionization

NARCIS (Netherlands)

Engelen, W.J.; Smakman, E.P.; Bakker, D.J.; Luiten, O.J.; Vredenbregt, E.J.D.

2014-01-01

We present a detailed description of measurements of the effective temperature of a pulsed electron source, based on near-threshold photoionization of laser-cooled atoms. The temperature is determined by electron beam waist scans, source size measurements with ion beams, and analysis with an

The effects of radiation on electronic systems

International Nuclear Information System (INIS)

Messenger, G.C.; Ash, M.S.

1986-01-01

This book is the first unified treatment of the analysis and design methods for protection of principally electronic systems from the deleterious effects of nuclear and electro-magnetic radiation. Coverage spans from a detailed description of the nuclear radiation sources to pertinent semiconductor physics, then to hardness assurance. This work combines the disciplines of solid state physics, semiconductor physics, circuit engineering, nuclear physics, together with electronics and electromagnetic theory into a book that can be used as a text with problems at the end of the majority of the chapters. Written by veterans in the field, the most significant feature of this book is its comprehensive treatment of the phenomena involved. This treatment includes the analysis and design of the effect of nuclear radiation on electronic systems from the experimental, theoretical, and engineering viewpoints. Unique pedagogical attempts are employed to make the material more understandable from the position of an enlightened engineering and scientific readership whose task is the design and analysis of radiation hardened electronic systems

Electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ

DEFF Research Database (Denmark)

Sing, M.; Schwingenschlögl, U.; Claessen, R.

2003-01-01

We study the electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ by means of density-functional band theory, Hubbard model calculations, and angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant quantitative and qualitative......-dimensional Hubbard model for the low-energy spectral behavior is attributed to interchain coupling and the additional effect of electron-phonon interaction....

On the description of electronic final states in the K-shell ionization by protons

International Nuclear Information System (INIS)

Aashamar, O.; Kocbach, L.

1976-06-01

The choice of free electronic wave functions in the description of K-shell ionization by protons is discussed. The previously known discrepancies between PWBA and SCA results are shown to be entirely due to two different choices of electronic wave functions. Calculations in the SCA framework with Hartree-Fock-Slater wave functions are reported. Some general features of the SCA calculations are discussed. (Auth.)

Atomic electron correlations in intense laser fields

International Nuclear Information System (INIS)

DiMauro, L.F.; Sheehy, B.; Walker, B.; Agostini, P.A.

1998-01-01

This talk examines two distinct cases in strong optical fields where electron correlation plays an important role in the dynamics. In the first example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two-level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although their ability to describe the one-electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unclear

Faults Classification Of Power Electronic Circuits Based On A Support Vector Data Description Method

Directory of Open Access Journals (Sweden)

Cui Jiang

2015-06-01

Full Text Available Power electronic circuits (PECs are prone to various failures, whose classification is of paramount importance. This paper presents a data-driven based fault diagnosis technique, which employs a support vector data description (SVDD method to perform fault classification of PECs. In the presented method, fault signals (e.g. currents, voltages, etc. are collected from accessible nodes of circuits, and then signal processing techniques (e.g. Fourier analysis, wavelet transform, etc. are adopted to extract feature samples, which are subsequently used to perform offline machine learning. Finally, the SVDD classifier is used to implement fault classification task. However, in some cases, the conventional SVDD cannot achieve good classification performance, because this classifier may generate some so-called refusal areas (RAs, and in our design these RAs are resolved with the one-against-one support vector machine (SVM classifier. The obtained experiment results from simulated and actual circuits demonstrate that the improved SVDD has a classification performance close to the conventional one-against-one SVM, and can be applied to fault classification of PECs in practice.

Electron localisation in static and time-dependent one-dimensional model systems

Science.gov (United States)

Durrant, T. R.; Hodgson, M. J. P.; Ramsden, J. D.; Godby, R. W.

2018-02-01

The most direct signature of electron localisation is the tendency of an electron in a many-body system to exclude other same-spin electrons from its vicinity. By applying this concept directly to the exact many-body wavefunction, we find that localisation can vary considerably between different ground-state systems, and can also be strongly disrupted, as a function of time, when a system is driven by an applied electric field. We use this measure to assess the well-known electron localisation function (ELF), both in its approximate single-particle form (often applied within density-functional theory) and its full many-particle form. The full ELF always gives an excellent description of localisation, but the approximate ELF fails in time-dependent situations, even when the exact Kohn-Sham orbitals are employed.

Electron-phonon coupling in one dimension

International Nuclear Information System (INIS)

Apostol, M.; Baldea, I.

1981-08-01

The Ward identity is derived for the electron-phonon coupling in one dimension and the spectrum of elementary excitations is calculated by assuming that the Fermi distribution is not strongly distorted by interaction. The electron-phonon vertex is renormalized in the case of the forward scattering and Migdal's theorem is discussed. A model is proposed for the giant Kohn anomaly. The dip in the phonon spectrum is obtained and found to be in agreement with the experimental data for KCP. (author)

One-electron oxidation of DNA: mechanism and consequences.

Science.gov (United States)

Schuster, Gary B

2009-01-01

All living organisms store the information necessary to maintain life in their DNA. Any process that damages DNA and causes loss or corruption of that information threatens the viability of the organism. One-electron oxidation is such a process. Loss of an electron from DNA generates a radical cation that is located primarily on its nucleobases. The radical cation migrates reversibly through duplex DNA by hopping until it is eventually trapped in an irreversible chemical reaction. The particular sequence of nucleobases in a DNA oligomer determines both the efficiency of hopping and the specific location and nature of the damaging chemical reaction. In its normal aqueous solutions, DNA is a polyanion because of the negative charge carried by its phosphate groups. Counter ions (typically Na(+)) to the phosphate groups play an important role in facilitating both the migration of the radical cation and in its eventual reaction with H(2)O. Irreversible reaction of a radical cation with H(2)O in duplex DNA occurs preferentially at the most reactive site. In normal DNA that is comprised of the four common DNA nucleobases, reaction occurs most commonly at a guanine and results in its conversion primarily to 8-oxo-7,8-dihydroguanine (8-OxoG). Both electronic and steric effects control the outcome of this process. If the DNA oligomer does not contain a suitable guanine, then reaction of the radical cation occurs at the thymine of a TT step primarily by a tandem process. The general outcomes revealed in the one-electron oxidation of DNA oligomers in solution appear to be generally valid also for more complex DNA structures and for the cellular DNA of living organisms.

ProbeZT: Simulation of transport coefficients of molecular electronic junctions under environmental effects using Büttiker's probes

Science.gov (United States)

Korol, Roman; Kilgour, Michael; Segal, Dvira

2018-03-01

We present our in-house quantum transport package, ProbeZT. This program provides linear response coefficients: electrical and electronic thermal conductances, as well as the thermopower of molecular junctions in which electrons interact with the surrounding thermal environment. Calculations are performed based on the Büttiker probe method, which introduces decoherence, energy exchange and dissipation effects phenomenologically using virtual electrode terminals called probes. The program can realize different types of probes, each introducing various environmental effects, including elastic and inelastic scattering of electrons. The molecular system is described by an arbitrary tight-binding Hamiltonian, allowing the study of different geometries beyond simple one-dimensional wires. Applications of the program to study the thermoelectric performance of molecular junctions are illustrated. The program also has a built-in functionality to simulate electron transport in double-stranded DNA molecules based on a tight-binding (ladder) description of the junction.

One-electron propagation in Fermi, Pasta, Ulam disordered chains with Gaussian acoustic pulse pumping

Science.gov (United States)

Silva, L. D. Da; Dos Santos, J. L. L.; Ranciaro Neto, A.; Sales, M. O.; de Moura, F. A. B. F.

In this work, we consider a one-electron moving on a Fermi, Pasta, Ulam disordered chain under effect of electron-phonon interaction and a Gaussian acoustic pulse pumping. We describe electronic dynamics using quantum mechanics formalism and the nonlinear atomic vibrations using standard classical physics. Solving numerical equations related to coupled quantum/classical behavior of this system, we study electronic propagation properties. Our calculations suggest that the acoustic pumping associated with the electron-lattice interaction promote a sub-diffusive electronic dynamics.

Electronic Government In Democratic Public Service In One Door Integrated Permit Handling Services Agency In The City Of Samarinda

Directory of Open Access Journals (Sweden)

Iman Surya

2015-01-01

Full Text Available ABSTRACT Electronic government needs to carry out in a fundamental public services of democracy. But in practice BPPTSP one door integrated permit service board of Samarinda not able to perform the activities. The aim of this research described analyzing electronic government and public services in a democracy. The methodology used in this research using descriptive qualitative approach the study was on the one door integrated permit service of Samarinda respondents in Samarinda the mayor head of Samarinda the citizen private group of government agencies and interests. Then variable measured in electronic government includes support capacity value and public services including democratic information consultancy and participation. The results of research shows that the variables measured having a deficiency and inability in accommodate aspirations built between citizens and the government in developing electronic democratic government. It is influenced by the absence of elements of liaison which is justice diversity and access electronic between government and public services that make democratic BPPTSP the inability of the city of Samarinda to make changes in depth in an effort to build and create a public being communicative with citizens.

Crystal field effect in light actinide dioxides and oxychalcogenides - a unified phenomenological description

Energy Technology Data Exchange (ETDEWEB)

Gajek, Z. E-mail: gajek@int.pan.wroc.pl

2004-05-01

The electronic properties of the actinide ions in the series of semi-conducting, antiferromagnetic compounds: dioxides, AnO{sub 2} and oxychalcogenides, AnOY, where An=U, Np and Y=S, Se, are re-examined from the point of view of the consistency of the crystal field (CF) model. The discussion is based on the supposition that the effective metal-ligand interaction solely determines the net CF effect in non-metallic compounds. The main question we address here is, whether a reliable, consistent description of the CF effect in terms of the intrinsic parameters can be achieved for this particular family of compounds. Encouraging calculations reported previously for the AnO{sub 2} and UOY series serve as a reference data in the present estimation of electronic structure parameters for neptunium oxychalcogenides.

Crystal field effect in light actinide dioxides and oxychalcogenides-a unified phenomenological description

Science.gov (United States)

Gajek, Z.

2004-05-01

The electronic properties of the actinide ions in the series of semi-conducting, antiferromagnetic compounds: dioxides, AnO2 and oxychalcogenides, AnOY, where An=U, Np and Y=S, Se, are re-examined from the point of view of the consistency of the crystal field (CF) model. The discussion is based on the supposition that the effective metal-ligand interaction solely determines the net CF effect in non-metallic compounds. The main question we address here is, whether a reliable, consistent description of the CF effect in terms of the intrinsic parameters can be achieved for this particular family of compounds. Encouraging calculations reported previously for the AnO2 and UOY series serve as a reference data in the present estimation of electronic structure parameters for neptunium oxychalcogenides.

Crystal field effect in light actinide dioxides and oxychalcogenides - a unified phenomenological description

International Nuclear Information System (INIS)

Gajek, Z.

2004-01-01

The electronic properties of the actinide ions in the series of semi-conducting, antiferromagnetic compounds: dioxides, AnO 2 and oxychalcogenides, AnOY, where An=U, Np and Y=S, Se, are re-examined from the point of view of the consistency of the crystal field (CF) model. The discussion is based on the supposition that the effective metal-ligand interaction solely determines the net CF effect in non-metallic compounds. The main question we address here is, whether a reliable, consistent description of the CF effect in terms of the intrinsic parameters can be achieved for this particular family of compounds. Encouraging calculations reported previously for the AnO 2 and UOY series serve as a reference data in the present estimation of electronic structure parameters for neptunium oxychalcogenides

The effects of two counterpropagating surface acoustic wave beams on single electron acoustic charge transport

International Nuclear Information System (INIS)

He Jianhong; Guo Huazhong; Song Li; Zhang Wei; Gao Jie; Lu Chuan

2010-01-01

We present a comprehensive study of the effects of two counterpropagating surface acoustic waves on the acoustoelectric current of single electron transport devices. A significant improvement in the accuracy of current quantization is achieved as a result of an additional surface acoustic wave beam. The experiments reveal the sinusoidally periodical modulation in the acoustoelectric current characteristic as a function of the relative phase of the two surface acoustic wave beams. Besides, by using standing surface acoustic waves, the acoustoelectric current is detected which we consider as the so-called anomalous acoustoelectric current produced by acoustic wave mechanical deformations. This kind current is contributed to one component of the acoustoelectric current in surface acoustic wave device, which could enable us to establish a more adequate description of acoustoelectric effects on single-electron acoustic charge transport.

From Task Descriptions via Coloured Petri Nets Towards an Implementation of a New Electronic Patient Record

DEFF Research Database (Denmark)

Jørgensen, Jens Bæk; Lassen, Kristian Bisgaard; van der Aalst, Willibrordus Martinus Pancratius

2008-01-01

help to validate and elicit requirements. The second CPN model is a Colored Workflow Net (CWN). The CWN is derived from the EUC. Together, the EUC and the CWN are used to close the gap between the given requirements specification and the realization of these requirements with the help of an IT system......We consider a given specification of functional requirements for a new electronic patient record system for Fyn County, Denmark. The requirements are expressed as task descriptions, which are informal descriptions of work processes to be supported. We describe how these task descriptions are used...

Ab initio description of the diluted magnetic semiconductor Ga1-xMnxAs: Ferromagnetism, electronic structure, and optical response

Science.gov (United States)

Craco, L.; Laad, M. S.; Müller-Hartmann, E.

2003-12-01

Motivated by a study of various experiments describing the electronic and magnetic properties of the diluted magnetic semiconductor Ga1-xMnxAs, we investigate its physical response in detail using a combination of first-principles band structure with methods based on dynamical mean field theory to incorporate strong, dynamical correlations, and intrinsic as well as extrinsic disorder in one single theoretical picture. We show how ferromagnetism is driven by double exchange (DE), in agreement with very recent observations, along with a good quantitative description of the details of the electronic structure, as probed by scanning tunneling microscopy and optical conductivity. Our results show how ferromagnetism can be driven by DE even in diluted magnetic semiconductors with small carrier concentration.

Experimental efforts at NIST towards one-electron ions in circular Rydberg states

International Nuclear Information System (INIS)

Tan, Joseph N; Guise, Nicholas D; Brewer, Samuel M

2011-01-01

Experimental effort is underway at NIST to enable tests of theory with one-electron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects that limit the accuracy of predicted energy levels for low-lying states are vanishingly small for high-angular-momentum (high-L) states; in particular, the nuclear size correction for high-L states is completely negligible for any foreseeable improvement of measurement precision. As an initial step towards realizing such states, highly charged ions are extracted from the NIST electron beam ion trap (EBIT) and steered through the electrodes of a Penning trap. The goal is to capture bare nuclei in the Penning trap for experiments to make one-electron atoms in circular Rydberg states with dipole (E1) transitions in the optical domain accessible to a frequency comb.

Electronic field emission models beyond the Fowler-Nordheim one

Science.gov (United States)

Lepetit, Bruno

2017-12-01

We propose several quantum mechanical models to describe electronic field emission from first principles. These models allow us to correlate quantitatively the electronic emission current with the electrode surface details at the atomic scale. They all rely on electronic potential energy surfaces obtained from three dimensional density functional theory calculations. They differ by the various quantum mechanical methods (exact or perturbative, time dependent or time independent), which are used to describe tunneling through the electronic potential energy barrier. Comparison of these models between them and with the standard Fowler-Nordheim one in the context of one dimensional tunneling allows us to assess the impact on the accuracy of the computed current of the approximations made in each model. Among these methods, the time dependent perturbative one provides a well-balanced trade-off between accuracy and computational cost.

Computationally efficient description of relativistic electron beam transport in dense plasma

Science.gov (United States)

Polomarov, Oleg; Sefkov, Adam; Kaganovich, Igor; Shvets, Gennady

2006-10-01

A reduced model of the Weibel instability and electron beam transport in dense plasma is developed. Beam electrons are modeled by macro-particles and the background plasma is represented by electron fluid. Conservation of generalized vorticity and quasineutrality of the plasma-beam system are used to simplify the governing equations. Our approach is motivated by the conditions of the FI scenario, where the beam density is likely to be much smaller than the plasma density and the beam energy is likely to be very high. For this case the growth rate of the Weibel instability is small, making the modeling of it by conventional PICs exceedingly time consuming. The present approach does not require resolving the plasma period and only resolves a plasma collisionless skin depth and is suitable for modeling a long-time behavior of beam-plasma interaction. An efficient code based on this reduced description is developed and benchmarked against the LSP PIC code. The dynamics of low and high current electron beams in dense plasma is simulated. Special emphasis is on peculiarities of its non-linear stages, such as filament formation and merger, saturation and post-saturation field and energy oscillations. *Supported by DOE Fusion Science through grant DE-FG02-05ER54840.

Description of the electron-hydrogen collision by the Coulomb Fourier transform method

International Nuclear Information System (INIS)

Levin, S.B.

2005-01-01

A recently developed Coulomb Fourier Transform method is applied to the system containing one heavy ion and two electrons. The transformed Hamiltonian is described with a controlled accuracy in an effective finite basis set as a finite dimensional operator matrix. The kernels of interaction are formulated in terms of the so called Nordsieck integrals

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

DEFF Research Database (Denmark)

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

2009-01-01

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

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

International Nuclear Information System (INIS)

Archubi, C. D.; Gravielle, M. S.; Silkin, V. M.

2011-01-01

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.

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.

One-Electron Theory of Metals. Cohesive and Structural Properties

DEFF Research Database (Denmark)

Skriver, Hans Lomholt

The work described in the report r.nd the 16 accompanying publications is based upon a one-electron theory obtained within the local approximation to density-functional theory, and deals with the ground state of metals as obtained from selfconsistent electronic-structure calculations performed...... by means of the Linear Muffin-Tin Orbital (LMTO) method. It has been the goal of the work to establish how well this one-electron approach describes physical properties such as the crystal structures of the transition metals, the structural phase transitions in the alkali, alkaline earth, and rare earth...

Two-electron one-photon decay rates in doubly ionized atoms

International Nuclear Information System (INIS)

Baptista, G.B.

1984-01-01

The transion rate for the two-electron one-photon and one-electron one-photon decaying processes in atoms bearing initially two K-shell vacancies were evaluated for Ne up to Zr. The two-electron one-photon decay process is considered to be the result of the interaction between the jumping electrons and their interaction with the radiation field. The calculation is performed in second order perturbation theory and the many particle states are constructed from single particle solutions. The present approach allows one to discuss several aspects of the decaying process. The results obtained for the branching ratio between the two processes reproduces reasonably well available experimental data and show an almost linear dependence on the second power of the atomic number. A comparison with other theoretical predictions is also presented for the two decaying processes and the strong dependence of the branching ratio on the initial configuration of the decaying atom is pointed out. (Author) [pt

Electron transport effects in ion induced electron emission

Energy Technology Data Exchange (ETDEWEB)

Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium)]. E-mail: adubus@ulb.ac.be; Pauly, N. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium); Roesler, M. [Karl-Pokern-Str. 12, D-12587 Berlin (Germany)

2007-03-15

Ion induced electron emission (IIEE) is usually described as a three-step process, i.e. electron excitation by the incident projectile, electron transport (and multiplication) and electron escape through the potential barrier at the surface. In many cases, the first step of the process has been carefully described. The second step of the process, i.e. electron transport and multiplication, has often been treated in a very rough way, a simple decreasing exponential law being sometimes used. It is precisely the aim of the present work to show the importance of a correct description of electron transport and multiplication in a theoretical calculation of IIEE. A short overview of the electron transport models developed for IIEE is given in this work. The so-called 'Infinite medium slowing-down model' often used in recent works is evaluated by means of Monte Carlo simulations. In particular, the importance of considering correctly the semi-infinite character of the medium and the boundary condition at the vacuum-medium interface is discussed. Quantities like the electron escape depth are also briefly discussed. This evaluation has been performed in the particular case of protons (25keV

Support Vector Data Descriptions and k-Means Clustering: One Class?

Science.gov (United States)

Gornitz, Nico; Lima, Luiz Alberto; Muller, Klaus-Robert; Kloft, Marius; Nakajima, Shinichi

2017-09-27

We present ClusterSVDD, a methodology that unifies support vector data descriptions (SVDDs) and k-means clustering into a single formulation. This allows both methods to benefit from one another, i.e., by adding flexibility using multiple spheres for SVDDs and increasing anomaly resistance and flexibility through kernels to k-means. In particular, our approach leads to a new interpretation of k-means as a regularized mode seeking algorithm. The unifying formulation further allows for deriving new algorithms by transferring knowledge from one-class learning settings to clustering settings and vice versa. As a showcase, we derive a clustering method for structured data based on a one-class learning scenario. Additionally, our formulation can be solved via a particularly simple optimization scheme. We evaluate our approach empirically to highlight some of the proposed benefits on artificially generated data, as well as on real-world problems, and provide a Python software package comprising various implementations of primal and dual SVDD as well as our proposed ClusterSVDD.

Photon and electron collimator effects on electron output and abutting segments in energy modulated electron therapy

International Nuclear Information System (INIS)

Olofsson, Lennart; Karlsson, Magnus G.; Karlsson, Mikael

2005-01-01

In energy modulated electron therapy a large fraction of the segments will be arranged as abutting segments where inhomogeneities in segment matching regions must be kept as small as possible. Furthermore, the output variation between different segments should be minimized and must in all cases be well predicted. For electron therapy with add-on collimators, both the electron MLC (eMLC) and the photon MLC (xMLC) contribute to these effects when an xMLC tracking technique is utilized to reduce the x-ray induced leakage. Two add-on electron collimator geometries have been analyzed using Monte Carlo simulations: One isocentric eMLC geometry with an isocentric clearance of 35 cm and air or helium in the treatment head, and one conventional proximity geometry with a clearance of 5 cm and air in the treatment head. The electron fluence output for 22.5 MeV electrons is not significantly affected by the xMLC if the shielding margins are larger than 2-3 cm. For small field sizes and 9.6 MeV electrons, the isocentric design with helium in the treatment head or shielding margins larger than 3 cm is needed to avoid a reduced electron output. Dose inhomogeneity in the matching region of electron segments is, in general, small when collimator positions are adjusted to account for divergence in the field. The effect of xMLC tracking on the electron output can be made negligible while still obtaining a substantially reduced x-ray leakage contribution. Collimator scattering effects do not interfere significantly when abutting beam techniques are properly applied

Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels

Energy Technology Data Exchange (ETDEWEB)

Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Gumbs, Godfrey [Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Abranyos, Yonatan [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Pepper, Michael; Kumar, Sanjeev [Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE (United Kingdom); London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom)

2015-11-15

For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.

Failure of single electron descriptions of molecular orbital collision processes. [Electron promotion mechanism

Energy Technology Data Exchange (ETDEWEB)

Elston, S.B.

1978-01-01

Inner-shell excitation occurring in low and moderate (keV range) energy collisions between light atomic and ionic systems is frequently describable in terms of molecular promotion mechanisms, which were extensively explored both theoretically and experimentally. The bulk of such studies have concentrated on processes understandable through the use of single- and independent-electron models. Nonetheless, it is possible to find cases of inner-shell excitation in relatively simple collision systems which involve nearly simultaneous multiple-electron transitions and transitions induced by inherently two-electron interactions. Evidence for these many- and nonindependent-electron phenomena in inner-shell excitation processes and the importance of considering such effects in the interpretation of collisionally induced excitation spectra is discussed. 13 references.

Effects of perceived descriptive norms on corrupt intention: The mediating role of moral disengagement.

Science.gov (United States)

Zhao, Huanhuan; Zhang, Heyun; Xu, Yan

2017-01-31

The present study attempts to examine the effect of perceived descriptive norms on corrupt intention (e.g., bribe-taking intention) and then further explore the psychological mechanism underlying this effect. Based on social cognitive theory, we established a mediation model in which moral disengagement partially mediated the link between perceived descriptive norms and corrupt intention. In Study 1, participants (N = 690) completed a series of questionnaires, and the results demonstrated that, while perceived descriptive norms were positively associated with corrupt intention, it was partially mediated by moral disengagement. In Study 2, we conducted a priming experiment (N = 161) to test the causal relationship and psychological mechanism between perceived descriptive norms and corrupt intention. The results revealed that perceived descriptive norms triggered the propensity of individuals to morally disengage, which in turn, partially increased their corrupt intention. This study not only extends previous research by providing evidence that moral disengagement may be one of the reasons why perceived descriptive norms facilitate corrupt intention, but also suggests that reshaping normative beliefs and preventing the moral disengagement of individuals may be the effective ways to curb corrupt behaviours. © 2017 International Union of Psychological Science.

Monte Carlo study of the effective Sherman function for electron polarimetry

International Nuclear Information System (INIS)

Drągowski, M.; Włodarczyk, M.; Weber, G.; Ciborowski, J.; Enders, J.; Fritzsche, Y.; Poliszczuk, A.

2016-01-01

The PEBSI Monte Carlo simulation was upgraded towards usefulness for electron Mott polarimetry. The description of Mott scattering was improved and polarisation transfer in Møller scattering was included in the code. An improved agreement was achieved between the simulation and available experimental data for a 100 keV polarised electron beam scattering off gold foils of various thicknesses. The dependence of the effective Sherman function on scattering angle and target thickness, as well as the method of finding optimal conditions for Mott polarimetry measurements were analysed.

On the importance of nonlocal effects on the description of emitter-plasmon coupling

DEFF Research Database (Denmark)

Tserkezis, Christos; Wubs, Martijn; Mortensen, N. Asger

2017-01-01

Plasmonic nanostructures present several characteristics that make them ideal templates for the modification and control of the emission properties of quantum emitters such as organic molecules, fluorescent dyes and quantum dots. State-of-the-art plasmonic architectures strongly enhance and confine...... dimensions, allowing the design of ultranarrow plasmonic cavities and the precise positioning of emitters inside them. In these situations, however, a description beyond classical electrodynamics is rendered unavoidable, as nonclassical effects such as electron spill-out, tunnelling, and nonlocal screening...

Positivity of the spherically averaged atomic one-electron density

DEFF Research Database (Denmark)

Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas

2008-01-01

We investigate the positivity of the spherically averaged atomic one-electron density . For a which stems from a physical ground state we prove that for r ≥  0. This article may be reproduced in its entirety for non-commercial purposes.......We investigate the positivity of the spherically averaged atomic one-electron density . For a which stems from a physical ground state we prove that for r ≥  0. This article may be reproduced in its entirety for non-commercial purposes....

On the role of the Chern-Simons action for the description of the QHE

International Nuclear Information System (INIS)

Cabo, A.; Oliva, D.

1990-05-01

The role of the Chern-Simons action in the description of the quantum Hall effects is stressed. The 2D-electromagnetic picture of Widom and Srivastava is shown to be valid in a superlattice of 2D-electron gases. A Meissner-like effect appears in such systems. In them, the difference between the external and the integer filling factor fields is exponentially screened by the surface (edge) currents. Also, effective Maxwell equations for one sheet or a superlattice are obtained. (author). 21 refs

Access to electronic health knowledge in five countries in Africa: a descriptive study

Directory of Open Access Journals (Sweden)

Honorati Masanja

2007-05-01

Full Text Available Abstract Background Access to medical literature in developing countries is helped by open access publishing and initiatives to allow free access to subscription only journals. The effectiveness of these initiatives in Africa has not been assessed. This study describes awareness, reported use and factors influencing use of on-line medical literature via free access initiatives. Methods Descriptive study in four teaching hospitals in Cameroon, Nigeria, Tanzania and Uganda plus one externally funded research institution in The Gambia. Survey with postgraduate doctors and research scientists to determine Internet access patterns, reported awareness of on-line medical information and free access initiatives; semi structured interviews with a sub-sample of survey participants to explore factors influencing use. Results In the four African teaching hospitals, 70% of the 305 postgraduate doctors reported textbooks as their main source of information; 66% had used the Internet for health information in the last week. In two hospitals, Internet cafés were the main Internet access point. For researchers at the externally-funded research institution, electronic resources were their main source, and almost all had used the Internet in the last week. Across all 333 respondents, 90% had heard of PubMed, 78% of BMJ on line, 49% the Cochrane Library, 47% HINARI, and 19% BioMedCentral. HINARI use correlates with accessing the Internet on computers located in institutions. Qualitative data suggested there are difficulties logging into HINARI and that sometimes it is librarians that limit access to passwords. Conclusion Text books remain an important resource for postgraduate doctors in training. Internet use is common, but awareness of free-access initiatives is limited. HINARI and other initiatives could be more effective with strong institutional endorsement and management to promote and ensure access.

Tunneling and resonant conductance in one-dimensional molecular structures

International Nuclear Information System (INIS)

Kozhushner, M.A.; Posvyanskii, V.S.; Oleynik, I.I.

2005-01-01

We present a theory of tunneling and resonant transitions in one-dimensional molecular systems which is based on Green's function theory of electron sub-barrier scattering off the structural units (or functional groups) of a molecular chain. We show that the many-electron effects are of paramount importance in electron transport and they are effectively treated using a formalism of sub-barrier scattering operators. The method which calculates the total scattering amplitude of the bridge molecule not only predicts the enhancement of the amplitude of tunneling transitions in course of tunneling electron transfer through onedimensional molecular structures but also allows us to interpret conductance mechanisms by calculating the bound energy spectrum of the tunneling electron, the energies being obtained as poles of the total scattering amplitude of the bridge molecule. We found that the resonant tunneling via bound states of the tunneling electron is the major mechanism of electron conductivity in relatively long organic molecules. The sub-barrier scattering technique naturally includes a description of tunneling in applied electric fields which allows us to calculate I-V curves at finite bias. The developed theory is applied to explain experimental findings such as bridge effect due to tunneling through organic molecules, and threshold versus Ohmic behavior of the conductance due to resonant electron transfer

On the limits of the effective description of hyperbolic materials in the presence of surface waves

International Nuclear Information System (INIS)

Tschikin, Maria; Biehs, Svend-Age; Messina, Riccardo; Ben-Abdallah, Philippe

2013-01-01

Here, we address the question of the validity of an effective description for hyperbolic metamaterials in the near-field region. We show that the presence of localized modes such as surface waves drastically limits the validity of the effective description, and requires revisiting the concept of homogenization in the near-field. We demonstrate, from exact scattering matrix calculations for multilayer hyperbolic structures, that one can find surface modes in spectral regions where the effective approach predicts hyperbolic modes only. Hence, the presence of surface modes which are not accounted for in the effective description can lead to physical misinterpretations in the description of hyperbolic materials and their related properties. In particular, we discuss in detail how the choice of the topmost layer affects the validity of the effective medium approach for calculating the local density of states and the super-Planckian thermal radiation. (paper)

The Influence of Non-Equilibrium Excitation on the Electron Density in One-Dimensional MFD Channel Flow

Energy Technology Data Exchange (ETDEWEB)

Eichert, K.; Kaeppeler, H. J. [Institut fuer Plasmaforschung der Technischen Hochschule Stuttgart, Federal Republic of Germany (Germany)

1966-10-15

In previous publications, a system of equations was derived from the gas-kinetic description of a multi-component reacting plasma and employed for the calculation of one-dimensional subsonic flows. This system is now extended to include non-equilibrium excitation. No thermal or chemical equilibrium between the various components of the plasma is assumed. The components of the plasma considered are a non-reacting working fluid, an alkali metal vapour as a seeding material, ions of this seeding substance, and electrons. Three levels for the excited states are introduced. The reactions considered are excitation and ionization by electron collisions, and photo-ionization, as well as the corresponding reverse processes. For the reaction velocities, analytical equations are introduced permitting insertion of any excitation or ionization cross-sections of either experimental or theoretical origin. The method employed had been previously suggested by one of the authors. As examples, the degrees of excitation and ionization in the flow of a helium working fluid with 1% caesium seeding through a channel against transverse magnetic fields of 15 and 40 kg at Mach numbers of 0.7 and 0.8, respectively, were calculated. The results of the calculations show that for relatively small magnetic fields there is no rapid rise of the ionization to Saha-equilibrium as a function of electron temperature. A comparison with the results of a calculation neglecting excitation shows that especially for relatively large magnetic fields non-equilibrium excitation has an essential influence on the electron density and its approach to equilibrium. Neglecting excitation, there results a nearly frozen behaviour of the degree of ionization within channel lengths of technical interest for small magnetic fields. (author)

Small-scale laser based electron accelerators for biology and medicine: a comparative study of the biological effectiveness

Science.gov (United States)

Labate, Luca; Andreassi, Maria Grazia; Baffigi, Federica; Basta, Giuseppina; Bizzarri, Ranieri; Borghini, Andrea; Candiano, Giuliana C.; Casarino, Carlo; Cresci, Monica; Di Martino, Fabio; Fulgentini, Lorenzo; Ghetti, Francesco; Gilardi, Maria Carla; Giulietti, Antonio; Köster, Petra; Lenci, Francesco; Levato, Tadzio; Oishi, Yuji; Russo, Giorgio; Sgarbossa, Antonella; Traino, Claudio; Gizzi, Leonida A.

2013-05-01

Laser-driven electron accelerators based on the Laser Wakefield Acceleration process has entered a mature phase to be considered as alternative devices to conventional radiofrequency linear accelerators used in medical applications. Before entering the medical practice, however, deep studies of the radiobiological effects of such short bunches as the ones produced by laser-driven accelerators have to be performed. Here we report on the setup, characterization and first test of a small-scale laser accelerator for radiobiology experiments. A brief description of the experimental setup will be given at first, followed by an overview of the electron bunch characterization, in particular in terms of dose delivered to the samples. Finally, the first results from the irradiation of biological samples will be briefly discussed.

Observation of Zero-Dimensional States in a One-Dimensional Electron Interferometer

NARCIS (Netherlands)

Wees, B.J. van; Kouwenhoven, L.P.; Harmans, C.J.P.M.; Williamson, J.G.; Timmering, C.E.; Broekaart, M.E.I.; Foxon, C.T.; Harris, J.J.

1989-01-01

We have studied the electron transport in a one-dimensional electron interferometer. It consists of a disk-shaped two-dimensional electron gas, to which quantum point contacts are attached. Discrete zero-dimensional states are formed due to constructive interference of electron waves traveling along

The Effectiveness of FRESH Technique to Teach Descriptive Paragraph

Directory of Open Access Journals (Sweden)

Faisal Faisal

2013-11-01

Full Text Available This study was aimed at knowing the effectiveness of FRESH technique in teaching descriptive paragraph. The method of this study was quasi experimental method. This study was conducted at one of the state madrasah aliyah in academic year 2012/2013. The total sample of this study was 78 respondents divided into two groups: the control class with no treatment and the experimental class with FRESH technique. The data collection technique used essay tests for pre-test and post-test. The evaluation covered content, organization, vocabulary, style, and mechanic. After data analyses, the students in the experimental class had better achievement than those in the control class. The result of t-test computation was 1.968, with t-table value = 1.664 at the significant level α = 0.05. The t-test result was higher than the value of t-table (1.968 > 1.664. It meant that the hypothesis was accepted or FRESH technique was effective in teaching descriptive paragraph to the students of that school in academic year 2012/2013.

Importance of σ Bonding Electrons for the Accurate Description of Electron Correlation in Graphene.

Science.gov (United States)

Zheng, Huihuo; Gan, Yu; Abbamonte, Peter; Wagner, Lucas K

2017-10-20

Electron correlation in graphene is unique because of the interplay between the Dirac cone dispersion of π electrons and long-range Coulomb interaction. Because of the zero density of states at Fermi level, the random phase approximation predicts no metallic screening at long distance and low energy, so one might expect that graphene should be a poorly screened system. However, empirically graphene is a weakly interacting semimetal, which leads to the question of how electron correlations take place in graphene at different length scales. We address this question by computing the equal time and dynamic structure factor S(q) and S(q,ω) of freestanding graphene using ab initio fixed-node diffusion Monte Carlo simulations and the random phase approximation. We find that the σ electrons contribute strongly to S(q,ω) for relevant experimental values of ω even at distances up to around 80 Å. These findings illustrate how the emergent physics from underlying Coulomb interactions results in the observed weakly correlated semimetal.

An effective medium description of 'Swiss Rolls', a magnetic metamaterial

International Nuclear Information System (INIS)

Wiltshire, M C K; Pendry, J B; Williams, W; Hajnal, J V

2007-01-01

The 'Swiss Roll' metamaterial medium is well suited to operation in the radio frequency (RF) range, because it has a low resonant frequency and a strong magnetic response. Two prisms of this material, one hexagonal and one square, have been constructed and characterized both at the metamaterial's resonant frequency of 21.5 MHz and above it, where the effective permeability is strongly negative. A series of spatial resonances is observed in the field patterns on the surfaces of the prisms. Using an effective medium description, we have carried out both analytical and numerical modelling of the electromagnetic behaviour of the metamaterial, and find, within certain obvious limitations, extremely good agreement between the measured and modelled results

Interactions between electrons, mesoscopic Josephson effect and asymmetric current fluctuations

Science.gov (United States)

Huard, B.

2006-07-01

This article discusses three experiments on the properties of electronic transport at the mesoscopic scale. The first one allowed to measure the energy exchange rate between electrons in a metal contaminated by a very weak concentration of magnetic impurities. The role played by magnetic impurities in the Kondo regime on those energy exchanges is quantitatively investigated, and the global measured exchange rate is larger than expected. The second experiment is a measurement of the current-phase relation in a system made of two superconductors linked through a single atom. We thus provide quantitative support for the recent description of the mesoscopic Josephson effect. The last experiment is a measurement of the asymmetry of the current fluctuations in a mesoscopic conductor, using a Josephson junction as a threshold detector. Cet ouvrage décrit trois expériences portant sur les propriétés du transport électronique à l'échelle mésoscopique. La première a permis de mesurer le taux d'échange d'énergie entre électrons dans un métal contenant une très faible concentration d'impuretés magnétiques. Nous avons validé la description quantitative du rôle des impuretés magnétiques dans le régime Kondo sur ces échanges énergétiques et aussi montré que le taux global d'échange est plus fort que prévu. La seconde expérience est une mesure de la relation courant-phase dans un système constitué de deux supraconducteurs couplés par un seul atome. Elle nous a permis de conforter quantitativement la récente description de l'effet Josephson mésoscopique. La dernière expérience est unemesure de l'asymétrie des fluctuations du courant dans un conducteur mésoscopique en utilisant une Jonction Josephson comme détecteur de seuil.

One-dimensional free-electron laser equations without the slowly varying envelope approximation

Directory of Open Access Journals (Sweden)

C. Maroli

2011-07-01

Full Text Available A set of one-dimensional equations has been deduced in the time domain from the Maxwell-Lorentz system with the aim of describing the free-electron laser radiation without using the slowly varying envelope approximation (SVEA. These equations are valid even in the case of arbitrarily short electron bunches and of current distributions with ripples on the scale of or shorter than the wavelength. Numerical examples are presented, showing that for long homogeneous bunches the new set of equations gives results in agreement with the SVEA free-electron laser theory and that the use of short or prebunched electron beams leads to a decrease of the emission lethargy. Furthermore, we demonstrate that in all cases in which the backward low frequency wave has negligible effects, these equations can be reduced to a form similar to the usual 1D SVEA equations but with a different definition of the bunching term.

To the theory of spin-charge separation in one-dimensional correlated electron systems

International Nuclear Information System (INIS)

Zvyagin, A.A.

2004-01-01

Spin-charge separation is considered to be one of the key properties that distinguish low-dimensional electron systems from others. Three-dimensional correlated electron systems are described by the Fermi liquid theory. There, low-energy excitations (quasiparticles) are reminiscent of noninteracting electrons: They carry charges -e and spins 1/2 . It is believed that for any one-dimensional correlated electron system, low-lying electron excitations carry either only spin and no charge, or only charge without spin. That is why recent experiments looked for such low-lying collective electron excitations, one of which carries only spin, and the other carries only charge. Here we show that despite the fact that for exactly solvable one-dimensional correlated electron models there exist excitations which carry only spin and only charge, in all these models with short-range interactions the low-energy physics is described by low-lying collective excitations, one of which carries both spin and charge

One electron-based smallest flexible logic cell

Science.gov (United States)

Kim, S. J.; Lee, J. J.; Kang, H. J.; Choi, J. B.; Yu, Y.-S.; Takahashi, Y.; Hasko, D. G.

2012-10-01

A one electron-based operating half-adder, the smallest arithmetic block, has been implemented on silicon-on-insulator structure whose basic element is a nanoscale single-electron transistor (SET) with two symmetrical side-wall gates. Grayscale contour plots of the resulting cell output voltages exhibit the Coulomb blockade-induced periodic alternating high/low features. Their voltage transfer characteristics display typical Sum and Carry-Out functions for binary, multi-valued (MV), and binary-MV mixed input voltages. Moreover, the half-adder function converts into a subtraction mode by adjusting control gates of the SET element. This flexible multi-valued cell provides an arithmetic block for the SET MV logic family of high density integration, operating with ultra-low power.

Effect of aberration of light in X-ray free electron lasers

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2015-11-01

We discuss the physics of a microbunched electron beam kicked by the dipole field of a corrector magnet by describing the kinematics of coherent undulator radiation after the kick. Particle tracking shows that the electron beam direction changes after the kick, while the orientation of the microbunching wavefront stays unvaried. Therefore, electrons motion and wavefront normal have different directions. Coherent radiation emission in a downstream undulator is expected to be dramatically suppressed as soon as the kick angle becomes larger than the divergence of the output radiation. In fact, according to conventional treatments, coherent radiation is emitted along the normal to the microbunching wavefront. Here we show that kinematics predicts a surprising effect. Namely, a description of coherent undulator radiation in the laboratory frame yields the radical notion that, due light aberration, strong coherent radiation is produced along the direction of the kick. We hold a recent FEL study made at the LCLS as a direct experimental evidence that coherent undulator radiation can be kicked by an angle of about five times the rms radiation divergence without suppression. We put forward our kinematical description of this experiment.

Acoustic and electronic properties of one-dimensional quasicrystals

International Nuclear Information System (INIS)

Nori, F.; Rodriguez, J.P.

1986-01-01

We study the acoustic and electronic properties of one-dimensional quasicrystals. Both numerical (nonperturbative) and analytical (perturbative) results are shown. The phonon and electronic spectra exhibit a self-similar hierarchy of gaps and many localized states in the gaps. We study quasiperiodic structures with any number of layers and several types of boundary conditions. We discuss the connection between our phonon model and recent experiments on quasiperiodic GaAs-AlAs superlattices. We predict the existence of many gap states localized at the surfaces

One-electron oxidation reactions of purine and pyrimidine bases in cellular DNA.

Science.gov (United States)

Cadet, Jean; Wagner, J Richard; Shafirovich, Vladimir; Geacintov, Nicholas E

2014-06-01

The aim of this survey is to critically review the available information on one-electron oxidation reactions of nucleobases in cellular DNA with emphasis on damage induced through the transient generation of purine and pyrimidine radical cations. Since the indirect effect of ionizing radiation mediated by hydroxyl radical is predominant in cells, efforts have been made to selectively ionize bases using suitable one-electron oxidants that consist among others of high intensity UVC laser pulses. Thus, the main oxidation product in cellular DNA was found to be 8-oxo-7,8-dihydroguanine as a result of direct bi-photonic ionization of guanine bases and indirect formation of guanine radical cations through hole transfer reactions from other base radical cations. The formation of 8-oxo-7,8-dihydroguanine and other purine and pyrimidine degradation products was rationalized in terms of the initial generation of related radical cations followed by either hydration or deprotonation reactions in agreement with mechanistic pathways inferred from detailed mechanistic studies. The guanine radical cation has been shown to be implicated in three other nucleophilic additions that give rise to DNA-protein and DNA-DNA cross-links in model systems. Evidence was recently provided for the occurrence of these three reactions in cellular DNA. There is growing evidence that one-electron oxidation reactions of nucleobases whose mechanisms have been characterized in model studies involving aqueous solutions take place in a similar way in cells. It may also be pointed out that the above cross-linked lesions are only produced from the guanine radical cation and may be considered as diagnostic products of the direct effect of ionizing radiation.

The impact of the self-interaction error on the density functional theory description of dissociating radical cations: ionic and covalent dissociation limits.

