Energy modulation of nonrelativistic electrons with a CO2 laser using a metal microslit
Jongsuck, Bae; Ryo, Ishikawa; Sumio, Okuyama; Takashi, Miyajima; Taiji, Akizuki; Tatsuya, Okamoto; Koji, Mizuno
2000-01-01
A metal microslit has been used as an interaction circuit between a CO2 laser beam and nonrelativistic free electrons. Evanescent waves which are induced on the slit by illumination of the laser light modulate the energy of electrons passing close to the surface of the slit. The electron-energy change of more than ±5 eV for the 80 keV electron beam has been observed using the 7 kW laser beam at the wavelength of 10.6 μm.
Energy modulation of nonrelativistic electrons with a CO2 laser using a metal microslit
Bae, Jongsuck; Ishikawa, Ryo; Okuyama, Sumio; Miyajima, Takashi; Akizuki, Taiji; Okamoto, Tatsuya; Mizuno, Koji
2000-04-01
A metal microslit has been used as an interaction circuit between a CO2 laser beam and nonrelativistic free electrons. Evanescent waves which are induced on the slit by illumination of the laser light modulate the energy of electrons passing close to the surface of the slit. The electron-energy change of more than ±5 eV for the 80 keV electron beam has been observed using the 7 kW laser beam at the wavelength of 10.6 μm.
On the relativistic and nonrelativistic electron descriptions in high-energy atomic collisions
International Nuclear Information System (INIS)
Voitkiv, A.B
2007-01-01
We consider the relativistic and nonrelativistic descriptions of an atomic electron in collisions with point-like charged projectiles moving at relativistic velocities. We discuss three different forms of the fully relativistic first-order transition amplitude. Using the Schroedinger-Pauli equation to describe the atomic electron we establish the correct form of the nonrelativistic first-order transition amplitude. We also show that the so-called semi-relativistic treatment, in which the Darwin states are used to describe the atomic electron, is in fact fully equivalent to the nonrelativistic consideration. The comparison of results obtained with the relativistic and nonrelativistic electron descriptions shows that the latter is accurate within 20-30% up to Z a ∼ a is the atomic nuclear charge
On non-relativistic electron theory
Energy Technology Data Exchange (ETDEWEB)
Woolley, R G
1975-01-01
A discussion of non-relativistic electron theory, which makes use of the electromagnetic field potentials only as useful working variables in the intermediate stages, is presented. The separation of the (transverse) radiation field from the longitudinal electric field due to the sources is automatic, and as a result, this formalism is often more convenient than the usual Coulomb gauge theory used in molecular physics.
Relativistic quantum Hall conductivity for 3D and 2D electron plasma in an external magnetic field
International Nuclear Information System (INIS)
Gonzalez Felipe, R.; Perez Martinez, A.; Perez-Rojas, H.
1990-05-01
The complete antisymmetric form of the conductivity tensor in the static limit, as well as the expression for the Hall conductivity, is obtained for the relativistic 3D and 2D electron gas in a magnetic field. The non-relativistic 2D limit is also discussed. The typical step form of the 2D Hall conductivity at zero temperature is obtained under the simple hypothesis of constancy of the chemical potential. (author). 6 refs, 1 