Science.gov (United States)

Gräfenstein, Jürgen; Kraka, Elfi; Cremer, Dieter

2004-01-08

Self-interaction corrected density functional theory was used to determine the self-interaction error for dissociating one-electron bonds. The self-interaction error of the unpaired electron mimics nondynamic correlation effects that have no physical basis where these effects increase for increasing separation distance. For short distances the magnitude of the self-interaction error takes a minimum and increases then again for decreasing R. The position of the minimum of the magnitude of the self-interaction error influences the equilibrium properties of the one-electron bond in the radical cations H2+ (1), B2H4+ (2), and C2H6+ (3), which differ significantly. These differences are explained by hyperconjugative interactions in 2 and 3 that are directly reflected by the self-interaction error and its orbital contributions. The density functional theory description of the dissociating radical cations suffers not only from the self-interaction error but also from the simplified description of interelectronic exchange. The calculated differences between ionic and covalent dissociation for 1, 2, and 3 provide an excellent criterion for determining the basic failures of density functional theory, self-interaction corrected density functional theory, and other methods. Pure electronic, orbital relaxation, and geometric relaxation contributions to the self-interaction error are discussed. The relevance of these effects for the description of transition states and charge transfer complexes is shown. Suggestions for the construction of new exchange-correlation functionals are given. In this connection, the disadvantages of recently suggested self-interaction error-free density functional theory methods are emphasized. (c) 2004 American Institute of Physics

Cost effective electronics for proportional and drift chambers of 'EPECUR' experiment

International Nuclear Information System (INIS)

Alekseev, I.G.; Andreev, V.A.; Budkovsky, P.E.; Filimonov, E.A.; Golubev, V.V.; Kanavets, V.P.; Kats, M.M.; Koroleva, L.I.; Kovalev, A.I.; Kozlenko, N.G.; Kozlov, V.S.; Krivshich, A.G.; Kulikov, V.V.; Morozov, B.V.; Nesterov, V.M.; Novinsky, D.V.; Ryltsov, V.V.; Sadler, M.E.; Sakharov, V.A.; Soboyede, D.; Sulimov, A.D.; Sumachev, V.V.; Svirida, D.N.; Trautman, V.Yu.; Walker, E.; Watson, S.

2007-01-01

The 'EPECUR' experimental setup is under construction at beam line 322 of the ITEP proton synchrotron. The experiment requires several large area drift chambers to provide reasonable acceptance and fine-pitch proportional chambers for beam particle tracking. The total number of electronic channels is about 7000. A new compact and cost effective readout system for these gaseous detectors was designed, prototyped and tested in the last two years. It is based on modern technologies in analog and digital electronics and data transfer protocols. This paper presents the functional description of the whole DAQ system, including test results as an illustration of its performance

Analysis of spin depolarizing effects in electron storage rings

International Nuclear Information System (INIS)

Boege, M.

1994-05-01

In this thesis spin depolarizing effects in electron storage rings are analyzed and the depolarizing effects in the HERA electron storage ring are studied in detail. At high beam energies the equilibrium polarization is limited by nonlinear effects. This will be particularly true in the case of HERA, when the socalled ''spin rotators'' are inserted which are designed to provide longitudinal electron polarization for the HERMES experiment in 1994 and later for the H1 and ZEUS experiment. It is very important to quantify the influence of these effects theoretically by a proper modelling of HERA, so that ways can be found to get a high degree of polarization in the real machine. In this thesis HERA is modelled by the Monte-Carlo tracking program SITROS which was originally written by J. Kewisch in 1982 to study the polarization in PETRA. The first part of the thesis is devoted to a detailed description of the fundamental theoretical concepts on which the program is based. Then the approximations which are needed to overcome computing time limitations are explained and their influence on the simulation result is discussed. The systematic and statistical errors are studied in detail. Extensions of the program which allow a comparison of SITROS with the results given by ''linear'' theory are explained. (orig.)

Relativistic effects on inner-shell electron properties

International Nuclear Information System (INIS)

Desclaux, J.P.

1976-01-01

The influence of relativistic effects on hydrogen-like systems is first reviewed. After having considered one-electron systems, the influence of the other electrons is to be taken into account when considering inner ionization energy and ionization cross sections. Two-hole states in inner shells being then dealt with, the problem of angular momentum coupling among electrons can no longer be neglected. In an other way, this implies that wave functions are to be built on a jj basis instead of a ls one. Ksub(α)sup(h) hypersatellite spectra and KLL Auger transition energies are successively discussed

Electronic Excitations in Solution: The Interplay between State Specific Approaches and a Time-Dependent Density Functional Theory Description.

Science.gov (United States)

Guido, Ciro A; Jacquemin, Denis; Adamo, Carlo; Mennucci, Benedetta

2015-12-08

We critically analyze the performances of continuum solvation models when coupled to time-dependent density functional theory (TD-DFT) to predict solvent effects on both absorption and emission energies of chromophores in solution. Different polarization schemes of the polarizable continuum model (PCM), such as linear response (LR) and three different state specific (SS) approaches, are considered and compared. We show the necessity of introducing a SS model in cases where large electron density rearrangements are involved in the excitations, such as charge-transfer transitions in both twisted and quadrupolar compounds, and underline the very delicate interplay between the selected polarization method and the chosen exchange-correlation functional. This interplay originates in the different descriptions of the transition and ground/excited state multipolar moments by the different functionals. As a result, the choice of both the DFT functional and the solvent polarization scheme has to be consistent with the nature of the studied electronic excitation.

ELECTRON CLOUD EFFECTS IN HIGH INTENSITY PROTON ACCELERATORS

International Nuclear Information System (INIS)

Wei, J.; Macek, R.J.

2002-01-01

One of the primary concerns in the design and operation of high-intensity proton synchrotrons and accumulators is the electron cloud and associated beam loss and instabilities. Electron-cloud effects are observed at high-intensity proton machines like the Los Alamos National Laboratory's PSR and CERN's SPS, and investigated experimentally and theoretically. In the design of next-generation high-intensity proton accelerators like the Spallation Neutron Source ring, emphasis is made in minimizing electron production and in enhancing Landau damping. This paper reviews the present understanding of the electron-cloud effects and presents mitigation measures

A computational study of the electronic properties of one-dimensional armchair phosphorene nanotubes

Energy Technology Data Exchange (ETDEWEB)

Yu, Sheng; Zhu, Hao; Eshun, Kwesi; Arab, Abbas; Badwan, Ahmad; Li, Qiliang [Department of Electrical and Computer Engineering, George Mason University, Fairfax, Virginia 22033 (United States)

2015-10-28

We have performed a comprehensive first-principle computational study of the electronic properties of one-dimensional phosphorene nanotubes (PNTs), and the strain effect on the mechanical and electrical properties of PNTs, including the elastic modulus, energy bandstructure, and carrier effective mass. The study has demonstrated that the armchair PNTs have semiconducting properties along the axial direction and the carrier mobility can be significantly improved by compressive strain. The hole mobility increases from 40.7 cm{sup 2}/V s to 197.0 cm{sup 2}/V s as the compressive strain increases to −5% at room temperature. The investigations of size effect on armchair PNTs indicated that the conductance increases significantly as the increasing diameter. Overall, this study indicated that the PNTs have very attractive electronic properties for future application in nanomaterials and devices.

Effective electron-electron and electron-phonon interactions in the Hubbard-Holstein model

International Nuclear Information System (INIS)

Aprea, G.; Di Castro, C.; Grilli, M. . E-mail marco.grilli@roma1.infn.it; Lorenzana, J.

2006-01-01

We investigate the interplay between the electron-electron and the electron-phonon interaction in the Hubbard-Holstein model. We implement the flow-equation method to investigate within this model the effect of correlation on the electron-phonon effective coupling and, conversely, the effect of phonons in the effective electron-electron interaction. Using this technique we obtain analytical momentum-dependent expressions for the effective couplings and we study their behavior for different physical regimes. In agreement with other works on this subject, we find that the electron-electron attraction mediated by phonons in the presence of Hubbard repulsion is peaked at low transferred momenta. The role of the characteristic energies involved is also analyzed

Implications of the effective one-component analysis of pair correlations in colloidal fluids with polydispersity

Science.gov (United States)

Pond, Mark J.; Errington, Jeffrey R.; Truskett, Thomas M.

2011-09-01

Partial pair-correlation functions of colloidal suspensions with continuous polydispersity can be challenging to characterize from optical microscopy or computer simulation data due to inadequate sampling. As a result, it is common to adopt an effective one-component description of the structure that ignores the differences between particle types. Unfortunately, whether this kind of simplified description preserves or averages out information important for understanding the behavior of the fluid depends on the degree of polydispersity and can be difficult to assess, especially when the corresponding multicomponent description of the pair correlations is unavailable for comparison. Here, we present a computer simulation study that examines the implications of adopting an effective one-component structural description of a polydisperse fluid. The square-well model that we investigate mimics key aspects of the experimental behavior of suspended colloids with short-range, polymer-mediated attractions. To characterize the partial pair-correlation functions and thermodynamic excess entropy of this system, we introduce a Monte Carlo sampling strategy appropriate for fluids with a large number of pseudo-components. The data from our simulations at high particle concentrations, as well as exact theoretical results for dilute systems, show how qualitatively different trends between structural order and particle attractions emerge from the multicomponent and effective one-component treatments, even with systems characterized by moderate polydispersity. We examine consequences of these differences for excess-entropy based scalings of shear viscosity, and we discuss how use of the multicomponent treatment reveals similarities between the corresponding dynamic scaling behaviors of attractive colloids and liquid water that the effective one-component analysis does not capture.

Determination of one-electron reduction potentials of some radiosensitive compounds by pulse radiolysis

International Nuclear Information System (INIS)

Zuo Zhihua; Yao Side; Li Hucheng; Lin Nianyun; Jin Yizun

1994-01-01

One-electron reduction potential (E 7 1 ) is one of the important parameters of radiosensitive compound with high electron affinity. In this work one-electron reduction potentials of some radiosensitizers, such as Miso, 911, CMNa, SMU-1, SMU-2, SMD, SNN, S 3 and BSO, were determined pulse radiolytically by using anthraquinone-2-sulfate (AQS), duroquinone (DQ) and methyl viologen (MV 2+ ) as references

Absolute total and one and two electron transfer cross sections for Ar8+ on Ar as a function of energy

International Nuclear Information System (INIS)

Vancura, J.; Kostroun, V.O.

1992-01-01

The absolute total and one and two electron transfer cross sections for Ar 8+ on Ar were measured as a function of projectile laboratory energy from 0.090 to 0.550 keV/amu. The effective one electron transfer cross section dominates above 0.32 keV/amu, while below this energy, the effective two electron transfer starts to become appreciable. The total cross section varies by a factor over the energy range explored. The overall error in the cross section measurement is estimated to be ± 15%

A unified picture of energy and electron transfer in primary photosynthesis

International Nuclear Information System (INIS)

Barter, Laura M.C.; Klug, David R.

2005-01-01

A quantitative structure-function relationship for an enzyme should relate the coordinates of atoms in a protein structure to the rates, equilibria and activation energies of the catalysed reaction. In effect, the calculational tools used for determining a structure-function relationship in an enzyme are linking two sets of experimental data, one data set being the coordinates of the enzymes constituent atoms and the other being measurements of its chemical activity. The ability to compare structure and function in this quantitative manner is an important stage in the ultimate development of engineering design rules for biological catalysts. This paper discusses the determination of parameters, in particular the state energies and the free energy surfaces that control the structure-function relationship, and thus the catalytic function of a photosynthetic enzyme. We discuss two different microscopic descriptions, one using conventional non-adiabatic electron transfer theory and the other a supermolecular description of the system (the Multimer Model), which takes into account the electron-phonon coupling in the system in a consistent manner. We demonstrate that although conventional non-adiabatic theory can be employed to reproduce the rates of electron transfer it cannot be employed to provide a consistent and unified description of all the spectroscopic data available in the literature from studies of this enzyme

A unified picture of energy and electron transfer in primary photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Barter, Laura M.C. [Molecular Dynamics Group, Room 266, Department of Chemistry, South Kensington Campus, Exhibition Road, Imperial College London, SW7 2AZ (United Kingdom)], E-mail: l.barter@ic.ac.uk; Klug, David R. [Molecular Dynamics Group, Room 266, Department of Chemistry, South Kensington Campus, Exhibition Road, Imperial College London, SW7 2AZ (United Kingdom)

2005-12-07

A quantitative structure-function relationship for an enzyme should relate the coordinates of atoms in a protein structure to the rates, equilibria and activation energies of the catalysed reaction. In effect, the calculational tools used for determining a structure-function relationship in an enzyme are linking two sets of experimental data, one data set being the coordinates of the enzymes constituent atoms and the other being measurements of its chemical activity. The ability to compare structure and function in this quantitative manner is an important stage in the ultimate development of engineering design rules for biological catalysts. This paper discusses the determination of parameters, in particular the state energies and the free energy surfaces that control the structure-function relationship, and thus the catalytic function of a photosynthetic enzyme. We discuss two different microscopic descriptions, one using conventional non-adiabatic electron transfer theory and the other a supermolecular description of the system (the Multimer Model), which takes into account the electron-phonon coupling in the system in a consistent manner. We demonstrate that although conventional non-adiabatic theory can be employed to reproduce the rates of electron transfer it cannot be employed to provide a consistent and unified description of all the spectroscopic data available in the literature from studies of this enzyme.

ELECTRON CLOUD EFFECTS IN HIGH INTENSITY PROTON ACCELERATORS.

Energy Technology Data Exchange (ETDEWEB)

WEI,J.; MACEK,R.J.

2002-04-14

One of the primary concerns in the design and operation of high-intensity proton synchrotrons and accumulators is the electron cloud and associated beam loss and instabilities. Electron-cloud effects are observed at high-intensity proton machines like the Los Alamos National Laboratory's PSR and CERN's SPS, and investigated experimentally and theoretically. In the design of next-generation high-intensity proton accelerators like the Spallation Neutron Source ring, emphasis is made in minimizing electron production and in enhancing Landau damping. This paper reviews the present understanding of the electron-cloud effects and presents mitigation measures.

Failure of single electron descriptions of molecular orbital collision processes

International Nuclear Information System (INIS)

Elston, S.B.

1978-01-01

Inner-shell excitation occurring in low and moderate (keV range) energy collisions between light atomic and ionic systems is frequently describable in terms of molecular promotion mechanisms, which were extensively explored both theoretically and experimentally. The bulk of such studies have concentrated on processes understandable through the use of single- and independent-electron models. Nonetheless, it is possible to find cases of inner-shell excitation in relatively simple collision systems which involve nearly simultaneous multiple-electron transitions and transitions induced by inherently two-electron interactions. Evidence for these many- and nonindependent-electron phenomena in inner-shell excitation processes and the importance of considering such effects in the interpretation of collisionally induced excitation spectra is discussed. 13 references

Quasi-one-dimensional electron transport over the surface of a liquid-helium film

International Nuclear Information System (INIS)

Sokolov, Sviatoslav; Studart, Nelson

2003-01-01

Quasi-one-dimensional mobility of surface electrons over a liquid-helium suspended film is studied for a conducting channel. The electron mobility is calculated taking into account the electron scattering by helium atoms in the vapor phase, ripplons, and surface defects of the film substrate both in one-electron regime and in the so-called complete-control limit where the influence of inter-electron collisions on the electron distribution function is taken into account. It is shown that the mobility for low temperatures is dominated by the surface-defect scattering and its temperature dependence is essentially different from that of the electron-ripplon scattering

Effects of curved midline and varying width on the description of the effective diffusivity of Brownian particles

Science.gov (United States)

Chávez, Yoshua; Chacón-Acosta, Guillermo; Dagdug, Leonardo

2018-05-01

Axial diffusion in channels and tubes of smoothly-varying geometry can be approximately described as one-dimensional diffusion in the entropy potential with a position-dependent effective diffusion coefficient, by means of the modified Fick–Jacobs equation. In this work, we derive analytical expressions for the position-dependent effective diffusivity for two-dimensional asymmetric varying-width channels, and for three-dimensional curved midline tubes, formed by straight walls. To this end, we use a recently developed theoretical framework using the Frenet–Serret moving frame as the coordinate system (2016 J. Chem. Phys. 145 074105). For narrow tubes and channels, an effective one-dimensional description reducing the diffusion equation to a Fick–Jacobs-like equation in general coordinates is used. From this last equation, one can calculate the effective diffusion coefficient applying Neumann boundary conditions.

Electron Cloud Effect in the Linear Colliders

International Nuclear Information System (INIS)

Pivi, M

2004-01-01

Beam induced multipacting, driven by the electric field of successive positively charged bunches, may arise from a resonant motion of electrons, generated by secondary emission, bouncing back and forth between opposite walls of the vacuum chamber. The electron-cloud effect (ECE) has been observed or is expected at many storage rings [1]. In the beam pipe of the Damping Ring (DR) of a linear collider, an electron cloud is produced initially by ionization of the residual gas and photoelectrons from the synchrotron radiation. The cloud is then sustained by secondary electron emission. This electron cloud can reach equilibrium after the passage of only a few bunches. The electron-cloud effect may be responsible for collective effects as fast coupled-bunch and single-bunch instability, emittance blow-up or incoherent tune shift when the bunch current exceeds a certain threshold, accompanied by a large number of electrons in the vacuum chamber. The ECE was identified as one of the most important R and D topics in the International Linear Collider Report [2]. Systematic studies on the possible electron-cloud effect have been initiated at SLAC for the GLC/NLC and TESLA linear colliders, with particular attention to the effect in the positron main damping ring (MDR) and the positron Low Emittance Transport which includes the bunch compressor system (BCS), the main linac, and the beam delivery system (BDS). We present recent computer simulation results for the main features of the electron cloud generation in both machine designs. Thus, single and coupled-bunch instability thresholds are estimated for the GLC/NLC design

Description of the artificial parameters in EGS4-Monte Carlo simulation and their influence on the absorbed depth dose from electrons in water

International Nuclear Information System (INIS)

Sandborg, M.; Alm Carlsson, G.

1990-01-01

This report described the background of the EGS4-Monte Carlo code. It gives a short description of the interaction between electrons and materia and a description of the artificial parameters used for EGS4-Monte Carlo simulating. It also gives advice to choose the right artificial parameters. (K.A.E)

Effective Conformal Descriptions of Black Hole Entropy

Directory of Open Access Journals (Sweden)

Steven Carlip

2011-07-01

Full Text Available It is no longer considered surprising that black holes have temperatures and entropies. What remains surprising, though, is the universality of these thermodynamic properties: their exceptionally simple and general form, and the fact that they can be derived from many very different descriptions of the underlying microscopic degrees of freedom. I review the proposal that this universality arises from an approximate conformal symmetry, which permits an effective “conformal dual” description that is largely independent of the microscopic details.

Dynamics in ion-molecule collisions at high velocities: One- and two-electron processes

International Nuclear Information System (INIS)

Wang, Yudong.

1992-01-01

This dissertation addresses the dynamic interactions in ion-molecule collisions. Theoretical methods are developed for single and multiple electron transitions in fast collisions with diatomic molecules by heavy-ion projectiles. Various theories and models are developed to treat the three basic inelastic processes (excitation, ionization and charge transfer) involving one and more electrons. The development, incorporating the understanding of ion-atom collision theories with some unique characteristics for molecular targets, provides new insights into phenomena that are absent from collisions with atomic targets. The influence from the multiple scattering centers on collision dynamics is assessed. For diatomic molecules, effects due to a fixed molecular orientation or alignment are calculated and compared with available experimental observations. Compared with excitation and ionization, electron capture, which probes deeper into the target, presents significant two-center interference and strong orientation dependence. Attention has been given in this dissertation to exploring mechanisms for two-and multiple electron transitions. Application of independent electron approximation to transfer excitation from molecular hydrogen is studied. Electron-electron interaction originated from projectile and target nuclear centers is studied in conjunction with the molecular nature of target. Limitations of the present theories and models as well as possible new areas for future theoretical and experimental applications are also discussed. This is the first attempt to describe multi-electron processes in molecular dynamics involving fast highly charged ions

Electron and ion magnetohydrodynamic effects in plasma opening switches

International Nuclear Information System (INIS)

Grossmann, J.M.; DeVore, C.R.; Ottinger, P.F.

1993-01-01

Preliminary results are presented of a numerical code designed to investigate electron and ion magnetohydrodynamic effects in plasma erosion opening switches. The present model is one-dimensional and resolves effects such as the JxB deformation of the plasma, and the penetration of magnetic field either by anomalous resistivity or electron magnetohydrodynamics (Hall effect). Comparisons with exact analytic results and experiment are made

Electronic structure of molecules using relativistic effective core potentials

International Nuclear Information System (INIS)

Hay, P.J.

1981-01-01

Starting with one-component Cowan-Griffin relativistic Hartree-Fock orbitals, which successfully incorporate the mass-velocity and Darwin terms present in more complicated wavefunctions such as Dirac-Hartree-Fock, one can derive relativistic effective core potentials (RECP's) to carry out molecular calculations. These potentials implicitly include the dominant relativistic terms for molecules while allowing one to use the traditional quantum chemical techniques for studying the electronic structure of molecules. The effects of spin-orbit coupling can then be included using orbitals from such calculations using an effective 1-electron, 1-center spin-orbit operator. Applications to molecular systems involving heavy atoms, show good agreement with available spectroscopic data on molecular geometries and excitation energies

Electronic structure description of the cis-MoOS unit in models for molybdenum hydroxylases.

Science.gov (United States)

Doonan, Christian J; Rubie, Nick D; Peariso, Katrina; Harris, Hugh H; Knottenbelt, Sushilla Z; George, Graham N; Young, Charles G; Kirk, Martin L

2008-01-09

The molybdenum hydroxylases catalyze the oxidation of numerous aromatic heterocycles and simple organics and, unlike other hydroxylases, utilize water as the source of oxygen incorporated into the product. The electronic structures of the cis-MoOS units in CoCp2[TpiPrMoVOS(OPh)] and TpiPrMoVIOS(OPh) (TpiPr = hydrotris(3-isopropylpyrazol-1-yl)borate), new models for molybdenum hydroxylases, have been studied in detail using S K-edge X-ray absorption spectroscopy, vibrational spectroscopy, and detailed bonding calculations. The results show a highly delocalized Mo=S pi* LUMO redox orbital that is formally Mo(dxy) with approximately 35% sulfido ligand character. Vibrational spectroscopy has been used to quantitate Mo-Ssulfido bond order changes in the cis-MoOS units as a function of redox state. Results support a redox active molecular orbital that has a profound influence on MoOS bonding through changes to the relative electro/nucleophilicity of the terminal sulfido ligand accompanying oxidation state changes. The bonding description for these model cis-MoOS systems supports enzyme mechanisms that are under orbital control and dominantly influenced by the unique electronic structure of the cis-MoOS site. The electronic structure of the oxidized enzyme site is postulated to play a role in polarizing a substrate carbon center for nucleophilic attack by metal activated water and acting as an electron sink in the two-electron oxidation of substrates.

Unified first principles description from warm dense matter to ideal ionized gas plasma: electron-ion collisions induced friction.

Science.gov (United States)

Dai, Jiayu; Hou, Yong; Yuan, Jianmin

2010-06-18

Electron-ion interactions are central to numerous phenomena in the warm dense matter (WDM) regime and at higher temperature. The electron-ion collisions induced friction at high temperature is introduced in the procedure of ab initio molecular dynamics using the Langevin equation based on density functional theory. In this framework, as a test for Fe and H up to 1000 eV, the equation of state and the transition of electronic structures of the materials with very wide density and temperature can be described, which covers a full range of WDM up to high energy density physics. A unified first principles description from condensed matter to ideal ionized gas plasma is constructed.

Modulation of continuous electron beams in plasma wake-fields

International Nuclear Information System (INIS)

Rosenzweig, J.B.

1988-01-01

In this paper we discuss the interaction of a continuous electron beam with wake-field generated plasma waves. Using a one-dimensional two fluid model, a fully nonlinear analytical description of the interaction is obtained. The phenomena of continuous beam modulation and wave period shortening are discussed. The relationship between these effects and the two-stream instability is also examined. 12 refs., 1 fig

Numerology, hydrogenic levels, and the ordering of excited states in one-electron atoms

Science.gov (United States)

Armstrong, Lloyd, Jr.

1982-03-01

We show that the observed ordering of Rydberg states of one-electron atoms can be understood by assuming that these states are basically hydrogenic in nature. Much of the confusion concerning this point is shown to arise from the failure to differentiate between hydrogenic ordering as the nuclear charge approaches infinity, and hydrogenic ordering for an effective charge of one. The origin of κ ordering of Rydberg levels suggested by Sternheimer is considered within this picture, and the predictions of κ ordering are compared with those obtained by assuming hydrogenic ordering.

Electronic structure of molecules using relativistic effective core potentials

International Nuclear Information System (INIS)

Hay, P.J.

1983-01-01

In this review an approach is outlined for studying molecules containing heavy atoms with the use of relativistic effective core potentials (RECP's). These potentials play the dual roles of (1) replacing the chemically-inert core electrons and (2) incorporating the mass velocity and Darwin term into a one-electron effective potential. This reduces the problem to a valence-electron problem and avoids computation of additional matrix elements involving relativistic operators. The spin-orbit effects are subsequently included using the molecular orbitals derived from the RECP calculation as a basis

Course Descriptions in Environmental Studies Part One: Historical Courses.

Science.gov (United States)

Hughes, Donald; And Others

1984-01-01

Presents descriptions (syllabi, outlines, goals) of selected environmental studies courses which approach the discipline from an historical and humanistic perspective. Areas explored in the courses include human ecology, American environmental history, environmental politics, and others. (JN)

Self-Consistent System of Equations for a Kinetic Description of the Low-Pressure Discharges Accounting for the Nonlocal and Collisionless Electron Dynamics

International Nuclear Information System (INIS)

Kaganovich, Igor D.; Polomarov, Oleg

2003-01-01

In low-pressure discharges, when the electron mean free path is larger or comparable with the discharge length, the electron dynamics is essentially non-local. Moreover, the electron energy distribution function (EEDF) deviates considerably from a Maxwellian. Therefore, an accurate kinetic description of the low-pressure discharges requires knowledge of the non-local conductivity operator and calculation of the non-Maxwellian EEDF. The previous treatments made use of simplifying assumptions: a uniform density profile and a Maxwellian EEDF. In the present study a self-consistent system of equations for the kinetic description of nonlocal, non-uniform, nearly collisionless plasmas of low-pressure discharges is derived. It consists of the nonlocal conductivity operator and the averaged kinetic equation for calculation of the non-Maxwellian EEDF. The importance of accounting for the non-uniform plasma density profile on both the current density profile and the EEDF is demonstrated

Shake-off processes at the electron transitions in atoms

International Nuclear Information System (INIS)

Matveev, V.I.; Parilis, Eh.S.

1982-01-01

Elementary processes in multielectron atoms - radiative and Auger transitions, photoionization and ionization by an electron impact etc. are usually followed by the relaxation of electron shells. The conditions under which such multielectron problem could be solved in the shake-off approximation are considered. The shake-off processes occurring. as a result of the electron transitions are described from the general point of view. The common characteristics and peculiar features of this type of excitation in comparison with the electron shake-off under nuclear transformations are pointed out. Several electron shake-off processes are considered, namely: radiative Auger effect, the transition ''two electrons-one photon'', dipole ionization, spectral line broadening, post collision interaction, Auger decay stimulated by collision with fast electrons, three-electron Auger transitions: double and half Auger effect. Their classification is given according to the type of the electron transition causing the shake-off process. The experimental data are presented and the methods of theoretical description are reviewed. Other similar effects, which could follow the transitions in electron shells are pointed out. The deduction of shake-off approximation is presented, and it is pointed out that this approach is analogous to the distorted waves approximation in the theory of scattering. It was shown that in atoms the shake-off approximation is a very effective method, which allows to obtain the probability of different electronic effects

The Effect of the Implementation of E-Crm Electronic Satisfaction and Loyalty, Electronic Consumers of Mellat Bank's Website

Directory of Open Access Journals (Sweden)

Mehdi Jamali

2017-02-01

Full Text Available Organizations that compete for power in the market constantly looking for ways to overcome their rivals. Today's customers want to engage with the organization. Successful customer relationship management is one of the major competitive advantages that organizations can use to prevent the transmission of clients to other organizations deemed of operation. The degree to which an organization is able to maintain effective communication with their clients, more opportunities to offer more services to its business customers will offer. Considering the above study to evaluate the effect of the implementation of E-CRM on e-satisfaction and customer loyalty has paid electronically, users of the Mellat Bank's website. To collect information from the questionnaire with Cronbach's alpha was used validation. Respondents were customers and users of online services of the Mellat Bank's website. Survey research method - has been described. To analyze the data, descriptive and inferential statistical methods such as correlation analysis, Pearson and Spearman correlation coefficient and linear regression analysis using SPSS software is used. The results show that the implementation of E-CRM is a positive and significant impact on customer satisfaction and loyalty-mail.

Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

CERN Document Server

Nikolaenko, V A; Gladchenko, S P

2002-01-01

Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B 0.9 K) and the electron-ripplon scattering (T 1(here omega sub c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron syst...

Theory of the one- and two-dimensional electron gas

International Nuclear Information System (INIS)

Emery, V.J.

1987-01-01

Two topics are discussed: (1) the competition between 2k/sub F/ and 4k/sub F/ charge state waves in a one-dimensional electron gas and (2) a two-dimensional model of high T/sub c/ superconductivity in the oxides

Correlation effects in magnetic materials: An ab initio investigation on electronic structure and spectroscopy

International Nuclear Information System (INIS)

Minár, J.; Braun, J.; Ebert, H.

2013-01-01

Highlights: ► We compare spin-resolved ARPES data of ferromagnetic 3d transition metals to many-body LSDA + DMFT based spectroscopic calculations. ► We document LSDA + DMFT provides a detailed and reliable interpretation of the data. ► We demonstrate that local correlations are dominant in Ni, whereas non-local correlations are important in Fe and Co. ► We reproduce the 6 eV satellite structure in ferromagnetic Ni LDSDA + DMFT in combination with the one-step model of photoemission provides a more or less complete description of the electronic structure of Fe, Co and Ni. -- Abstract: Various technical developments enlarged the potential of angle-resolved photoemission spectroscopy (ARPES) tremendously during the last two decades. In particular improved momentum and energy resolution in combination with spin-resolution as well as the use of photon energies from few eV up to several keV makes ARPES a rather unique tool to investigate the electronic properties of solids and surfaces. Obviously, this rises the need for a corresponding theoretical formalism that allows to accompany experimental ARPES studies in an adequate way. As will be demonstrated by several examples this goal could be achieved by various recent developments on the basis of density functional theory (DFT) in combination with dynamical mean field theory (DMFT) and with the one-step model of photoemission (1SM). A concrete realization of electronic structure calculations in the framework of multiple scattering theory further more provides direct access to the spectral function of the initial states via the one-electron Green function. Based on this bare spectral function matrix-element and final-state effects as well as surface related features may be calculated in addition using the one-step formalism that offers the possibility to analyse corresponding angle-resolved photoemission experiments in a quantitative sense. The impact of chemical disorder can be handled by means of the coherent

Spin-dependent electron many-body effects in GaAs

Science.gov (United States)

Nemec, P.; Kerachian, Y.; van Driel, H. M.; Smirl, Arthur L.

2005-12-01

Time- and polarization-resolved differential transmission measurements employing same and oppositely circularly polarized 150fs optical pulses are used to investigate spin characteristics of conduction band electrons in bulk GaAs at 295K . Electrons and holes with densities in the 2×1016cm-3-1018cm-3 range are generated and probed with pulses whose center wavelength is between 865 and 775nm . The transmissivity results can be explained in terms of the spin sensitivity of both phase-space filling and many-body effects (band-gap renormalization and screening of the Coulomb enhancement factor). For excitation and probing at 865nm , just above the band-gap edge, the transmissivity changes mainly reflect spin-dependent phase-space filling which is dominated by the electron Fermi factors. However, for 775nm probing, the influence of many-body effects on the induced transmission change are comparable with those from reduced phase space filling, exposing the spin dependence of the many-body effects. If one does not take account of these spin-dependent effects one can misinterpret both the magnitude and time evolution of the electron spin polarization. For suitable measurements we find that the electron spin relaxation time is 130ps .

Graphic Description: The Mystery of Ibn Khafaja\\'s Success in Description

Directory of Open Access Journals (Sweden)

جواد رنجبر

2009-12-01

Full Text Available Graphic Description:   The Mystery of Ibn Khafaja's Success in Description    Ali Bagher Taheriniya *  Javad Ranjbar **      Abstract Ibn Khafaja is one of the poets and men of letters in Spain. He is titled to Sanobari of Spain. He is one of the masters of description. Hence, the analysis of successful techniques he has used in the descriptive art could illuminate the way for others. Al-Taswir al-harfi (graphic description is a term which denotes the highest and most detailed poems. On this basis, the best descriptive poem is one which is closer to a painting. He has used some elements called conforming elements of description which contain: imagination, feeling, faculty, and dialogue as well as three other elements: to be inborn in description, enchanting nature and convenient life. This article is going to give an analysis of the reasons for Ibn Khafaja’s success in description and portrait making.   Key words: Ibn Khafaja, poetry, description, portrait   * Associate Professor, Bu Ali Sina University of Hamadan E-mail: bTaheriniya@yahoo.com  ** M.A. in Arabic Language and Literature

The verbal facilitation effect: re-reading person descriptions as a system variable to improve identification performance.

Science.gov (United States)

Sporer, Siegfried L; Kaminski, Kristina S; Davids, Maike C; McQuiston, Dawn

2016-11-01

When witnesses report a crime, police usually ask for a description of the perpetrator. Several studies suggested that verbalising faces leads to a detriment in identification performance (verbal overshadowing effect [VOE]) but the effect has been difficult to replicate. Here, we sought to reverse the VOE by inducing context reinstatement as a system variable through re-reading one's own description before an identification task. Participants (N = 208) watched a video film and were then dismissed (control group), only described the perpetrator, or described and later re-read their own descriptions before identification in either target-present or target-absent lineups after a 2-day or a 5-week delay. Identification accuracy was significantly higher after re-reading (85.0%) than in the no description control group (62.5%) irrespective of target presence. Data were internally replicated using a second target and corroborated by several small meta-analyses. Identification accuracy was related to description quality. Moreover, there was a tendency towards a verbal facilitation effect (VFE) rather than a VOE. Receiver operating characteristic (ROC) curve analyses confirm that our findings are not due to a shift in response bias but truly reflect improvement of recognition performance. Differences in the ecological validity of study paradigms are discussed.

Descriptive Research

DEFF Research Database (Denmark)

Wigram, Anthony Lewis

2003-01-01

Descriptive research is described by Lathom-Radocy and Radocy (1995) to include Survey research, ex post facto research, case studies and developmental studies. Descriptive research also includes a review of the literature in order to provide both quantitative and qualitative evidence of the effect...... starts will allow effect size calculations to be made in order to evaluate effect over time. Given the difficulties in undertaking controlled experimental studies in the creative arts therapies, descriptive research methods offer a way of quantifying effect through descriptive statistical analysis...

Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

International Nuclear Information System (INIS)

Nikolaenko, V.A.; Kovdrya, Yu.Z.; Gladchenko, S.P.

2002-01-01

Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B xx of the conducting channels mainly grows with increasing B for both the electron-gas atom scattering (T > 0.9 K) and the electron-ripplon scattering (T c τ>1(here ω c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron system

Effect of nonlinear wave-particle interaction on electron-cyclotron absorption

Energy Technology Data Exchange (ETDEWEB)

Tsironis, C; Vlahos, L [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

2006-09-15

We perform a self-consistent analysis of the nonlinear interaction of magnetized plasmas with electron-cyclotron (EC) waves. A closed set of equations is derived, which consists of the relativistic equations of motion under the wave field and the wave equation for the vector potential. The plasma is described in terms of ensembles of electrons which collectively determine the evolution of the wave amplitude and frequency through the current response. This description allows for effects of the electron motions on the efficiency of the wave absorption, for example, the asynchrony between the wave phase and the gyroperiod. As an application, we study the absorption of an EC wave beam in a simplified tokamak geometry, for plasma parameters relevant to current and future fusion experiments. We conclude that, within the limits of our model, there are cases where the linear theory for the absorption of EC waves, used widely in the current literature, may overestimate the energy deposition. In such cases, nonlinear effects are essential for the accurate estimation of the plasma-wave coupling and their inclusion should be considered, especially when the wave power is dramatically increased as in the case of ITER.

Effect of nonlinear wave-particle interaction on electron-cyclotron absorption

International Nuclear Information System (INIS)

Tsironis, C; Vlahos, L

2006-01-01

We perform a self-consistent analysis of the nonlinear interaction of magnetized plasmas with electron-cyclotron (EC) waves. A closed set of equations is derived, which consists of the relativistic equations of motion under the wave field and the wave equation for the vector potential. The plasma is described in terms of ensembles of electrons which collectively determine the evolution of the wave amplitude and frequency through the current response. This description allows for effects of the electron motions on the efficiency of the wave absorption, for example, the asynchrony between the wave phase and the gyroperiod. As an application, we study the absorption of an EC wave beam in a simplified tokamak geometry, for plasma parameters relevant to current and future fusion experiments. We conclude that, within the limits of our model, there are cases where the linear theory for the absorption of EC waves, used widely in the current literature, may overestimate the energy deposition. In such cases, nonlinear effects are essential for the accurate estimation of the plasma-wave coupling and their inclusion should be considered, especially when the wave power is dramatically increased as in the case of ITER

Many-body problem in one-dimension

International Nuclear Information System (INIS)

Emery, V.J.

1979-11-01

This work attempts to give a qualitative feeling for the more important physical ideas involved with the study of many-body systems in one dimension, and considers a particular strong-coupling model. This model provides an excellent description of the chains of mercury ions in Hg/sub 3-delta/AsF 6 ; some of the predictions of the theory can be checked by x-ray and neutron diffraction. Much of the physics of nearly one-dimensional materials is concerned with understanding the possible types of phase transition that may take place, and establishing the conditions in which one or another will be predominant. The most significant feature of purely one-dimensional systems is the dominant effect of fluctuations. The paper is organized as follows: introduction; qualitative aspects of one-dimensional systems (general survey, mathematical model, qualitative discussion of strong coupling - strong attractive U, strong repulsive U, large V); strong coupling between parallel spins (independent spin systems, coupling between opposite spins); mercury chains; electrons with arbitrary coupling; boson representations of operators; and classical Coulomb gas

One- or two-electron water oxidation, hydroxyl radical, or H_2O_2 evolution

International Nuclear Information System (INIS)

Siahrostami, Samira; Li, Guo-Ling; Viswanathan, Venkatasubramanian; Nørskov, Jens K.

2017-01-01

Electrochemical or photoelectrochemcial oxidation of water to form hydrogen peroxide (H_2O_2) or hydroxyl radicals (•OH) offers a very attractive route to water disinfection, and the first process could be the basis for a clean way to produce hydrogen peroxide. A major obstacle in the development of effective catalysts for these reactions is that the electrocatalyst must suppress the thermodynamically favored four-electron pathway leading to O_2 evolution. Here, we develop a thermochemical picture of the catalyst properties that determine selectivity toward the one, two, and four electron processes leading to •OH, H_2O_2, and O_2.

One-dimensional versus two-dimensional electronic states in vicinal surfaces

International Nuclear Information System (INIS)

Ortega, J E; Ruiz-Oses, M; Cordon, J; Mugarza, A; Kuntze, J; Schiller, F

2005-01-01

Vicinal surfaces with periodic arrays of steps are among the simplest lateral nanostructures. In particular, noble metal surfaces vicinal to the (1 1 1) plane are excellent test systems to explore the basic electronic properties in one-dimensional superlattices by means of angular photoemission. These surfaces are characterized by strong emissions from free-electron-like surface states that scatter at step edges. Thereby, the two-dimensional surface state displays superlattice band folding and, depending on the step lattice constant d, it splits into one-dimensional quantum well levels. Here we use high-resolution, angle-resolved photoemission to analyse surface states in a variety of samples, in trying to illustrate the changes in surface state bands as a function of d

Resonant tunneling of electrons in quantum wires

International Nuclear Information System (INIS)

Krive, I.V.; Shekhter, R.I.; Jonson, M.; Krive, I.V.

2010-01-01

We considered resonant electron tunneling in various nanostructures including single wall carbon nanotubes, molecular transistors and quantum wires formed in two-dimensional electron gas. The review starts with a textbook description of resonant tunneling of noninteracting electrons through a double-barrier structure. The effects of electron-electron interaction in sequential and resonant electron tunneling are studied by using Luttinger liquid model of electron transport in quantum wires. The experimental aspects of the problem (fabrication of quantum wires and transport measurements) are also considered. The influence of vibrational and electromechanical effects on resonant electron tunneling in molecular transistors is discussed.

Electron beam effects in auger electron spectroscopy and scanning electron microscopy

International Nuclear Information System (INIS)

Fontaine, J.M.; Duraud, J.P.; Le Gressus, C.

1979-01-01

Electron beam effects on Si(100) and 5% Fe/Cr alloy samples have been studied by measurements of the secondary electron yield delta, determination of the surface composition by Auger electron spectroscopy and imaging with scanning electron microscopy. Variations of delta as a function of the accelerating voltage Esub(p) (0.5 -9 Torr has no effect on technological samples covered with their reaction layers; the sensitivities to the beam depend rather on the earlier mechanical, thermal and chemical treatment of the surfaces. (author)

Effective fluid description of the dark universe

Directory of Open Access Journals (Sweden)

M. Cadoni

2018-01-01

Full Text Available We propose an effective anisotropic fluid description for a generic infrared-modified theory of gravity. In our framework, the additional component of the acceleration, commonly attributed to dark matter, is explained as a radial pressure generated by the reaction of the dark energy fluid to the presence of baryonic matter. Using quite general assumptions, and a microscopic description of the fluid in terms of a Bose–Einstein condensate of gravitons, we find the static, spherically symmetric solution for the metric in terms of the Misner–Sharp mass function and the fluid pressure. At galactic scales, we correctly reproduce the leading MOND-like log⁡(r and subleading (1/rlog⁡(r terms in the weak-field expansion of the potential. Our description also predicts a tiny (of order 10−6 for a typical spiral galaxy Machian modification of the Newtonian potential at galactic scales, which is controlled by the cosmological acceleration.

One-electron transfer equilibria and redox potentials of radicals studied by pulse radiolysis

International Nuclear Information System (INIS)

Meisel, D.; Czapski, G.

1975-01-01

The pulse radiolysis technique is utilized for measurements of the equilibrium constants for electron transfer between the durosemiquinone radical anion and oxygen, menadione, and indigodisulfonate. These equilibrium constants are in turn used for calculations of one-electron redox potentials for these systems. Each of these equilibrium constants was determined experimentally and independently and found to be self-consistent. Only for the reactions of the semiquinone radical ions with oxygen could the electron transfer reaction be followed directly. For the reactions between the various quinone-semiquinone systems substantial indirect evidence is presented that these equilibria are achieved rapidly. In those cases equilibrium constants were determined from studies of the effect of quinone concentrations on the relative yields of the semiquinones. A method for distinguishing between kinetic competition and equilibrium is outlined and its usefulness is emphasized. The DQ parallel DQ - (DQ = duroquinone) and IDS parallel IDS - (IDS = indigodisulfonate) systems were employed as reference couples as the redox potentials for those systems are either available in the literature (IDS parallel IDS - ) or may be calculated from available data (DQ parallel DQ - ). Taking E 7 1 , the redox potential for the first one-electron reduction step at pH 7, of DQ parallel DQ - as -0.235 V or of IDS parallelIDS - as -0.247 V both yield E 7 1 = -0.325 V for the O 2 parallel O 2 - system (1 atm of O 2 ) and E 2 1 = -0.20 V for the menadione system. (U.S.)

Effect of electron-photon interaction on the knight shift

International Nuclear Information System (INIS)

Tripathi, G.S.; Misra, C.M.; Tripathi, P.; Misra, P.K.

1990-01-01

The effect of electron-phonon interaction is considered on the spin (K s ), orbital (K o ) and spin-orbit (K so ) contributions to the Knight shift. In case of K s , it is found that the modifications caused due to the magnetic field dependence of electron self-energy in the presence of electron-phonon interaction is cancelled by the electron-phonon mass enhancement. However, in the presence of both electron-electron and electron-phonon interactions, the exchange enhancement parameter α is modified to α(1+γ) -1 where γ is the electron-phonon mass enhancement parameter. The orbital and spin-orbital contributions are mainly modified through the changes in the one-electron energies and wave functions. (orig.)

Effective temperature of an ultracold electron source based on near-threshold photoionization.

Science.gov (United States)

Engelen, W J; Smakman, E P; Bakker, D J; Luiten, O J; Vredenbregt, E J D

2014-01-01

We present a detailed description of measurements of the effective temperature of a pulsed electron source, based on near-threshold photoionization of laser-cooled atoms. The temperature is determined by electron beam waist scans, source size measurements with ion beams, and analysis with an accurate beam line model. Experimental data is presented for the source temperature as a function of the wavelength of the photoionization laser, for both nanosecond and femtosecond ionization pulses. For the nanosecond laser, temperatures as low as 14 ± 3 K were found; for femtosecond photoionization, 30 ± 5 K is possible. With a typical source size of 25 μm, this results in electron bunches with a relative transverse coherence length in the 10⁻⁴ range and an emittance of a few nm rad. © 2013 Elsevier B.V. All rights reserved.

EFFECTIVE ELECTRONIC TUTORIAL

Directory of Open Access Journals (Sweden)

Andrei A. Fedoseev

2014-01-01

Full Text Available The article analyzes effective electronic tutorials creation and application based on the theory of pedagogy. Herewith the issues of necessary electronic tutorial functional, ways of the educational process organization with the use of information and communication technologies and the logistics of electronic educational resources are touched upon. 

Correlated electrons and generalized statistics

International Nuclear Information System (INIS)

Wang, Q.A.

2003-01-01

Several important generalizations of Fermi-Dirac distribution are compared to numerical and experimental results for correlated electron systems. It is found that the quantum distributions based on incomplete information hypothesis can be useful for describing this kind of systems. We show that the additive incomplete fermion distribution gives very good description of weakly correlated electrons and that the non-additive one is suitable to very strong correlated cases. (author)

Quantum-chemical studies of quasi-one-dimensional electron systems. Part 2. Cumulenes and origin of the forbidden zone

Directory of Open Access Journals (Sweden)

Yuriy Kruglyak

2015-06-01

Full Text Available This review is devoted to the basic problem in quantum theory of quasi-one-dimensional electron systems like polyenes (Part 1 and cumulenes (Part 2 – physical origin of the forbidden zone in these and analogous 1D electron systems due to two possible effects – Peierls instability (bond alternation and Mott instability (electron correlation. Both possible contradiction and coexistence of the Mott and Peierls instabilities are summerized on the basis of the Kiev quantum chemistry team research projects.

Electron energy-loss spectroscopy of quasi-one-dimensional cuprates and vanadates

International Nuclear Information System (INIS)

Atzkern, S.

2001-01-01

In a combination of experimental and theoretical methods in this thesis the electronic structures of quasi-one-dimensional cuprates and vanadates were studied. For this the momentum-dependent loss function was measured by means of the electron energy-loss spectroscopy in transmission on monocrystals of Li 2 CuO 2 , CuGeO 3 , V 2 O 5 and α'-NaVO 5 . The comparison of the experimental data with results from band-structure and cluster calculations allowed conclusions on the mobility and correlations of the electrons in these systems

Electron affinities: theoretical

International Nuclear Information System (INIS)

Kaufman, J.J.

1976-01-01

A brief description is given of the conceptual background and formalism of the various ab-initio and semi-ab-initio quantum computational techniques for calculating atomic and molecular electron affinities: Hartree--Fock--Roothaan SCF, configuration interaction (CI), multiconfiguration SCF (MC-SCF), Bethe--Goldstone, superposition of configurations (SOC), ab-initio effective core model potentials, Xα-MS, plus other less common methods. Illustrative and comparative examples of electron affinities calculated by these various methods are presented

Synchronizing a single-electron shuttle to an external drive

Science.gov (United States)

Moeckel, Michael J.; Southworth, Darren R.; Weig, Eva M.; Marquardt, Florian

2014-04-01

The nanomechanical single-electron shuttle is a resonant system in which a suspended metallic island oscillates between and impacts at two electrodes. This setup holds promise for one-by-one electron transport and the establishment of an absolute current standard. While the charge transported per oscillation by the nanoscale island will be quantized in the Coulomb blockade regime, the frequency of such a shuttle depends sensitively on many parameters, leading to drift and noise. Instead of considering the nonlinearities introduced by the impact events as a nuisance, here we propose to exploit the resulting nonlinear dynamics to realize a highly precise oscillation frequency via synchronization of the shuttle self-oscillations to an external signal. We link the established phenomenological description of synchronization based on the Adler equation to the microscopic nonlinear dynamics of the electron shuttle by calculating the effective Adler constant analytically in terms of the microscopic parameters.

Synchronizing a single-electron shuttle to an external drive

International Nuclear Information System (INIS)

Moeckel, Michael J; Southworth, Darren R; Weig, Eva M; Marquardt, Florian

2014-01-01

The nanomechanical single-electron shuttle is a resonant system in which a suspended metallic island oscillates between and impacts at two electrodes. This setup holds promise for one-by-one electron transport and the establishment of an absolute current standard. While the charge transported per oscillation by the nanoscale island will be quantized in the Coulomb blockade regime, the frequency of such a shuttle depends sensitively on many parameters, leading to drift and noise. Instead of considering the nonlinearities introduced by the impact events as a nuisance, here we propose to exploit the resulting nonlinear dynamics to realize a highly precise oscillation frequency via synchronization of the shuttle self-oscillations to an external signal. We link the established phenomenological description of synchronization based on the Adler equation to the microscopic nonlinear dynamics of the electron shuttle by calculating the effective Adler constant analytically in terms of the microscopic parameters

Electron-electron collision effects on the bremsstrahlung emission in Lorentzian plasmas

International Nuclear Information System (INIS)

Jung, Young-Dae; Kato, Daiji

2009-01-01

Electron-electron collision effects on the electron-ion bremsstrahlung process are investigated in Lorentzian plasmas. The effective electron-ion interaction potential is obtained by including the far-field terms caused by electron-electron collisions with an effective Debye length in Lorentzian plasmas. The bremsstrahlung radiation cross section is obtained as a function of the electron energy, photon energy, collision frequency, spectral index and Debye length using the Born approximation for the initial and final states of the projectile electron. It is shown that the non-Maxwellian character suppresses the bremsstrahlung radiation cross section. It is also shown that the electron-electron collision effect enhances the bremsstrahlung emission spectrum. In addition, the bremsstrahlung radiation cross section decreases with an increase in the plasma temperature.

Radiation effects on relativistic electrons in strong external fields

International Nuclear Information System (INIS)

Iqbal, Khalid

2013-01-01

The effects of radiation of high energy electron beams are a major issue in almost all types of charged particle accelerators. The objective of this thesis is both the analytical and numerical study of radiation effects. Due to its many applications the study of the self force has become a very active and productive field of research. The main part of this thesis is devoted to the study of radiation effects in laser-based plasma accelerators. Analytical models predict the existence of radiation effects. The investigation of radiation reaction show that in laser-based plasma accelerators, the self force effects lower the energy gain and emittance for moderate energies electron beams and increase the relative energy spread. However, for relatively high energy electron beams, the self radiation and retardation (radiation effects of one electron on the other electron of the system) effects increase the transverse emittance of the beam. The energy gain decreases to even lower value and relative energy spread increases to even higher value due to high radiation losses. The second part of this thesis investigates with radiation reaction in focused laser beams. Radiation effects are very weak even for high energy electrons. The radiation-free acceleration and the simple practical setup make direct acceleration in a focused laser beam very attractive. The results presented in this thesis can be helpful for the optimization of future electron acceleration experiments, in particular in the case of laser-plasma accelerators.

Electron linacs

International Nuclear Information System (INIS)

Loew, G.A.

1976-01-01

To study the present status of the thousand or so electron linacs in the world, and future trends in the field, we have classified these machines according to their use: medical, industrial, and nuclear physics. In the medical category, two types of electron linacs are discussed: the conventional ones which are used for X-ray and electron therapy, and those which may in the future be used for negative pion therapy. The section on industrial machines includes linacs for radiographic and other specialized applications. In the nuclear physics category, the status of conventional low- and medium-energy as well as high duty cycle linacs is reviewed. The question of how one might obtain a C.W., 1 GeV, 100 μA electron linac is raised and various options using recirculation and stretchers are examined. In this connection, the status of RF superconductivity is summarized. Following, there is a review of linacs for injectors into synchrotrons and e +- storage rings. The paper ends with a description of recent work done to upgrade the only multi-GeV linac, namely SLAC. (author)

Electron Fluid Description of Wave-Particle Interactions in Strong Buneman Turbulence

Science.gov (United States)

Che, Haihong

2013-10-01

To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation associated with electron heating in Buneman instability. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions can be described by a set of electron fluid equations. These equations show that the energy dissipation and momentum transports in Buneman instability are locally quasi-static but globally non-static and irreversible. Turbulence drag dissipates both the bulk energy of electron streams and the associated magnetic energy. The decrease of magnetic field maintains an inductive electric field that re-accelerates electrons. The net loss of streaming energy is converted into electron heat and increases the electron Boltzmann entropy. The growth of self-sustained Buneman waves satisfies a Bernoulli-like equation which relates the turbulence-induced convective momentum transport and thermal momentum transport. Electron trapping and de-trapping drives local momentum transports, while phase mixing converts convective momentum into thermal momentum.These two local momentum transports sustain the Buneman waves and act as the micro-macro link in the anomalous heating process. This research is supported by the NASA Postdoctoral Program at NASA/GSFC administered by Oak Ridge Associated Universities through a contract with NASA.

Effective one-body potential of DFT plus correlated kinetic energy density for two-electron spherical model atoms

International Nuclear Information System (INIS)

March, N.H.; Ludena, Eduardo V.

2004-01-01

For three model problems concerning two-electron spin-compensated ground states with spherical density, the third-order linear homogeneous differential equation constructed for the determination of ρ(r) is used here in conjunction with the von Weizsacker functional to characterize the one-body potential of density functional theory (DFT). Correlated von Weizsacker-type terms are compared to the exact DFT functional

Proceedings of eighth joint workshop on electron cyclotron emission and electron cyclotron resonance heating. Vol. 1

International Nuclear Information System (INIS)

1993-03-01

The theory of electron cyclotron resonance phenomena is highly developed. The main theoretical tools are well established, generally accepted and able to give a satisfactory description of the main results obtained in electron cyclotron emission, absorption and current drive experiments. In this workshop some advanced theoretical and numerical tools have been presented (e.g., 3-D Fokker-Planck codes, treatment of the r.f. beam as a whole, description of non-linear and finite-beam effects) together with the proposal for new scenarios for ECE and ECA measurements (e.g., for diagnosing suprathermal populations and their radial transport). (orig.)

Proceedings of eighth joint workshop on electron cyclotron emission and electron cyclotron resonance heating. Vol. 2

International Nuclear Information System (INIS)

1993-03-01

The theory of electron cyclotron resonance phenomena is highly developed. The main theoretical tools are well established, generally accepted and able to give a satisfactory description of the main results obtained in electron cyclotron emission, absorption and current drive experiments. In this workshop some advanced theoretical and numerical tools have been presented (e.g., 3-D Fokker-Planck codes, treatment of the r.f. beam as a whole, description of non-linear and finite-beam effects) together with the proposal for new scenarios for ECE and ECA measurements (e.g., for diagnosing suprathermal populations and their radial transport). (orig.)

The effect of intramolecular quantum modes on free energy relationships for electron transfer reactions

DEFF Research Database (Denmark)

Ulstrup, Jens; Jortner, Joshua

1975-01-01

A general quantum mechanical description of exothermic electron transfer reactions is formulated by treating such reactions as the nonradiative decay of a ''supermolecule'' consisting of the electron donor, the electron acceptor, and the polar solvent. In particular, the role of the high-frequenc...

Viral Etiology of Encephalitis in Children in Southern Vietnam: Results of a One-Year Prospective Descriptive Study

NARCIS (Netherlands)

Tan, L.V.; Qui, P.T.; Ha, D.Q.; Hue, N.B.; Bao, L.Q.; Cam, B.V.; Khanh, T.H.; Hien, T.T.; Chau, N.V.V.; Tram, T.T.; Hien, V.M.; Nga, T.V.T.; Schultsz, C.; Farrar, J.; van Doorn, H.R.; de Jong, M.D.

2010-01-01

Background: Acute encephalitis is an important and severe disease in children in Vietnam. However, little is known about the etiology while such knowledge is essential for optimal prevention and treatment. To identify viral causes of encephalitis, in 2004 we conducted a one-year descriptive study at

COMPUTATIONAL ELECTROCHEMISTRY: AQUEOUS ONE-ELECTRON OXIDATION POTENTIALS FOR SUBSTITUTED ANILINES

Science.gov (United States)

Semiempirical molecular orbital theory and density functional theory are used to compute one-electron oxidation potentials for aniline and a set of 21 mono- and di-substituted anilines in aqueous solution. Linear relationships between theoretical predictions and experiment are co...

Effects of non-local electron transport in one-dimensional and two-dimensional simulations of shock-ignited inertial confinement fusion targets

Energy Technology Data Exchange (ETDEWEB)

Marocchino, A.; Atzeni, S.; Schiavi, A. [Dipartimento SBAI, Università di Roma “La Sapienza” and CNISM, Roma 00161 (Italy)

2014-01-15

In some regions of a laser driven inertial fusion target, the electron mean-free path can become comparable to or even longer than the electron temperature gradient scale-length. This can be particularly important in shock-ignited (SI) targets, where the laser-spike heated corona reaches temperatures of several keV. In this case, thermal conduction cannot be described by a simple local conductivity model and a Fick's law. Fluid codes usually employ flux-limited conduction models, which preserve causality, but lose important features of the thermal flow. A more accurate thermal flow modeling requires convolution-like non-local operators. In order to improve the simulation of SI targets, the non-local electron transport operator proposed by Schurtz-Nicolaï-Busquet [G. P. Schurtz et al., Phys. Plasmas 7, 4238 (2000)] has been implemented in the DUED fluid code. Both one-dimensional (1D) and two-dimensional (2D) simulations of SI targets have been performed. 1D simulations of the ablation phase highlight that while the shock profile and timing might be mocked up with a flux-limiter; the electron temperature profiles exhibit a relatively different behavior with no major effects on the final gain. The spike, instead, can only roughly be reproduced with a fixed flux-limiter value. 1D target gain is however unaffected, provided some minor tuning of laser pulses. 2D simulations show that the use of a non-local thermal conduction model does not affect the robustness to mispositioning of targets driven by quasi-uniform laser irradiation. 2D simulations performed with only two final polar intense spikes yield encouraging results and support further studies.

Effects of non-local electron transport in one-dimensional and two-dimensional simulations of shock-ignited inertial confinement fusion targets

International Nuclear Information System (INIS)

Marocchino, A.; Atzeni, S.; Schiavi, A.

2014-01-01

In some regions of a laser driven inertial fusion target, the electron mean-free path can become comparable to or even longer than the electron temperature gradient scale-length. This can be particularly important in shock-ignited (SI) targets, where the laser-spike heated corona reaches temperatures of several keV. In this case, thermal conduction cannot be described by a simple local conductivity model and a Fick's law. Fluid codes usually employ flux-limited conduction models, which preserve causality, but lose important features of the thermal flow. A more accurate thermal flow modeling requires convolution-like non-local operators. In order to improve the simulation of SI targets, the non-local electron transport operator proposed by Schurtz-Nicolaï-Busquet [G. P. Schurtz et al., Phys. Plasmas 7, 4238 (2000)] has been implemented in the DUED fluid code. Both one-dimensional (1D) and two-dimensional (2D) simulations of SI targets have been performed. 1D simulations of the ablation phase highlight that while the shock profile and timing might be mocked up with a flux-limiter; the electron temperature profiles exhibit a relatively different behavior with no major effects on the final gain. The spike, instead, can only roughly be reproduced with a fixed flux-limiter value. 1D target gain is however unaffected, provided some minor tuning of laser pulses. 2D simulations show that the use of a non-local thermal conduction model does not affect the robustness to mispositioning of targets driven by quasi-uniform laser irradiation. 2D simulations performed with only two final polar intense spikes yield encouraging results and support further studies

Effects of non-local electron transport in one-dimensional and two-dimensional simulations of shock-ignited inertial confinement fusion targets

Science.gov (United States)

Marocchino, A.; Atzeni, S.; Schiavi, A.

2014-01-01

In some regions of a laser driven inertial fusion target, the electron mean-free path can become comparable to or even longer than the electron temperature gradient scale-length. This can be particularly important in shock-ignited (SI) targets, where the laser-spike heated corona reaches temperatures of several keV. In this case, thermal conduction cannot be described by a simple local conductivity model and a Fick's law. Fluid codes usually employ flux-limited conduction models, which preserve causality, but lose important features of the thermal flow. A more accurate thermal flow modeling requires convolution-like non-local operators. In order to improve the simulation of SI targets, the non-local electron transport operator proposed by Schurtz-Nicolaï-Busquet [G. P. Schurtz et al., Phys. Plasmas 7, 4238 (2000)] has been implemented in the DUED fluid code. Both one-dimensional (1D) and two-dimensional (2D) simulations of SI targets have been performed. 1D simulations of the ablation phase highlight that while the shock profile and timing might be mocked up with a flux-limiter; the electron temperature profiles exhibit a relatively different behavior with no major effects on the final gain. The spike, instead, can only roughly be reproduced with a fixed flux-limiter value. 1D target gain is however unaffected, provided some minor tuning of laser pulses. 2D simulations show that the use of a non-local thermal conduction model does not affect the robustness to mispositioning of targets driven by quasi-uniform laser irradiation. 2D simulations performed with only two final polar intense spikes yield encouraging results and support further studies.

Industrial application of electron sources with plasma emitters

CERN Document Server

Belyuk, S I; Rempe, N G

2001-01-01

Paper contains a description, operation, design and parameters of electron sources with plasma emitters. One presents examples of application of these sources as part of automated electron-beam welding lines. Paper describes application of such sources for electron-beam deposition of composite powders. Electron-beam deposition is used to rebuild worn out part and to increase strength of new parts of machines and tools. Paper presents some examples of rebuilding part and the advantages gained in this case

Dynamic mapping of EDDL device descriptions to OPC UA

Science.gov (United States)

Atta Nsiah, Kofi; Schappacher, Manuel; Sikora, Axel

2017-07-01

OPC UA (Open Platform Communications Unified Architecture) is already a well-known concept used widely in the automation industry. In the area of factory automation, OPC UA models the underlying field devices such as sensors and actuators in an OPC UA server to allow connecting OPC UA clients to access device-specific information via a standardized information model. One of the requirements of the OPC UA server to represent field device data using its information model is to have advanced knowledge about the properties of the field devices in the form of device descriptions. The international standard IEC 61804 specifies EDDL (Electronic Device Description Language) as a generic language for describing the properties of field devices. In this paper, the authors describe a possibility to dynamically map and integrate field device descriptions based on EDDL into OPCUA.

Electron Effective-Attenuation-Length Database

Science.gov (United States)

SRD 82 NIST Electron Effective-Attenuation-Length Database (PC database, no charge)   This database provides values of electron effective attenuation lengths (EALs) in solid elements and compounds at selected electron energies between 50 eV and 2,000 eV. The database was designed mainly to provide EALs (to account for effects of elastic-eletron scattering) for applications in surface analysis by Auger-electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS).

Damping of acoustic flexural phonons in silicene: influence on high-field electronic transport

Science.gov (United States)

Rengel, Raúl; Iglesias, José M.; Mokhtar Hamham, El; Martín, María J.

2018-06-01

Silicene is a two-dimensional buckled material with broken horizontal mirror symmetry and Dirac-like dispersion. Under such conditions, flexural acoustic (ZA) phonons play a dominant role. Consequently, it is necessary to consider some suppression mechanism for electron–phonon interactions with long wavelengths in order to reach mobilities useful for electronic applications. In this work, we analyze, by means of an ensemble Monte Carlo simulator, the influence of several possibilities for the description of the effect of ZA phonon damping on electronic transport in silicene. The results show that a hard cutoff situation (total suppression for phonons with a wavelength longer than a critical one), as it has been proposed in the literature, does not yield a realistic picture regarding the electronic distribution function, and it artificially induces a negative differential resistance at moderate and high fields. Sub-parabolic dispersions, on the other hand, may provide a more realistic description in terms of the behavior of the electron distribution in the momentum space, but need extremely short cutoff wavelengths to reach functional mobility and drift velocity values.

Application of nonlinear models to estimate the gain of one-dimensional free-electron lasers

Science.gov (United States)

Peter, E.; Rizzato, F. B.; Endler, A.

2017-06-01

In the present work, we make use of simplified nonlinear models based on the compressibility factor (Peter et al., Phys. Plasmas, vol. 20 (12), 2013, 123104) to predict the gain of one-dimensional (1-D) free-electron lasers (FELs), considering space-charge and thermal effects. These models proved to be reasonable to estimate some aspects of 1-D FEL theory, such as the position of the onset of mixing, in the case of a initially cold electron beam, and the position of the breakdown of the laminar regime, in the case of an initially warm beam (Peter et al., Phys. Plasmas, vol. 21 (11), 2014, 113104). The results given by the models are compared to wave-particle simulations showing a reasonable agreement.

Electron localization in one-dimensional systems

International Nuclear Information System (INIS)

Chao, K.A.

1984-01-01

The pure regional localization and the global localization have been investigated via the inverse participation ratio and te moment analysis. If the envelop function of a localized state is more complicated than the simple exponential function e sup(-r/xi), the inverse participation ratio is inadequate to describe the localization properties of an electron. This is the case discovered recently in a stereo-irregular chain fo atoms including the electron-electron interaction and the structure disorder. The localization properties in this system are analysed in terms of the moments. (Author) [pt

Electronics all-in-one for dummies

CERN Document Server

Lowe, Doug

2011-01-01

Take your electronics skills to the next level! If you're looking for a solitary resource that covers everything you need to know about electronics, then look no further. This friendly-and-straightforward guide introduces the basics of electronics and enhances your learning experience by debunking and explaining concepts such as circuits, analog and digital, schematics, voltage, safety concerns, and more. Packed with nearly 900 pages of detailed information, this book shows you how to develop your own breadboard, design your own circuit, and get savvy with schematics. Cover

A multi-frequency approach to free electron lasers driven by short electron bunches

International Nuclear Information System (INIS)

Piovella, Nicola

1997-01-01

A multi-frequency model for free electron lasers (FELs), based on the Fourier decomposition of the radiation field coupled with the beam electrons, is discussed. We show that the multi-frequency approach allows for an accurate description of the evolution of the radiation spectrum, also when the FEL is driven by short electron bunches, of arbitrary longitudinal profile. We derive from the multi-frequency model, by averaging over one radiation period, the usual FEL equations modelling the slippage between radiation and particles and describing the super-radiant regime in high-gain FELs. As an example of application of the multi-frequency model, we discuss the coherent spontaneous emission (CSE) from short electron bunches

Week Long Topography Study of Young Adults Using Electronic Cigarettes in Their Natural Environment.

Science.gov (United States)

Robinson, R J; Hensel, E C; Roundtree, K A; Difrancesco, A G; Nonnemaker, J M; Lee, Y O

2016-01-01

Results of an observational, descriptive study quantifying topography characteristics of twenty first generation electronic nicotine delivery system users in their natural environment for a one week observation period are presented. The study quantifies inter-participant variation in puffing topography between users and the intra-participant variation for each user observed during one week of use in their natural environment. Puff topography characteristics presented for each user include mean puff duration, flow rate and volume for each participant, along with descriptive statistics of each quantity. Exposure characteristics including the number of vaping sessions, total number of puffs and cumulative volume of aerosol generated from ENDS use (e-liquid aerosol) are reported for each participant for a one week exposure period and an effective daily average exposure. Significant inter-participant and intra-participant variation in puff topography was observed. The observed range of natural use environment characteristics is used to propose a set of topography protocols for use as command inputs to drive machine-puffed electronic nicotine delivery systems in a controlled laboratory environment.

Week Long Topography Study of Young Adults Using Electronic Cigarettes in Their Natural Environment.

Directory of Open Access Journals (Sweden)

R J Robinson

Full Text Available Results of an observational, descriptive study quantifying topography characteristics of twenty first generation electronic nicotine delivery system users in their natural environment for a one week observation period are presented. The study quantifies inter-participant variation in puffing topography between users and the intra-participant variation for each user observed during one week of use in their natural environment. Puff topography characteristics presented for each user include mean puff duration, flow rate and volume for each participant, along with descriptive statistics of each quantity. Exposure characteristics including the number of vaping sessions, total number of puffs and cumulative volume of aerosol generated from ENDS use (e-liquid aerosol are reported for each participant for a one week exposure period and an effective daily average exposure. Significant inter-participant and intra-participant variation in puff topography was observed. The observed range of natural use environment characteristics is used to propose a set of topography protocols for use as command inputs to drive machine-puffed electronic nicotine delivery systems in a controlled laboratory environment.

Electron beam-cured coating

International Nuclear Information System (INIS)

Kishi, Naoyuki

1976-01-01

The method for hardening coatings by the irradiation with electron beams is reviewed. The report is divided into seven parts, namely 1) general description and characteristics of electron beam-cured coating, 2) radiation sources of curing, 3) hardening conditions and reaction behaviour, 4) uses and advantages, 5) latest trends of the industry, 6) practice in the field of construction materials, and 7) economy. The primary characteristics of the electron beam hardening is that graft reaction takes place between base resin and coating to produce strong adhesive coating without any pretreatment. A variety of base resins are developed. High class esters of acrylic acid monomers and methacrylic acid monomers are mainly used as dilutants recently. At present, scanning type accelerators are used, but the practical application of the system producing electron beam of curtain type is expected. The dose rate dependence, the repetitive irradiation and the irradiation atmosphere are briefly described. The filed patent applications on the electron beam hardening were analyzed by the officer of Japan Patent Agency. The production lines for coatings by the electron beam hardening in the world are listed. In the electron beam-cured coating, fifty percent of given energy is consumed effectively for the electron beam hardening, and the solvents discharged from ovens and polluting atmosphere are not used, because the paints of high solid type is used. The running costs of the electron beam process are one sixth of the thermal oven process. (Iwakiri, K.)

Partial vs. integer electron transfer in molecular assemblies: On the importance of multideterminant theoretical description and the necessity to find a solution within DFT

Energy Technology Data Exchange (ETDEWEB)

Geskin, Victor; Cornil, Jérôme [Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, B-7000 Mons (Belgium); Stadler, Robert [Department of Physical Chemistry, University of Vienna, Sensengasse 8/7, A-1090 Vienna (Austria)

2015-01-22

Nonequilibrium Green's function techniques (NEGF) combined with density functional theory (DFT) calculations have become a standard tool for the description of electron transport through single molecule nanojunctions in the coherent tunneling (CT) regime. However, the applicability of these methods for transport in the Coulomb blockade (CB) regime is questionable. For a molecular assembly model, with multideterminant calculations as a benchmark, we show how a closed-shell ansatz, the usual ingredient of mean-field methods, fails to properly describe the step like electron-transfer characteristic in weakly coupled systems. Detailed analysis of this misbehavior allows us to propose a practical scheme to extract the addition energies in the CB regime for single-molecule junctions from NEGF DFT within the local-density approximation (closed shell). We show also that electrostatic screening effects are taken into account within this simple approach.

Unified description of perturbation theory and band center anomaly in one-dimensional Anderson localization

International Nuclear Information System (INIS)

Kang, Kai; Qin, Shaojing; Wang, Chuilin

2011-01-01

We calculated numerically the localization length of one-dimensional Anderson model with diagonal disorder. For weak disorder, we showed that the localization length changes continuously as the energy changes from the band center to the boundary of the anomalous region near the band edge. We found that all the localization lengths for different disorder strengths and different energies collapse onto a single curve, which can be fitted by a simple equation. Thus the description of the perturbation theory and the band center anomaly were unified into this equation. -- Highlights: → We study the band center anomaly of one-dimensional Anderson localization. → We study numerically the Lyapunov exponent through a parametrization method of the transfer matrix. → We give a unified equation to describe the band center anomaly and perturbation theory.

Effect of the hydrostatic pressure on the electron mobility in delta-doped systems

Energy Technology Data Exchange (ETDEWEB)

Oubram, O; Mora-Ramos, M E; Gaggero-Sager, L M, E-mail: 1gaggero@uaem.m [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico)

2009-05-01

The influence of hydrostatic pressure on the electron states and low-temperature mobility in n-type GaAs delta-doped single quantum wells is studied. Values of hydrostatic pressure consider are below the so-called GAMMA-X crossover, keeping all attention in the electronic properties at the Brillouin zone center. The effect of the pressure on the electron mobility is described via a relative quantity that is proportional to the ratio between P not = 0 and zero pressure results. Calculation is performed using an analytical description of the potential energy function profile, based on the Thomas-Fermi approach, taking explicitly into account the dependence upon P of the main input parameters: effective masses and dielectric constant. The relative mobility increases for higher values of P. The cases of zero and finite -although small- temperature are studied, showing that the influence of T is mainly to lower the values of the relative mobility in the entire range of P considered. Numerical results are reported for a two-dimensional density of ionized impurities equals to 7.5 x 10{sup 12} cm{sup -2}.

Sideband instability analysis based on a one-dimensional high-gain free electron laser model

Science.gov (United States)

Tsai, Cheng-Ying; Wu, Juhao; Yang, Chuan; Yoon, Moohyun; Zhou, Guanqun

2017-12-01

When an untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. The FEL radiation power or efficiency can be increased by undulator tapering. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation where the FEL power growth stops even with a tapered undulator system. The sideband instability is one of the primary reasons leading to this second saturation. In this paper, we provide a quantitative analysis on how the gradient of undulator tapering can mitigate the sideband growth. The study is carried out semianalytically and compared with one-dimensional numerical simulations. The physical parameters are taken from Linac Coherent Light Source-like electron bunch and undulator systems. The sideband field gain and the evolution of the radiation spectra for different gradients of undulator tapering are examined. It is found that a strong undulator tapering (˜10 %) provides effective suppression of the sideband instability in the postsaturation regime.

Effective International Medical Disaster Relief: A Qualitative Descriptive Study.

Science.gov (United States)

Broby, Nicolette; Lassetter, Jane H; Williams, Mary; Winters, Blaine A

2018-04-01

Purpose The aim of this study was to assist organizations seeking to develop or improve their medical disaster relief effort by identifying fundamental elements and processes that permeate high-quality, international, medical disaster relief organizations and the teams they deploy. A qualitative descriptive design was used. Data were gathered from interviews with key personnel at five international medical response organizations, as well as during field observations conducted at multiple sites in Jordan and Greece, including three refugee camps. Data were then reviewed by the research team and coded to identify patterns, categories, and themes. The results from this qualitative, descriptive design identified three themes which were key characteristics of success found in effective, well-established, international medical disaster relief organizations. These characteristics were first, ensuring an official invitation had been extended and the need for assistance had been identified. Second, the response to that need was done in an effective and sustainable manner. Third, effective organizations strived to obtain high-quality volunteers. By following the three key characteristics outlined in this research, organizations are more likely to improve the efficiency and quality of their work. In addition, they will be less likely to impede the overall recovery process. Broby N , Lassetter JH , Williams M , Winters BA . Effective international medical disaster relief: a qualitative descriptive study. Prehosp Disaster Med. 2018;33(2):119-126.

Relativistic description of atomic nuclei

International Nuclear Information System (INIS)

Krutov, V.A.

1985-01-01

Papers on the relativistic description of nuclei are reviewed. The Brown and Rho ''small'' bag'' model is accepted for hardrons. Meson exchange potentials of the nucleon-nucleon interaction have been considered. Then the transition from a system of two interacting nucleons has been performed to the relativistic nucleus description as a multinucleon system on the basis of OBEP (one-boson exchange potential). The proboem of OPEP (one-pion-exchange potential) inclusion to a relativistic scheme is discussed. Simplicity of calculations and attractiveness of the Walecka model for specific computations and calculations was noted. The relativistic model of nucleons interacting through ''effective'' scalar and vector boson fields was used in the Walacka model for describing neutronaand nuclear mater matters

The Self-Regulation Effect of Fertility Status on Inbreeding Aversion: When Fertile, Disgust Increases more in Response to Descriptions of One's Own than of Others' Inbreeding

Directory of Open Access Journals (Sweden)

Jan Antfolk

2014-07-01

Full Text Available The ovulatory shift modulates emotions related to female sexuality. Because fertility status only affects the individual's own opportunity cost, the adaptive value of this shift is expected to stem from self-regulation. To test this assumption we asked women to contemplate various inbreeding descriptions: 1 they themselves having sex with male relatives; 2 their sister having sex with their common male relatives; and 3 an unrelated woman having sex with her male relatives (in 1, but not 2 and 3, negative fitness consequences are affected by the participant's fertility. We dichotomized the dependent variable disgust (ceiling vs. non-ceiling and analyzed the interaction between fertility status and description type. The ovulatory shift was stronger in descriptions where they themselves were described as engaging in inbreeding. A smaller increase was also found in reactions to others engaging in inbreeding. We explain the latter effect as due to self-reflection.

Phenomenological description of anisotropy effects in some ferromagnetic superconductors

Energy Technology Data Exchange (ETDEWEB)

Shopova, Diana V., E-mail: sho@issp.bas.bg [TCCM Research Group, Institute of Solid State Physics, Bulgarian Academy of Sciences, BG-1784 Sofia (Bulgaria); Todorov, Michail D. [Department of Applied Mathematics and Computer Science, Technical University of Sofia, 1000 Sofia (Bulgaria)

2015-07-03

We study phenomenologically the role of anisotropy in ferromagnetic superconductors UGe{sub 2}, URhGe, and UCoGe for the description of their phase diagrams. We use the Ginzburg–Landau free energy in its uniform form as we will consider only spatially independent solutions. This is an expansion of previously derived results where the effect of Cooper-pair and crystal anisotropies is not taken into account. The three compounds are separately discussed with the special stress on UGe{sub 2}. The main effect comes from the strong uniaxial anisotropy of magnetization while the anisotropy of Cooper pairs and crystal anisotropy only slightly change the phase diagram in the vicinity of Curie temperature. The limitations of this approach are also discussed. - Highlights: • Anisotropic Landau energy for description of ferromagnetic superconductors is proposed. • Meissner phases are described with their existence and stability conditions. • The application of the model to UGe{sub 2} is discussed. • The limitations to apply the model for description of experimental data are explained.

States of the electron in hydrocarbon liquids

International Nuclear Information System (INIS)

Mozumder, A.

2005-01-01

Some features of the stationary and dynamic states of the electron are critically examined. Outline of a quantum mechanical description of electron thermalization is attempted qualitatively. The effects of both the mean free path and the reaction inefficiency on electron-ion geminate escape probability are investigated by a recently developed Metropolis method. The trapped state is interpreted in terms of Anderson localization, yielding an approximate number of molecules interacting with the trapped electron

Electronic structure and transport properties of quasi-one-dimensional carbon nanomaterials

Directory of Open Access Journals (Sweden)

Y. N. Wu

2017-09-01

Full Text Available Based on the density functional theory combined with the nonequilibrium Green’s function, the influence of the wrinkle on the electronic structures and transport properties of quasi-one-dimensional carbon nanomaterials have been investigated, in which the wrinkled armchair graphene nanoribbons (wAGNRs and the composite of AGNRs and single walled carbon nanotubes (SWCNTs were considered with different connection of ripples. The wrinkle adjusts the electronic structures and transport properties of AGNRs. With the change of the strain, the wAGNRs for three width families reveal different electrical behavior. The band gap of AGNR(6 increases in the presence of the wrinkle, which is opposite to that of AGNR(5 and AGNR(7. The transport of AGNRs with the widths 6 or 7 has been modified by the wrinkle, especially by the number of isolated ripples, but it is insensitive to the strain. The nanojunctions constructed by AGNRs and SWCNTs can form the quantum wells, and some specific states are confined in wAGNRs. Although these nanojunctions exhibit the metallic, they have poor conductance due to the wrinkle. The filling of C20 into SWCNT has less influence on the electronic structure and transport of the junctions. The width and connection type of ripples have greatly influenced on the electronic structures and transport properties of quasi-one-dimensional nanomaterials.

Electronic structure and transport properties of quasi-one-dimensional carbon nanomaterials

Science.gov (United States)

Wu, Y. N.; Cheng, P.; Wu, M. J.; Zhu, H.; Xiang, Q.; Ni, J.

2017-09-01

Based on the density functional theory combined with the nonequilibrium Green's function, the influence of the wrinkle on the electronic structures and transport properties of quasi-one-dimensional carbon nanomaterials have been investigated, in which the wrinkled armchair graphene nanoribbons (wAGNRs) and the composite of AGNRs and single walled carbon nanotubes (SWCNTs) were considered with different connection of ripples. The wrinkle adjusts the electronic structures and transport properties of AGNRs. With the change of the strain, the wAGNRs for three width families reveal different electrical behavior. The band gap of AGNR(6) increases in the presence of the wrinkle, which is opposite to that of AGNR(5) and AGNR(7). The transport of AGNRs with the widths 6 or 7 has been modified by the wrinkle, especially by the number of isolated ripples, but it is insensitive to the strain. The nanojunctions constructed by AGNRs and SWCNTs can form the quantum wells, and some specific states are confined in wAGNRs. Although these nanojunctions exhibit the metallic, they have poor conductance due to the wrinkle. The filling of C20 into SWCNT has less influence on the electronic structure and transport of the junctions. The width and connection type of ripples have greatly influenced on the electronic structures and transport properties of quasi-one-dimensional nanomaterials.

Effects of Thermal Resistance on One-Dimensional Thermal Analysis of the Epidermal Flexible Electronic Devices Integrated with Human Skin

Science.gov (United States)

Li, He; Cui, Yun

2017-12-01

Nowadays, flexible electronic devices are increasingly used in direct contact with human skin to monitor the real-time health of human body. Based on the Fourier heat conduction equation and Pennes bio-heat transfer equation, this paper deduces the analytical solutions of one - dimensional heat transfer for flexible electronic devices integrated with human skin under the condition of a constant power. The influence of contact thermal resistance between devices and skin is considered as well. The corresponding finite element model is established to verify the correctness of analytical solutions. The results show that the finite element analysis agrees well with the analytical solution. With bigger thermal resistance, temperature increase of skin surface will decrease. This result can provide guidance for the design of flexible electronic devices to reduce the negative impact that exceeding temperature leave on human skin.

Transient state of electron transport in semiconductors: over velocity and ballistic effect

International Nuclear Information System (INIS)

Laval, S.

1984-01-01

As the dimensions of the active regions of electronic components are reduced, transient effects must be considered when electrons encounter a high electric field gradient. The electron velocity can overshoot its stationary value over a few tenths of a micron and during about one picosecond. This has been observed experimentally and permits to forecast new ultrafast electronic devices [fr

Effects of one-loop corrections in the Weinberg-Salam theory

International Nuclear Information System (INIS)

Bardin, D.Y.; Fedorenko, O.M.; Christova, P.C.

1982-01-01

We have studied the one-loop effects in the Weinberg-Salam theory in the natural renormalization scheme which we have generalized to the case of an arbitrary unitary mixing of the fermion fields. We have discussed in detail the problems which are connected with carrying out the renormalization program in the Weinberg-Salam theory. We have calculated the masses of the W and Z bosons. We present a description of the finite renormalizations which relate to each other the three definitions of the Weinberg parameter sin 2 theta/sub W/

The Quasi-Electron Shell Structure of the Fractional Quantum Hall Effect

Science.gov (United States)

Haxton, Wick; Haxton, Daniel

2015-04-01

The fractional quantum Hall effect (FQHE) formulated on a sphere resembles the nuclear shell model, with the desired translationally invariant states having total angular momentum zero. This property was exploited by Ginocchio and Haxton (GH) to derive a new set of scalar operators and a first-Landau-level representation of the full set of hierarchy states (fillings 1/3, 2/5, 3/7, etc.), with overlaps identical to those of Jain, who used unphysical higher Landau levels excitations followed by numerical projection. We demonstrate that the GH operators produce an appealing description of the FQHE as shells filled by non-interacting quasi-electrons, or composite fermions. These are explicitly constructed, and their planar forms are also found. The evolution of the shells and their quasi-electrons is quite unusual. The connections with electron correlations and Laughlin's variational arguments are described. We discuss how ``new states'' found experimentally at fillings such as 4/11 and 5/13 fit into this scheme. Work support in part by the US DOE Offices of Nuclear Physics and Basic Energy Sciences.

Charge transfer in quasi-one-electron systems at 'high' energy

Energy Technology Data Exchange (ETDEWEB)

Gay, T.J.; Redd, E.; Blankenship, D.M.; Park, J.T.; Peacher, J.L.; Seeley, D.G.

1988-08-14

We have made absolute and relative measurements of differential cross sections for single-electron transfer in collisions between Mg/sup +/ (30-150 keV) and Be/sup +/ (56.25 keV) ions and He atoms. The behaviour of transfer probability as a function of impact parameter can be understood qualitatively from recent molecular orbital calculations of quasi-one-electron systems.

Kinetic description of self-field effects on laser and betatron emission in wiggler-pumped ion-channel free electron lasers

International Nuclear Information System (INIS)

Alimohamadi, M; Mehdian, H; Hasanbeigi, A

2011-01-01

The effects of self-fields on the free electron lasers (FELs) with a helical wiggler and ion-channel guiding are considered. The steady-state orbits for a single electron in this configuration are obtained. The rate of change of axial velocity with energy, the characteristic function Φ, is derived and studied numerically. A kinetic approach has been used to get the effects of self-field on the FEL and betatron gain formula in the low-gain-pre-pass limit. It is shown that betatron gain is smaller than FEL gain. We also found a gain decrement (enhancement), arising from diamagnetism (paramagnetism) generated by the self-magnetic field for group I (group II) orbits. It is interesting that the gain enhancement is found for the non-relativistic part of group II orbits. The FEL gain and betatron gain have also been investigated for different relativistic factors γ.

One-electron reduction reactions with enzymes in solution

International Nuclear Information System (INIS)

Bisby, R.H.; Cundall, R.B.; Redpath, J.L.; Adams, G.E.

1976-01-01

At pH 8 and above, hydrated electrons react with ribonuclease lysozyme and α-chymotrypsin to form transient products whose spectra resemble, but are not identical to, those for the RSSR - radical anion already known for simple disulphides. Assuming a value for the extinction coefficient similar to that for RSSR - in simple disulphides, only a fraction of the hydrated electrons are shown to react with the disulphide bridges: the remainder react at other sites in the protein molecule, such as histidine, tyrosine and, in lysozyme, tryptophan residues, giving rise to comparatively weak optical absorptions between 300 and 400 nm. This has been substantiated by studying the reaction of e - sub(aq) with subtilisin Novo (an enzyme which does not contain disulphide bridges), with enzymes in which the sulphur bridges have been oxidised and with some amino acid derivatives. On lowering the pH of the solution the intensity of the RSSR - absorption diminishes as the protonated histidine residues become the favoured reaction sites. In acid solutions (pH 2 to 3) the transient optical absoptions observed are due to reactions of hydrogen atoms with the aromatic amino acids tyrosine, tryptophan and phenylalanine. The CO - 2 radical anion is only observed to transfer an electron to disulphide groups in ribonuclease, although the effect of repeated pulsing shows that some reaction must occur elsewhere in the protein molecule. In acid solutions, protonation of the electron adduct appears to produce the RSSRH. radical, whose spectrum has a maximum at 340 nm. (author)

Reversal of local spins in transport of electrons through a one-dimensional chain

International Nuclear Information System (INIS)

Hu, D.-S.; Xiong, S.-J.

2003-01-01

We investigate the spin reversal of two coupled magnetic impurities in the transport processes of electrons in a one-dimensional chain. The impurities are side coupled to the chain and the electrons are injected and tunneling through it. The transmission coefficient of electrons and the polarization of impurities are calculated by the use of the equivalent single-particle network method for the correlated system. It is found that both the transmission coefficient and the polarization of impurities depend on the initial state of impurities and the impurity spins can be converted into the direction of electron spin if the injected electrons are polarized and the number of electrons is large enough. The evolution of the spin-reversal processes is studied in details

Effective lagrangian description on discrete gauge symmetries

International Nuclear Information System (INIS)

Banks, T.

1989-01-01

We exhibit a simple low-energy lagrangian which describes a system with a discrete remnant of a spontaneously broken continuous gauge symmetry. The lagrangian gives a simple description of the effects ascribed to such systems by Krauss and Wilczek: black holes carry discrete hair and interact with cosmic strings, and wormholes cannot lead to violation of discrete gauge symmetries. (orig.)

Calculation of two-center one-electron molecular integrals with STOs

International Nuclear Information System (INIS)

Rico, J.F.; Lopez, R.; Paniagua, M.; Ramirez, G.

1991-01-01

A program for the calculation of two-center one-electron integrals (overlap, nuclear attraction and kinetic energy) between real Slater-type orbitals (STOs) is reported. The integrals are obtained by recursion over simple auxiliary matrices, whose elements are calculated in terms of further auxiliary functions evaluated in a quick and accurate way. (orig.)

A CALCULATION OF SEMI-EMPIRICAL ONE-ELECTRON WAVE FUNCTIONS FOR MULTI-ELECTRON ATOMS USED FOR ELEMENTARY PROCESS SIMULATION IN NONLOCAL PLASMA

Directory of Open Access Journals (Sweden)

M. V. Tchernycheva

2017-01-01

Full Text Available Subject of Research. The paper deals with development outcomes for creation method of one-electron wave functions of complex atoms, relatively simple, symmetrical for all atom electrons and free from hard computations. The accuracy and resource intensity of the approach are focused on systematic calculations of cross sections and rate constants of elementary processes of inelastic collisions of atoms or molecules with electrons (ionization, excitation, excitation transfer, and others. Method. The method is based on a set of two iterative processes. At the first iteration step the Schrödinger equation was solved numerically for the radial parts of the electron wave functions in the potential of the atomic core self-consistent field. At the second iteration step the new approximationfor the atomic core field is created that uses found solutions for all one-electron wave functions. The solution optimization for described multiparameter problem is achieved by the use of genetic algorithm. The suitability of the developed method was verified by comparing the calculation results with numerous data on the energies of atoms in the ground and excited states. Main Results. We have created the run-time version of the program for creation of sets of one-electron wave functions and calculation of the cross sections and constants of collisional transition rates in the first Born approximation. The priori available information about binding energies of the electrons for any many-particle system for creation of semi-empirical refined solutions for the one-electron wave functions can be considered at any step of this procedure. Practical Relevance. The proposed solution enables a simple and rapid preparation of input data for the numerical simulation of nonlocal gas discharge plasma. The approach is focused on the calculation of discharges in complex gas mixtures requiring inclusion in the model of a large number of elementary collisional and radiation

Effects of deformation on the electronic properties of B-C-N nanotubes

Energy Technology Data Exchange (ETDEWEB)

Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58059-900 Joao Pessoa-PB (Brazil); Rosas, A. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58059-900 Joao Pessoa-PB (Brazil); Machado, M. [Departamento de Fisica, Universidade Federal de Pelotas, Caixa Postal 354, 96010-900 Pelotas-RS (Brazil); Kaschny, J.R. [Instituto Federal da Bahia-Campus Vitoria da Conquista, Av. Amazonas 3150, 45030-220 Vitoria da Conquista-BA (Brazil); Chacham, H. [Departamento de Fisica, ICEX, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 Belo Horizonte-MG (Brazil)

2013-01-15

We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC{sub 2}N and C-doped BNNTs. Four different types of BC{sub 2}N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. - Graphical Abstract: We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC{sub 2}N and C-doped BNNTs. Four different types of BC{sub 2}N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. Highlights: Black-Right-Pointing-Pointer We investigated electronic properties of flattened BC{sub 2}N nanotubes. Black-Right-Pointing-Pointer The electronic states depend strongly on compression. Black-Right-Pointing-Pointer It is studied flattened BN nanotubes doped with a carbon atom. Black-Right-Pointing-Pointer The flattened C-doped structures, presents a significant reduction of the gap.

Electrochemical One-Electron Oxidation of Low-Generation Polyamidoamine-Type Dendrimers with a 1,4-Phenylenediamine Core

DEFF Research Database (Denmark)

Hammerich, Ole; Hansen, Thomas; Thorvildsen, Asbjørn

2009-01-01

voltammetry (DPV) in methanol, acetonitrile, dichloromethane, and dimethyl sulfoxide. The dendrimers are more difficult to oxidize than N,N,N',N'-tetramethyl-p-phenylenediamine (TMePD). The oxidation potentials decrease with increasing dendrimer generation up to G0.5, after which the potential is essentially......A series of polyamidoamine (PAMAM)-type dendrimers with a 1,4-phenylenediamine (PD) core is prepared from PD by procedures including Michael addition of methyl acrylate followed by aminolysis with 1,2-ethanediamine. Their one-electron oxidation potentials are determined by differential pulse......,N,N',N'-tetra-n-alkyl-p-phenylenediamines, including a planar arrangement of the atoms linked to the two PD nitrogen atoms. Thus, the effect of chain size on the oxidation potential appears to be caused primarily by a simple electronic effect. The calculations indicate considerable reorientation of the dendrimer side chains on oxidation, presumably...

Correlation, temperature and disorder: Recent developments in the one-step description of angle-resolved photoemission

Science.gov (United States)

Braun, Jürgen; Minár, Ján; Ebert, Hubert

2018-04-01

Various apparative developments extended the potential of angle-resolved photoemission spectroscopy tremendously during the last two decades. Modern experimental arrangements consisting of new photon sources, analyzers and detectors supply not only extremely high angle and energy resolution but also spin resolution. This provides an adequate platform to study in detail new materials like low-dimensional magnetic structures, Rashba systems, topological insulator materials or high TC superconductors. The interest in such systems has grown enormously not only because of their technological relevance but even more because of exciting new physics. Furthermore, the use of photon energies from few eV up to several keV makes this experimental technique a rather unique tool to investigate the electronic properties of solids and surfaces. The following article reviews the corresponding recent theoretical developments in the field of angle-resolved photoemission with a special emphasis on correlation effects, temperature and relativistic aspects. The most successful theoretical approach to deal with angle-resolved photoemission is the so-called spectral function or one-step formulation of the photoemission process. Nowadays, the one-step model allows for photocurrent calculations for photon energies ranging from a few eV to more than 10 keV, to deal with arbitrarily ordered and disordered systems, to account for finite temperatures, and considering in addition strong correlation effects within the dynamical mean-field theory or similar advanced approaches.

Doing one's utmost: nurses' descriptions of caring for dying patients in an intensive care environment.

Science.gov (United States)

Fridh, Isabell; Forsberg, Anna; Bergbom, Ingegerd

2009-10-01

The aim of this study was to explore nurses' experiences and perceptions of caring for dying patients in an intensive care unit (ICU) with focus on unaccompanied patients, the proximity of family members and environmental aspects. Interviews were conducted with nine experienced ICU nurses. A qualitative descriptive approach was employed. The analysis was performed by means of conventional content analysis [Hsieh HF, Shannon SE. Three approaches to qualitative content analysis. Qual Health Res 2005;15:1277-88] following the steps described by e.g. Elo and Kyngas [Elo S, Kyngas H. The qualitative content analysis process. J Adv Nurs 2008;62:107-15]. The analysis resulted in a main category; Doing one's utmost, described by four generic categories and 15 sub-categories, comprising a common vision of the patients' last hours and dying process. This description was dominated by the nurses' endeavour to provide dignified end-of-life care (EOLC) and, when relatives were present, to give them an enduring memory of their loved one's death as a calm and dignified event despite his/her previous suffering and death in a high-technological environment. This study contributes new knowledge about what ICU nurses focus on when providing EOLC to unaccompanied patients but also to those whose relatives were present. Nurses' EOLC was mainly described as their relationship and interaction with the dying patient's relatives, while patients who died alone were considered tragic but left a lesser impression in the nurses' memory.

Electric dipole, polarizability and structure of cesium chloride clusters with one-excess electron

International Nuclear Information System (INIS)

Jraij, A.; Allouche, A.R.; Rabilloud, F.; Korek, M.; Aubert-Frecon, M.; Rayane, D.; Compagnon, I.; Antoine, R.; Broyer, M.; Dugourd, Ph.

2006-01-01

The measurement of the electric dipole of gas phase one-excess electron Cs n Cl n-1 clusters is reported together with a theoretical ab initio prediction of stable structures, dipole moments and electronic polarizabilities for these species in their ground state. Results are in agreement with NaCl cubic structures

ASPEN: A fully kinetic, reduced-description particle-in-cell model for simulating parametric instabilities

International Nuclear Information System (INIS)

Vu, H.X.; Bezzerides, B.; DuBois, D.F.

1999-01-01

A fully kinetic, reduced-description particle-in-cell (RPIC) model is presented in which deviations from quasineutrality, electron and ion kinetic effects, and nonlinear interactions between low-frequency and high-frequency parametric instabilities are modeled correctly. The model is based on a reduced description where the electromagnetic field is represented by three separate temporal envelopes in order to model parametric instabilities with low-frequency and high-frequency daughter waves. Because temporal envelope approximations are invoked, the simulation can be performed on the electron time scale instead of the time scale of the light waves. The electrons and ions are represented by discrete finite-size particles, permitting electron and ion kinetic effects to be modeled properly. The Poisson equation is utilized to ensure that space-charge effects are included. The RPIC model is fully three dimensional and has been implemented in two dimensions on the Accelerated Strategic Computing Initiative (ASCI) parallel computer at Los Alamos National Laboratory, and the resulting simulation code has been named ASPEN. The authors believe this code is the first particle-in-cell code capable of simulating the interaction between low-frequency and high-frequency parametric instabilities in multiple dimensions. Test simulations of stimulated Raman scattering, stimulated Brillouin scattering, and Langmuir decay instability are presented

The need for an electronic multilingual dictionary

Directory of Open Access Journals (Sweden)

Anna Kisiel

2014-09-01

Full Text Available The need for an electronic multilingual dictionary The paper analyses the issue of providing adequate equivalents in multilingual dictionaries. If equivalents are adequate, it means that: (1 the scope of meaning of one item is identical to its equivalent (cf. drive: drive a nail vs. drive a car; and (2 the collocations of the equivalents overlap. Two significant problems arise when searching for adequate equivalents: the lack of equivalents whose meanings are identical (narrower/wider meanings, partial overlap of meanings, more than equally good equivalent, and equivalents with homographs in a given language. Because such issues are difficult to resolve in a printed dictionary, we put forward some methods of addressing the problems in an electronic dictionary. The paper offers an example entry from such a dictionary, which presents a suggestion of a layout. We also took into consideration the potential problems which may appear if the entry is presented in this manner: first, one must set a limit for the description (a defined number of lexical units; second, one must avoid circularity, but at the same time also strive for an exhaustive description. Electronic dictionaries offer greater possibilities of presenting modern vocabulary and adding new classifiers (e.g. a classifier of politeness.

APES: Acute Precipitating Electron Spectrometer - A High Time Resolution Monodirectional Magnetic Deflection Electron Spectrometer

Science.gov (United States)

Michell, R. G.; Samara, M.; Grubbs, G., II; Ogasawara, K.; Miller, G.; Trevino, J. A.; Webster, J.; Stange, J.

2016-01-01

We present a description of the Acute Precipitating Electron Spectrometer (APES) that was designed and built for the Ground-to-Rocket Electron Electrodynamics Correlative Experiment (GREECE) auroral sounding rocket mission. The purpose was to measure the precipitating electron spectrum with high time resolution, on the order of milliseconds. The trade-off made in order to achieve high time resolution was to limit the aperture to only one look direction. The energy selection was done by using a permanent magnet to separate the incoming electrons, such that the different energies would fall onto different regions of the microchannel plate and therefore be detected by different anodes. A rectangular microchannel plate (MCP) was used (15 mm x 100 mm), and there was a total of 50 discrete anodes under the MCP, each one 15 mm x 1.5 mm, with a 0.5 mm spacing between anodes. The target energy range of APES was 200 eV to 30 keV.

Effects of emitted electron temperature on the plasma sheath

International Nuclear Information System (INIS)

Sheehan, J. P.; Kaganovich, I. D.; Wang, H.; Raitses, Y.; Sydorenko, D.; Hershkowitz, N.

2014-01-01

It has long been known that electron emission from a surface significantly affects the sheath surrounding that surface. Typical fluid theory of a planar sheath with emitted electrons assumes that the plasma electrons follow the Boltzmann relation and the emitted electrons are emitted with zero energy and predicts a potential drop of 1.03T e /e across the sheath in the floating condition. By considering the modified velocity distribution function caused by plasma electrons lost to the wall and the half-Maxwellian distribution of the emitted electrons, it is shown that ratio of plasma electron temperature to emitted electron temperature significantly affects the sheath potential when the plasma electron temperature is within an order of magnitude of the emitted electron temperature. When the plasma electron temperature equals the emitted electron temperature the emissive sheath potential goes to zero. One dimensional particle-in-cell simulations corroborate the predictions made by this theory. The effects of the addition of a monoenergetic electron beam to the Maxwellian plasma electrons were explored, showing that the emissive sheath potential is close to the beam energy only when the emitted electron flux is less than the beam flux

Data description and quality assessment of ionospheric electron density profiles for ARPA modeling project. Technical report

International Nuclear Information System (INIS)

Conkright, R.O.

1977-03-01

This report presents a description of the automated method used to produce electron density (N(h)) profiles from ionograms recorded on 35mm film and an assessment of the resulting data base. A large data base of about 30,000 profiles was required for an ionospheric modeling project. This motivated a search for an automated method of producing profiles. The automated method used is fully described, the resulting data are given a quality grade, and the noon and midnight profiles are presented. Selected portions of this data base are compared with profiles produced by the standard profiling method in use by the Environmental Data Service at Boulder, Colorado

Are Electronic Books Effective in Teaching Young Children Reading and Comprehension?

Science.gov (United States)

Grant, Jamillah M. A.

2004-01-01

Whether electronic books, CD-ROM'S, or interactive media are beneficial in teaching reading should be determined on evidence that they aid reading comprehension. Reading is worthless unless one comprehends. In order to examine the effectiveness of electronic books in a reading program, the characteristics and attributes of how…

Effect of electron correlation on the forced electric dipole transition probabilities in fsup(N) systems

International Nuclear Information System (INIS)

Jankowski, K.; Smentek-Mielczarek, L.

1981-01-01

Results of model studies of the impact of electron correlation on the forced electric dipole transition probabilities between states of the 4fsup(N) configuration are reported for the [ 3 P] 0 - [ 3 F] 4 , [ 3 H] 4 transitions in Pr 3+ : LaCl 3 and for [ 7 F] 0 - [ 5 D] 2 , [ 7 F] 1 - [ 5 D] 1 hypersensitive transitions in Eu 3+ : LaCl 3 . For the former system the correlation effects cause a modification of earlier results by 40-95 per cent, whereas for the latter the probability changes by as much as two orders of magnitude. The great changes found in the case of hypersensitive transitions suggest that electron correlation effects may belong to the most important factors determining the nature of these transitions. Several types of effective correlation operators are considered and their relative importance is discussed. The results indicate that intermediate configurations including g orbitals are very important for the description of correlation effects. (author)

Electron Cloud Effects in Accelerators

International Nuclear Information System (INIS)

Furman, M A

2013-01-01

We present a brief summary of various aspects of the electron-cloud effect (ECE) in accelerators. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire 'ECLOUD' series. In addition, the proceedings of the various flavors of Particle Accelerator Conferences contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC. (author)

Bare and effective fluid description in brane world cosmology

Energy Technology Data Exchange (ETDEWEB)

Cruz, Norman [Universidad de Santiago, Departamento de Fisica, Facultad de Ciencia, Casilla 307, Santiago (Chile); Lepe, Samuel; Saavedra, Joel [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Casilla 4950, Valparaiso (Chile); Pena, Francisco [Universidad de La Frontera, Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Avda. Francisco Salazar 01145, Casilla 54-D, Temuco (Chile)

2010-03-15

An effective fluid description, for a brane world model in five dimensions, is discussed for both signs of the brane tension. We found several cosmological scenarios where the effective equation differs widely from the bare equation of state. For universes with negative brane tension, with a bare fluid satisfying the strong energy condition, the effective fluid can cross the barrier {omega} {sub eff}=-1. (orig.)

A descriptive study of effect-size reporting in research reviews.

Science.gov (United States)

Floyd, Judith A

2017-06-01

To describe effect-size reporting in research reviews completed in support of evidence-based practice in nursing. Many research reviews report nurses' critical appraisal of level, quality and overall strength of evidence available to address clinical questions. Several studies of research-review quality suggest effect-size information would be useful to include in these reviews, but none focused on reviewers' attention to effect sizes. Descriptive. One hundred and four reviews indexed in CINAHL as systematic reviews and published from July 2012-February 2014 were examined. Papers were required to be peer-reviewed, written in English, contain an abstract and have at least one nurse author. Reviews were excluded if they did not use critical appraisal methods to address evidence of correlation, prediction or effectiveness. Data from remaining papers (N = 73) were extracted by three or more independent coders using a structured coding form and detailed codebook. Data were stored, viewed and analysed using Microsoft Office Excel ® spreadsheet functions. Sixteen percent (n = 12) of the sample contained effect-size information. Of the 12, six included all the effect-size information recommended by APA guidelines. Independent of completeness of reporting, seven contained discussion of effect sizes in the paper, but none included effect-size information in abstracts. Research reviews available to practicing nurses often fail to include information needed to accurately assess how much improvement may result from implementation of evidence-based policies, programs, protocols or practices. Manuscript reviewers are urged to hold authors to APA standards for reporting/discussing effect-size information in both primary research reports and research reviews. © 2016 John Wiley & Sons Ltd.

Electronic structure at metal-smiconductor surfaces and interfaces: effects of disorder

International Nuclear Information System (INIS)

Rodrigues, D.E.

1988-01-01

The main concern of this work is the study of the electronic structure at metal and semiconductor surfaces or interfaces, with special emphasis in the effects of disorder and local microstructure upon them. Various factors which determine this structure are presented and those of central importance are identified. A model that allows the efficient and exact calculation of the local density of states at disordered interfaces is described. This model is based on a tight-binding hamiltonian that has enough flexibility so as to allow an adequate description of real solids. The disorder is taken into account by including stochastic perturbations in the diagonal elements of the hamiltonian in a site orbital basis. These perturbations are taken at each layer from a lorentzian probability distribution. An exact expression for the calculation of the local density of states is derived and applied to a model surface built up from a type orbitals arranged in a simple cubic lattice. The effects of disorder on the local densities of states and on the existence of surface Tamm states are studied. The properties of the electronic states with this kind of model of disorder are considered. The self-consistent calculation of the electronic structure of the Si(111) - (1x1) surface is presented. The effects of disorder on the electronic properties such as the work function or the position of surface states within the gap are evaluated. The surface of the metallic compound NiSi 2 is also treated. The first self-consistent calculation of the electronic structure of its (111) surface is presented. The electronic structure of the Si/NiSi 2 (111) interfaces is calculated for the two types of junctions that can be grown experimentally. The origin of the difference between the Schottky barrier heights at both interfaces is discussed. The results are compared with available experimental data. The implications of this calculation on existing theories about the microscopic mechanism that causes

Plasmonic photocatalytic reactions enhanced by hot electrons in a one-dimensional quantum well

Directory of Open Access Journals (Sweden)

H. J. Huang

2015-11-01

Full Text Available The plasmonic endothermic oxidation of ammonium ions in a spinning disk reactor resulted in light energy transformation through quantum hot charge carriers (QHC, or quantum hot electrons, during a chemical reaction. It is demonstrated with a simple model that light of various intensities enhance the chemical oxidization of ammonium ions in water. It was further observed that light illumination, which induces the formation of plasmons on a platinum (Pt thin film, provided higher processing efficiency compared with the reaction on a bare glass disk. These induced plasmons generate quantum hot electrons with increasing momentum and energy in the one-dimensional quantum well of a Pt thin film. The energy carried by the quantum hot electrons provided the energy needed to catalyze the chemical reaction. The results indicate that one-dimensional confinement in spherical coordinates (i.e., nanoparticles is not necessary to provide an extra excited state for QHC generation; an 8 nm Pt thin film for one-dimensional confinement in Cartesian coordinates can also provide the extra excited state for the generation of QHC.

Electronic de-multipliers II (ring-shape systems)

International Nuclear Information System (INIS)

Raievski, V.

1948-09-01

This report describes a new type of ring-shape fast electronic counter (de-multiplier) with a resolution capacity equivalent to the one made by Regener (Rev. of Scientific Instruments USA 1946, 17, 180-89) but requiring two-times less electronic valves. This report follows the general description of electronic de-multipliers made by J. Ailloud (CEA--001). The ring comprises 5 flip-flop circuits with two valves each. The different elements of the ring are calculated with enough details to allow the transfer of this calculation to different valve types. (J.S.)

Effect of electron temperature on small-amplitude electron acoustic solitary waves in non-planar geometry

Science.gov (United States)

Bansal, Sona; Aggarwal, Munish; Gill, Tarsem Singh

2018-04-01

Effects of electron temperature on the propagation of electron acoustic solitary waves in plasma with stationary ions, cold and superthermal hot electrons is investigated in non-planar geometry employing reductive perturbation method. Modified Korteweg-de Vries equation is derived in the small amplitude approximation limit. The analytical and numerical calculations of the KdV equation reveal that the phase velocity of the electron acoustic waves increases as one goes from planar to non planar geometry. It is shown that the electron temperature ratio changes the width and amplitude of the solitary waves and when electron temperature is not taken into account,our results completely agree with the results of Javidan & Pakzad (2012). It is found that at small values of τ , solitary wave structures behave differently in cylindrical ( {m} = 1), spherical ( {m} = 2) and planar geometry ( {m} = 0) but looks similar at large values of τ . These results may be useful to understand the solitary wave characteristics in laboratory and space environments where the plasma have multiple temperature electrons.

Effects of buried high-Z layers on fast electron propagation

International Nuclear Information System (INIS)

Yang, Xiaohu; Zhuo, Hongbin; Ma, Yanyun; Shao, Fuqiu; Xu, Han; Yin Yan; Borghesi, M.

2014-01-01

The transport through high density plasmas of relativistic electron beams generated by ultra-intense laser-plasma interaction has potential applications in laser-driven ion acceleration and in the fast igniter scheme for inertial confinement fusion. By extending a prior model [A.R. Bell, J.R. Davies, S.M. Guerin, Phys. Rev. E 58, 2471 (1998)], the magnetic field generated during the transport of a fast electron beam driven by an ultra-intense laser in a solid target is derived analytically and applied to estimate the effect of such field on fast electron propagation through a buried high-Z layer in a lower-Z target. It is found that the effect gets weaker with the increase of the depth of the buried layer, the divergence of the fast electrons, and the laser intensity, indicating that magnetic field effects on the fast electron divergence as measured from K a X-ray emission may need to be considered for moderate laser intensities. On the basis of the calculations, some considerations are made on how one can mitigate the effect of the magnetic field generated at the interface. (authors)

A theoretical model on surface electronic behavior: Strain effect

International Nuclear Information System (INIS)

Qin, W.G.; Shaw, D.

2009-01-01

Deformation from mechanical loading can affect surface electronic behavior. Surface deformation and electronic behavior can be quantitatively expressed using strain and work function, respectively, and their experimental relationship can be readily determined using the Kelvin probing technique. However, the theoretical correlation between work function and strain has been unclear. This study reports our theoretical exploration, for the first time, of the effect of strain on work function. We propose a simple electrostatic action model by considering the effect of a dislocation on work function of a one-dimensional lattice and further extend this model to the complex conditions for the effect of dislocation density. Based on this model, we established successfully a theoretical correlation between work function and strain.

Differential cross sections for the one electron two center symmetric systems

International Nuclear Information System (INIS)

Maidagan, J.M.; Piacentini, R.D.; Rivarola, R.D.; Universidad Autonoma de Madrid

1982-01-01

We use the two-state atomic expansion with variable nuclear charge to study charge-exchange differential cross sections for symmetrical one-electron systems at intermediate energy. The nonclassical small angle diffraction scattering is discussed. Our results are compared with data for H + -H collisions. (orig.)

Differential cross sections for the one electron two center symmetric systems

Energy Technology Data Exchange (ETDEWEB)

Maidagan, J.M.; Piacentini, R.D. (Universidad Nacional de Rosario (Argentina). Dept. de Fisica); Rivarola, R.D. (Bordeaux-1 Univ., 33 - Talence (France). Lab. d' Astrophysique; Universidad Autonoma de Madrid (Spain). Dept. de Quimica Fisica y Quimica Cuantica)

1982-03-01

We use the two-state atomic expansion with variable nuclear charge to study charge-exchange differential cross sections for symmetrical one-electron systems at intermediate energy. The nonclassical small angle diffraction scattering is discussed. Our results are compared with data for H/sup +/-H collisions.

Concept of APDL, the atomic process description language

International Nuclear Information System (INIS)

Sasaki, Akira

2004-01-01

The concept of APDL, the Atomic Process Description Language, which provides simple and complete description of atomic model is presented. The syntax to describe electron orbital and configuration is defined for the use in the atomic structure, kinetics and spectral synthesis simulation codes. (author)

The Effect of Electronic Devices Self-Efficacy, Electronic Devices Usage and Information Security Awareness on Identity-Theft Anxiety Level

Science.gov (United States)

Sanga, Sushma

2016-01-01

Identity-theft means stealing someone's personal information and using it without his or her permission. Each year, millions of Americans are becoming the victims of identity-theft, and this is one of the seriously growing and widespread issues in the U.S. This study examines the effect of electronic devices self-efficacy, electronic devices…

Electron inertia effects for an electron fluid model by the applied-B ion diode

Energy Technology Data Exchange (ETDEWEB)

Gordeev, A V; Levchenko, S V [Kurchatov Institute, Moscow (Russian Federation). Nuclear Fusion Institute

1997-12-31

Numerical calculations within the framework of the one-dimensional vortex-like electron fluid model in applied-B ion diodes, taking account the electron inertia effects, are presented. The existence of the additional relation between the magnetic field and the electric potential offers an opportunity to reduce the ion diode problem to the system of the algebraic equations for the constants introduced. The ion current density in an ion diode is determined only by the magnetic flux cut out by the virtual cathode. As an illustration, the ion diode impedance for the KALIF device was calculated. (author). 2 figs., 6 refs.

Fabrication and description of a cold cathode electron gun

International Nuclear Information System (INIS)

Sari, A.H.; Ghorannevis, M.; Hantehzadeh, M.R.; Yousefi, M.R.

2003-01-01

In this study the structure and schematic configuration of a cold cathode electron gun has been shown, which use obstructed discharge for electron producing. This type of discharge and mechanism of secondary electron emission by ions and fast neutral interaction have been described. The experiment starts in pressure of 1*10 -3 torr, in existence of helium gas. A negative DC voltage apply to a concave cathode up to -20 k V which determine electron energy

Theory and measurement of the electron cloud effect

CERN Document Server

Harkay, K C

1999-01-01

Photoelectrons produced through the interaction of synchrotron radiation and the vacuum chamber walls can be accelerated by a charged particle beam, acquiring sufficient energy to produce secondary electrons (SEs) in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, a runaway condition can develop. In addition to the SEY, the degree of amplification depends on the beam intensity and temporal distribution. As the electron cloud builds up along a train of stored bunches, a transverse perturbation of the head bunch can be communicated to trailing bunches in a wakefield-like interaction with the cloud. The electron cloud effect is especially of concern for the high-intensity PEP-II (SLAC) and KEK B-factories and at the Large Hadron Collider (LHC) at CERN. An initiative was undertaken at the Advanced Photon Source (APS) storage ring to characterize the electron cloud in order to provide realistic limits on critical input parameters in the models ...

Electronic Health Record Implementation: A SWOT Analysis.

Science.gov (United States)

Shahmoradi, Leila; Darrudi, Alireza; Arji, Goli; Farzaneh Nejad, Ahmadreza

2017-10-01

Electronic Health Record (EHR) is one of the most important achievements of information technology in healthcare domain, and if deployed effectively, it can yield predominant results. The aim of this study was a SWOT (strengths, weaknesses, opportunities, and threats) analysis in electronic health record implementation. This is a descriptive, analytical study conducted with the participation of a 90-member work force from Hospitals affiliated to Tehran University of Medical Sciences (TUMS). The data were collected by using a self-structured questionnaire and analyzed by SPSS software. Based on the results, the highest priority in strength analysis was related to timely and quick access to information. However, lack of hardware and infrastructures was the most important weakness. Having the potential to share information between different sectors and access to a variety of health statistics was the significant opportunity of EHR. Finally, the most substantial threats were the lack of strategic planning in the field of electronic health records together with physicians' and other clinical staff's resistance in the use of electronic health records. To facilitate successful adoption of electronic health record, some organizational, technical and resource elements contribute; moreover, the consideration of these factors is essential for HER implementation.

Printable Spacecraft: Flexible Electronic Platforms for NASA Missions. Phase One

Science.gov (United States)

Short, Kendra (Principal Investigator); Van Buren, David (Principal Investigator)

2012-01-01

Atmospheric confetti. Inchworm crawlers. Blankets of ground penetrating radar. These are some of the unique mission concepts which could be enabled by a printable spacecraft. Printed electronics technology offers enormous potential to transform the way NASA builds spacecraft. A printed spacecraft's low mass, volume and cost offer dramatic potential impacts to many missions. Network missions could increase from a few discrete measurements to tens of thousands of platforms improving areal density and system reliability. Printed platforms could be added to any prime mission as a low-cost, minimum resource secondary payload to augment the science return. For a small fraction of the mass and cost of a traditional lander, a Europa flagship mission might carry experimental printed surface platforms. An Enceladus Explorer could carry feather-light printed platforms to release into volcanic plumes to measure composition and impact energies. The ability to print circuits directly onto a variety of surfaces, opens the possibility of multi-functional structures and membranes such as "smart" solar sails and balloons. The inherent flexibility of a printed platform allows for in-situ re-configurability for aerodynamic control or mobility. Engineering telemetry of wheel/soil interactions are possible with a conformal printed sensor tape fit around a rover wheel. Environmental time history within a sample return canister could be recorded with a printed sensor array that fits flush to the interior of the canister. Phase One of the NIAC task entitled "Printable Spacecraft" investigated the viability of printed electronics technologies for creating multi-functional spacecraft platforms. Mission concepts and architectures that could be enhanced or enabled with this technology were explored. This final report captures the results and conclusions of the Phase One study. First, the report presents the approach taken in conducting the study and a mapping of results against the proposed

Development and implementation of theoretical methods for the description of electronically core-excited states

Energy Technology Data Exchange (ETDEWEB)

Wenzel, Jan

2016-03-23

-cc-series, a mean error of -0.23% ±0.12% for core-excitation energies can be identified at the CVS-ADC(2)-x level for carbon, nitrogen and oxygen K-edge excitations, whereas CVS-ADC(3) exhibits errors of 0.61% ± 0.32%. This is due to fortuitous error compensation of basis set truncation, electron correlation, orbital relaxation and neglect of relativistic effects at the CVS-ADC(2)-x level. Transition moments and spectral features, as well as static dipole moments, are excellently described with both CVS-ADC(2)-x and CVS-ADC(3). Especially the 6-311++G** basis set provides an excellent ratio of accuracy to computational time. Another important topic is the description of orbital relaxation effects. In the scope of this thesis, I show, how these effects are included indirectly within the CVS-ADC approaches. For this purpose, two different descriptors are used, i.e. electron promotion numbers and the amount of doubly excited amplitudes. Furthermore, with the help of detachment/attachment (D/A) densities, which can be constructed via the CVS-ISR approach, relaxation effects can be visualized. For this purpose, the (D/A) densities are compared with hole/electron (h/e) densities based on the transition density matrix. With this knowledge, the X-ray absorption spectra of medium-sized molecules and radicals from the fields of organic electronics and biology are investigated and analyzed. On the basis of these studies, the restricted and unrestricted versions of CVS-ADC(2)-x in combination with the 6-311++G** basis set exhibit mean errors of core-excitation energies around 0.1%, compared to experimental values. Additionally, core-excited state characters are analyzed with the help of state densities obtained via the CVS-ISR approach or the transition density matrix. To demonstrate the computational savings as a function of the size of the core space, several systems are investigated. CVS-ADC(3) calculations take about 8-10 times longer than CVS-ADC(2)-x calculations and since the

Probing mesoscopic crystals with electrons: One-step simultaneous inelastic and elastic scattering theory

Science.gov (United States)

Nazarov, Vladimir U.; Silkin, Vyacheslav M.; Krasovskii, Eugene E.

2017-12-01

Inelastic scattering of the medium-energy (˜10 -100 eV) electrons underlies the method of the high-resolution electron energy-loss spectroscopy (HREELS), which has been successfully used for decades to characterize pure and adsorbate-covered surfaces of solids. With the emergence of graphene and other quasi-two-dimensional (Q2D) crystals, HREELS could be expected to become the major experimental tool to study this class of materials. We, however, identify a critical flaw in the theoretical picture of the HREELS of Q2D crystals in the context of the inelastic scattering only ("energy-loss functions" formalism), in contrast to its justifiable use for bulk solids and surfaces. The shortcoming is the neglect of the elastic scattering, which we show is inseparable from the inelastic one, and which, affecting the spectra dramatically, must be taken into account for the meaningful interpretation of the experiment. With this motivation, using the time-dependent density functional theory for excitations, we build a theory of the simultaneous inelastic and elastic electron scattering at Q2D crystals. We apply this theory to HREELS of graphene, revealing an effect of the strongly coupled excitation of the π +σ plasmon and elastic diffraction resonances. Our results open a path to the theoretically interpretable study of the excitation processes in crystalline mesoscopic materials by means of HREELS, with its supreme resolution on the meV energy scale, which is far beyond the capacity of the now overwhelmingly used EELS in transmission electron microscopy.

Electrons and Phonons in Semiconductor Multilayers

Science.gov (United States)

Ridley, B. K.

1996-11-01

This book provides a detailed description of the quantum confinement of electrons and phonons in semiconductor wells, superlattices and quantum wires, and shows how this affects their mutual interactions. It discusses the transition from microscopic to continuum models, emphasizing the use of quasi-continuum theory to describe the confinement of optical phonons and electrons. The hybridization of optical phonons and their interactions with electrons are treated, as are other electron scattering mechanisms. The book concludes with an account of the electron distribution function in three-, two- and one-dimensional systems, in the presence of electrical or optical excitation. This text will be of great use to graduate students and researchers investigating low-dimensional semiconductor structures, as well as to those developing new devices based on these systems.

A Electronic Map Data Model Based on PDF

Science.gov (United States)

Zhou, Xiaodong; Yang, Chuncheng; Meng, Nina; Peng, Peng

2018-05-01

In this paper, we proposed the PDFEMAP (PDF electronic map) that is a kind of new electronic map products aiming at the current situation and demand of the use of electronic map products. Firstly gives the definition and characteristics of PDFEMAP, followed by a detailed description of the data model and method for generating PDFEMAP, and finally expounds application modes of the PDFEMAP which feasibility and effectiveness are verified.

PIC simulation of the electron-ion collision effects on suprathermal electrons

International Nuclear Information System (INIS)

Wu Yanqing; Han Shensheng

2000-01-01

The generation and transportation of suprathermal electrons are important to both traditional ICF scheme and 'Fast Ignition' scheme. The author discusses the effects of electron-ion collision on the generation and transportation of the suprathermal electrons by parametric instability. It indicates that the weak electron-ion term in the PIC simulation results in the enhancement of the collisional absorption and increase of the hot electron temperature and reduction in the maximum electrostatic field amplitude while wave breaking. Therefore the energy and distribution of the suprathermal electrons are changed. They are distributed more close to the phase velocity of the electrostatic wave than the case without electron-ion collision term. The electron-ion collision enhances the self-consistent field and impedes the suprathermal electron transportation. These factors also reduce the suprathermal electron energy. In addition, the authors discuss the effect of initial condition on PIC simulation to ensure that the results are correct

Effects of target plasma electron-electron collisions on correlated motion of fragmented H2+ protons

International Nuclear Information System (INIS)

Barriga-Carrasco, Manuel D.

2006-01-01

The objective of the present work is to examined the effects of plasma target electron-electron collisions on H 2 + protons traversing it. Specifically, the target is deuterium in a plasma state with temperature T e =10 eV and density n=10 23 cm -3 , and proton velocities are v p =v th , v p =2v th , and v p =3v th , where v th is the electron thermal velocity of the target plasma. Proton interactions with plasma electrons are treated by means of the dielectric formalism. The interactions among close protons through plasma electronic medium are called vicinage forces. It is checked that these forces always screen the Coulomb explosions of the two fragmented protons from the same H 2 + ion decreasing their relative distance. They also align the interproton vector along the motion direction, and increase the energy loss of the two protons at early dwell times while for longer times the energy loss tends to the value of two isolated protons. Nevertheless, vicinage forces and effects are modified by the target electron collisions. These collisions enhance the calculated self-stopping and vicinage forces over the collisionless results. Regarding proton correlated motion, when these collisions are included, the interproton vector along the motion direction overaligns at slower proton velocities (v p =v th ) and misaligns for faster ones (v p =2v th , v p =3v th ). They also contribute to a great extend to increase the energy loss of the fragmented H 2 + ion. This later effect is more significant in reducing projectile velocity

Pulse-radiolytic one-electron reduction of anthraquinone and chloro-anthraquinones in aqueous-isopropanol-acetone mixed solvent

International Nuclear Information System (INIS)

Rath, M.C.; Pal, H.; Mukherjee, T.

1996-01-01

One-electron reduction of 9,10-anthraquinone and some chloro-anthraquinones and the characteristics of the semiquinones thus formed have been investigated in aqueous-isipropanol-acetone mixed solvent using electron pulse radiolysis technique. Spectroscopic characteristics, kinetic parameters of formation and decay, and the acid/base behaviour of the semiquinones have been investigated. The one-electron reduction potential of the quinones have been measured following electron transfer equilibria with a reference redox system (methyl viologen) and the values thus obtained have been compared with those of some other anthrasemiquinone systems. An analysis of the characteristics of the semiquinones shows that α-chloro substituents adjacent to the C=O group act as electron withdrawing groups. (author)

Fermi-degeneracy and discrete-ion effects in the spherical-cell model and electron-electron correlation effects in hot dense plasmas

International Nuclear Information System (INIS)

Furukawa, H.; Nishihara, K.

1992-01-01

The spherical-cell model [F. Perrot, Phys. Rev. A 25, 489 (1982); M. W. C. Dharma-wardana and F. Perrot, ibid. 26, 2096 (1982)] is improved to investigate laser-produced hot, dense plasmas. The free-electron distribution function around a test free electron is calculated by using the Fermi integral in order that the free-electron--free-electron correlation function includes Fermi-degeneracy effects, and also that the calculation includes the discrete-ion effect. The free-electron--free-electron, free-electron--ion, and ion-ion correlation effects are coupled, within the framework of the hypernetted-chain approximation, through the Ornstein-Zernike relation. The effective ion-ion potential includes the effect of a spatial distribution of bound electrons. The interparticle correlation functions and the effective potential acting on either an electron or an ion in hot, dense plasmas are calculated numerically. The Fermi-degeneracy effect on the correlation functions between free electrons becomes clear for the degeneracy parameter θ approx-lt 1. The discrete-ion effect in the calculation of the correlation functions between free electrons affects the electron-ion pair distribution functions for r s approx-gt 3. As an application of the proposed model, the strong-coupling effect on the stopping power of charged particles [Xin-Zhong Yan, S. Tanaka, S. Mitake, and S. Ichimaru, Phys. Rev. A 32, 1785 (1985)] is estimated. While the free-electron--ion strong-coupling effect and the Fermi-degeneracy effect incorporated in the calculation of the free-electron distribution function around a test free electron enhance the stopping number, the quantum-diffraction effect incorporated in the quantal hypernetted-chain equations [J. Chihara, Prog. Theor. Phys. 72, 940 (1984); Phys. Rev. A 44, 1247 (1991); J. Phys. Condens. Matter 3, 8715 (1991)] reduces the stopping number substantially

Effect of electromagnetic field in fusion facility on electronic personal dosimeter

International Nuclear Information System (INIS)

Yamada, Junya; Kawano, Takao; Uda, Tatsuhiko; Shimo, Michikuni

2010-01-01

The effect of electromagnetic field on electronic personal dosimeters in a nuclear fusion facility was examined in a Magnetic Resonance Imaging (MRI) examination room instead of a nuclear fusion facility. Three types of electronic personal dosimeters, the PDM-111, the 112, and the 117, were used as typical ones. We surveyed the electromagnetic field distribution and dosimeters were placed at locations with various strengths of the electromagnetic field. The natural radiation dose was measured for about one week. We found that while dosimeters were not affected by the electric field, they were affected by the magnetic one. Dosimeters detected radiation levels less sensitively as the magnetic field strength was increased up to 150 mT. The dosimeters underestimated the environmental radiation dose rates by about 10-30% when the magnetic field strength was larger than 150 mT. We assumed that hall-effect caused the reduction in radiation sensitivity. We concluded that the strength of the magnetic field needs to be carefully considered when an electronic personal dosimeter is used for monitoring both personal and area dose in a nuclear fusion facility. (author)

Charge transfer dynamics from adsorbates to surfaces with single active electron and configuration interaction based approaches

Energy Technology Data Exchange (ETDEWEB)

Ramakrishnan, Raghunathan, E-mail: r.ramakrishnan@unibas.ch [Institute of Physical Chemistry, National Center for Computational Design and Discovery of Novel Materials (MARVEL), Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Nest, Mathias [Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching (Germany)

2015-01-13

Highlights: • We model electron dynamics across cyano alkanethiolates attached to gold cluster. • We present electron transfer time scales from TD-DFT and TD-CI based simulations. • Both DFT and CI methods qualitatively predict the trend in time scales. • TD-CI predicts the experimental relative time scale very accurately. - Abstract: We employ wavepacket simulations based on many-body time-dependent configuration interaction (TD-CI), and single active electron theories, to predict the ultrafast molecule/metal electron transfer time scales, in cyano alkanethiolates bonded to model gold clusters. The initial states represent two excited states where a valence electron is promoted to one of the two virtual π{sup ∗} molecular orbitals localized on the cyanide fragment. The ratio of the two time scales indicate the efficiency of one charge transfer channel over the other. In both our one-and many-electron simulations, this ratio agree qualitatively with each other as well as with the previously reported experimental time scales (Blobner et al., 2012), measured for a macroscopic metal surface. We study the effect of cluster size and the description of electron correlation on the charge transfer process.

Mathematical descriptions of a one- and five-year old child for use in dosimetry calculations

Energy Technology Data Exchange (ETDEWEB)

Hwang, J.M.L.; Shoup, R.L.; Warner, G.G.; Poston, J.W.

1976-03-01

Mathematical representations for estimating the absorbed radiation dose from external and internal radiation sources of a one-year old and a five-year old human have been designed. The phantoms used consist of head, trunk and leg regions with a skeletal system and twenty-two internal organs, each. The mathematical descriptions of these phantoms have been coded into Fortran computer language for use with a Monte-Carlo photon transport code. This computer code was used to calculate absorbed fractions of energy deposited in different targets organs from a radionuclide deposited uniformly in a source organ. Absorbed dose calculations were performed for two /sup 99m/Tc-labeled pharmaceuticals. Photon absorbed fraction estimates for the pediatric phantoms from Monte-Carlo calculations were combined with biological data to estimate dose distributions in one-year old and five-year old children. (CH)

Mathematical descriptions of a one- and five-year old child for use in dosimetry calculations

International Nuclear Information System (INIS)

Hwang, J.M.L.; Shoup, R.L.; Warner, G.G.; Poston, J.W.

1976-03-01

Mathematical representations for estimating the absorbed radiation dose from external and internal radiation sources of a one-year old and a five-year old human have been designed. The phantoms used consist of head, trunk and leg regions with a skeletal system and twenty-two internal organs, each. The mathematical descriptions of these phantoms have been coded into Fortran computer language for use with a Monte-Carlo photon transport code. This computer code was used to calculate absorbed fractions of energy deposited in different targets organs from a radionuclide deposited uniformly in a source organ. Absorbed dose calculations were performed for two /sup 99m/Tc-labeled pharmaceuticals. Photon absorbed fraction estimates for the pediatric phantoms from Monte-Carlo calculations were combined with biological data to estimate dose distributions in one-year old and five-year old children

Electron cloud effects in hadron beams

Energy Technology Data Exchange (ETDEWEB)

Petrov, Fedor; Boine-Frankenheim, Oliver; Weiland, Thomas [TU-Darmstadt, Institut fuer Theorie Elektromagnetischer Felder,Schlossgartenstr. 8 64289 Darmstadt (Germany)

2013-07-01

Accelerators operating with intense positively charged beams can suffer from the electron cloud phenomenon. For example, it is the intensity limiting factor in CERN LHC and SPS. In past decades a lot of progress in understanding the electron cloud effects was made worldwide. Methods to suppress or weaken the electron cloud phenomenon were proposed. Theories governing the bunch stability in presence of the electron cloud were developed. Recently the theory was introduced to describe the bunch energy loss due to the electron cloud. However, most of the publications concern the single bunch electron cloud effects. In reality bunches are packed into trains. A disturbance of the cloud caused by the bunch in the beginning of the train affects the subsequent bunches. We present a further investigation of single-bunch electron cloud effects and planned activities to study the phenomenon in case of multiple bunches.

Effects of Neutron-Star Dynamic Tides on Gravitational Waveforms within the Effective-One-Body Approach.

Science.gov (United States)

Hinderer, Tanja; Taracchini, Andrea; Foucart, Francois; Buonanno, Alessandra; Steinhoff, Jan; Duez, Matthew; Kidder, Lawrence E; Pfeiffer, Harald P; Scheel, Mark A; Szilagyi, Bela; Hotokezaka, Kenta; Kyutoku, Koutarou; Shibata, Masaru; Carpenter, Cory W

2016-05-06

Extracting the unique information on ultradense nuclear matter from the gravitational waves emitted by merging neutron-star binaries requires robust theoretical models of the signal. We develop a novel effective-one-body waveform model that includes, for the first time, dynamic (instead of only adiabatic) tides of the neutron star as well as the merger signal for neutron-star-black-hole binaries. We demonstrate the importance of the dynamic tides by comparing our model against new numerical-relativity simulations of nonspinning neutron-star-black-hole binaries spanning more than 24 gravitational-wave cycles, and to other existing numerical simulations for double neutron-star systems. Furthermore, we derive an effective description that makes explicit the dependence of matter effects on two key parameters: tidal deformability and fundamental oscillation frequency.

Effects of Neutron-Star Dynamic Tides on Gravitational Waveforms within the Effective-One-Body Approach

Science.gov (United States)

Hinderer, Tanja; Taracchini, Andrea; Foucart, Francois; Buonanno, Alessandra; Steinhoff, Jan; Duez, Matthew; Kidder, Lawrence E.; Pfeiffer, Harald P.; Scheel, Mark A.; Szilagyi, Bela; Hotokezaka, Kenta; Kyutoku, Koutarou; Shibata, Masaru; Carpenter, Cory W.

2016-05-01

Extracting the unique information on ultradense nuclear matter from the gravitational waves emitted by merging neutron-star binaries requires robust theoretical models of the signal. We develop a novel effective-one-body waveform model that includes, for the first time, dynamic (instead of only adiabatic) tides of the neutron star as well as the merger signal for neutron-star-black-hole binaries. We demonstrate the importance of the dynamic tides by comparing our model against new numerical-relativity simulations of nonspinning neutron-star-black-hole binaries spanning more than 24 gravitational-wave cycles, and to other existing numerical simulations for double neutron-star systems. Furthermore, we derive an effective description that makes explicit the dependence of matter effects on two key parameters: tidal deformability and fundamental oscillation frequency.

Electrons in Nanostructures

DEFF Research Database (Denmark)

Flindt, Christian

2007-01-01

in the possibilities o®ered by the quantum mechanical behavior of electrons when it comes to informa- tion processing. This branch of research is also concerned with fundamental questions in physics. Besides an introduction to the above-mentioned subjects, the thesis con- tains a number of contributions to the ¯elds...... of coherent electron manip- ulation and the statistical description of electron transport through nano- devices. The physics of the electrons are described with a combination of numerical methods, developed and applied in the thesis, and more analytical approaches, which are also discussed. The thesis......-based communication. The statistical description of electron transport through nanostructures is based on rate equations, and the primary contribution of the thesis in that respect is the development of a method that allows for the calculation of the distribution of electrons passing through a device. The method...

Local and global properties of eigenfunctions and one-electron densities of Coulombic Schrödinger operators

DEFF Research Database (Denmark)

Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas

2008-01-01

We review recent results by the authors on the regularity of molecular eigenfunctions ψ and their corresponding one-electron densities ρ, as well as of the spherically averaged one-electron atomic density ρ. Furthermore, we prove an exponentially decreasing lower bound for ρ in the case when...

Path integrals for electronic densities, reactivity indices, and localization functions in quantum systems.

Science.gov (United States)

Putz, Mihai V

2009-11-10

The density matrix theory, the ancestor of density functional theory, provides the immediate framework for Path Integral (PI) development, allowing the canonical density be extended for the many-electronic systems through the density functional closure relationship. Yet, the use of path integral formalism for electronic density prescription presents several advantages: assures the inner quantum mechanical description of the system by parameterized paths; averages the quantum fluctuations; behaves as the propagator for time-space evolution of quantum information; resembles Schrödinger equation; allows quantum statistical description of the system through partition function computing. In this framework, four levels of path integral formalism were presented: the Feynman quantum mechanical, the semiclassical, the Feynman-Kleinert effective classical, and the Fokker-Planck non-equilibrium ones. In each case the density matrix or/and the canonical density were rigorously defined and presented. The practical specializations for quantum free and harmonic motions, for statistical high and low temperature limits, the smearing justification for the Bohr's quantum stability postulate with the paradigmatic Hydrogen atomic excursion, along the quantum chemical calculation of semiclassical electronegativity and hardness, of chemical action and Mulliken electronegativity, as well as by the Markovian generalizations of Becke-Edgecombe electronic focalization functions - all advocate for the reliability of assuming PI formalism of quantum mechanics as a versatile one, suited for analytically and/or computationally modeling of a variety of fundamental physical and chemical reactivity concepts characterizing the (density driving) many-electronic systems.

Path Integrals for Electronic Densities, Reactivity Indices, and Localization Functions in Quantum Systems

Directory of Open Access Journals (Sweden)

Mihai V. Putz

2009-11-01

Full Text Available The density matrix theory, the ancestor of density functional theory, provides the immediate framework for Path Integral (PI development, allowing the canonical density be extended for the many-electronic systems through the density functional closure relationship. Yet, the use of path integral formalism for electronic density prescription presents several advantages: assures the inner quantum mechanical description of the system by parameterized paths; averages the quantum fluctuations; behaves as the propagator for time-space evolution of quantum information; resembles Schrödinger equation; allows quantum statistical description of the system through partition function computing. In this framework, four levels of path integral formalism were presented: the Feynman quantum mechanical, the semiclassical, the Feynman-Kleinert effective classical, and the Fokker-Planck non-equilibrium ones. In each case the density matrix or/and the canonical density were rigorously defined and presented. The practical specializations for quantum free and harmonic motions, for statistical high and low temperature limits, the smearing justification for the Bohr’s quantum stability postulate with the paradigmatic Hydrogen atomic excursion, along the quantum chemical calculation of semiclassical electronegativity and hardness, of chemical action and Mulliken electronegativity, as well as by the Markovian generalizations of Becke-Edgecombe electronic focalization functions – all advocate for the reliability of assuming PI formalism of quantum mechanics as a versatile one, suited for analytically and/or computationally modeling of a variety of fundamental physical and chemical reactivity concepts characterizing the (density driving many-electronic systems.

Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

Energy Technology Data Exchange (ETDEWEB)

Fitterer, M. [Fermilab; Stancari, G. [Fermilab; Valishev, A. [Fermilab; Bruce, R. [CERN; Papotti, G [CERN; Redaelli, S. [CERN; Valentino, G. [Malta U.; Valentino, G. [CERN; Valuch, D. [CERN; Xu, C. [CERN

2017-06-13

Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

Scaling laws in high energy electron-nuclear processes

International Nuclear Information System (INIS)

Chemtob, M.

1980-11-01

We survey the parton model description of high momentum transfer electron scattering processes with nuclei. We discuss both nucleon and quark parton models and confront the patterns of scaling laws violations, induced by binding effects, in the former, and perturbative QCD effects, in the latter

Magnetic properties of confined electron gas

International Nuclear Information System (INIS)

Felicio, J.R.D. de.

1977-04-01

The effects of confinement by a two or three-dimensional harmonic potential on the magnetic properties of a free electron gas are investigated using the grand-canonical ensemble framework. At high temperatures an extension of Darwin's, Felderhof and Raval's works is made taking into account spin effects at low temperature. A comprehensive description of the magnetic properties of a free electron gas is given. The system is regarded as finite, but the boundary condition psi=0 is not introduced. The limits of weak and strong confinement are also analysed [pt

The effect of electron-electron interaction induced dephasing on electronic transport in graphene nanoribbons

Energy Technology Data Exchange (ETDEWEB)

Kahnoj, Sina Soleimani; Touski, Shoeib Babaee [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Pourfath, Mahdi, E-mail: pourfath@ut.ac.ir, E-mail: pourfath@iue.tuwien.ac.at [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Institute for Microelectronics, TU Wien, Gusshausstrasse 27–29/E360, 1040 Vienna (Austria)

2014-09-08

The effect of dephasing induced by electron-electron interaction on electronic transport in graphene nanoribbons is theoretically investigated. In the presence of disorder in graphene nanoribbons, wavefunction of electrons can set up standing waves along the channel and the conductance exponentially decreases with the ribbon's length. Employing the non-equilibrium Green's function formalism along with an accurate model for describing the dephasing induced by electron-electron interaction, we show that this kind of interaction prevents localization and transport of electrons remains in the diffusive regime where the conductance is inversely proportional to the ribbon's length.

A drift-ordered short mean-free path description of a partially ionized magnetized plasma

International Nuclear Information System (INIS)

Simakov, Andrei N

2009-01-01

Neutral particles that are present at the edge of plasma magnetic confinement devices can play an important role in energy and momentum transport, and their effects should be accounted for. This work uses the drift ordering to derive a closed fluid description for a collisional, magnetized, partially ionized plasma. Charge-exchange, ionization and recombination processes are taken into account. It is assumed that electron distribution function is unaffected by atomic processes, so that electron-ion momentum and energy exchange are described by the usual expressions for a fully ionized plasma, and that neutral-neutral collisions are unimportant. The collisional fluid equations derived herein generalize the drift-ordered description of a fully ionized collisional plasma (Catto P J et al 2004 Phys. Plasmas 11 90), agree with the MHD-ordered description of a partially ionized plasma (Helander P et al 1994 Phys. Plasmas 1 3174) in the large-flow limit and can be used to describe both turbulent and collisional behavior of a partially ionized plasma.

Electron-electron coincidence spectroscopies at surfaces

International Nuclear Information System (INIS)

Stefani, G.; Iacobucci, S.; Ruocco, A.; Gotter, R.

2002-01-01

In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have contributed to a deeper understanding of electron-electron correlation effects. In more recent years this technique has been extended to the study of solid surfaces. This class of one photon IN two electrons OUT experiments will be discussed with an emphasis on grazing incidence geometry, that is expected to be particularly suited for studying surfaces. The crucial question of which is the dominant mechanism that leads to ejection of pairs of electron from the surface will be addressed. It will be shown that, depending on the kinematics chosen, the correlated behaviour of the pairs of electrons detected might be singled out from independent particle one

Order αGsub(μ) corrections to the parity-violating electron-quark potential in the Weinberg-Salam theory: parity-violations in one-electron atoms

International Nuclear Information System (INIS)

Lynn, B.W.

We have calculated the order αGsub(μ) corrections to the order Gsub(μ) parity-violating (PV) electron-quark potential Hsub(PV)sup(e-q) at q 2 =0 in the standard SU(2)sub(L) x U(1) theory using a renormalization scheme which has Msub(W), Msub(Z) and Msub(H) (Higgs' mass) as input parameters. We then use SU(3) relations to write an effective PV electron-nucleon potential Hsub(PV)sup(e-N) in terms of the dimensionless parameters Csub(1P), Csub(1N) (nuclear spin independent) Csub(2P), Csub(2N) (nuclear spin dependent) and Csub(3P), Csub(3N) (electron anomalous magnetic moment dependent). For ssub(theta) 2 identical to 1-Msub(W) 2 /Msub(Z) 2 approx.= .23 and small Higgs' mass Msub(H) or approx.1 TeV. Csub(3P), and Csub(3N) are first induced at one loop and are small. We show that Csub(2P) and Csub(2N) suffer from large uncertainties due to the strong interactions which make the theoretical interpretation of experiments designed to measure these quantities less clear than was previously thought. The other parameters are relatively free from strong interaction uncertainties. We review the diseases of the old 1934 four-fermion theory and give an overview of the renormalization of the Weinberg-Salam theory. We discuss the possibility of high-precision experiments in one-electron atoms to measure these radiative corrections and remind the reader of a previously proposed experiment in hydrogen or deuterium which will measure Csub(1P) or Csub(1P)+Csub(1N) respectively. (author)

Calculation of two-center one-electron molecular integrals with STOs. [BICEN

Energy Technology Data Exchange (ETDEWEB)

Rico, J.F.; Lopez, R.; Paniagua, M.; Ramirez, G. (Universidad Autonoma de Madrid (Spain). Dept. de Quimica Fisica y Quimica Cuantica)

1991-05-01

A program for the calculation of two-center one-electron integrals (overlap, nuclear attraction and kinetic energy) between real Slater-type orbitals (STOs) is reported. The integrals are obtained by recursion over simple auxiliary matrices, whose elements are calculated in terms of further auxiliary functions evaluated in a quick and accurate way. (orig.).

On parasupersymmetries and relativistic descriptions for spin one particles. Pt. 1. The free context

International Nuclear Information System (INIS)

Beckers, J.; Debergh, N.; Nikitin, A.G.

1995-01-01

This series of two papers is devoted to a constructive review of the relativistic wave equations for vector mesons due to the recent impact of spin one developments in connection with parasupersymmetric quantum mechanics. The free case as well as the interacting context with an electromagnetic field will be successively visited and discussed. Their associated parasupersymmetric properties will be pointed out. In this first part, the free context is presented by studying systematically the (symmetric) forms of wave equations subtended by a 16-dimensional reducible representation of the Lie algebra sl (2, C) or, evidently, so (3, 1), this representation playing a well known role in p = 2-parastatistical developments. Their hamiltonian forms are also discussed and some second order descriptions are finally reviewed. (orig.)

Role descriptions induce gender mismatch effects in eye movements during reading

Directory of Open Access Journals (Sweden)

Chiara eReali

2015-11-01

Full Text Available The present eye-tracking study investigates the effect of gender typicality on the resolution of anaphoric personal pronouns in English. Participants read descriptions of a person performing a typically male, typically female or gender-neutral occupational activity. The description was followed by an anaphoric reference (he or she which revealed the referent's gender. The first experiment presented roles which were highly typical for men (e.g., blacksmith or for women (e.g., beautician, the second experiment presented role descriptions with a moderate degree of gender typicality (e.g., psychologist, lawyer. Results revealed a gender mismatch effect in early and late measures in the first experiment and in an early measure in the second experiment. Moreover, eye-movement data for highly typical roles correlated with explicit typicality ratings. The results are discussed from a cross-linguistic perspective, comparing natural gender languages and grammatical gender languages. An interpretation of the cognitive representation of typicality beliefs is proposed.

One size fits all electronics for insole-based activity monitoring.

Science.gov (United States)

Hegde, Nagaraj; Bries, Matthew; Melanson, Edward; Sazonov, Edward

2017-07-01

Footwear based wearable sensors are becoming prominent in many areas of monitoring health and wellness, such as gait and activity monitoring. In our previous research we introduced an insole based wearable system SmartStep, which is completely integrated in a socially acceptable package. From a manufacturing perspective, SmartStep's electronics had to be custom made for each shoe size, greatly complicating the manufacturing process. In this work we explore the possibility of making a universal electronics platform for SmartStep - SmartStep 3.0, which can be used in the most common insole sizes without modifications. A pilot human subject experiments were run to compare the accuracy between the one-size fits all (SmartStep 3.0) and custom size SmartStep 2.0. A total of ~10 hours of data was collected in the pilot study involving three participants performing different activities of daily living while wearing SmartStep 2.0 and SmartStep 3.0. Leave one out cross validation resulted in a 98.5% average accuracy from SmartStep 2.0, while SmartStep 3.0 resulted in 98.3% accuracy, suggesting that the SmartStep 3.0 can be as accurate as SmartStep 2.0, while fitting most common shoe sizes.

Effect of strong correlations on the high energy anomaly in hole- and electron-doped high-Tc superconductors

International Nuclear Information System (INIS)

Moritz, B; Johnston, S; Greven, M; Shen, Z-X; Devereaux, T P; Schmitt, F; Meevasana, W; Motoyama, E M; Lu, D H; Kim, C; Scalettar, R T

2009-01-01

Recently, angle-resolved photoemission spectroscopy (ARPES) has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). This paper demonstrates, using a combination of new ARPES measurements and quantum Monte Carlo simulations, that the HEA is not simply the by-product of matrix element effects, but rather represents a cross-over from a quasi-particle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character, in both hole- and electron-doped cuprates. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. the 'waterfall'-like behavior, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying both hole and electron doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram.

Valence one-electron and shake-up ionization bands of fluorene, carbazole and dibenzofuran

International Nuclear Information System (INIS)

Reza Shojaei, S.H.; Morini, Filippo; Deleuze, Michael S.

2013-01-01

Highlights: • The photoelectron spectra of the title compounds are assigned in details. • Shake-up lines are found to severely contaminate both π- and σ-ionization bands. • σ-ionization onsets are subject to severe vibronic coupling complications. • We compare the results of OVGF, ADC(3) and TDDFT calculations. - Abstract: A comprehensive study of the He (I) ultra-violet photoelectron spectra of fluorene, carbazole and dibenzofuran is presented with the aid of one-particle Green’s Function calculations employing the outer-valence Green’s Function (OVGF) approach and the third-order algebraic diagrammatic construction [ADC(3)] scheme, along with Dunning’s correlation consistent basis sets of double and triple zeta quality (cc-pVDZ, cc-pVTZ). Extrapolations of the ADC(3) results for the outermost one-electron π-ionization energies to the cc-pVTZ basis set enable theoretical insights into He (I) measurements within ∼0.15 eV accuracy, up to the σ-ionization onset. The lower ionization energy of carbazole is the combined result of mesomeric and electronic relaxation effects. OVGF/cc-pVDZ or OVGF/cc-pVTZ pole strengths smaller than 0.85 systematically corroborate a breakdown of the orbital picture of ionization at the ADC(3) level. Comparison is made with calculations of the lowest doublet–doublet excitation energies of the radical cation of fluorene, by means of time-dependent density functional theory (TDDFT)

One-electron oxidation of BD84, an ellipticine antitumor derivative

International Nuclear Information System (INIS)

Sekaki, A.; Gardes-Albert, M.; Houee-Levin, C.; Ferradini, C.; Rivalle, C.; Bisagni, E.; Hickel, B.

1991-01-01

The one-electron oxidation of BD84, an ellipticine-related drug, has been studied by pulse radiolysis using OH· radicals as oxidizing agents. In the absence of oxygen, R· radicals are formed. They disappear by recombination. In the presence of oxygen, R· radicals react with O 2 to give peroxy radicals RO 2 ·, which decay by a second-order process. These results are compared to those obtained for other ellipticine derivatives [fr

Phase-space description of wave packet approach to electronic transport in nanoscale systems

International Nuclear Information System (INIS)

Szydłowski, D; Wołoszyn, M; Spisak, B J

2013-01-01

The dynamics of conduction electrons in resonant tunnelling nanosystems is studied within the phase-space approach based on the Wigner distribution function. The time evolution of the distribution function is calculated from the time-dependent quantum kinetic equation for which an effective numerical method is presented. Calculations of the transport properties of a double-barrier resonant tunnelling diode are performed to illustrate the proposed techniques. Additionally, analysis of the transient effects in the nanosystem is carried out and it is shown that for some range of the bias voltage the temporal variations of electronic current can take negative values. The explanation of this effect is based on the analysis of the time changes of the Wigner distribution function. The decay time of the temporal current oscillations in the nanosystem as a function of the bias voltage is determined. (paper)

An empirical investigation on the effects of electronic banking on key customer relationship management

Directory of Open Access Journals (Sweden)

Kazem Chavoshi

2013-12-01

Full Text Available In recent years, there has been good progress on information and communication technology influencing businesses with a new emerging concept called customer relationship management (CRM and it has made significant changes in electronic banking. The primary objective of this paper is to survey electronic banking effects on key CRM components in one of Iranian banks in city of Tehran, Iran. The survey designs a questionnaire and distributes it among some experts in one of selected regions and the results are verified based on t-student and Freedman tests. Results show that all electronic banking services influence on CRM. In addition, that there are no significant differences among effects of electronic services on CRM but each CRM component has different effects on electronic services. In fact, according to freedman test, improving customer relationship process is the most important factor followed by providing appropriate service for each customer, providing appropriate service on appropriate time for each customer and providing appropriate service by appropriate channel for each customer.

Foldy-Wouthuysen transformations for the classical relativistic electron. Non grassmannian description

International Nuclear Information System (INIS)

Pupasov-Maksimov, Andrey; Deriglazov, Alexei

2012-01-01

Full text: We consider a classical model of the relativistic electron proposed by A. Deriglazov in Phys. Lett. A 376 (2012) 309-313. Though this model contains only bosonic variables, its quantization leads to the Dirac equation and one-particle relativistic quantum mechanics of the electron. There are constraints and gauge symmetries, therefore 18 initial variables of the model {x μ , p μ , ω A , π A }, μ is an element of (0,4), A is an element of (0,5) do not correspond to the observable quantities. There are 10 physical degrees of freedom implying another set of 10 gauge invariant variables which will be interpreted as physically observable quantities. On the other hand, to have a consistent one-particle relativistic quantum mechanics one has to consider only even operators which do not mix quantum states with positive and negative energy states. Such separation can be obtained with the Foldy-Wouthuysen transformation and leads to the Foldy-Wouthuysen representation with new operators for coordinates and spin (so-called Newton-Wigner coordinates). In the present work we match these to pictures by comparing the choice of the gauge invariant classical variables and the transition to the even operators in the quantum mechanics. We study different canonical transformations of this classical model in order to separate the set of observable quantities from variables with ambiguous dynamics. The constraints of the model in the case of free particle can be chosen in such a way that the Dirac brackets coincide with the Poisson brackets. This choice significantly simplify calculations of transformed variables. Moreover, new variables are canonical variables by construction. It is shown that the following generator of an infinitesimal canonical transformation S=1/2J 5j p j A(p 2 ), can be associated with the Foldy-Wouthuysen transformation. Thus we obtain a classical analog of the Foldy- Wouthuysen transformation. Moreover, the gauge invariant variables in the

Breakdown of the one-electron picture in XPS, XES and AES spectra involving 4s and 4p holes in Pd to Xe

International Nuclear Information System (INIS)

Ohno, M.; Wendin, G.

1981-01-01

Certain XES spectra of Pd to Xe have been calculated using diagrammatic many-body theory within the framework of a free atom calculation. Both XPS an XES spectra demonstrate breakdown of the one-electron picture of a 4p hole due to strong dynamical grant-Coster Kronig (gCK) fluctuation and decay processes. For a 4s hole, there is a large energy shift due to gCK fluctuation, but an effective one-electron model of the 4s hole is valid. For elements Cd to Te, gCK fluctuation and decay lead to broad continuance spectrum and breakdown of the 4p model. Breakdown of the one-electron, or even quasi-particle, model must occur when 4s and 4p holes are part of multiple vacancies

Calculation of the electron trajectory for 200 kV self-shielded electron accelerator

International Nuclear Information System (INIS)

Wang Shuiqing

2000-01-01

In order to calculate the electron trajectory of 200 kV self-shielded electron accelerator, the electric field is calculated with a TRAJ program. In this program, following electron track mash points one by one, the electron beam trajectories are calculated. Knowing the effect of grid voltage on electron optics and gaining grid voltage focusing effect in the various energy grades, the authors have gained scientific basis for adjusting grid voltage, and also accumulated a wealth of experience for designing self-shielded electron accelerator or electron curtain in future

Two-fluid turbulence including electron inertia

Energy Technology Data Exchange (ETDEWEB)

Andrés, Nahuel, E-mail: nandres@iafe.uba.ar; Gómez, Daniel [Instituto de Astronomía y Física del Espacio, CC. 67, suc. 28, 1428 Buenos Aires (Argentina); Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón I, 1428 Buenos Aires (Argentina); Gonzalez, Carlos; Martin, Luis; Dmitruk, Pablo [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, 1428 Buenos Aires (Argentina)

2014-12-15

We present a full two-fluid magnetohydrodynamic (MHD) description for a completely ionized hydrogen plasma, retaining the effects of the Hall current, electron pressure, and electron inertia. According to this description, each plasma species introduces a new spatial scale: the ion inertial length λ{sub i} and the electron inertial length λ{sub e}, which are not present in the traditional MHD description. In the present paper, we seek for possible changes in the energy power spectrum in fully developed turbulent regimes, using numerical simulations of the two-fluid equations in two-and-a-half dimensions. We have been able to reproduce different scaling laws in different spectral ranges, as it has been observed in the solar wind for the magnetic energy spectrum. At the smallest wavenumbers where plain MHD is valid, we obtain an inertial range following a Kolmogorov k{sup −5∕3} law. For intermediate wavenumbers such that λ{sub i}{sup −1}≪k≪λ{sub e}{sup −1}, the spectrum is modified to a k{sup −7∕3} power-law, as has also been obtained for Hall-MHD neglecting electron inertia terms. When electron inertia is retained, a new spectral region given by k>λ{sub e}{sup −1} arises. The power spectrum for magnetic energy in this region is given by a k{sup −11∕3} power law. Finally, when the terms of electron inertia are retained, we study the self-consistent electric field. Our results are discussed and compared with those obtained in the solar wind observations and previous simulations.

One-electron redox potentials and rate of electron transfer in aqueous micellar solution. Partially solubilized quinones

International Nuclear Information System (INIS)

Almgren, M.; Grieser, F.; Thomas, J.K.

1979-01-01

The electron transfer equilibrium between AQS/AQS - and DQ/DQ - (where AQS is sodium 9,10-arthraquinone-2-sulfonate and DQ, duroquinone) has been studied by pulse radiolysis in aqueous micellar solutions of sodium lauryl sulfate. The equilibrium constant is changed as would be expected if AQS, AQS - , and DQ- were all mainly in the aqueous solution, and DQ distributed between the micelles and the aqueous phase with a distribution constant of K/sub D//N = 150 M -1 , in agreement with the independently determined value of this constant. The kinetics of the equilibration show, however, that electron transfer at the micelle surface is important, indicating that also AQS and DQ - are associated with the micelle to some extent. With reasonable assumptions regarding the distribution constants of these species (that have some independent support), the observed catalytic effect of the micelles on the electron transfer from DQ - to AQS can be understood

Electron scattering off nuclei

International Nuclear Information System (INIS)

Gattone, A.O.

1989-01-01

Two recently developed aspects related to the scattering of electrons off nuclei are presented. On the one hand, a model is introduced which emphasizes the relativistic aspects of the problem in the impulse approximation, by demanding strict maintenance of the algebra of the Poincare group. On the other hand, the second model aims at a more sophisticated description of the nuclear response in the case of collective excitations. Basically, it utilizes the RPA formalism with a new development which enables a more careful treatment of the states in the continuum as is the case for the giant resonances. Applications of both models to the description of elastic scattering, inelastic scattering to discrete levels, giant resonances and the quasi-elastic region are discussed. (Author) [es

Activated aging dynamics and effective trap model description in the random energy model

Science.gov (United States)

Baity-Jesi, M.; Biroli, G.; Cammarota, C.

2018-01-01

We study the out-of-equilibrium aging dynamics of the random energy model (REM) ruled by a single spin-flip Metropolis dynamics. We focus on the dynamical evolution taking place on time-scales diverging with the system size. Our aim is to show to what extent the activated dynamics displayed by the REM can be described in terms of an effective trap model. We identify two time regimes: the first one corresponds to the process of escaping from a basin in the energy landscape and to the subsequent exploration of high energy configurations, whereas the second one corresponds to the evolution from a deep basin to the other. By combining numerical simulations with analytical arguments we show why the trap model description does not hold in the former but becomes exact in the second.

Dynamics of coupled electron-nuclei-systems in laser fields

International Nuclear Information System (INIS)

Falge, Mirjam

2012-01-01

This work aimed at the theoretical analysis of high harmonic generation in molecules and the influence of coupled electron and nuclear dynamics on ultra-short pulse ionization processes. In the first part of this thesis, the isotope effect and influence of vibrational excitation on high harmonic generation were investigated for the isotope pairs H 2 O/D 2 O and H 2 /D 2 . It was shown that on the one hand high harmonic intensities strongly depend on the vibrational quantum number of the initial state of the water molecule and on the other hand the spectra of H 2 O and D 2 O exhibit a clear isotope effect for certain vibrationally excited states. Also it was shown that high harmonics of vibrationally excited states show an even more pronounced isotope effect than the ground state. The second and third part of this work treats the influence of coupled electron and nuclear dynamics on photoelectron spectra. In order to facilitate a numerically exact description of this dynamics, a simple one-dimensional model system (Shin-Metiu model) was used. It consists of only a single electronic and nuclear degree-of-freedom and allows for a switching between adiabatic and strongly non-adiabatic dynamics by its parameterization. This model served for the analysis of the dynamics of three different cases ranging from weak over intermediate to strong electron-nuclear coupling. To investigate the influence of non-adiabatic effects on photoelectron spectra, time-resolved photoelectron spectra were calculated applying two methods: a numerically exact treatment and an adiabatic approach neglecting the electron-nuclear coupling. Subsequently, the dependence of the efficiency of a non-adiabatic transition on the nuclear mass was analysed. To this end, the population dynamics and photoelectron spectra were calculated numerically exactly for a strong electron and nuclear coupling. Thereafter the asymmetry in forward and backward direction of time-resolved photoelectron spectra and the

Electronic Health Record Implementation: A SWOT Analysis

Directory of Open Access Journals (Sweden)

Leila Shahmoradi

2017-12-01

Full Text Available Electronic Health Record (EHR is one of the most important achievements of information technology in healthcare domain, and if deployed effectively, it can yield predominant results. The aim of this study was a SWOT (strengths, weaknesses, opportunities, and threats analysis in electronic health record implementation. This is a descriptive, analytical study conducted with the participation of a 90-member work force from Hospitals affiliated to Tehran University of Medical Sciences (TUMS. The data were collected by using a self-structured questionnaire and analyzed by SPSS software. Based on the results, the highest priority in strength analysis was related to timely and quick access to information. However, lack of hardware and infrastructures was the most important weakness. Having the potential to share information between different sectors and access to a variety of health statistics was the significant opportunity of EHR. Finally, the most substantial threats were the lack of strategic planning in the field of electronic health records together with physicians’ and other clinical staff’s resistance in the use of electronic health records. To facilitate successful adoption of electronic health record, some organizational, technical and resource elements contribute; moreover, the consideration of these factors is essential for HER implementation.

Analysis of operating model of electronic invoice colombian Colombian electronic billing analysis of the operational model

Directory of Open Access Journals (Sweden)

Sérgio Roberto da Silva

2016-06-01

Full Text Available Colombia has been one of the first countries to introduce electronic billing process on a voluntary basis, from a traditional to a digital version. In this context, the article analyzes the electronic billing process implemented in Colombia and the advantages. Methodological research is applied, qualitative, descriptive and documentary; where the regulatory framework and the conceptualization of the model is identified; the process of adoption of electronic billing is analyzed, and finally the advantages and disadvantages of its implementation is analyzed. The findings indicate that the model applied in Colombia to issue an electronic billing in sending and receiving process, is not complex, but it requires a small adequate infrastructure and trained personnel to reach all sectors, especially the micro and business which is the largest business network in the country.

Triboelectric effect: A new perspective on electron transfer process

Science.gov (United States)

Pan, Shuaihang; Zhang, Zhinan

2017-10-01

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

One-photon two-electron processes in helium close to the double ionization threshold

International Nuclear Information System (INIS)

Bouri, C.

2007-04-01

This work presents a study of the 1 P 0 excited states of He that can be reached by absorption of a single photon carrying an energy close to the double ionization threshold (DIT) (79 eV). Above the DIT, these states are the double continuum states; below, they are the double excited states. These two types of states are tightly coupled to the single continuum states with or without excitation of the residual ion He + , owing to their degeneracy in energy. In a one-photon process, these states can only be formed owing to the electronic correlations in the system which must be well described to obtain quantitative good results. Our study is a part of the work which aims at a united description of all these doubly excited, ionized-excited, and double continuum states. We use the Hyperspherical R-Matrix with Semiclassical Outgoing Waves (HRM-SOW) method, initially dedicated to double photoionization studies. We extend it to extract information on the single continuum. This extension allows us to compute cross sections of single photoionization with or without excitation up to n 50 for an excess of 100 meV just above the double ionization threshold. A deep insight into this process is given by a partial waves analysis. The results obtained shed light on the key role of angular and radial correlations. The numerous data we obtain on double and single ionization allow us to establish a continuity relation between these two processes. We show that single ionization with an infinite excitation of the residual ion merges into double photoionization when the excess energy is redistributed between the two electrons. It appears that this relation is valid not only for low but also for high photon energies. Since the HRM-SOW can produce the integrated cross section for double photoionization with high accuracy in the low energy domain, we check the Wannier threshold law. The parameters extracted support strongly this threshold law, and are in good agreement with experimental

Description of a Mobile-based Electronic Informed Consent System Development.

Science.gov (United States)

Hwang, Min-A; Kwak, In Ja

2015-01-01

Seoul National University Hospital constructed and implemented a computer-based informed consent system in December 2011. As of 2013, 30% of the informed consents were still filled out manually on paper. Patients and medical staff continuously suggested the implementation of a system for electronic informed consent using portable devices. Therefore, a mobile-based system for electronic informed consent was developed in 2013 to prevent the issues that arise with computer-based systems and paper informed consent. The rate of filling out electronic informed consent increased from 69% to 95% following the implementation of the mobile-based electronic informed consent. This construction of a mobile-based electronic informed consent system would be a good reference point for the development of a mobile-based Electronic Medical Record and for various mobile system environments in medical institutions.

Kinetic and spectral descriptions of autoionization phenomena associated with atomic processes in plasmas

Science.gov (United States)

Jacobs, Verne L.

2017-06-01

This investigation has been devoted to the theoretical description and computer modeling of atomic processes giving rise to radiative emission in energetic electron and ion beam interactions and in laboratory plasmas. We are also interested in the effects of directed electron and ion collisions and of anisotropic electric and magnetic fields. In the kinetic-theory description, we treat excitation, de-excitation, ionization, and recombination in electron and ion encounters with partially ionized atomic systems, including the indirect contributions from processes involving autoionizing resonances. These fundamental collisional and electromagnetic interactions also provide particle and photon transport mechanisms. From the spectral perspective, the analysis of atomic radiative emission can reveal detailed information on the physical properties in the plasma environment, such as non-equilibrium electron and charge-state distributions as well as electric and magnetic field distributions. In this investigation, a reduced-density-matrix formulation is developed for the microscopic description of atomic electromagnetic interactions in the presence of environmental (collisional and radiative) relaxation and decoherence processes. Our central objective is a fundamental microscopic description of atomic electromagnetic processes, in which both bound-state and autoionization-resonance phenomena can be treated in a unified and self-consistent manner. The time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations of the reduced-density-matrix approach are developed in a unified and self-consistent manner. This is necessary for our ultimate goal of a systematic and self-consistent treatment of non-equilibrium (possibly coherent) atomic-state kinetics and high-resolution (possibly overlapping) spectral-line shapes. We thereby propose the introduction of a generalized collisional-radiative atomic-state kinetics model based on a reduced

Studying the effect of trust and quality of electronic services on ...

African Journals Online (AJOL)

The aim of this study is to investigate the impact of trust and quality of electronic services on customer satisfaction. The nature of this research regarding the purpose is applied and considering the method of data collection, it is descriptive of correlational-survey type. Study population is composed of customers of branches ...

Description logics of context

CSIR Research Space (South Africa)

Klarman, S

2013-05-01

Full Text Available We introduce Description Logics of Context (DLCs) - an extension of Description Logics (DLs) for context-based reasoning. Our approach descends from J. McCarthy's tradition of treating contexts as formal objects over which one can quantify...

Asymptotic value of screening parameter as determined from the one-electron fragment of the kinetic energy or electrostatic potential at the nucleus

Energy Technology Data Exchange (ETDEWEB)

Teruya, Hirohide; Anno, Tosinobu

1985-09-01

Numerical value of lim sub(Z ..-->.. infinity) delta(i, j)/delta Zsub(i), where (i, j) stands for average interaction energy of a pair of electrons embedded in hydrogenic orbitals (HAO's) is presented for a wide range of HAO's. Data to be presented should be useful to calculate the asymptotic limit of screening effect seen by an electron embedded in a given kind of orbital for an isoelectronic series of atoms as determined from the ''one-electron component'' of the total kinetic energy of or of the electrostatic potential at the nucleus within an atom.

Field theory of the spinning electron: Internal motions

OpenAIRE

Salesi, Giovanni; Recami, Erasmo

1996-01-01

We present here a field theory of the spinning electron, by writing down a new equation for the 4-velocity field v^mu (different from that of Dirac theory), which allows a classically intelligible description of the electron. Moreover, we make explicit the noticeable kinematical properties of such velocity field (which also result different from the ordinary ones). At last, we analyze the internal zitterbewegung (zbw) motions, for both time-like and light-like speeds. We adopt in this paper t...

Vacuum nanoelectronic devices novel electron sources and applications

CERN Document Server

Evtukh, Anatoliy; Yilmazoglu, Oktay; Mimura, Hidenori; Pavlidis, Dimitris

2015-01-01

Introducing up-to-date coverage of research in electron field emission from nanostructures, Vacuum Nanoelectronic Devices outlines the physics of quantum nanostructures, basic principles of electron field emission, and vacuum nanoelectronic devices operation, and offers as insight state-of-the-art and future researches and developments.  This book also evaluates the results of research and development of novel quantum electron sources that will determine the future development of vacuum nanoelectronics. Further to this, the influence of quantum mechanical effects on high frequency vacuum nanoelectronic devices is also assessed. Key features: In-depth description and analysis of the fundamentals of Quantum Electron effects in novel electron sources. Comprehensive and up-to-date summary of the physics and technologies for THz sources for students of physical and engineering specialties and electronics engineers. Unique coverage of quantum physical results for electron-field emission and novel electron sourc...

Dynamic screening and electron dynamics in low-dimensional metal systems

International Nuclear Information System (INIS)

Silkin, V.M.; Quijada, M.; Vergniory, M.G.; Alducin, M.; Borisov, A.G.; Diez Muino, R.; Juaristi, J.I.; Sanchez-Portal, D.; Chulkov, E.V.; Echenique, P.M.

2007-01-01

Recent advances in the theoretical description of dynamic screening and electron dynamics in metallic media are reviewed. The time-dependent building-up of screening in different situations is addressed. Perturbative and non-perturbative theories are used to study electron dynamics in low-dimensional systems, such as metal clusters, image states, surface states and quantum wells. Modification of the electronic lifetimes due to confinement effects is analyzed as well

Density functional theory for the description of charge-transfer processes at TTF/TCNQ interfaces

KAUST Repository

Van Regemorter, Tanguy; Guillaume, Maxime; Sini, Gjergji; Sears, John S.; Geskin, Victor; Bré das, Jean-Luc; Beljonne, David; Cornil, Jé rô me

2012-01-01

In the field of organic electronics, a central issue is to assess how the frontier electronic levels of two adjacent organic layers align with respect to one another at the interface. This alignment can be driven by the presence of a partial charge transfer and the formation of an interface dipole; it plays a key role for instance in determining the rates of exciton dissociation or exciton formation in organic solar cells or light-emitting diodes, respectively. Reliably modeling the processes taking place at these interfaces remains a challenge for the computational chemistry community. Here, we review our recent theoretical work on the influence of the choice of density functional theory (DFT) methodology on the description of the charge-transfer character in the ground state of TTF/ TCNQ model complexes and interfaces. Starting with the electronic properties of the isolated TTF and TCNQ molecules and then considering the charge transfer and resulting interface dipole in TTF/TCNQ donor-acceptor stacks and bilayers, we examine the impact of the choice of DFT functional in describing the interfacial electronic structure. Finally, we employ computations based on periodic boundary conditions to highlight the impact of depolarization effects on the interfacial dipole moment. © Springer-Verlag 2012.

Density functional theory for the description of charge-transfer processes at TTF/TCNQ interfaces

KAUST Repository

Van Regemorter, Tanguy

2012-09-15

In the field of organic electronics, a central issue is to assess how the frontier electronic levels of two adjacent organic layers align with respect to one another at the interface. This alignment can be driven by the presence of a partial charge transfer and the formation of an interface dipole; it plays a key role for instance in determining the rates of exciton dissociation or exciton formation in organic solar cells or light-emitting diodes, respectively. Reliably modeling the processes taking place at these interfaces remains a challenge for the computational chemistry community. Here, we review our recent theoretical work on the influence of the choice of density functional theory (DFT) methodology on the description of the charge-transfer character in the ground state of TTF/ TCNQ model complexes and interfaces. Starting with the electronic properties of the isolated TTF and TCNQ molecules and then considering the charge transfer and resulting interface dipole in TTF/TCNQ donor-acceptor stacks and bilayers, we examine the impact of the choice of DFT functional in describing the interfacial electronic structure. Finally, we employ computations based on periodic boundary conditions to highlight the impact of depolarization effects on the interfacial dipole moment. © Springer-Verlag 2012.

Lagrangian fluid description with simple applications in compressible plasma and gas dynamics

International Nuclear Information System (INIS)

Schamel, Hans

2004-01-01

-dimension (1D). In cosmology referring to the pancake model of Zel'dovich and the adhesion model of Gurbatov and Saichev, both assuming a clumping of matter at the intersection points of fluid particle trajectories (i.e. at the caustics), the foam-like large-scale structure of our Universe observed recently by Chandra X-ray observatory may be explained by the 3D convection of weakly interacting dark matter. Recent developments in plasma and nanotechnology - the miniaturization and fabrication of nanoelectronic devices being one example - have reinforced the interest in the quasi-ballistic electron transport in diodes and triodes, a field which turns out to be best treated by the Lagrangian fluid description. It is shown that the well-known space-charge-limited flow given by Child-Langmuir turns out to be incorrect in cases of finite electron injection velocities at the emitting electrode. In that case it is an intrinsic bifurcation scenario which is responsible for current limitation rather than electron reflection at the virtual cathode as intuitively assumed by Langmuir. The inclusion of a Drude friction term in the electron momentum equation can be handled solely by the Lagrangian fluid description. Exploiting the formula in case of field emission it is possible to bridge ballistic and drift-dominated transport. Furthermore, the transient processes in the electron transport triggered by the switching of the anode potential are shown to be perfectly accounted for by means of the Lagrangian fluid description. Finally, by use of the Lagrangian ion fluid equations in case of a two component, current driven plasma we derive a system of two coupled scalar wave equations which involve the specific volume of ions and electrons, respectively. It has a small amplitude strange soliton solution with unusual scaling properties. In case of charge neutrality the existence of two types of collapses are predicted, one being associated with a density excavation, the other one with a density

Lagrangian fluid description with simple applications in compressible plasma and gas dynamics

Science.gov (United States)

Schamel, Hans

2004-03-01

). In cosmology referring to the pancake model of Zel'dovich and the adhesion model of Gurbatov and Saichev, both assuming a clumping of matter at the intersection points of fluid particle trajectories (i.e. at the caustics), the foam-like large-scale structure of our Universe observed recently by Chandra X-ray observatory may be explained by the 3D convection of weakly interacting dark matter. Recent developments in plasma and nanotechnology-the miniaturization and fabrication of nanoelectronic devices being one example-have reinforced the interest in the quasi-ballistic electron transport in diodes and triodes, a field which turns out to be best treated by the Lagrangian fluid description. It is shown that the well-known space-charge-limited flow given by Child-Langmuir turns out to be incorrect in cases of finite electron injection velocities at the emitting electrode. In that case it is an intrinsic bifurcation scenario which is responsible for current limitation rather than electron reflection at the virtual cathode as intuitively assumed by Langmuir. The inclusion of a Drude friction term in the electron momentum equation can be handled solely by the Lagrangian fluid description. Exploiting the formula in case of field emission it is possible to bridge ballistic and drift-dominated transport. Furthermore, the transient processes in the electron transport triggered by the switching of the anode potential are shown to be perfectly accounted for by means of the Lagrangian fluid description. Finally, by use of the Lagrangian ion fluid equations in case of a two component, current driven plasma we derive a system of two coupled scalar wave equations which involve the specific volume of ions and electrons, respectively. It has a small amplitude strange soliton solution with unusual scaling properties. In case of charge neutrality the existence of two types of collapses are predicted, one being associated with a density excavation, the other one with a density clumping

Fermi-edge singularity in one-dimensional electron systems with long-range Coulomb interactions

International Nuclear Information System (INIS)

Otani, H.; Ogawa, T.

1996-01-01

Effects of long-range Coulomb interactions on the Fermi-edge singularity in optical spectra are investigated theoretically for one-dimensional spin-1/2 fermion systems with the use of the Tomonaga-Luttinger bosonization technique. Low-energy excitation spectrum near the Fermi level shows that dispersion of the charge-density fluctuation remains gapless but is nonlinear when the electron-electron (e-e) Coulomb interaction is of the x -1 type (i.e., an infinite force range). Temporal behavior of the current-current correlation function is calculated analytically for arbitrary force ranges, λ e and λ h , of the e-e and the electron-hole (e-h) Coulomb interactions. (i) When both the e-e and the e-h interactions have large but finite force ranges (λ e h max[λ e ,λ h ]/v F . Corresponding optical spectrum near the Fermi edge (within an energy range of ℎv F /max[λ e ,λ h ]) exhibits the power-law divergence or the power-law convergence, which is an ordinary Fermi-edge singularity. (ii) When either the e-e or the e-h interaction is of the x -1 type (i.e., λ e →∞ and/or λ h →∞), an exponent of the correlation function is dependent on time to lead the faster decay than that of any power laws. Then the optical spectra show no power law dependence and always converge (become zero) at the Fermi edge, which is in striking contrast to the ordinary power-law singularity

Simple model of the slingshot effect

Directory of Open Access Journals (Sweden)

Gaetano Fiore

2016-07-01

Full Text Available We present a detailed quantitative description of the recently proposed “slingshot effect.” Namely, we determine a broad range of conditions under which the impact of a very short and intense laser pulse normally onto a low-density plasma (or matter locally completely ionized into a plasma by the pulse causes the expulsion of a bunch of surface electrons in the direction opposite to the one of propagation of the pulse, and the detailed, ready-for-experiments features of the expelled electrons (energy spectrum, collimation, etc. The effect is due to the combined actions of the ponderomotive force and the huge longitudinal field arising from charge separation. Our predictions are based on estimating 3D corrections to a simple, yet powerful plane 2-fluid magnetohydrodynamic (MHD model where the equations to be solved are reduced to a system of Hamilton equations in one dimension (or a collection of which become autonomous after the pulse has overcome the electrons. Experimental tests seem to be at hand. If confirmed by the latter, the effect would provide a new extraction and acceleration mechanism for electrons, alternative to traditional radio-frequency-based or Laser-Wake-Field ones.

Space charge effects and electronic bistability

International Nuclear Information System (INIS)

Ruffini, A.; Strumia, F.; Tommasi, O.

1996-01-01

The excitation of metastable states in an atomic beam apparatus by means of electron collision is a widespread technique. The authors have observed a large bistable behaviour in apparatus designed to provide an intense and collimated beam of metastable helium by excitation with orthogonally impinging electrons. This bistable behaviour largely affects the efficiency of the apparatus and is therefore worth of being carefully investigated. The apparatus has an electrode configuration equivalent to that of a tetrode valve with large intergrid distances. The bistability consists in a hysteresis cycle in the curve of the anode current vs. grid voltage. Experimental measurements, supported by a simple theoretical model and by numerical simulation, stress out the crucial role played by space charge effects for the onset of bistability. A comparison with previous observations of this phenomenon is given. Spontaneous current oscillations with various shapes have been recorded in one of the two curves of the hysteresis cycle

Magnetic-Field Control Of Tunnel-Coupling In Strongly Confined One-Dimensional Electron Systems

Science.gov (United States)

Fischer, S. F.; Apetrii, G.; Kunze, U.; Schuh, D.; Abstreiter, G.

2007-04-01

One-dimensional (1D) ballistic electron transport is studied through stacked 1D quantum conductors separated by a thin tunneling barrier. The 1D electron systems of large 1D subband spacings (more than 10 meV) allow single mode operation. Degeneracies of 1D subbands of equal lateral mode index are lifted by the formation of symmetric and antisymmetric states and are depicted by anti-crossings of transconductance maxima. We observe a mode-dependent turnover from level anti-crossings to crossings in longitudinal magnetic fields.

Microscopic description of production cross sections including deexcitation effects

Science.gov (United States)

Sekizawa, Kazuyuki

2017-07-01

Background: At the forefront of the nuclear science, production of new neutron-rich isotopes is continuously pursued at accelerator laboratories all over the world. To explore the currently unknown territories in the nuclear chart far away from the stability, reliable theoretical predictions are inevitable. Purpose: To provide a reliable prediction of production cross sections taking into account secondary deexcitation processes, both particle evaporation and fission, a new method called TDHF+GEMINI is proposed, which combines the microscopic time-dependent Hartree-Fock (TDHF) theory with a sophisticated statistical compound-nucleus deexcitation model, GEMINI++. Methods: Low-energy heavy ion reactions are described based on three-dimensional Skyrme-TDHF calculations. Using the particle-number projection method, production probabilities, total angular momenta, and excitation energies of primary reaction products are extracted from the TDHF wave function after collision. Production cross sections for secondary reaction products are evaluated employing GEMINI++. Results are compared with available experimental data and widely used grazing calculations. Results: The method is applied to describe cross sections for multinucleon transfer processes in 40Ca+124Sn (Ec .m .≃128.54 MeV ), 48Ca+124Sn (Ec .m .≃125.44 MeV ), 40Ca+208Pb (Ec .m .≃208.84 MeV ), 58Ni+208Pb (Ec .m .≃256.79 MeV ), 64Ni+238U (Ec .m .≃307.35 MeV ), and 136Xe+198Pt (Ec .m .≃644.98 MeV ) reactions at energies close to the Coulomb barrier. It is shown that the inclusion of secondary deexcitation processes, which are dominated by neutron evaporation in the present systems, substantially improves agreement with the experimental data. The magnitude of the evaporation effects is very similar to the one observed in grazing calculations. TDHF+GEMINI provides better description of the absolute value of the cross sections for channels involving transfer of more than one proton, compared to the grazing

Theoretical and experimental study of the electron distribution function in the plasma of an electron cyclotron resonance ion source

International Nuclear Information System (INIS)

Girard, A.; Perret, C.; Bourg, F.; Khodja, H.; Melin, G.; Lecot, C.

1997-01-01

Electron Cyclotron Resonance Ion Sources (ECRIS) are mirror machines which can deliver important fluxes of Highly Charged Ions (HCI). These performances are strongly correlated with hot electrons sustained by an RF wave. This paper presents an analysis of the EDF in an ECR source. In the first part of the paper a one-dimensional Fokker-Planck code for the Electron Distribution Function is presented: this code includes a quasilinear diffusion operator for the RF wave, a collision term and a source term due to electron impact ionization. The present status of this code is presented. In the second part of the paper experiments related to the measurement of the EDF are presented: electron density, diamagnetism, electron endloss current have been measured at the Quadrumafios ECRIS. With these results it is possible to give a precise description of the EDF. (author)

Energetic electron processes fluorescence effects for structured nanoparticles X-ray analysis and nuclear medicine applications

Energy Technology Data Exchange (ETDEWEB)

Taborda, A.; Desbrée, A. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM/SDI/LEDI, BP-17, 31, Avenue de la Division Leclerc, 92262 Fontenay-aux-Roses (France); Carvalho, A. [IEQUALTECS, Lda, Rua Dr. Francisco Sá Carneiro, 36, 2500-065 S. Gregório CLD (Portugal); Chaves, P.C. [C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km 139.7, 2685-066 Bobadela LRS (Portugal); Reis, M.A., E-mail: mareis@ctn.tecnico.ulisboa.pt [IEQUALTECS, Lda, Rua Dr. Francisco Sá Carneiro, 36, 2500-065 S. Gregório CLD (Portugal); C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km 139.7, 2685-066 Bobadela LRS (Portugal)

2016-08-15

Superparamagnetic iron oxide (SPIO) nanoparticles are widely used as contrast agents for nuclear magnetic resonance imaging (MRI), and can be modified for improved imaging or to become tissue-specific or even protein-specific. The knowledge of their detailed elemental composition characterisation and potential use in nuclear medicine applications, is, therefore, an important issue. X-ray fluorescence techniques such as particle induced X-ray emission (PIXE) or X-ray fluorescence spectrometry (XRF), can be used for elemental characterisation even in problematic situations where very little sample volume is available. Still, the fluorescence coefficient of Fe is such that, during the decay of the inner-shell ionised atomic structure, keV Auger electrons are produced in excess to X-rays. Since cross-sections for ionisation induced by keV electrons, for low atomic number atoms, are of the order of 10{sup 3} barn, care should be taken to account for possible fluorescence effects caused by Auger electrons, which may lead to the wrong quantification of elements having atomic number lower than the atomic number of Fe. Furthermore, the same electron processes will occur in iron oxide nanoparticles containing {sup 57}Co, which may be used for nuclear medicine therapy purposes. In the present work, simple approximation algorithms are proposed for the quantitative description of radiative and non-radiative processes associated with Auger electrons cascades. The effects on analytical processes and nuclear medicine applications are quantified for the case of iron oxide nanoparticles, by calculating both electron fluorescence emissions and energy deposition on cell tissues where the nanoparticles may be embedded.

Effect of two-temperature electrons distribution on an electrostatic plasma sheath

International Nuclear Information System (INIS)

Ou, Jing; Xiang, Nong; Gan, Chunyun; Yang, Jinhong

2013-01-01

A magnetized collisionless plasma sheath containing two-temperature electrons is studied using a one-dimensional model in which the low-temperature electrons are described by Maxwellian distribution (MD) and high-temperature electrons are described by truncated Maxwellian distribution (TMD). Based on the ion wave approach, a modified sheath criterion including effect of TMD caused by high-temperature electrons energy above the sheath potential energy is established theoretically. The model is also used to investigate numerically the sheath structure and energy flux to the wall for plasmas parameters of an open divertor tokamak-like. Our results show that the profiles of the sheath potential, two-temperature electrons and ions densities, high-temperature electrons and ions velocities as well as the energy flux to the wall depend on the high-temperature electrons concentration, temperature, and velocity distribution function associated with sheath potential. In addition, the results obtained in the high-temperature electrons with TMD as well as with MD sheaths are compared for the different sheath potential

One-Dimensional Electron Transport Layers for Perovskite Solar Cells

Directory of Open Access Journals (Sweden)

Ujwal K. Thakur

2017-04-01

Full Text Available The electron diffusion length (Ln is smaller than the hole diffusion length (Lp in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D structures such as nanowires (NWs and nanotubes (NTs as electron transport layers (ETLs is a promising method of achieving high performance halide perovskite solar cells (HPSCs. ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs. This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells.

One-Dimensional Electron Transport Layers for Perovskite Solar Cells

Science.gov (United States)

Thakur, Ujwal K.; Kisslinger, Ryan; Shankar, Karthik

2017-01-01

The electron diffusion length (Ln) is smaller than the hole diffusion length (Lp) in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as electron transport layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs) as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs). This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells. PMID:28468280

Probability Theory Plus Noise: Descriptive Estimation and Inferential Judgment.

Science.gov (United States)

Costello, Fintan; Watts, Paul

2018-01-01

We describe a computational model of two central aspects of people's probabilistic reasoning: descriptive probability estimation and inferential probability judgment. This model assumes that people's reasoning follows standard frequentist probability theory, but it is subject to random noise. This random noise has a regressive effect in descriptive probability estimation, moving probability estimates away from normative probabilities and toward the center of the probability scale. This random noise has an anti-regressive effect in inferential judgement, however. These regressive and anti-regressive effects explain various reliable and systematic biases seen in people's descriptive probability estimation and inferential probability judgment. This model predicts that these contrary effects will tend to cancel out in tasks that involve both descriptive estimation and inferential judgement, leading to unbiased responses in those tasks. We test this model by applying it to one such task, described by Gallistel et al. ). Participants' median responses in this task were unbiased, agreeing with normative probability theory over the full range of responses. Our model captures the pattern of unbiased responses in this task, while simultaneously explaining systematic biases away from normatively correct probabilities seen in other tasks. Copyright © 2018 Cognitive Science Society, Inc.

The effect of electron scattering from disordered grain boundaries on the resistivity of metallic nanostructures

International Nuclear Information System (INIS)

Arenas, Claudio; Henriquez, Ricardo; Moraga, Luis; Muñoz, Enrique; Munoz, Raul C.

2015-01-01

Highlights: • Quantum theory of the resistivity arising from electron-grain boundary scattering in nanometric metallic structures. • The resistivity is controlled by the collective properties of the grain assembly, by the allowed Kronig-Penney (KP) bands and by the electron transmission probability across successive grains. • When the grain diameter d is larger than the electron mean free path l, the increase in resistivity arises mainly from a decrease of the number of states at the Fermi surface that are allowed KP bands. • When the grain diameter d is smaller than the electron mean free path l, the increase in resistivity arises primarily from Anderson localization caused by electron transmission across successive grains. - Abstract: We calculate the electrical resistivity of a metallic specimen, under the combined effects of electron scattering by impurities, grain boundaries, and rough surfaces limiting the film, using a quantum theory based upon the Kubo formalism. Grain boundaries are represented by a one-dimensional periodic array of Dirac delta functions separated by a distance “d” giving rise to a Kronig–Penney (KP) potential. We use the Green's function built from the wave functions that are solutions of this KP potential; disorder is included by incorporating into the theory the probability that an electron is transmitted through several successive grain boundaries. We apply this new theory to analyze the resistivity of samples S1, S2, S7 and S8 measured between 4 and 300 K reported in Appl. Surf. Science273, 315 (2013). Although both the classical and the quantum theories predict a resistivity that agrees with experimental data to within a few percent or better, the phenomena giving rise to the increase of resistivity over the bulk are remarkably different. Classically, each grain boundary contributes to the electrical resistance by reflecting a certain fraction of the incoming electrons. In the quantum description, there are states

The effect of electron scattering from disordered grain boundaries on the resistivity of metallic nanostructures

Energy Technology Data Exchange (ETDEWEB)

Arenas, Claudio [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago 8370449 (Chile); Synopsys Inc., Avenida Vitacura 5250, Oficina 708, Vitacura, Santiago (Chile); Henriquez, Ricardo [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Casilla 110-V, Valparaíso (Chile); Moraga, Luis [Universidad Central de Chile, Toesca 1783, Santiago (Chile); Muñoz, Enrique [Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 7820436 (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)

2015-02-28

Highlights: • Quantum theory of the resistivity arising from electron-grain boundary scattering in nanometric metallic structures. • The resistivity is controlled by the collective properties of the grain assembly, by the allowed Kronig-Penney (KP) bands and by the electron transmission probability across successive grains. • When the grain diameter d is larger than the electron mean free path l, the increase in resistivity arises mainly from a decrease of the number of states at the Fermi surface that are allowed KP bands. • When the grain diameter d is smaller than the electron mean free path l, the increase in resistivity arises primarily from Anderson localization caused by electron transmission across successive grains. - Abstract: We calculate the electrical resistivity of a metallic specimen, under the combined effects of electron scattering by impurities, grain boundaries, and rough surfaces limiting the film, using a quantum theory based upon the Kubo formalism. Grain boundaries are represented by a one-dimensional periodic array of Dirac delta functions separated by a distance “d” giving rise to a Kronig–Penney (KP) potential. We use the Green's function built from the wave functions that are solutions of this KP potential; disorder is included by incorporating into the theory the probability that an electron is transmitted through several successive grain boundaries. We apply this new theory to analyze the resistivity of samples S1, S2, S7 and S8 measured between 4 and 300 K reported in Appl. Surf. Science273, 315 (2013). Although both the classical and the quantum theories predict a resistivity that agrees with experimental data to within a few percent or better, the phenomena giving rise to the increase of resistivity over the bulk are remarkably different. Classically, each grain boundary contributes to the electrical resistance by reflecting a certain fraction of the incoming electrons. In the quantum description, there are states

Optical guiding and beam bending in free-electron lasers

International Nuclear Information System (INIS)

Scharlemann, E.T.

1987-01-01

The electron beam in a free-electron laser (FEL) can act as an optical fiber, guiding or bending the optical beam. The refractive and gain effects of the bunched electron beam can compensate for diffraction, making possible wigglers that are many Rayleigh ranges (i.e., characteristic diffraction lengths) long. The origin of optical guiding can be understood by examining gain and refractive guiding in a fiber with a complex index of refraction, providing a mathematical description applicable also to the FEL, with some extensions. In the exponential gain regime of the FEL, the electron equations of motion must be included, but a self-consistent description of exponential gain with diffraction fully included becomes possible. The origin of the effective index of refraction of an FEL is illustrated with a simple example of bunched, radiating dipoles. Some of the properties of the index of refraction are described. The limited experimental evidence for optical beam bending is summarized. The evidence does not yet provide conclusive proof of the existence of optical guiding, but supports the idea. Finally, the importance of refractive guiding for the performance of a high-gain tapered-wiggler FEL amplifier is illustrated with numerical simulations

Organic electronic materials: Recent advances in the dft description of the ground and excited states using tuned range-separated hybrid functionals

KAUST Repository

Körzdörfer, Thomas

2014-11-18

Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers.In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter.We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of π-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the

Effects of geometry in itinerant electron magnets

Energy Technology Data Exchange (ETDEWEB)

Nakamura, H [Graduate School of Material Science, University of Hyogo, Kamigori, Ako-gun, Hyogo 678-1297 (Japan); Muro, Y [Graduate School of Material Science, University of Hyogo, Kamigori, Ako-gun, Hyogo 678-1297 (Japan); Kohara, T [Graduate School of Material Science, University of Hyogo, Kamigori, Ako-gun, Hyogo 678-1297 (Japan); Shiga, M [Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501 (Japan)

2007-04-11

The magnetism of quasi-one-dimensional itinerant electron magnets RMn{sub 4}Al{sub 8} is compared with that of the typical frustrated itinerant electron magnet YMn{sub 2}. The possible formation and observation of the spin pseudogap are discussed in connection with the spin-liquid state in strongly correlated itinerant electron systems.

One-Port Electronic Detection Strategies for Improving Sensitivity in Piezoelectric Resonant Sensor Measurements

Directory of Open Access Journals (Sweden)

Zhongxu Hu

2016-10-01

Full Text Available This paper describes a one-port mechanical resonance detection scheme utilized on a piezoelectric thin film driven silicon circular diaphragm resonator and discusses the limitations to such an approach in degenerate mode mass detection sensors. The sensor utilizes degenerated vibration modes of a radial symmetrical microstructure thereby providing both a sense and reference mode allowing for minimization of environmental effects on performance. The circular diaphragm resonator was fabricated with thickness of 4.5 µm and diameter of 140 µm. A PZT thin film of 0.75 µm was patterned on the top surface for the purposes of excitation and vibration sensing. The device showed a resonant frequency of 5.8 MHz for the (1, 1 mode. An electronic interface circuit was designed to cancel out the large static and parasitic capacitance allowing for electrical detection of the mechanical vibration thereby enabling the frequency split between the sense and reference mode to be measured accurately. The extracted motional current, proportional to the vibration velocity, was fed back to the drive to effectively increase the Q factor, and therefore device sensitivity, by more than a factor of 8. A software phase-locked loop was implemented to automatically track the resonant frequencies to allow for faster and accurate resonance detection. Results showed that by utilizing the absolute mode frequencies as an indication of sensor temperature, the variation in sensor temperature due to the heating from the drive electronics was accounted for and led to an ultimate measurement sensitivity of 2.3 Hz.

One-Port Electronic Detection Strategies for Improving Sensitivity in Piezoelectric Resonant Sensor Measurements

Science.gov (United States)

Hu, Zhongxu; Hedley, John; Keegan, Neil; Spoors, Julia; Gallacher, Barry; McNeil, Calum

2016-01-01

This paper describes a one-port mechanical resonance detection scheme utilized on a piezoelectric thin film driven silicon circular diaphragm resonator and discusses the limitations to such an approach in degenerate mode mass detection sensors. The sensor utilizes degenerated vibration modes of a radial symmetrical microstructure thereby providing both a sense and reference mode allowing for minimization of environmental effects on performance. The circular diaphragm resonator was fabricated with thickness of 4.5 µm and diameter of 140 µm. A PZT thin film of 0.75 µm was patterned on the top surface for the purposes of excitation and vibration sensing. The device showed a resonant frequency of 5.8 MHz for the (1, 1) mode. An electronic interface circuit was designed to cancel out the large static and parasitic capacitance allowing for electrical detection of the mechanical vibration thereby enabling the frequency split between the sense and reference mode to be measured accurately. The extracted motional current, proportional to the vibration velocity, was fed back to the drive to effectively increase the Q factor, and therefore device sensitivity, by more than a factor of 8. A software phase-locked loop was implemented to automatically track the resonant frequencies to allow for faster and accurate resonance detection. Results showed that by utilizing the absolute mode frequencies as an indication of sensor temperature, the variation in sensor temperature due to the heating from the drive electronics was accounted for and led to an ultimate measurement sensitivity of 2.3 Hz. PMID:27792154

Electron correlation effects in the half-metallic NiMnSb within a cluster-perturbation approach with ab-initio parameters

Directory of Open Access Journals (Sweden)

H. Allmaier

2008-06-01

Full Text Available  Using a combination of electronic-structure and many-body calculations, we investigate correlations effects in the halfmetallic ferromagnet NiMnSb. A realistic many-body Hamiltonian, containing only Mn-d orbitals shows the importance of non-quasiparticle states just above the Fermi level. Our results suggest that for a better description of low energy states around Fermi level, Ni-d orbitals should be explicitly included.

Studies of isotopic effects in the excited electronic states of molecular systems

International Nuclear Information System (INIS)

1982-01-01

Rare gas halogen (RGH) lasers serve as convenient tools for a range of photophysical processes which exhibit isotope effects. This document summarizes progress in the production of molecular systems in their electronic excited states with the aid of RGH lasers, and the various isotopic effects one can study under these conditions. We conclude that the basic physical mechanisms involved in the isotopically sensitive characteristics of excited molecular electronic states are sufficiently selective to be useful in both the detection and separation of many atomic materials

Correlated electron pseudopotentials for 3d-transition metals

International Nuclear Information System (INIS)

Trail, J. R.; Needs, R. J.

2015-01-01

A recently published correlated electron pseudopotentials (CEPPs) method has been adapted for application to the 3d-transition metals, and to include relativistic effects. New CEPPs are reported for the atoms Sc − Fe, constructed from atomic quantum chemical calculations that include an accurate description of correlated electrons. Dissociation energies, molecular geometries, and zero-point vibrational energies of small molecules are compared with all electron results, with all quantities evaluated using coupled cluster singles doubles and triples calculations. The CEPPs give better results in the correlated-electron calculations than Hartree-Fock-based pseudopotentials available in the literature

Electronic cigarettes: human health effects

OpenAIRE

Callahan-Lyon, Priscilla

2014-01-01

Objective With the rapid increase in use of electronic nicotine delivery systems (ENDS), such as electronic cigarettes (e-cigarettes), users and non-users are exposed to the aerosol and product constituents. This is a review of published data on the human health effects of exposure to e-cigarettes and their components. Methods Literature searches were conducted through September 2013 using multiple electronic databases. Results Forty-four articles are included in this analysis. E-cigarette ae...

Electron-phonon coupling from finite differences

Science.gov (United States)

Monserrat, Bartomeu

2018-02-01

The interaction between electrons and phonons underlies multiple phenomena in physics, chemistry, and materials science. Examples include superconductivity, electronic transport, and the temperature dependence of optical spectra. A first-principles description of electron-phonon coupling enables the study of the above phenomena with accuracy and material specificity, which can be used to understand experiments and to predict novel effects and functionality. In this topical review, we describe the first-principles calculation of electron-phonon coupling from finite differences. The finite differences approach provides several advantages compared to alternative methods, in particular (i) any underlying electronic structure method can be used, and (ii) terms beyond the lowest order in the electron-phonon interaction can be readily incorporated. But these advantages are associated with a large computational cost that has until recently prevented the widespread adoption of this method. We describe some recent advances, including nondiagonal supercells and thermal lines, that resolve these difficulties, and make the calculation of electron-phonon coupling from finite differences a powerful tool. We review multiple applications of the calculation of electron-phonon coupling from finite differences, including the temperature dependence of optical spectra, superconductivity, charge transport, and the role of defects in semiconductors. These examples illustrate the advantages of finite differences, with cases where semilocal density functional theory is not appropriate for the calculation of electron-phonon coupling and many-body methods such as the GW approximation are required, as well as examples in which higher-order terms in the electron-phonon interaction are essential for an accurate description of the relevant phenomena. We expect that the finite difference approach will play a central role in future studies of the electron-phonon interaction.

Asymptotic value of screening parameter as determined from the one-electron fragment of the kinetic energy or electrostatic potential at the nucleus

International Nuclear Information System (INIS)

Teruya, Hirohide; Anno, Tosinobu

1985-01-01

Numerical value of lim sub(Z → infinity) delta(i, j)/delta Zsub(i), where (i, j) stands for average interaction energy of a pair of electrons embedded in hydrogenic orbitals (HAO's) is presented for a wide range of HAO's. Data to be presented should be useful to calculate the asymptotic limit of screening effect seen by an electron embedded in a given kind of orbital for an isoelectronic series of atoms as determined from the ''one-electron component'' of the total kinetic energy of or of the electrostatic potential at the nucleus within an atom. (author)

Experimental test accelerator: description and results of initial experiments

International Nuclear Information System (INIS)

Fessenden, T.; Birx, D.; Briggs, R.

1980-01-01

The ETA is a high current (10,000 Amp) linear induction accelerator that produces short (30 ns) pulses of electrons at 5 MeV twice per second or in bursts of 5 pulses separated by as little as one millisecond. At this time the machine has operated at 65% of its design current and 90% of the design voltage. This report contains a description of the accelerator and its diagnostics; the results of the initial year of operation; a comparison of design codes with experiments on beam transport; and a discussion of some of the special problems and their status

One phonon resonant Raman scattering in semiconductor quantum wires: Magnetic field effect

Energy Technology Data Exchange (ETDEWEB)

Betancourt-Riera, Re., E-mail: rbriera@posgrado.cifus.uson.mx [Instituto Tecnologico de Hermosillo, Avenida Tecnologico S/N, Colonia Sahuaro, C.P. 83170, Hermosillo, Sonor, (Mexico); Departamento de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, C.P. 83190, Hermosillo, Sonora (Mexico); Betancourt-Riera, Ri. [Instituto Tecnologico de Hermosillo, Avenida Tecnologico S/N, Colonia Sahuaro, C.P. 83170, Hermosillo, Sonora (Mexico); Nieto Jalil, J.M. [Tecnologico de Monterrey-Campus Sonora Norte, Bulevar Enrique Mazon Lopez No. 965, C.P. 83000, Hermosillo, Sonora (Mexico); Riera, R. [Departamento de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, C.P. 83190, Hermosillo, Sonora (Mexico)

2013-02-01

We have developed a theory of one phonon resonant Raman scattering in a semiconductor quantum wire of cylindrical geometry in the presence of an external magnetic field distribution, parallel to the cylinder axis. The effect of the magnetic field in the electron and hole states, and in the Raman scattering efficiency, is determinate. We consider the electron-phonon interaction using a Froehlich-type Hamiltonian, deduced for the case of complete confinement phonon modes by Comas and his collaborators. We also assume T=0 K, a single parabolic conduction and valence bands. The spectra are discussed for different magnetic field values and the selection rules for the processes are also studied.

Formation of quinones by one-electron oxidation in the metabolism of benzo[a]pyrene and 6-fluorobenzo[a]pyrene

International Nuclear Information System (INIS)

Cavalieri, E.; Wong, A.; Cremonesi, P.; Warner, C.; Rogan, E.

1986-01-01

Metabolic activation of polycyclic aromatic hydrocarbons (PAH), as well as other chemical carcinogens, occurs by two major pathways: One-electron oxidation and two-electron oxidation, or monooxygenation. One-electron oxidation generates radical cations or radicals, depending on the molecule in which the oxidation occurs, whereas two-electron oxidation produces oxygenated metabolites. Radical cations of PAH are ultimate electrophilic metabolites capable of binding to cellular macromolecules to initiate the tumor process. In this paper the authors will provide evidence that one-electron oxidation is involved not only in PAH carcinogenesis, but also in the formation of certain metabolites. Metabolism of benzo[a]pyrene (BP) by cytochrome P-450 monooxygenase yields three classes of products: phenols, dihydrodiols and the quinones, 1,6-, 3,6- and 6,12- dione

From quantum to classical modeling of radiation reaction: A focus on stochasticity effects

Science.gov (United States)

Niel, F.; Riconda, C.; Amiranoff, F.; Duclous, R.; Grech, M.

2018-04-01

Radiation reaction in the interaction of ultrarelativistic electrons with a strong external electromagnetic field is investigated using a kinetic approach in the nonlinear moderately quantum regime. Three complementary descriptions are discussed considering arbitrary geometries of interaction: a deterministic one relying on the quantum-corrected radiation reaction force in the Landau and Lifschitz (LL) form, a linear Boltzmann equation for the electron distribution function, and a Fokker-Planck (FP) expansion in the limit where the emitted photon energies are small with respect to that of the emitting electrons. The latter description is equivalent to a stochastic differential equation where the effect of the radiation reaction appears in the form of the deterministic term corresponding to the quantum-corrected LL friction force, and by a diffusion term accounting for the stochastic nature of photon emission. By studying the evolution of the energy moments of the electron distribution function with the three models, we are able to show that all three descriptions provide similar predictions on the temporal evolution of the average energy of an electron population in various physical situations of interest, even for large values of the quantum parameter χ . The FP and full linear Boltzmann descriptions also allow us to correctly describe the evolution of the energy variance (second-order moment) of the distribution function, while higher-order moments are in general correctly captured with the full linear Boltzmann description only. A general criterion for the limit of validity of each description is proposed, as well as a numerical scheme for the inclusion of the FP description in particle-in-cell codes. This work, not limited to the configuration of a monoenergetic electron beam colliding with a laser pulse, allows further insight into the relative importance of various effects of radiation reaction and in particular of the discrete and stochastic nature of high

Equivalent circuit-level model of quantum cascade lasers with integrated hot-electron and hot-phonon effects

Science.gov (United States)

Yousefvand, H. R.

2017-12-01

We report a study of the effects of hot-electron and hot-phonon dynamics on the output characteristics of quantum cascade lasers (QCLs) using an equivalent circuit-level model. The model is developed from the energy balance equation to adopt the electron temperature in the active region levels, the heat transfer equation to include the lattice temperature, the nonequilibrium phonon rate to account for the hot phonon dynamics and simplified two-level rate equations to incorporate the carrier and photon dynamics in the active region. This technique simplifies the description of the electron-phonon interaction in QCLs far from the equilibrium condition. Using the presented model, the steady and transient responses of the QCLs for a wide range of sink temperatures (80 to 320 K) are investigated and analysed. The model enables us to explain the operating characteristics found in QCLs. This predictive model is expected to be applicable to all QCL material systems operating in pulsed and cw regimes.

Disruption or innovation? A qualitative descriptive study on the use of electronic patient-physician communication in patients with advanced cancer.

Science.gov (United States)

Voruganti, Teja; Husain, Amna; Grunfeld, Eva; Webster, Fiona

2018-03-04

In the advanced cancer context, care coordination is often inadequate, leading to suboptimal continuity of care. We evaluated an electronic web-based tool which assembles the patient, their caregivers, and their healthcare providers in a virtual space for team-based communication. We sought to understand participant perceptions on electronic communication in general and the added value of the new tool in particular. We conducted a qualitative descriptive study with participants (patients, caregivers, cancer physicians) who participated in a 3-month pilot trial evaluating the tool. Interviews were thematically analyzed and the perspectives from patients, caregivers, and cancer physicians were triangulated. Interviews from six patients, five of their caregivers, and seven cancer physicians conducted alongside monthly outcome assessments were analyzed. We identified five themes relating participants' perspectives on electronic communication to their experience of care: (1) apparent gaps in care, (2) uncertainty in defining the circle of care, (3) relational aspects of communication, (4) incongruence between technology and social norms of patient-physician communication, and (5) appreciation but apprehension about the team-based communication tool for improving the experience of care. The potential of tools for electronic communication to bring together a team of healthcare providers with the patient and caregivers is significant but may pose new challenges to existing team structure and interpersonal dynamics. Patients and physicians were worried about the impact that electronic communication may have on the patient-physician relationship. Implementation approaches, which build on the relationship and integrate the team as a whole, could positively position electronic communication to enhance the team-based care.

Twelve Tips for Effective Electronic Presentation.

Science.gov (United States)

Crosby, Joy

1994-01-01

Offers 12 tips for effective electronic presentation. This article is intended for readers who may be considering using electronic presentation for the first time. Offers reasons for its popularity and occasions when it may be used. The tips offer assistance in the design and presentation of electronic material. (LZ)

Cost-effectiveness of electronic training in domestic violence risk assessment: ODARA 101.

Science.gov (United States)

Hilton, N Zoe; Ham, Elke

2015-03-01

The need for domestic violence training has increased with the development of evidence-based risk assessment tools, which must be scored correctly for valid application. Emerging research indicates that training in domestic violence risk assessment can increase scoring accuracy, but despite the increasing popularity of electronic training, it is not yet known whether it can be an effective method of risk assessment training. In the present study, 87 assessors from various professions had training in the Ontario Domestic Assault Risk Assessment either face-to-face or using an electronic training program. The two conditions were equally effective, as measured by performance on a post-training skill acquisition test. Completion rates were 100% for face-to-face and 86% for electronic training, an improvement over a previously evaluated manual-only condition. The estimated per-trainee cost of electronic training was one third that of face-to-face training and expected to decrease. More rigorous evaluations of electronic training for risk assessment are recommended. © The Author(s) 2014.

The effects of local correlations on the electronic structure of FeSe

Science.gov (United States)

Watson, Matthew; Kim, Timur; Haghighirad, Amir; Coldea, Amalia

FeSe is structurally the simplest of Fe-based superconductors, but its complex and unique properties pose important theoretical questions. One important aspect of the physics of FeSe is the understanding of the strength and effects of electronic correlations. In order to explore this, we have performed angle-resolved photo-emission spectroscopy (ARPES) measurements on high quality bulk single crystals of FeSe over a wide range of binding energies, in different scattering geometries and with varying incident photon energies, analysing the quasiparticle renormalisations, scattering rates and degree of coherence. We find that FeSe exhibits moderately strong, orbital-dependent correlation effects which are understood to arise primarily due to local electron-electron interactions on the Fe sites. We conclude that electronic correlations constitute a key ingredient in understanding the electronic structure of FeSe. Part of this work was supported by EPSRC, UK (EP/I004475/1, EP/I017836/1). We thank Diamond Light Source for access to Beamline I05.

Effect of EMIC Wave Normal Angle Distribution on Relativistic Electron Scattering

Science.gov (United States)

Gamayunov, K. V.; Khazanov, G. V.

2006-01-01

The flux level of outer-zone relativistic electrons (above 1 MeV) is extremely variable during geomagnetic storms, and controlled by a competition between acceleration and loss. Precipitation of these electrons due to resonant pitch-angle scattering by electromagnetic ion cyclotron (EMIC) waves is considered one of the major loss mechanisms. This mechanism was suggested in early theoretical studies more than three decades ago. However, direct experimental evidence of the wave role in relativistic electrons precipitation is difficult to obtain because of lack of concurrent measurements of precipitating electrons at low altitudes and the waves in a magnetically conjugate equatorial region. Recently, the data from balloon-borne X-ray instruments provided indirect but strong evidence on an efficiency of the EMIC wave induced loss for the outer-zone relativistic electrons. These observations stimulated theoretical studies that, particularly, demonstrated that EMIC wave induced pitch-angle diffusion of MeV electrons can operate in the strong diffusion limit and this mechanism can compete with relativistic electron depletion caused by the Dst effect during the initial and main phases of storm. Although an effectiveness of relativistic electron scattering by EMIC waves depends strongly on the wave spectral properties, the most favorable assumptions regarding wave characteristics has been made in all previous theoretical studies. Particularly, only quasi field-aligned EMIC waves have been considered as a driver for relativistic electron loss. At the same time, there is growing experimental and theoretical evidence that these waves can be highly oblique; EMIC wave energy can occupy not only the region of generation, i.e. the region of small wave normal angles, but also the entire wave normal angle region, and even only the region near 90 degrees. The latter can dramatically change he effectiveness of relativistic electron scattering by EMIC waves. In the present study, we

Correlation between resistance-change effect in transition-metal oxides and secondary-electron contrast of scanning electron microscope images

International Nuclear Information System (INIS)

Kinoshita, K.; Kishida, S.; Yoda, T.

2011-01-01

Conductive atomic-force microscopy (C-AFM) writing is attracting attention as a technique for clarifying the switching mechanism of resistive random-access memory by providing a wide area filled with filaments, which can be regarded as one filament with large radius. The writing area on a nickel-oxide (NiO) film formed by conductive atomic-force microscopy was observed by scanning electron microscope, and a correlation between the contrast in a secondary-electron image (SEI) and the resistance written by C-AFM was revealed. In addition, the dependence of the SEI contrast on the beam accelerating voltage (V accel ) suggests that the resistance-change effect occurs near the surface of the NiO film. As for the effects of electron irradiation and vacuum annealing on the C-AFM writing area, it was shown that the resistance-change effect is caused by exchange of oxygen with the atmosphere at the surface of the NiO film. This result suggests that the low-resistance and high-resistance areas are, respectively, p-type Ni 1+δ O (δ 1+δ O (δ≥ 0).

Effect of secondary electron emission on the Jeans instability in a dusty plasma

International Nuclear Information System (INIS)

Sarkar, Susmita; Roy, Banamali; Maity, Saumyen; Khan, Manoranjan; Gupta, M. R.

2007-01-01

In this paper the effect of secondary electron emission on Jeans instability in a dusty plasma has been investigated. Due to secondary electron emission, dust grains may have two stable equilibrium states out of which one is negative and the other is positive. Here both cases have been considered separately. It has been shown that secondary electron emission enhances Jeans instability when equilibrium dust charge is negative. It has also been shown that growth rate of Jeans instability reduces with increasing secondary electron emission when equilibrium dust charge is positive

Theoretical modeling of the electronic structure and exchange interactions in a Cu(II)Pc one-dimensional chain

Science.gov (United States)

Wu, Wei; Fisher, A. J.; Harrison, N. M.

2011-07-01

We calculate the electronic structure and exchange interactions in a copper(II)phthalocyanine [Cu(II)Pc] crystal as a one-dimensional molecular chain using hybrid exchange density functional theory (DFT). In addition, the intermolecular exchange interactions are also calculated in a molecular dimer using Green’s function perturbation theory (GFPT) to illustrate the underlying physics. We find that the exchange interactions depend strongly on the stacking angle, but weakly on the sliding angle (defined in the text). The hybrid DFT calculations also provide an insight into the electronic structure of the Cu(II)Pc molecular chain and demonstrate that on-site electron correlations have a significant effect on the nature of the ground state, the band gap, and magnetic excitations. The exchange interactions predicted by our DFT calculations and GFPT calculations agree qualitatively with the recent experimental results on newly found η-Cu(II)Pc and the previous results for the α and β phases. This work provides a reliable theoretical basis for the further application of Cu(II)Pc to molecular spintronics and organic-based quantum information processing.

Theory and measurement of the electron cloud effect

International Nuclear Information System (INIS)

Harkey, K. C.

1999-01-01

Photoelectrons produced through the interaction of synchrotrons radiation and the vacuum chamber walls can be accelerated by a charged particle beam, acquiring sufficient energy to produce secondary electrons (SES) in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, a run-away condition can develop. In addition to the SEY, the degree of amplification depends on the beam intensity and temporal distribution. As the electron cloud builds up along a train of stored bunches, a transverse perturbation of the head bunch can be communicated to trailing bunches in a wakefield-like interaction with the cloud. The electron cloud effect is especially of concern for the high-intensity PEP-II (SLAC) and KEK B-factories and at the Large Hadron Collider (LHC) at CERN. An initiative was undertaken at the Advanced Photon Source (APS) storage ring to characterize the electron cloud in order to provide realistic limits on critical input parameters in the models and improve their predictive capabilities. An intensive research program was undertaken at CERN to address key issues relating to the LHC. After giving an overview, the recent theoretical and experimental results from the APS and the other laboratories will be discussed

Self-field effects on electron dynamics in free-electron lasers with axial magnetic field

International Nuclear Information System (INIS)

Mirzanejhad, S.; Maraghechi, B.; Mohsenpour, T.

2004-01-01

A self-consistent method for the analysis of self-magnetic field for a free-electron laser with a one-dimensional helical wiggler and an axial guide magnetic field is presented. The equilibrium orbits and their stability, under the influence of self-electric and self-magnetic fields, are analyzed. New unstable orbits, in the first part of the Group I orbits and in the resonance region of the Group II orbits, are found. It is shown that an increase in the defocusing effect of self-fields will widen the unstable orbits. An anomalous self-field regime is found where an increase in the defocusing effect of self-fields can have stabilizing effect on the resonance region

Probabilistic model for the simulation of secondary electron emission

Directory of Open Access Journals (Sweden)

M. A. Furman

2002-12-01

Full Text Available We provide a detailed description of a model and its computational algorithm for the secondary electron emission process. The model is based on a broad phenomenological fit to data for the secondary-emission yield and the emitted-energy spectrum. We provide two sets of values for the parameters by fitting our model to two particular data sets, one for copper and the other one for stainless steel.

High-energy inverse free-electron laser accelerator

International Nuclear Information System (INIS)

Courant, E.D.; Pellegrini, C.; Zakowicz, W.

1985-01-01

We study the inverse free electron laser (IFEL) accelerator and show that it can accelerate electrons to the few hundred GeV region with average acceleration rates of the order of 200 meV/m. Several possible accelerating structures are analyzed, and the effect of synchrotron radiation losses is studied. The longitudinal phase stability of accelerated particles is also analyzed. A Hamiltonian description, which takes into account the dissipative features of the IFEL accelerator, is introduced to study perturbations from the resonant acceleration. Adiabatic invariants are obtained and used to estimate the change of the electron phase space density during the acceleration process

One electron reduction of triphenyl methane dyes by hydrated electrons

Energy Technology Data Exchange (ETDEWEB)

Bhasikuttan, A C; Shastri, L V; Sapre, A V; Rama Rao, K V.S. [Bhabha Atomic Research Centre, Bombay (India). Chemistry Div.

1994-12-31

Electron reaction rates for the triphenylmethane (TPM) dyes have been evaluated. Spectral characteristics of the resulting dye radicals have been determined. Evolution of the transient spectra shows intramolecular rearrangement in the radical from brilliant green and malachite green. (author). 3 refs., 1 fig., 1 tab.

One electron reduction of triphenyl methane dyes by hydrated electrons

International Nuclear Information System (INIS)

Bhasikuttan, A.C.; Shastri, L.V.; Sapre, A.V.; Rama Rao, K.V.S.

1994-01-01

Electron reaction rates for the triphenylmethane (TPM) dyes have been evaluated. Spectral characteristics of the resulting dye radicals have been determined. Evolution of the transient spectra shows intramolecular rearrangement in the radical from brilliant green and malachite green. (author). 3 refs., 1 fig., 1 tab

Interaction effects in liquids with low electron densities

International Nuclear Information System (INIS)

Warren, W.W. Jr.

1987-01-01

The author discusses two complementary classes of systems in which strong electron-electron or electron-ion interactions appear at low electron densities. The first are the expanded liquid alkali metals (cesium) in which electron correlation effects have a profound effect on the magnetic properties on the metallic side of the metal-nonmetal transition. The second group are molten alkali halides containing low densities of localized electrons introduced, say, by dissolution of small amounts of excess metal. (Auth.)

Analytical description of photon beam phase spaces in inverse Compton scattering sources

Directory of Open Access Journals (Sweden)

C. Curatolo

2017-08-01

Full Text Available We revisit the description of inverse Compton scattering sources and the photon beams generated therein, emphasizing the behavior of their phase space density distributions and how they depend upon those of the two colliding beams of electrons and photons. The main objective is to provide practical formulas for bandwidth, spectral density, brilliance, which are valid in general for any value of the recoil factor, i.e. both in the Thomson regime of negligible electron recoil, and in the deep Compton recoil dominated region, which is of interest for gamma-gamma colliders and Compton sources for the production of multi-GeV photon beams. We adopt a description based on the center of mass reference system of the electron-photon collision, in order to underline the role of the electron recoil and how it controls the relativistic Doppler/boost effect in various regimes. Using the center of mass reference frame greatly simplifies the treatment, allowing us to derive simple formulas expressed in terms of rms momenta of the two colliding beams (emittance, energy spread, etc. and the collimation angle in the laboratory system. Comparisons with Monte Carlo simulations of inverse Compton scattering in various scenarios are presented, showing very good agreement with the analytical formulas: in particular we find that the bandwidth dependence on the electron beam emittance, of paramount importance in Thomson regime, as it limits the amount of focusing imparted to the electron beam, becomes much less sensitive in deep Compton regime, allowing a stronger focusing of the electron beam to enhance luminosity without loss of mono-chromaticity. A similar effect occurs concerning the bandwidth dependence on the frequency spread of the incident photons: in deep recoil regime the bandwidth comes out to be much less dependent on the frequency spread. The set of formulas here derived are very helpful in designing inverse Compton sources in diverse regimes, giving a

Future directions in electron--ion collision physics

International Nuclear Information System (INIS)

Reed, K.J.; Griffin, D.C.

1992-01-01

This report discusses the following topics: Summary of session on synergistic co-ordination of theory and experiment; synergism between experiment and theory in atomic physics; comparison of theory and experiment for electron-ion excitation and ionization; summary of session on new theoretical and computational methods; new theoretical and computational methods-r-matrix calculations; the coulomb three-body problem: a progress report; summary of session on needs and applications for electron-ion collisional data; electron-ion collisions in the plasma edge; needs and applications of theoretical data for electron impact excitation; summary of session on relativistic effects, indirect effects, resonance, etc; direct and resonant processes in electron-ion collisions; relativistic calculations of electron impact ionization and dielectronic recombination cross section for highly charged ions; electron-ion recombination in the close-coupling approximation; modified resonance amplitudes with strongly correlated channels; a density-matrix approach to the broadening of spectral lines by autoionization, radiative transitions and electron-ion collisions; towards a time-dependent description of electron-atom/ion collisions two electron systems; and comments on inclusion of the generalized bright interaction in electron impact excitation of highly charged ions

Electronic properties of III-nitride semiconductors: A first-principles investigation using the Tran-Blaha modified Becke-Johnson potential

International Nuclear Information System (INIS)

Araujo, Rafael B.; Almeida, J. S. de; Ferreira da Silva, A.

2013-01-01

In this work, we use density functional theory to investigate the influence of semilocal exchange and correlation effects on the electronic properties of III-nitride semiconductors considering zinc-blende and wurtzite crystal structures. We find that the inclusion of such effects through the use of the Tran-Blaha modified Becke-Johnson potential yields an excellent description of the electronic structures of these materials giving energy band gaps which are systematically larger than the ones obtained with standard functionals such as the generalized gradient approximation. The discrepancy between the experimental and theoretical band gaps is then significantly reduced with semilocal exchange and correlation effects. However, the effective masses are overestimated in the zinc-blende nitrides, but no systematic trend is found in the wurtzite compounds. New results for energy band gaps and effective masses of zinc-blende and wurtzite indium nitrides are presented

Electron emission of cathode holder of vacuum diode of an intense electron-beam accelerator and its effect on the output voltage

OpenAIRE

Xin-Bing Cheng; Jin-Liang Liu; Hong-Bo Zhang; Zhi-Qiang Hong; Bao-Liang Qian

2011-01-01

The vacuum diode which is used to generate relativistic electron beams is one of the most important parts of a pulsed-power modulator. In this paper, the electron emission of cathode holder of a vacuum diode and its effect on the output voltage is investigated by experiments on an intense electron-beam accelerator with 180 ns full width at half maximum and 200–500 kV output voltage. First, the field emission is analyzed and the electric field of the vacuum chamber is calculated. Then, the fla...

Bend-imitating theory and electron scattering in sharply-bent quantum nanowires

International Nuclear Information System (INIS)

Vakhnenko, O.O.

2011-01-01

The concept of bend-imitating description as applied to the one-electron quantum mechanics in sharply-bent ideal electron waveguides and its development into a self consistent theory are presented. In the framework of bend-imitating approach, the investigation of the electron scattering in a doubly-bent 2D quantum wire with S-like bend has been made, and the explicit dependences of the transmission and reflection coefficients on geometrical parameters of a structure, as well as on the electron energy, have been obtained. The total elimination of the mixing between the scattering channels of a S-like bent quantum wire is predicted.

Electron Technology: ELTE 2016

Science.gov (United States)

Pisarkiewicz, Tadeusz; Kucewicz, Wojciech

2016-12-01

In this paper we present a review of research results and technical accomplishments presented by researchers from technical universities, governmental institutes and research companies during the XIIth Scientific Conference Electron Technology, ELTE 2016. This review is based on materials presented at four topical conference sessions: Microelectronics and Nanoelectronics, Photonics, Materials and Technologies, and Microsystems and also on materials presented by invited speakers at two dedicated sessions. Oral sessions were accompanied by the poster sessions. In effect about 50 papers gathered in this volume reflect the topics discussed at the Conference. A short description of technological and measurement possibilities in the laboratories of Academic Centre for Materials and Nanotechnology and also in the Department of Electronics of the Faculty of Computer Science, Electronics and Telecommunications AGH UST are given.

The quantum flux in quasis one-dimensional conductors

International Nuclear Information System (INIS)

Ventura, J.

1989-01-01

A method is presented which quantizes electromagnetic fluxes directly in flux space. It is based on the commutation law [φ B , φ E ] = i, where φ B is the magnetic flux, and φ E the longitudinal electric flux of a quasi one-dimensional conductor. The relevance of such a method for the description of the quantized Hall plateaus is discussed. In a second step, the polarization electric flux is introduced, together with a method for quantization of hybrid variables formed with pure electromagnetic fluxes plus electronic variables. (author) [pt

Effect of electron-electron interaction on cyclotron resonance in high-mobility InAs/AlSb quantum wells

Energy Technology Data Exchange (ETDEWEB)

Krishtopenko, S. S., E-mail: sergey.krishtopenko@mail.ru; Gavrilenko, V. I. [Institute for Physics of Microstructures, Russian Academy of Sciences, 603950 Nizhny Novgorod, GSP-105 (Russian Federation); Lobachevsky State University, 23 Prospekt Gagarina, 603950 Nizhny Novgorod (Russian Federation); Ikonnikov, A. V. [Institute for Physics of Microstructures, Russian Academy of Sciences, 603950 Nizhny Novgorod, GSP-105 (Russian Federation); Orlita, M. [Laboratoire National des Champs Magnétiques Intenses (LNCMI-G), CNRS, 25 rue des Martyrs, B.P. 166, 38042 Grenoble (France); Sadofyev, Yu. G. [P.N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow 119991, GSP-1, 53 Leninskiy Prospect (Russian Federation); Goiran, M. [Laboratoire National des Champs Magnétiques Intenses (LNCMI-T), CNRS, 143 Avenue de Rangueil, 31400 Toulouse (France); Teppe, F.; Knap, W. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221, GIS-TERALAB, Universite Montpellier II, 34095 Montpellier (France)

2015-03-21

We report observation of electron-electron (e-e) interaction effect on cyclotron resonance (CR) in InAs/AlSb quantum well heterostructures. High mobility values allow us to observe strongly pronounced triple splitting of CR line at noninteger filling factors of Landau levels ν. At magnetic fields, corresponding to ν > 4, experimental values of CR energies are in good agreement with single-electron calculations on the basis of eight-band k ⋅ p Hamiltonian. In the range of filling factors 3 < ν < 4 pronounced, splitting of CR line, exceeding significantly the difference in single-electron CR energies, is discovered. The strength of the splitting increases when occupation of the partially filled Landau level tends to a half, being in qualitative agreement with previous prediction by MacDonald and Kallin [Phys. Rev. B 40, 5795 (1989)]. We demonstrate that such behaviour of CR modes can be quantitatively described if one takes into account both electron correlations and the mixing between conduction and valence bands in the calculations of matrix elements of e-e interaction.

Magnetic effects in the paraxial regime of elastic electron scattering

Science.gov (United States)

Edström, Alexander; Lubk, Axel; Rusz, Ján

2016-11-01

Motivated by a recent claim [Phys. Rev. Lett. 116, 127203 (2016), 10.1103/PhysRevLett.116.127203] that electron vortex beams can be used to image magnetism at the nanoscale in elastic scattering experiments, using transmission electron microscopy, a comprehensive computational study is performed to study magnetic effects in the paraxial regime of elastic electron scattering in magnetic solids. Magnetic interactions from electron vortex beams, spin polarized electron beams, and beams with phase aberrations are considered, as they pass through ferromagnetic FePt or antiferromagnetic LaMnAsO. The magnetic signals are obtained by comparing the intensity over a disk in the diffraction plane for beams with opposite angular momentum or aberrations. The strongest magnetic signals are obtained from vortex beams with large orbital angular momentum, where relative magnetic signals above 10-3 are indicated for 10 ℏ orbital angular momentum, meaning that relative signals of one percent could be expected with the even larger orbital angular momenta, which have been produced in experimental setups. All results indicate that beams with low acceleration voltage and small convergence angles yield stronger magnetic signals, which is unfortunately problematic for the possibility of high spatial resolution imaging. Nevertheless, under atomic resolution conditions, relative magnetic signals in the order of 10-4 are demonstrated, corresponding to an increase with one order of magnitude compared to previous work.

Descriptive set theory

CERN Document Server

Moschovakis, YN

1987-01-01

Now available in paperback, this monograph is a self-contained exposition of the main results and methods of descriptive set theory. It develops all the necessary background material from logic and recursion theory, and treats both classical descriptive set theory and the effective theory developed by logicians.

Impurity effects in two-electron coupled quantum dots: entanglement modulation

International Nuclear Information System (INIS)

Acosta Coden, Diego S; Romero, Rodolfo H; Ferrón, Alejandro; Gomez, Sergio S

2013-01-01

We present a detailed analysis of the electronic and optical properties of two-electron quantum dots with a two-dimensional Gaussian confinement potential. We study the effects of Coulomb impurities and the possibility of manipulating the entanglement of the electrons by controlling the confinement potential parameters. The degree of entanglement becomes highly modulated by both the location and charge screening of the impurity atom, resulting in two regimes: one of low entanglement and the other of high entanglement, with both of them mainly determined by the magnitude of the charge. It is shown that the magnitude of the oscillator strength of the system could provide an indication of the presence and characteristics of impurities and, therefore, the degree of entanglement. (paper)

Effective atomic numbers and electron density of dosimetric material

Directory of Open Access Journals (Sweden)

Kaginelli S

2009-01-01

Full Text Available A novel method for determination of mass attenuation coefficient of x-rays employing NaI (Tl detector system and radioactive sources is described.in this paper. A rigid geometry arrangement and gating of the spectrometer at FWHM position and selection of absorber foils are all done following detailed investigation, to minimize the effect of small angle scattering and multiple scattering on the mass attenuation coefficient, m/r, value. Firstly, for standardization purposes the mass attenuation coefficients of elemental foils such as Aluminum, Copper, Molybdenum, Tantalum and Lead are measured and then, this method is utilized for dosimetric interested material (sulfates. The experimental mass attenuation coefficient values are compared with the theoretical values to find good agreement between the theory and experiment within one to two per cent. The effective atomic numbers of the biological substitute material are calculated by sum rule and from the graph. The electron density of dosimetric material is calculated using the effective atomic number. The study has discussed in detail the attenuation coefficient, effective atomic number and electron density of dosimetric material/biological substitutes.

Search for scalar electrons at PEP

International Nuclear Information System (INIS)

Wilson, R.J.

1983-08-01

Experimental results from e + e - reactions at the Positron Electron Project (PEP) using the High Resolution Spectrometer (HRS) are presented. Events with two electrons, and no other charged particles, in the final state are studied. Limits are given for the production of scalar-electrons predicted by models based on supersymmetry. In particular the pair production of such particles through s-channel single photon annihilation and t-channel inelastic scattering is considered. The data are well described by quantum electrodynamics (QED) but we observe one event which is also consistent with a supersymmetric model. Using this single event we find that the mass, M/sub se/, of these scalar-electrons es excluded, to 95% CL, in the range 1.8 less than or equal to M/sub se/ less than or equal to 14.2 GeV/c 2 . A description of the HRS detector is given with particular emphasis on the electronic trigger system

Data Acquisition System for Electron Energy Loss Coincident Spectrometers

International Nuclear Information System (INIS)

Zhang Chi; Yu Xiaoqi; Yang Tao

2005-01-01

A Data Acquisition System (DAQ) for electron energy loss coincident spectrometers (EELCS) has been developed. The system is composed of a Multiplex Time-Digital Converter (TDC) that measures the flying time of positive and negative ions and a one-dimension position-sensitive detector that records the energy loss of scattering electrons. The experimental data are buffered in a first-in-first-out (FIFO) memory module, then transferred from the FIFO memory to PC by the USB interface. The DAQ system can record the flying time of several ions in one collision, and allows of different data collection modes. The system has been demonstrated at the Electron Energy Loss Coincident Spectrometers at the Laboratory of Atomic and Molecular Physics, USTC. A detail description of the whole system is given and experimental results shown

Effect of electronic radiation in Nb monocrystals

International Nuclear Information System (INIS)

Otero, M.P.; Lucki, G.

1984-01-01

The effect of the electronic irradiation in the Nb monocrystalline samples is studied. The irradiation source were the electrons from the high voltage electronic microscopy from the Argonne National Laboratory operating in 900 KeV. With the irradiation and deformation 'in-situ' experiments, dislocations in the samples were observed and the effect of the electrons in those dislocations during 59m of irradiation was studied. The follow applied deformation, show the differences in the displacements behavior of the non-irradiated and irradiated region. The growth rate of the displacements rings were determined. (E.G.) [pt

Fokker-Planck simulation of runaway electron generation in disruptions with the hot-tail effect

Energy Technology Data Exchange (ETDEWEB)

Nuga, H., E-mail: nuga@p-grp.nucleng.kyoto-u.ac.jp; Fukuyama, A. [Department of Engineering, Kyoto University, Kyoto 615-8540 (Japan); Yagi, M. [National Institutes for Quantum and Radiological Science and Technology, Aomori 039-3212 (Japan)

2016-06-15

To study runaway electron generation in disruptions, we have extended the three-dimensional (two-dimensional in momentum space; one-dimensional in the radial direction) Fokker-Planck code, which describes the evolution of the relativistic momentum distribution function of electrons and the induced toroidal electric field in a self-consistent manner. A particular focus is placed on the hot-tail effect in two-dimensional momentum space. The effect appears if the drop of the background plasma temperature is sufficiently rapid compared with the electron-electron slowing down time for a few times of the pre-quench thermal velocity. It contributes to not only the enhancement of the primary runaway electron generation but also the broadening of the runaway electron distribution in the pitch angle direction. If the thermal energy loss during the major disruption is assumed to be isotropic, there are hot-tail electrons that have sufficiently large perpendicular momentum, and the runaway electron distribution becomes broader in the pitch angle direction. In addition, the pitch angle scattering also yields the broadening. Since the electric field is reduced due to the burst of runaway electron generation, the time required for accelerating electrons to the runaway region becomes longer. The longer acceleration period makes the pitch-angle scattering more effective.

One-electron standard reduction potentials of nitroaromatic and cyclic nitramine explosives

International Nuclear Information System (INIS)

Uchimiya, Minori; Gorb, Leonid; Isayev, Olexandr; Qasim, Mohammad M.; Leszczynski, Jerzy

2010-01-01

Extensive studies have been conducted in the past decades to predict the environmental abiotic and biotic redox fate of nitroaromatic and nitramine explosives. However, surprisingly little information is available on one-electron standard reduction potentials (E o (R-NO 2 /R-NO 2 - )). The E o (R-NO 2 /R-NO 2 - ) is an essential thermodynamic parameter for predicting the rate and extent of reductive transformation for energetic residues. In this study, experimental (linear free energy relationships) and theoretical (ab initio calculation) approaches were employed to determine E o (R-NO 2 /R-NO 2 - ) for nitroaromatic, (caged) cyclic nitramine, and nitroimino explosives that are found in military installations or are emerging contaminants. The results indicate a close agreement between experimental and theoretical E o (R-NO 2 /R-NO 2 - ) and suggest a key trend: E o (R-NO 2 /R-NO 2 - ) value decreases from di- and tri-nitroaromatic (e.g., 2,4-dinitroanisole) to nitramine (e.g., RDX) to nitroimino compound (e.g., nitroguanidine). The observed trend in E o (R-NO 2 /R-NO 2 - ) agrees with reported rate trends for reductive degradation, suggesting a thermodynamic control on the reduction rate under anoxic/suboxic conditions. - Reduction of explosives becomes less thermodynamically favorable as the one-electron standard reduction potential decreases from di- and tri-nitroaromatic, nitramine, to nitroimino compounds.

Spin rotation after a spin-independent scattering. Spin properties of an electron gas in a solid

International Nuclear Information System (INIS)

Zayets, V.

2014-01-01

It is shown that spin direction of an electron may not be conserved after a spin-independent scattering. The spin rotations occur due to a quantum-mechanical fact that when a quantum state is occupied by two electrons of opposite spins, the total spin of the state is zero and the spin direction of each electron cannot be determined. It is shown that it is possible to divide all conduction electrons into two group distinguished by their time-reversal symmetry. In the first group the electron spins are all directed in one direction. In the second group there are electrons of all spin directions. The number of electrons in each group is conserved after a spin-independent scattering. This makes it convenient to use these groups for the description of the magnetic properties of conduction electrons. The energy distribution of spins, the Pauli paramagnetism and the spin distribution in the ferromagnetic metals are described within the presented model. The effects of spin torque and spin-torque current are described. The origin of spin-transfer torque is explained within the presented model

Communication: satisfying fermionic statistics in the modeling of open time-dependent quantum systems with one-electron reduced density matrices.

Science.gov (United States)

Head-Marsden, Kade; Mazziotti, David A

2015-02-07

For an open, time-dependent quantum system, Lindblad derived the most general modification of the quantum Liouville equation in the Markovian approximation that models environmental effects while preserving the non-negativity of the system's density matrix. While Lindblad's modification is correct for N-electron density matrices, solution of the Liouville equation with a Lindblad operator causes the one-electron reduced density matrix (1-RDM) to violate the Pauli exclusion principle. Consequently, after a short time, the 1-RDM is not representable by an ensemble N-electron density matrix (not ensemble N-representable). In this communication, we derive the necessary and sufficient constraints on the Lindbladian matrix within the Lindblad operator to ensure that the 1-RDM remains N-representable for all time. The theory is illustrated by considering the relaxation of an excitation in several molecules F2, N2, CO, and BeH2 subject to environmental noise.

Fractional conductance oscillations in quantum rings: wave packet picture of transport in a few-electron system.

Science.gov (United States)

Chwiej, T; Szafran, B

2013-04-17

We study electron transfer across a two-terminal quantum ring using a time-dependent description of the scattering process. For the considered scattering event the quantum ring is initially charged with one or two electrons, with another electron incident to the ring from the input channel. We study the electron transfer probability (T) as a function of the external magnetic field. We determine the periodicity of T for a varied number of electrons confined within the ring. For that purpose we develop a method to describe the wave packet dynamics for a few electrons participating in the scattering process, taking into full account the electron-electron correlations. We find that electron transfer across the quantum ring initially charged by a single electron acquires a distinct periodicity of half of the magnetic flux quantum (Φ0/2), corresponding to the formation of a transient two-electron state inside the ring. In the case of a three-electron scattering problem with two electrons initially occupying the ring, a period of Φ0/3 for T is formed in the limit of thin channels. The effect of disorder present in the confinement potential of the ring is also discussed.

On the effect of electron's runaway in partially ionized hydrogen semiclassical nonideal plasma

International Nuclear Information System (INIS)

Turekhanova, K.M.

2011-01-01

Complete text of publication follows. The effect of runaway electrons occurs frequently in tokamak plasmas. The majority of experiments in tokamak research have been devoted to the study of confinement properties of runaway electrons. Runaway electrons are reason of various destroying untolarance in tokamak plasmas. At high plasma density, when the critical energy is comparable with the rest energy the multiplication of runaway electrons accelerate at the sacrifice of increase of plasma density. The plasma conductivity is determined by electrons with energy several times higher than the thermal one and does not practically depend on slower electrons distribution. It is important to analyze the probability of runaway electrons at investigation of physical properties of nonideal plasmas under external electric field and running numerical simulations of their. The present paper is devoted to the investigation of effect of runaway electrons in partially ionized hydrogen dense plasma using the effective potentials of particle's interaction. At the investigation of composition of plasma we used the Saha equation with corrections to nonideality (lowering of ionization potentials). The Saha equation was solved for obtaining of plasma ionization stages at the different number density and temperature. As well, when take into account quantum-mechanical diffraction and screening effects, whereas free path of electrons increases with increase of plasma coupling parameter. The condition for appearance of runaway electrons in semiclassical partially ionized plasma is more favorable in regime of dense plasma. In summary it means that the probability of runaway electron in dense plasma is more than the same in rarified plasma that is possibly connected with formation of some ordered structures in dense plasma.

Towards a formal definition of static and dynamic electronic correlations.

Science.gov (United States)

Benavides-Riveros, Carlos L; Lathiotakis, Nektarios N; Marques, Miguel A L

2017-05-24

Some of the most spectacular failures of density-functional and Hartree-Fock theories are related to an incorrect description of the so-called static electron correlation. Motivated by recent progress in the N-representability problem of the one-body density matrix for pure states, we propose a method to quantify the static contribution to the electronic correlation. By studying several molecular systems we show that our proposal correlates well with our intuition of static and dynamic electron correlation. Our results bring out the paramount importance of the occupancy of the highest occupied natural spin-orbital in such quantification.

Coalescence of two polarized photons with antiparallel momenta into one on an electron

International Nuclear Information System (INIS)

Galynskii, M.V.

1989-01-01

The matrix elements have been calculated for the coalescence of two photons with antiparallel momenta and equal frequencies into one on an electron. An explicit expression for the differential probability for the process, with allowance for the polarization of all the particles, has been obtained in the nonrelativistic approximation

Self-Attractive Hartree Decomposition: Partitioning Electron Density into Smooth Localized Fragments.

Science.gov (United States)

Zhu, Tianyu; de Silva, Piotr; Van Voorhis, Troy

2018-01-09

Chemical bonding plays a central role in the description and understanding of chemistry. Many methods have been proposed to extract information about bonding from quantum chemical calculations, the majority of them resorting to molecular orbitals as basic descriptors. Here, we present a method called self-attractive Hartree (SAH) decomposition to unravel pairs of electrons directly from the electron density, which unlike molecular orbitals is a well-defined observable that can be accessed experimentally. The key idea is to partition the density into a sum of one-electron fragments that simultaneously maximize the self-repulsion and maintain regular shapes. This leads to a set of rather unusual equations in which every electron experiences self-attractive Hartree potential in addition to an external potential common for all the electrons. The resulting symmetry breaking and localization are surprisingly consistent with chemical intuition. SAH decomposition is also shown to be effective in visualization of single/multiple bonds, lone pairs, and unusual bonds due to the smooth nature of fragment densities. Furthermore, we demonstrate that it can be used to identify specific chemical bonds in molecular complexes and provides a simple and accurate electrostatic model of hydrogen bonding.

Effects of electronic communication in general practice

NARCIS (Netherlands)

van der Kam, WJ; Moorman, PW; Koppejan-Mulder, MJ

2000-01-01

Objective: To obtain insight into the effects of electronic communication on GPs by studying those publications in literature describing the effects of structured electronic clinical communication in general practice. Methods: We retrieved all publications in the English language indexed in MEDLINE

Fractional conductance oscillations in quantum rings: wave packet picture of transport in a few-electron system

International Nuclear Information System (INIS)

Chwiej, T; Szafran, B

2013-01-01

We study electron transfer across a two-terminal quantum ring using a time-dependent description of the scattering process. For the considered scattering event the quantum ring is initially charged with one or two electrons, with another electron incident to the ring from the input channel. We study the electron transfer probability (T) as a function of the external magnetic field. We determine the periodicity of T for a varied number of electrons confined within the ring. For that purpose we develop a method to describe the wave packet dynamics for a few electrons participating in the scattering process, taking into full account the electron–electron correlations. We find that electron transfer across the quantum ring initially charged by a single electron acquires a distinct periodicity of half of the magnetic flux quantum (Φ 0 /2), corresponding to the formation of a transient two-electron state inside the ring. In the case of a three-electron scattering problem with two electrons initially occupying the ring, a period of Φ 0 /3 for T is formed in the limit of thin channels. The effect of disorder present in the confinement potential of the ring is also discussed. (paper)

Double differential distributions of electron emission in ion-atom and electron-atom collisions using an electron spectrometer

International Nuclear Information System (INIS)

Misra, Deepankar; Thulasiram, K.V.; Fernandes, W.; Kelkar, Aditya H.; Kadhane, U.; Kumar, Ajay; Singh, Yeshpal; Gulyas, L.; Tribedi, Lokesh C.

2009-01-01

We study electron emission from atoms and molecules in collisions with fast electrons and heavy ions (C 6+ ). The soft collision electrons (SE), two center electron emission (TCEE), the binary encounter (BE) events and the KLL Auger lines along with the elastically scattered peaks (in electron collisions) are studied using a hemispherical electrostatic electron analyzer. The details of the measurements along with description of the spectrometer and data acquisition system are given. The angular distributions of the low energy (few eV) electrons in soft collisions and the binary encounter electrons at keV energies are compared with quantum mechanical models based on the first Born (B1) and the continuum distorted wave-Eikonal initial state approximation (CDW-EIS).

Investigating the effect of electron emission pattern on RF gun beam quality

Energy Technology Data Exchange (ETDEWEB)

Rajabi, A. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Shokri, B., E-mail: b-shokri@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of)

2016-05-11

Thermionic radio frequency gun is one of the most promising choices to gain a high quality electron beam, used in the infrared free electron lasers and synchrotron radiation injectors. To study the quality of the beam in a compact electron source, the emission pattern effect on the beam dynamics should be investigated. In the presented work, we developed a 3D simulation code to model the real process of thermionic emission and to investigate the effect of emission pattern, by considering geometrical constraints, on the beam dynamics. According to the results, the electron bunch emittance varies considerably with the emission pattern. Simulation results have been validated via comparison with the well-known simulation codes such as ASTRA simulation code and CST microwave studio, as well as other simulation results in the literature. It was also demonstrated that by using a continuous wave laser beam for heating the cathode, the emission pattern full width at half maximum (FWHM) of the transverse emission distribution is proportional to FWHM of the Gaussian profile for the laser beam. Additionally, by using the developed code, the effect of wall structure around the cathode on the back bombardment effect has been studied. According to the results, for a stable operation of the RF gun, one should consider the nose cone in vicinity of the cathode surface to reduce the back-bombardment effect. - Highlights: • We developed a 3D code to simulate the beam dynamics of thermionic RF gun. • Te impact of the emission pattern on the beam dynamic was investigated. • Different emission pattern results different emittance in the gun exit. • Using a nosecone around the cathode adjacent wall reduces back bombardment effect.

Effective interactions for description of multistep processes

International Nuclear Information System (INIS)

Avrigeanu, M.; Stetcu, I.; Avrigeanu, V.; Antonov, A.N.; Lenske, H.

2000-01-01

The reliability of realistic M3Y effective NN interactions to describe multistep direct (MSD) processes is proved by analysing the corresponding real optical potentials. This trial is done in order to overcome the uncertainties of the effective NN-interaction strength V 0 obtained by direct fit to the experimental data. The microscopic potential for the nucleon-nucleus scattering at energies lower than 100 MeV has been calculated by using nucleonic and mesonic form factors. It has been analysed through (i) a comparison with phenomenological optical potentials, and (ii) its use for description of nucleon elastic scattering angular distributions. It results that the strongly simplified model interactions usually involved within MSD reaction theory, e.g. 1 fm range Yukawa (1Y) term, neglect important dynamical details of such processes. An 1Y-equivalent V 0 strength of a realistic effective NN interaction is determined by corresponding optical-potential volume integrals, and involved within Feshbach-Kerman-Koonin theory calculations with the final goal of MSD studies without any V 0 free parameter. (authors)

Electron-atom scattering

International Nuclear Information System (INIS)

McCarthy, I.E.

1991-07-01

The coupled-channels-optical method has been implemented using two different approximations to the optical potential. The half-on-shell optical potential involves drastic approximations for numerical feasibility but still gives a good semiquantitative description of the effect of uncoupled channels on electron scattering from hydrogen, helium and sodium. The distorted-wave optical potential makes no approximations other than the weak coupling approximation for uncoupled channels. In applications to hydrogen and sodium it shows promise of describing scattering phenomena excellently at all energies. 27 refs., 5 figs

Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR

Energy Technology Data Exchange (ETDEWEB)

Smith, Albert A.; Corzilius, Björn; Haze, Olesya; Swager, Timothy M.; Griffin, Robert G., E-mail: rgg@mit.edu [Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2013-12-07

We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization—suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.

Effects of electron-electron interactions on electronic transport in disordered systems

International Nuclear Information System (INIS)

Foley, Simon Timothy

2002-01-01

This thesis is concerned with the role of electron-electron interactions on electronic transport in disordered systems. We first consider a novel non-linear sigma model in order to microscopically treat the effects of disorder and electronic interaction. We successfully reproduce the perturbative results for the zero-bias anomaly and the interaction correction to the conductivity in a weakly disordered system, and discuss possible directions for future work. Secondly we consider the fluctuations of the dephasing rate for a closed diffusive and quantum dot system. Using the Keldysh technique we derive an expression for the inelastic scattering rate with which we self-consistently obtain the fluctuations in the dephasing rate. For the diffusive regime we find the relative fluctuations is given by F ∼ (L φ /L) 2 /g 2 , where g is the dimensionless conductance, L φ is the dephasing length and L is the sample size. For the quantum dot regime we find a perturbative divergence due to the presence of the zero mode. By mapping divergent diagrams to those for the two-level correlation function, we conjecture the existence of an exact relation between the two. Finally we discuss the consequences of this relation. (author)

Stability of the atomic magnetic moments in La2-xSrxCuO4 and effect of their fluctuations on the electronic density of states

International Nuclear Information System (INIS)

Hocquet, T.; Jardin, J.P.; Germain, P.; Labbe, J.

1994-01-01

We calculate the band structure of the antiferromagnetic phase of La 2-x Sr x CuO 4 in a bidimensional itinerant electron model. Then, we discuss the stability of the antiferromagnetic phase and we calculate the size of the atomic magnetic moments with respect to the temperature and the doping ratio x. We show that the antiferromagnetic solution is in any case much more stable than the ferromagnetic one. Finally, we give a description of the antiferromagnetic fluctuations from which merges an explicit physical meaning of the pseudo-gap found in the electronic density of states. Implications for superconductivity are proposed. (orig.)

One-electron reduction of anthraquinone sulphonates: a pulse radiolysis study

International Nuclear Information System (INIS)

Pal, H.; Palit, D.K.; Mukherjee, T.; Mittal, J.P.

1991-01-01

Semiquinone free radicals, derived from 2-sulphonate, 1,5-disulphonate and 2,6-disulphonate derivatives of 9,10-anthraquinone, have been studied using pulse radiolysis and kinetic absorption spectrophotometry techniques. Spectroscopic characteristics of both neutral and anionic species have been ascertained. Kinetics of formation and decay, reactivity with oxygen and one-electron reduction potential values have been estimated. The semiquinone radicals have been shown to be very stable under suitable pH conditions where the equilibrium (2 semiquinone ↔ quinone + hydroquinone) lies predominantly to the left. From a measurement of the equilibrium constants at different pH, values of E 2 and E m have been calculated. (author)

Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition.

Science.gov (United States)

Glazyrin, K; Pourovskii, L V; Dubrovinsky, L; Narygina, O; McCammon, C; Hewener, B; Schünemann, V; Wolny, J; Muffler, K; Chumakov, A I; Crichton, W; Hanfland, M; Prakapenka, V B; Tasnádi, F; Ekholm, M; Aichhorn, M; Vildosola, V; Ruban, A V; Katsnelson, M I; Abrikosov, I A

2013-03-15

We discover that hcp phases of Fe and Fe(0.9)Ni(0.1) undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio, and Mössbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe.

First principles studies of electron tunneling in proteins

Science.gov (United States)

Hayashi, Tomoyuki; Stuchebrukhov, Alexei A.

2014-01-01

A first principles study of electronic tunneling along the chain of seven Fe/S clusters in respiratory complex I, a key enzyme in the respiratory electron transport chain, is described. The broken-symmetry states of the Fe/S metal clusters calculated at both DFT and semi-empirical ZINDO levels were utilized to examine both the extremely weak electronic couplings between Fe/S clusters and the tunneling pathways, which provide a detailed atomistic-level description of the charge transfer process in the protein. One-electron tunneling approximation was found to hold within a reasonable accuracy, with only a moderate induced polarization of the core electrons. The method is demonstrated to be able to calculate accurately the coupling matrix elements as small as 10−4 cm−1. A distinct signature of the wave properties of electrons is observed as quantum interferences of multiple tunneling pathways. PMID:25383312

Effect of strong correlations on the high energy anomaly in hole- and electron-doped high-T{sub c} superconductors

Energy Technology Data Exchange (ETDEWEB)

Moritz, B; Johnston, S; Greven, M; Shen, Z-X; Devereaux, T P [Stanford Institute for Materials and Energy Science, SLAC National Accelerator Laboratory and Stanford University, Stanford, CA 94305 (United States); Schmitt, F; Meevasana, W; Motoyama, E M [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Lu, D H [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Kim, C [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Scalettar, R T [Physics Department, University of California-Davis, Davis, CA 95616 (United States)], E-mail: moritzb@slac.stanford.edu

2009-09-15

Recently, angle-resolved photoemission spectroscopy (ARPES) has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). This paper demonstrates, using a combination of new ARPES measurements and quantum Monte Carlo simulations, that the HEA is not simply the by-product of matrix element effects, but rather represents a cross-over from a quasi-particle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character, in both hole- and electron-doped cuprates. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. the 'waterfall'-like behavior, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying both hole and electron doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram.

Charged particle emission effects on the characteristics of glow discharges with oscillating electrons

CERN Document Server

Nikulin, S P

2001-01-01

One discusses the effect of selection of charged particles on conditions to maintain and the characteristics of a glow discharge with oscillating electrons. It is shown that there is a pressure dependent optimal level of ion selection when the energy efficiency of ion source reaches its maximum value. It is determined that departure of fast ionizing electrons affects negatively the discharge maintenance wile emission of slow plasma electrons may promote maintenance of a discharge high current shape. It is shown that high efficient electron emission without violation of a discharge stability may take place in a magnetic field due to different nature of spatial distributions of fast and slow particles in discharges with electron oscillation

The 88-Inch Cyclotron: A One-Stop Facility for Electronics Radiation and Detector Testing

Energy Technology Data Exchange (ETDEWEB)

Kireeff Covo, M.; Albright, R. A.; Ninemire, B. F.; Johnson, M. B.; Hodgkinson, A.; Loew, T.; Benitez, J. Y.; Todd, D. S.; Xie, D. Z.; Perry, T.; Phair, L.; Bernsteiny, L. A.; Bevins, J.; Brown, J. A.; Goldblum, B. L.; Harasty, M.; Harrig, K. P.; Laplace, T. A.; Matthews, E. F.; Bushmaker, A.; Walker, D.; Oklejas, V.; Hopkins, A. R.; Bleuel, D. L.; Chen, J.; Cronin, S. B.

2017-10-01

In outer space down to the altitudes routinely flown by larger aircrafts, radiation can pose serious issues for microelectronics circuits. The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron and home of the Berkeley Accelerator Space Effects Facility, where the effects of energetic particles on sensitive microelectronics are studied with the goal of designing electronic systems for the space community. This paper describes the flexibility of the facility and its capabilities for testing the bombardment of electronics by heavy ions, light ions, and neutrons. Experimental capabilities for the generation of neutron beams from deuteron breakups and radiation testing of carbon nanotube field effect transistor will be discussed.

Electronic Transport Properties of One Dimensional Zno Nanowires Studied Using Maximally-Localized Wannier Functions

Science.gov (United States)

Sun, Xu; Gu, Yousong; Wang, Xueqiang

2012-08-01

One dimensional ZnO NWs with different diameters and lengths have been investigated using density functional theory (DFT) and Maximally Localized Wannier Functions (MLWFs). It is found that ZnO NWs are direct band gap semiconductors and there exist a turn on voltage for observable current. ZnO nanowires with different diameters and lengths show distinctive turn-on voltage thresholds in I-V characteristics curves. The diameters of ZnO NWs are greatly influent the transport properties of ZnO NWs. For the ZnO NW with large diameter that has more states and higher transmission coefficients leads to narrow band gap and low turn on voltage. In the case of thinner diameters, the length of ZnO NW can effects the electron tunneling and longer supercell lead to higher turn on voltage.

Problems of noise modeling in the presence of total current branching in high electron mobility transistor and field-effect transistor channels

International Nuclear Information System (INIS)

Shiktorov, P; Starikov, E; Gružinskis, V; Varani, L; Sabatini, G; Marinchio, H; Reggiani, L

2009-01-01

In the framework of analytical and hydrodynamic models for the description of carrier transport and noise in high electron mobility transistor/field-effect transistor channels the main features of the intrinsic noise of transistors are investigated under continuous branching of the current between channel and gate. It is shown that the current-noise and voltage-noise spectra at the transistor terminals contain an excess noise related to thermal excitation of plasma wave modes in the dielectric layer between the channel and gate. It is found that the set of modes of excited plasma waves can be governed by the external embedding circuits, thus violating a universal description of noise in terms of Norton and Thevenin noise generators

Electronic sputtering by swift highly charged ions of nitrogen on amorphous carbon

International Nuclear Information System (INIS)

Caron, M.; Haranger, F.; Rothard, H.; Ban d'Etat, B.; Boduch, P.; Clouvas, A.; Potiriadis, C.; Neugebauer, R.; Jalowy, T.

2001-01-01

Electronic sputtering with heavy ions as a function of both electronic energy loss dE/dx and projectile charge state q was studied at the French heavy ion accelerator GANIL. Amorphous carbon (untreated, and sputter-cleaned and subsequently exposed to nitrogen) was irradiated with swift highly charged ions (Z=6-73, q=6-54, energy 6-13 MeV/u) in an ultrahigh vacuum scattering chamber. The fluence dependence of ion-induced electron yields allows to deduce a desorption cross-section σ which varies approximately as σ∼(dE/dx) 1.65 or σ∼q 3.3 for sputter-cleaned amorphous carbon exposed to nitrogen. This q dependence is close to the cubic charge dependence observed for the emission of H + secondary ions which are believed to be emitted from the very surface. However, the power law σ∼(dE/dx) 1.65 , related to the electronic energy loss gives the best empirical description. The dependence on dE/dx is close to a quadratic one thus rather pointing towards a thermal evaporation-like effect

Electron cloud and ion effects

CERN Document Server

Arduini, Gianluigi

2002-01-01

The significant progress in the understanding and control of machine impedances has allowed obtaining beams with increasing brilliance. Dense positively charged beams generate electron clouds via gas ionization, photoemission and multipacting. The electron cloud in turn interacts with the beam and the surrounding environment originating fast coupled and single bunch instabilities, emittance blow-up, additional loads to vacuum and cryogenic systems, perturbation to beam diagnostics and feedbacks and it constitutes a serious limitation to machine performance. In a similar way high brilliance electron beams are mainly affected by positively charged ions produced by residual gas ionization. Recent observations of electron cloud build-up and its effects in present accelerators are reviewed and compared with theory and with the results of state-of-the-art computer simulations. Two-stream instabilities induced by the interaction between electron beams and ions are discussed. The implications for future accelerators ...

Patient characteristics upon initial presentation to chiropractic teaching clinics: A descriptive study conducted at one university

Science.gov (United States)

Kaeser, Martha A.; Hawk, Cheryl; Anderson, Michelle

2014-01-01

Objective The purpose of this study was to compare demographics and chief complaints of the new patient population at our institution's fee-for-service clinics to the patient population of practicing chiropractors in the United States. We also compared the prevalence of obesity and hypertension to reference standards for the adult population. Methods Patient data were obtained from the electronic health records. All records identified as new patients during October 2013 were included. Variables of interest were clinic site, patient demographics, blood pressure, body mass index (BMI), chief complaint, and ICD-9 codes. Descriptive statistics were computed and compared to reference standards from previous reports. Results During October 2013, there were 224 new patients that entered the clinics. The average patient was a 31- to 50-year-old white male. Our clinic patients differed from those seen by US chiropractors in the distribution of all demographic variables. For adult patients, 31.4% were overweight, 29% were obese, and 8% stage 1 or 2 hypertension. Conclusion New patients in the fee-for-service teaching clinics appear to be dissimilar to those of US practicing chiropractors in several important demographics, characteristics, and types of complaints. The new patients had lower levels of overweight, obesity, and hypertension compared to US reference standards. PMID:25162982

Transport of excess electrons in dense dielectric fluids. Phenomenological interpretation and application to a one-dimensional argon fluid

International Nuclear Information System (INIS)

Leycuras, A.; Larour, J.

1978-01-01

The main results about the drift velocities of excess electrons in dense argon are summarized. The weaknesses of the available theories are mainly due to poor information concerning the electron-atom potential during an atom-atom collision. The drift velocities, as a function of the applied electric field present the following features at high fields: the drift velocity reaches a limit that is at most one order of magnitude larger than the sound velocity at the same density. These remarks and the attractive nature of the electron-atom potential suggest a transport model, the collisional transfer model analog to the one applied to the determination of the sound velocity. Drift velocities obtained with this model applied to a one-dimensional molecular dynamics simulation are presented [fr

Kinetic description of electron-proton instability in high-intensity proton linacs and storage rings based on the Vlasov-Maxwell equations

Directory of Open Access Journals (Sweden)

Ronald C. Davidson

1999-05-01

Full Text Available The present analysis makes use of the Vlasov-Maxwell equations to develop a fully kinetic description of the electrostatic, electron-ion two-stream instability driven by the directed axial motion of a high-intensity ion beam propagating in the z direction with average axial momentum γ_{b}m_{b}β_{b}c through a stationary population of background electrons. The ion beam has characteristic radius r_{b} and is treated as continuous in the z direction, and the applied transverse focusing force on the beam ions is modeled by F_{foc}^{b}=-γ_{b}m_{b}ω_{βb}^{0^{2}}x_{⊥} in the smooth-focusing approximation. Here, ω_{βb}^{0}=const is the effective betatron frequency associated with the applied focusing field, x_{⊥} is the transverse displacement from the beam axis, (γ_{b}-1m_{b}c^{2} is the ion kinetic energy, and V_{b}=β_{b}c is the average axial velocity, where γ_{b}=(1-β_{b}^{2}^{-1/2}. Furthermore, the ion motion in the beam frame is assumed to be nonrelativistic, and the electron motion in the laboratory frame is assumed to be nonrelativistic. The ion charge and number density are denoted by +Z_{b}e and n_{b}, and the electron charge and number density by -e and n_{e}. For Z_{b}n_{b}>n_{e}, the electrons are electrostatically confined in the transverse direction by the space-charge potential φ produced by the excess ion charge. The equilibrium and stability analysis retains the effects of finite radial geometry transverse to the beam propagation direction, including the presence of a perfectly conducting cylindrical wall located at radius r=r_{w}. In addition, the analysis assumes perturbations with long axial wavelength, k_{z}^{2}r_{b}^{2}≪1, and sufficiently high frequency that |ω/k_{z}|≫v_{Tez} and |ω/k_{z}-V_{b}|≫v_{Tbz}, where v_{Tez} and v_{Tbz} are the characteristic axial thermal speeds of the background electrons and beam ions. In this regime, Landau damping (in axial velocity space v_{z} by resonant ions and

Resonant tunneling and persistent current of a non-interacting and weakly interacting one-dimensional electron gas

International Nuclear Information System (INIS)

Krive, I.V.; Sandstroem, P.

1997-01-01

The persistent current for a one-dimensional ring with two tunneling barriers is considered in the limit of weakly interacting electrons. In addition to small off-resonance current, there are two kinds of resonant behaviour; (i) a current independent of the barrier transparency (true resonance) and (ii) a current analogous to the one for a ring with only single barrier (''semi''-resonance). For a given barrier transparency the realization of this or that type of resonant behaviour depends both on the geometrical factor (the ratio of interbarrier distance to a ring circumference) and on the strength of electron-electron interaction. It is shown that repulsive interaction favours the ''semi''-resonance behaviour. For a small barrier transparency the ''semi''-resonance peaks are easily washed out by temperature whereas the true resonance peaks survive. (author). 22 refs, 2 figs

Electron beams and applications

International Nuclear Information System (INIS)

Haouat, G.; Couillaud, C.

1998-01-01

Studies of the physical properties of the ELSA-linac electron beam are presented. They include measurements of the characteristic beam parameter and analyzes of the beam transport using simulation codes. The aim of these studies is to determine the best conditions for production of intense and very short electron bunches and to optimize the transport of space-charge dominated beams. Precise knowledge of the transport dynamics allows to produce beams with the required characteristics for light production in Free-Electron Laser (FEL), and to give a good description of energy-transfer phenomena between electrons and photons in the wriggler. The particular features of ELSA authorize studies of high-intensity, high-brightness beam properties, especially the halo surrounding the dense core of the electron bunches, which is formed by the space charge effects. It is also shown that the ELSA facility is well suited for the fabrication of very short γ and X-rays sources for applied research in nuclear and plasma physics, or for time response studies of fast detectors. (author)

ANISOTROPY EFFECTS IN ELECTRON-CAPTURE BY O6+ FROM ALIGNED NA-ASTERISK(3P)

NARCIS (Netherlands)

SCHLATMANN, AR; WIERSEMA, WP; HOEKSTRA, R; MORGENSTERN, R; OLSON, RE; PASCALE, J

1994-01-01

We report results of one electron capture by highly charged ions colliding with laser excited aligned Na*(3p). The 0 vi(10-->8) photon emission cross section after electron capture by the O6+ projectile is measured in the collision energy range 2-8 keV/amu. Effects of the Na*(3p) orbital alignment

Parametric instabilities in an electron beam-plasma system: magnetic field effects

International Nuclear Information System (INIS)

Gell, Y.; Levush, B.; Nakach, R.

1981-09-01

The effects of a magnetic field on the excitation of low-frequency parametric instabilities in a beam-plasma system are considered. The dispersion relation of the three-dimensional beamless configuration, is analytically evaluated for an electrostatic pump wave having a finite wave-vector parallel to the magnetic field. The results of this analysis serve as a guide to the numerical study of the stability of the involved system including the beam. As for the one-dimensional case, one finds that two low-frequency electrostatic instability branches having different growth rates may exist simultaneously. The effects of the magnetic field on these instabilities could be summarized as follows: the small growth rate instability is negligibly small when the electron gyrofrequency is about equal to the pump wave frequency. This instability is magnetic field independent for high enough values of the field. When the plasma electron Debye length is greater than the beam electron Debye length, a large growth rate instability is excited and appears to be weakly dependent on the magnetic field, while the two instability branches are quite sensitive to change of the magnetic field, when the two Debye lengths are equal. Other characteristics of this system are also discussed

Investigation on the traceability of three dimensional scanning electron microscope measurements based on the stereo-pair technique

DEFF Research Database (Denmark)

Bariani, Paolo; De Chiffre, Leonardo; Hansen, Hans Nørgaard

2005-01-01

An investigation was carried out concerning the traceability of dimensional measurements performed with the scanning electron microscope (SEM) using reconstruction of surface topography through stereo-photogrammetry. A theoretical description of the effects that the main instrumental variables...... with the scanning electron microscope (SEM) using reconstruction of surface topography through stereo-photogrammetry. A theoretical description of the effects that the main instrumental variables and measurement parameters have on the reconstruction accuracy of any point on the surface of the object being imaged......-dimensional topography of the type C roughness standards showed good agreement with the nominal profile wavelength values. An investigation was carried out concerning the traceability of dimensional measurements performed with the scanning electron microscope (SEM) using reconstruction of surface topography through...

Modelling high-resolution electron microscopy based on core-loss spectroscopy

International Nuclear Information System (INIS)

Allen, L.J.; Findlay, S.D.; Oxley, M.P.; Witte, C.; Zaluzec, N.J.

2006-01-01

There are a number of factors affecting the formation of images based on core-loss spectroscopy in high-resolution electron microscopy. We demonstrate unambiguously the need to use a full nonlocal description of the effective core-loss interaction for experimental results obtained from high angular resolution electron channelling electron spectroscopy. The implications of this model are investigated for atomic resolution scanning transmission electron microscopy. Simulations are used to demonstrate that core-loss spectroscopy images formed using fine probes proposed for future microscopes can result in images that do not correspond visually with the structure that has led to their formation. In this context, we also examine the effect of varying detector geometries. The importance of the contribution to core-loss spectroscopy images by dechannelled or diffusely scattered electrons is reiterated here

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.

Electron-phonon interaction and its manifestation in high-temperature superconductors

International Nuclear Information System (INIS)

Maksimov, E.G.

1995-01-01

Different types of band structure approaches for a description of electrons in systems with strong correlations are discussed. It is shown that all methods considered give different electron energy dispersions and Fermi surfaces. The good agreement between measured Fermi surfaces and those calculated by LDA shows that the spatial dispersion of the correlation interaction is not so important in HTSC systems. The same conclusion can be obtained from the optical and photoemission spectra. It is shown that the most important contribution beyond a band structure approach is given by an energy dependence of the electron self-energy. The most likely interaction responsible for this energy dependence is the electron-phonon one. Evidences about this fact are given

Electron collision effects on the bremsstrahlung emission in Lorentzian plasmas

International Nuclear Information System (INIS)

Jung, Young-Dae; Kato, Daiji

2009-06-01

The electron-electron collision effects on the electron-ion bemsstranhlung process are investigated in warm Lorentzian plasmas. The effective electron-ion interaction potential is obtained by including the far-field terms caused by the electron-electron collisions with the effective Debye length in Lorentzian plasmas. The bremsstranhlung radiation cross section is obtained as a function of the electron energy, photon energy, collision frequency, spectral index, and Debye length using the Born approximation for the initial and final states of the projectile electron. It is shown that the non-Maxwellian character suppresses the bremsstrahlung radiation cross section. It is also shown that the electron-electron collision effect enhances the bremsstrahlung emission spectrum. In addition, the bremsstrahlung radiation cross section decreases with an increase of the plasma temperature. (author)

One-electron standard reduction potentials of nitroaromatic and cyclic nitramine explosives

Energy Technology Data Exchange (ETDEWEB)

Uchimiya, Minori, E-mail: sophie.uchimiya@ars.usda.go [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180 (United States); Gorb, Leonid [SpecPro Inc, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States); Isayev, Olexandr [Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106 (United States); Qasim, Mohammad M. [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180 (United States); Leszczynski, Jerzy [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180 (United States); Interdisciplinary Center for Nanotoxicity, Jackson State University, Jackson, MS 39217 (United States)

2010-10-15

Extensive studies have been conducted in the past decades to predict the environmental abiotic and biotic redox fate of nitroaromatic and nitramine explosives. However, surprisingly little information is available on one-electron standard reduction potentials (E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -})). The E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) is an essential thermodynamic parameter for predicting the rate and extent of reductive transformation for energetic residues. In this study, experimental (linear free energy relationships) and theoretical (ab initio calculation) approaches were employed to determine E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) for nitroaromatic, (caged) cyclic nitramine, and nitroimino explosives that are found in military installations or are emerging contaminants. The results indicate a close agreement between experimental and theoretical E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) and suggest a key trend: E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) value decreases from di- and tri-nitroaromatic (e.g., 2,4-dinitroanisole) to nitramine (e.g., RDX) to nitroimino compound (e.g., nitroguanidine). The observed trend in E{sup o}(R-NO{sub 2}/R-NO{sub 2}{sup -}) agrees with reported rate trends for reductive degradation, suggesting a thermodynamic control on the reduction rate under anoxic/suboxic conditions. - Reduction of explosives becomes less thermodynamically favorable as the one-electron standard reduction potential decreases from di- and tri-nitroaromatic, nitramine, to nitroimino compounds.

Charge transfer through single molecule contacts: How reliable are rate descriptions?

Directory of Open Access Journals (Sweden)

Denis Kast

2011-08-01

Full Text Available Background: The trend for the fabrication of electrical circuits with nanoscale dimensions has led to impressive progress in the field of molecular electronics in the last decade. However, a theoretical description of molecular contacts as the building blocks of future devices is challenging, as it has to combine the properties of Fermi liquids in the leads with charge and phonon degrees of freedom on the molecule. Outside of ab initio schemes for specific set-ups, generic models reveal the characteristics of transport processes. Particularly appealing are descriptions based on transfer rates successfully used in other contexts such as mesoscopic physics and intramolecular electron transfer. However, a detailed analysis of this scheme in comparison with numerically exact solutions is still elusive.Results: We show that a formulation in terms of transfer rates provides a quantitatively accurate description even in domains of parameter space where strictly it is expected to fail, e.g., at lower temperatures. Typically, intramolecular phonons are distributed according to a voltage driven steady state that can only roughly be captured by a thermal distribution with an effective elevated temperature (heating. An extension of a master equation for the charge–phonon complex, to effectively include the impact of off-diagonal elements of the reduced density matrix, provides very accurate solutions even for stronger electron–phonon coupling.Conclusion: Rate descriptions and master equations offer a versatile model to describe and understand charge transfer processes through molecular junctions. Such methods are computationally orders of magnitude less expensive than elaborate numerical simulations that, however, provide exact solutions as benchmarks. Adjustable parameters obtained, e.g., from ab initio calculations allow for the treatment of various realizations. Even though not as rigorously formulated as, e.g., nonequilibrium Green’s function

CEPXS/ONELD: A one-dimensional coupled electron-photon discrete ordinates code package

International Nuclear Information System (INIS)

Lorence, L.J. Jr.; Morel, J.E.

1992-01-01

CEPXS/ONELD is a discrete ordinates transport code package that can model the electron-photon cascade from 100 MeV to 1 keV. The CEPXS code generates fully-coupled multigroup-Legendre cross section data. This data is used by the general-purpose discrete ordinates code, ONELD, which is derived from the Los Alamos ONEDANT and ONBTRAN codes. Version 1.0 of CEPXS/ONELD was released in 1989 and has been primarily used to analyze the effect of radiation environments on electronics. Version 2.0 is under development and will include user-friendly features such as the automatic selection of group structure, spatial mesh structure, and S N order

Combinatorial description of space and strong interactions

International Nuclear Information System (INIS)

Zenczykowski, P.

1988-01-01

A reinterpretation is given of a successful phenomenological approach to hadron self-energy effects known as the unitarized quark model. General arguments are given that the proper description of strong interactions may require abandoning the assignment of a primary role to continuous concepts such as position and momentum in favor of discrete ones such as spin or W-spin. The reinterpretation exploits an analogy between the W-spin diagrams occurring in the calculations of hadronic loop effects and the spin network idea of Penrose. A connection between the S-matrix approach to hadron masses and the purely algebraic approach characteristic of the quark model is indicated. Several hadron mass relations generated by a resulting SU(6)/sub w/-group-theoretic expression are presented and discussed. Results of an attempt to generalize the scheme to the description of hadron vertices are reported

Spin entanglement in elastic electron scattering from quasi-one electron atoms

Science.gov (United States)

Fonseca Dos Santos, Samantha; Bartschat, Klaus

2017-04-01

We have extended our work on e-Li collisions to investigate low-energy elastic electron collisions with atomic hydrogen and other alkali targets (Na,K,Rb). These systems have been suggested for the possibility of continuously varying the degree of entanglement between the elastically scattered projectile and the valence electron. In order to estimate how well such a scheme may work in practice, we carried out overview calculations for energies between 0 and 10 eV and the full range of scattering angles 0° -180° . In addition to the relative exchange asymmetry parameter that characterizes the entanglement, we present the differential cross section in order to estimate whether the count rates in the most interesting energy-angle regimes are sufficient to make such experiments feasible in practice. Work supported by the NSF under PHY-1403245.

Electron impact excitation of xenon from the metastable state to the excited states

Energy Technology Data Exchange (ETDEWEB)

Jiang Jun; Dong Chenzhong; Xie Luyou; Zhou Xiaoxin [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Wang Jianguo [Institute of Applied Physics and Computational Mathematic, Beijing 100088 (China)], E-mail: dongcz@nwnu.edu.cn

2008-12-28

The electron impact excitation cross sections from the lowest metastable state 5p{sup 5}6sJ = 2 to the six lowest excited states of the 5p{sup 5}6p configuration of xenon are calculated systematically by using the fully relativistic distorted wave method. In order to discuss the effects of target state descriptions on the electron impact excitation cross sections, two correlation models are used to describe the target states based on the multiconfiguration Dirac-Fock (MCDF) method. It is found that the correlation effects play a very important role in low energy impact. For high energy impact, however, the cross sections are not sensitive to the description of the target states, but many more partial waves must be included.

DFT modeling of the electronic and magnetic structures and chemical bonding properties of intermetallic hydrides

International Nuclear Information System (INIS)

Al Alam, A.F.

2009-06-01

This thesis presents an ab initio study of several classes of intermetallics and their hydrides. These compounds are interesting from both a fundamental and an applied points of view. To achieve this aim two complementary methods, constructed within the DFT, were chosen: (i) pseudo potential based VASP for geometry optimization, structural investigations and electron localization mapping (ELF), and (ii) all-electrons ASW method for a detailed description of the electronic structure, chemical bonding properties following different schemes as well as quantities depending on core electrons such as the hyperfine field. A special interest is given with respect to the interplay between magneto-volume and chemical interactions (metal-H) effects within the following hydrided systems: binary Laves (e.g. ScFe 2 ) and Haucke (e.g. LaNi 5 ) phases on one hand, and ternary cerium based (e.g. CeRhSn) and uranium based (e.g. U 2 Ni 2 Sn) alloys on the other hand. (author)

Consistent Probabilistic Description of the Neutral Kaon System: Novel Observable Effects

CERN Document Server

Bernabeu, J.; Villanueva-Perez, P.

2013-01-01

The neutral Kaon system has both CP violation in the mass matrix and a non-vanishing lifetime difference in the width matrix. This leads to an effective Hamiltonian which is not a normal operator, with incompatible (non-commuting) masses and widths. In the Weisskopf-Wigner Approach (WWA), by diagonalizing the entire Hamiltonian, the unphysical non-orthogonal "stationary" states $K_{L,S}$ are obtained. These states have complex eigenvalues whose real (imaginary) part does not coincide with the eigenvalues of the mass (width) matrix. In this work we describe the system as an open Lindblad-type quantum mechanical system due to Kaon decays. This approach, in terms of density matrices for initial and final states, provides a consistent probabilistic description, avoiding the standard problems because the width matrix becomes a composite operator not included in the Hamiltonian. We consider the dominant-decay channel to two pions, so that one of the Kaon states with definite lifetime becomes stable. This new approa...

Electron-plasmon model in the electron liquid theory

Directory of Open Access Journals (Sweden)

M.V.Vavrukh

2005-01-01

Full Text Available Here we propose an accurate approach to the description of the electron liquid model in the electron and plasmon terms. Our ideas in the present paper are close to the conception of the collective variables which was developed in the papers of Bohm and Pines. However we use another body of mathematics in the transition to the expanded space of variable particles and plasmons realized by the transition operator. It is evident that in the Random Phase Approximation (RPA, the model which consists of two interactive subsystems of electrons and plasmons is equivalent to the electron liquid model with Coulomb interaction.

Hot-electron effect in spin relaxation of electrically injected electrons in intrinsic Germanium.

Science.gov (United States)

Yu, T; Wu, M W

2015-07-01

The hot-electron effect in the spin relaxation of electrically injected electrons in intrinsic germanium is investigated by the kinetic spin Bloch equations both analytically and numerically. It is shown that in the weak-electric-field regime with E ≲ 0.5 kV cm(-1), our calculations have reasonable agreement with the recent transport experiment in the hot-electron spin-injection configuration (2013 Phys. Rev. Lett. 111 257204). We reveal that the spin relaxation is significantly enhanced at low temperature in the presence of weak electric field E ≲ 50 V cm(-1), which originates from the obvious center-of-mass drift effect due to the weak electron-phonon interaction, whereas the hot-electron effect is demonstrated to be less important. This can explain the discrepancy between the experimental observation and the previous theoretical calculation (2012 Phys. Rev. B 86 085202), which deviates from the experimental results by about two orders of magnitude at low temperature. It is further shown that in the strong-electric-field regime with 0.5 ≲ E ≲ 2 kV cm(-1), the spin relaxation is enhanced due to the hot-electron effect, whereas the drift effect is demonstrated to be marginal. Finally, we find that when 1.4 ≲ E ≲ 2 kV cm(-1) which lies in the strong-electric-field regime, a small fraction of electrons (≲5%) can be driven from the L to Γ valley, and the spin relaxation rates are the same for the Γ and L valleys in the intrinsic sample without impurity. With the negligible influence of the spin dynamics in the Γ valley to the whole system, the spin dynamics in the L valley can be measured from the Γ valley by the standard direct optical transition method.

Band-structure-based collisional model for electronic excitations in ion-surface collisions

International Nuclear Information System (INIS)

Faraggi, M.N.; Gravielle, M.S.; Alducin, M.; Silkin, V.M.; Juaristi, J.I.

2005-01-01

Energy loss per unit path in grazing collisions with metal surfaces is studied by using the collisional and dielectric formalisms. Within both theories we make use of the band-structure-based (BSB) model to represent the surface interaction. The BSB approach is based on a model potential and provides a precise description of the one-electron states and the surface-induced potential. The method is applied to evaluate the energy lost by 100 keV protons impinging on aluminum surfaces at glancing angles. We found that when the realistic BSB description of the surface is used, the energy loss obtained from the collisional formalism agrees with the dielectric one, which includes not only binary but also plasmon excitations. The distance-dependent stopping power derived from the BSB model is in good agreement with available experimental data. We have also investigated the influence of the surface band structure in collisions with the Al(100) surface. Surface-state contributions to the energy loss and electron emission probability are analyzed

Faithful effective-one-body waveforms of small-mass-ratio coalescing black hole binaries

International Nuclear Information System (INIS)

Damour, Thibault; Nagar, Alessandro

2007-01-01

We address the problem of constructing high-accuracy, faithful analytic waveforms describing the gravitational wave signal emitted by inspiralling and coalescing binary black holes. We work within the effective-one-body (EOB) framework and propose a methodology for improving the current (waveform) implementations of this framework based on understanding, element by element, the physics behind each feature of the waveform and on systematically comparing various EOB-based waveforms with exact waveforms obtained by numerical relativity approaches. The present paper focuses on small-mass-ratio nonspinning binary systems, which can be conveniently studied by Regge-Wheeler-Zerilli-type methods. Our results include (i) a resummed, 3 PN-accurate description of the inspiral waveform, (ii) a better description of radiation reaction during the plunge, (iii) a refined analytic expression for the plunge waveform, (iv) an improved treatment of the matching between the plunge and ring-down waveforms. This improved implementation of the EOB approach allows us to construct complete analytic waveforms which exhibit a remarkable agreement with the exact ones in modulus, frequency, and phase. In particular, the analytic and numerical waveforms stay in phase, during the whole process, within ±1.1% of a cycle. We expect that the extension of our methodology to the comparable-mass case will be able to generate comparably accurate analytic waveforms of direct use for the ground-based network of interferometric detectors of gravitational waves

Effective atomic numbers and effective electron densities for trommel sieve waste and some commonly used building materials

International Nuclear Information System (INIS)

Kurudirek, M.; Canimkurbey, B.; Coban, M.; Ayguen, M.; Erzeneoglu, S. Z.

2010-01-01

Trommel sieve waste and some commonly used building materials (Portland cement, lime and pointing) have been investigated in terms of effective atomic numbers (Z e ff) and effective electron densities (N e ) by using X- and γ- rays at 22.1, 25 and 88 keV photon energies. A high resolution Si(Li) detector was employed to detect X- and/or γ- radiation coming through in a narrow beam good geometry set-up. Chemical compositions of the materials used in the present study were determined using a wave length dispersive X-ray fluorescence spectrometer (WDXRFS). The variations in photon interaction parameters were discussed regarding the photon energy and chemical composition. The experimental values of effective atomic numbers and effective electron densities were compared with the ones obtained from theory.

Effects of lower hybrid fast electron populations on electron temperature measurements at JET

International Nuclear Information System (INIS)

Tanzi, C.P.; Bartlett, D.V.; Schunke, B.

1993-01-01

The Lower Hybrid Current Drive (LHCD) system on JET has to date achieved up to 1.5 MA of driven current. This current is carried by a fast electron population with energies more than ten times the electron temperature and density about 10 -4 of the bulk plasma. This paper discusses the effects of this fast electron population on our ability to make reliable temperature measurements using ECE and reviews the effects on other plasma diagnostics which rely on ECE temperature measurements for their interpretation. (orig.)

Introductory statistical mechanics for electron storage rings

International Nuclear Information System (INIS)

Jowett, J.M.

1986-07-01

These lectures introduce the beam dynamics of electron-positron storage rings with particular emphasis on the effects due to synchrotron radiation. They differ from most other introductions in their systematic use of the physical principles and mathematical techniques of the non-equilibrium statistical mechanics of fluctuating dynamical systems. A self-contained exposition of the necessary topics from this field is included. Throughout the development, a Hamiltonian description of the effects of the externally applied fields is maintained in order to preserve the links with other lectures on beam dynamics and to show clearly the extent to which electron dynamics in non-Hamiltonian. The statistical mechanical framework is extended to a discussion of the conceptual foundations of the treatment of collective effects through the Vlasov equation

Towards a First-Principles Determination of Effective Coulomb Interactions in Correlated Electron Materials: Role of Intershell Interactions.

Science.gov (United States)

Seth, Priyanka; Hansmann, Philipp; van Roekeghem, Ambroise; Vaugier, Loig; Biermann, Silke

2017-08-04

The determination of the effective Coulomb interactions to be used in low-energy Hamiltonians for materials with strong electronic correlations remains one of the bottlenecks for parameter-free electronic structure calculations. We propose and benchmark a scheme for determining the effective local Coulomb interactions for charge-transfer oxides and related compounds. Intershell interactions between electrons in the correlated shell and ligand orbitals are taken into account in an effective manner, leading to a reduction of the effective local interactions on the correlated shell. Our scheme resolves inconsistencies in the determination of effective interactions as obtained by standard methods for a wide range of materials, and allows for a conceptual understanding of the relation of cluster model and dynamical mean field-based electronic structure calculations.

Investigation of electron momentum distributions for outer valence orbitals of trichlorofluoromethane by (e, 2e) electron momentum spectroscopy

International Nuclear Information System (INIS)

Zhou, L.X.; Shan, X.; Chen, X.J.; Yin, X.F.; Zhang, X.H.; Xu, C.K.; Wei, Z.; Xu, K.Z.

2006-01-01

The binding energy spectra and electron momentum distributions for the outer valence orbitals of trichlorofluoromethane (CFCl 3 ) have been measured by binary (e, 2e) electron momentum spectroscopy (EMS) at an impact energy of 1200 eV + binding energy. The experimental electron momentum profiles are compared with Hartree-Fock and density functional theory (DFT) calculations with different-sized basis sets. Generally, the DFT calculations employing B3LYP functional with large basis sets of AUG-cc-pVDZ and AUG-cc-pVTZ give better description of the experimental results. But for 3e orbital, all the theoretical calculations underestimate the experiment, which is probably due to the distorted-wave effect that often occurs in π*-like molecular orbital

Many-beam effects in electron microscope images of lattice defects

International Nuclear Information System (INIS)

Izui, Kazuhiko; Nishida, Takahiko; Furuno, Shigemi; Otsu, Hitoshi

1974-01-01

Multi-beam effects in electron microscopic images were investigated. A computation program was developed on the basis of a matrix theory of the multi-beam effects. The matrix theory for a perfect crystal and an imperfect crystal is described, and expression for absorption coefficient is presented. The amplitude of electron wave penetrating through lattice defects is expressed by using scattering matrices which correspond to crystal slices. Calculation of extinction distance was performed, and compared with experimental results. In case of systematic reflection, the difference between two beams and from four to eight beams approximation was small, while a large effect was seen in case of accidental reflection. The intensity profile of bend contour was calculated for silicon and copper-aluminum alloy. Distance between submaxima becomes short with increase of thickness. The change in stacking fault fringes with diffraction condition was investigated. Samples were copper-aluminum alloy. Systematic behavior of the fringes was obtained, and the calculated results reproduced experimental ones. (Kato, T.)

Effect of increasing length on the electronic transport of an armchair graphene nano-ribbons

Directory of Open Access Journals (Sweden)

Sh Aghamiri Esfahani

2015-12-01

Full Text Available In this research, we have investigated the effect of increasing length on the electronic transport of an armchair graphene nano-ribbons with nitrogen atom impurity and without impurity. The semi-infinite, one-dimensional molecular systems are connected to two electrodes and the electron-electron interaction is ignored. The system is described by a simple tight binding model. All calculations are based on the Green's function and Landauer–Buttiker approach, and the electrodes are described in a wide band approximation.

Numerical simulation of runaway electron effect on Plasma Facing Components

International Nuclear Information System (INIS)

Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato; Kunugi, Tomoaki

1998-07-01

The runaway electron effects on Plasma Facing Components (PFCs) are studied by the numerical analyses. The present study is the first investigation of time-dependent thermal response of PFCs caused by runaway electron impact. For this purpose, we developed a new integrated numerical code, which consists of the Monte Carlo code for the coupled electrons and photons transport analysis and the finite element code for the thermo-mechanical analysis. In this code, we apply the practical incident parameters and distribution of runaway electrons recently proposed by S. Putvinski, which can express the time-dependent behavior of runaway electrons impact. The incident parameters of electrons in this study are the energy density ranging from 10 to 75 MJ/m 2 , the average electrons' energy of 12.5 MeV, the incident angle of 0.01deg and the characteristic time constant for decay of runaway electrons event of 0.15sec. The numerical results showed that the divertor with CFC (Carbon-Fiber-Composite) armor did not suffer serious damage. On the other hand, maximum temperatures at the surface of the divertor with tungsten armor and the first wall with beryllium armor exceed the melting point in case of the incident energy density of 20 and 50 MJ/m 2 . Within the range of the incident condition of runaway electrons, the cooling pipe of each PFCs can be prevented from the melting or burn-out caused by runaway electrons impact, which is one of the possible consequences of runaway electrons event so far. (author)

The effects of verbal descriptions on performance in lineups and showups.

Science.gov (United States)

Wilson, Brent M; Seale-Carlisle, Travis M; Mickes, Laura

2018-01-01

Verbally describing a face has been found to impair subsequent recognition of that face from a photo lineup, a phenomenon known as the verbal overshadowing effect (Schooler & Engstler-Schooler, 1990). Recently, a large direct replication study successfully reproduced that original finding (Alogna et al., 2014). However, in both the original study and the replication studies, memory was tested using only target-present lineups (i.e., lineups containing the previously seen target face), making it possible to compute the correct identification rate (correct ID rate; i.e., the hit rate) but not the false identification rate (false ID rate; i.e., the false alarm rate). Thus, the lower correct ID rate for the verbal condition could reflect either reduced discriminability or a conservative criterion shift relative to the control condition. In four verbal overshadowing experiments reported here, we measured both correct ID rates and false ID rates using photo lineups (Experiments 1 and 2) or single-photo showups (Experiments 3 and 4). The experimental manipulation (verbally describing the face or not) occurred either immediately after encoding (Experiments 1 and 3) or 20-min after encoding (Experiments 2 and 4). In the immediate condition, discriminability did not differ between groups, but in the delayed condition, discriminability was lower in the verbal description group (i.e., a verbal overshadowing effect was observed). A fifth experiment found that the effect of the immediate-versus-delayed manipulation may be attributable to a change in the content of verbal descriptions, with the ratio of diagnostic to generic facial features in the descriptions decreasing as delay increases. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Radiation dose effects, hardening of electronic components

International Nuclear Information System (INIS)

Dupont-Nivet, E.

1991-01-01

This course reviews the mechanism of interaction between ionizing radiation and a silicon oxide type dielectric, in particular the effect of electron-hole pairs creation in the material. Then effects of cumulated dose on electronic components and especially in MOS technology are examined. Finally methods hardening of these components are exposed. 93 refs

Level crossing analysis of chemically induced dynamic nuclear polarization: Towards a common description of liquid-state and solid-state cases

Energy Technology Data Exchange (ETDEWEB)

Sosnovsky, Denis V.; Ivanov, Konstantin L., E-mail: ivanov@tomo.nsc.ru [International Tomography Centre of SB RAS, Institutskaya 3a, 630090, Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova 2, 630090, Novosibirsk (Russian Federation); Jeschke, Gunnar [Institut für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich (Switzerland); Matysik, Jörg [Institut für Analytische Chemie, Universität Leipzig, Linnéstr. 3, D-04103 Leipzig (Germany); Vieth, Hans-Martin [International Tomography Centre of SB RAS, Institutskaya 3a, 630090, Novosibirsk (Russian Federation); Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin (Germany)

2016-04-14

Chemically Induced Dynamic Nuclear Polarization (CIDNP) is an efficient method of creating non-equilibrium polarization of nuclear spins by using chemical reactions, which have radical pairs as intermediates. The CIDNP effect originates from (i) electron spin-selective recombination of radical pairs and (ii) the dependence of the inter-system crossing rate in radical pairs on the state of magnetic nuclei. The CIDNP effect can be investigated by using Nuclear Magnetic Resonance (NMR) methods. The gain from CIDNP is then two-fold: it allows one to obtain considerable amplification of NMR signals; in addition, it provides a very useful tool for investigating elusive radicals and radical pairs. While the mechanisms of the CIDNP effect in liquids are well established and understood, detailed analysis of solid-state CIDNP mechanisms still remains challenging; likewise a common theoretical frame for the description of CIDNP in both solids and liquids is missing. Difficulties in understanding the spin dynamics that lead to the CIDNP effect in the solid-state case are caused by the anisotropy of spin interactions, which increase the complexity of spin evolution. In this work, we propose to analyze CIDNP in terms of level crossing phenomena, namely, to attribute features in the CIDNP magnetic field dependence to Level Crossings (LCs) and Level Anti-Crossings (LACs) in a radical pair. This approach allows one to describe liquid-state CIDNP; the same holds for the solid-state case where anisotropic interactions play a significant role in CIDNP formation. In solids, features arise predominantly from LACs, since in most cases anisotropic couplings result in perturbations, which turn LCs into LACs. We have interpreted the CIDNP mechanisms in terms of the LC/LAC concept. This consideration allows one to find analytical expressions for a wide magnetic field range, where several different mechanisms are operative; furthermore, the LAC description gives a way to determine CIDNP sign

Time-Dependent Close-Coupling Methods for Electron-Atom/Molecule Scattering

International Nuclear Information System (INIS)

Colgan, James

2014-01-01

The time-dependent close-coupling (TDCC) method centers on an accurate representation of the interaction between two outgoing electrons moving in the presence of a Coulomb field. It has been extensively applied to many problems of electrons, photons, and ions scattering from light atomic targets. Theoretical Description: The TDCC method centers on a solution of the time-dependent Schrödinger equation for two interacting electrons. The advantages of a time-dependent approach are two-fold; one treats the electron-electron interaction essentially in an exact manner (within numerical accuracy) and a time-dependent approach avoids the difficult boundary condition encountered when two free electrons move in a Coulomb field (the classic three-body Coulomb problem). The TDCC method has been applied to many fundamental atomic collision processes, including photon-, electron- and ion-impact ionization of light atoms. For application to electron-impact ionization of atomic systems, one decomposes the two-electron wavefunction in a partial wave expansion and represents the subsequent two-electron radial wavefunctions on a numerical lattice. The number of partial waves required to converge the ionization process depends on the energy of the incoming electron wavepacket and on the ionization threshold of the target atom or ion.

An Analysis of the Regulatory Environment Governing Hearsay Electronic Evidence in South Africa: Suggestions for Reform – Part One

Directory of Open Access Journals (Sweden)

Lee Swales

2018-03-01

Full Text Available The purpose of this two-part article is to examine the regulatory environment governing hearsay electronic evidence in South Africa – with a view to providing clear, practical suggestions for regulatory reform in the context of the South African Law Reform Commission's most recent Discussion Paper on electronic evidence. Technology has become an indispensable part of modern life. In particular, the Internet has facilitated new forms of business enterprise, and shifted basic communication norms. From a legal perspective, technology has presented several novel challenges for courts and legal practitioners to deal with – one of these key challenges relates to electronic evidence and in particular the application of the hearsay rules to the digital environment. The South African Law Reform Commission has identified the application of the hearsay rule as one of the core concerns with regard to electronic evidence, and certain academic analysis has revealed inefficiency in the current legal position which may involve multiple sources of law. Moreover, the Law Society of South Africa has stated that there is some confusion amongst members of the profession in relation to hearsay as it applies to electronic evidence. With the pervasive and burgeoning nature of technology, and with the Internet in mind, it is natural to assume that electronic evidence will be relevant in most forms of legal proceedings in future, and hearsay electronic evidence in particular will play an increasingly important role in years to come. Consequently, part one of this article will consider the key definitional concept in relation to electronic evidence – data messages - and examine whether the definition should be revised. In addition, part one of this article will answer two further critical questions posed by the South African Law Reform Commission in relation to data messages and hearsay evidence, namely: should a data message constitute hearsay? And, how should one

Pulse radiolytic one-electron reduction of 2-hydroxy- and 2,6-dihydroxy-9,10-anthraquinones

International Nuclear Information System (INIS)

Pal, Haridas; Mukherjee, Tulsi; Mittal, J.P.

1994-01-01

The semiquinone free radicals produced by one-electron reduction of 2-hydroxy-9-10-anthraquinone (2HAQ) and 2,6-dihydroxy-9,10-anthraquinone (26DHAQ) in aqueous formate solution, water-isopropyl alcohol-acetone mixed solvent and isopropyl alcohol have been studied using the pulse radiolysis technique. The absorption characteristics, kinetic parameters of formation and decay, acid-base behaviour and redox characteristics of the semiquinones have been investigated and compared with the corresponding characteristics of a few intramolecularly hydro-bonded anthrasemiquinone derivatives. The non-hydrogen-bonded semiquinones show two pKsub(a) values (4.7 and 10.7 for 2HAQ and 5.4 and 8.7 for 26DHAQ, respectively) within the pH range 1-14, whereas other intramolecularly hydrogen-bonded semiquinones show only one pKsub(a). The one-electron reduction potential (E' 7 ) values for 2HAQ (-440 mV) and 26DHAQ (- 400 mV) are more negative than those of the intramolecularly hydrogen-bonded systems. (Author)

Regulatory fit effects for injunctive versus descriptive social norms: Evidence from the promotion of sustainable products

NARCIS (Netherlands)

Melnyk, V.; Herpen, van E.; Fischer, A.R.H.; Trijp, van J.C.M.

2013-01-01

Consumers face marketing messages using social norms in many situations where different goals are dominant. This research examines moderating effects of regulatory focus for descriptive and injunctive norms in the promotion of sustainable products. More specifically, it shows that descriptive norms

One electron reduction and absorption characteristics of Cresyl violet in micellar medium

International Nuclear Information System (INIS)

Gawandi, Vijay B.; Guha, S.N.; Hari Mohan

2000-01-01

Effect of surfactant micelles on absorption characteristics of Cresyl violet (CV) and on its redox reactions have been studied. Among the various surfactants investigated anionic surfactants particularly sodium lauryl sulfate (SLS) and sodium dodecyl benzene sulfonate (SDDBS) showed marked effect on these properties. Reactions of hydrated electron in these micellar media were studied using the technique of nanosecond pulse radiolysis. Results of other surfactants, viz.BSS, CTAB and TritonX-100 have also been presented. (author)

Nonequilibrium Transport and the Bernoulli Effect of Electrons in a Two-Dimensional Electron Gas

Science.gov (United States)

Kaya, Ismet I.

2013-02-01

Nonequilibrium transport of charged carriers in a two-dimensional electron gas is summarized from an experimental point of view. The transport regime in which the electron-electron interactions are enhanced at high bias leads to a range of striking effects in a two-dimensional electron gas. This regime of transport is quite different than the ballistic transport in which particles propagate coherently with no intercarrier energy transfer and the diffusive transport in which the momentum of the electron system is lost with the involvement of the phonons. Quite a few hydrodynamic phenomena observed in classical gasses have the electrical analogs in the current flow. When intercarrier scattering events dominate the transport, the momentum sharing via narrow angle scattering among the hot and cold electrons lead to negative resistance and electron pumping which can be viewed as the analog of the Bernoulli-Venturi effect observed classical gasses. The recent experimental findings and the background work in the field are reviewed.

Quasiparticle properties of a coupled quantum-wire electron-phonon system

DEFF Research Database (Denmark)

Hwang, E. H.; Hu, Ben Yu-Kuang; Sarma, S. Das

1996-01-01

We study leading-order many-body effects of longitudinal-optical phonons on electronic properties of one-dimensional quantum-wire systems. We calculate the quasiparticle properties of a weakly polar one-dimensional electron gas in the presence of both electron-phonon and electron-electron interac......We study leading-order many-body effects of longitudinal-optical phonons on electronic properties of one-dimensional quantum-wire systems. We calculate the quasiparticle properties of a weakly polar one-dimensional electron gas in the presence of both electron-phonon and electron......-electron interactions, The leading-order dynamical screening approximation (GW approximation) is used to obtain the electron self-energy, the quasiparticle spectral function, and the quasiparticle damping rate in our calculation by treating electrons and phonons on an equal footing. Our theory includes effects (within...... theoretical results for quasiparticle properties....

Electronic commerce

OpenAIRE

Zvolánková, Pavla

2010-01-01

The thesis deals with a description of electronic commerce from its beginning up to present situation in this area. It explains basic terms connected with electronic commerce and it summarizes the relevant legislation. Moreover it describes e-contracts and rights and duties of both contractual parties. The main view is the view of Internet retailer, which is reflected in the practical part focused on concrete problems of retailers.

Vertical one-dimensional electron cyclotron emission imaging diagnostic for HT-7 tokamak

International Nuclear Information System (INIS)

Wang Jun; Xu Xiaoyuan; Wen Yizhi; Yu Changxuan; Wan Baonian; Luhmann, N.C.; Wang, Jian; Xia, Z.G.

2005-01-01

A vertical resolved 16-channel electron cyclotron emission imaging (ECEI) diagnostic has been developed and installed on the HT7 Tokamak for measuring plasma electron cyclotron emission with a temporal resolution of 0.5 us. The system is working on a fixed frequency 97.5 GHz in the first stage. The sample volumes of the system are aligned vertically with a vertical channel spacing of 11 mm, and can be shifted across the plasma cross-section by varying the toroidal magnetic field. The high spatial resolution of the system is achieved by utilizing a low cost linear mixer/receiver array and an optical imaging system. The focus location may be shifted horizontally via translation of one of the optical imaging elements. The detail of the system design and laboratory testing of the ECE Imaging optics are presented, together with HT7 plasma data. (author)

Quasi-static electron density fluctuations of atoms in hot compressed matter

International Nuclear Information System (INIS)

Grimaldi, F.; Grimaldi-Lecourt, A.

1982-01-01

The standard theoretical methods for the calculation of properties of hot compressed matter lead to a description based on the Average Atom model. In this model the degenerate orbitals are populated with the Fermi-Dirac (FD) density, partitioned according to the binomial distribution. Since the one particle picture is inadequate to evaluate reliable optical properties, a method involving correlated population fluctuations, but limited to unrelaxed orbitals and lacking time dependence, has been examined. The probability distribution of fluctuations in a particular level is evaluated through a decoupling procedure. The method is carried out self consistently. For each level this leads to the definition of an effective 1st order ionization energy as a statistical sum of all possible transition energies. As a result the effective number of electrons exchanged with the outside weights the chemical potential. This defines an effective chemical potential μsup(k) for each level. In many cases of interest the statistics leads to FD type average occupation numbers. This allows a treatment of the continuum in a Thomas-Fermi like model using the effective ionization energy and μsup(k). We obtain a simultaneous description of charge rearrangements and net fluctuations in the Wigner-Seitz cell. The discussion is supported by numerical results for iron. (author)

Effect mutual carrying away of electrons and photons on thermomagnet and thermoelectric phenomena in semiconductors with generated statistics of current carriers

International Nuclear Information System (INIS)

Kuliev, I.G.

2000-01-01

One studied the effects of the mutual carrying away of electrons and phonons on the thermomagnetic and thermoelectric phenomena in semiconductors with the degenerated statistics of current carriers. One estimated the conduction current within nonequilibrium electron-phonon system in the linear approximation on the basis of the degeneration parameter. Under the isothermal conductors the mutual carrying away was shown to affect essentially the values of the Nernst-Ettingshausen effects. One estimated the heat flow and analyzed the dependence of heat conductivity and of the Muggy-Regge (MR) effect on the magnetic field. The contribution of the mutual carrying away into the isothermal MR-effect was determined to be proportional to the degeneration parameter. One studied thermomagnetic and thermoelectric effects in the degenerated conductors with regard to the mutual carrying away of electrons and phonons both under the isothermal and under the adiabatic conditions [ru

Electron-neutrino scattering off nuclei from two different theoretical perspectives

Science.gov (United States)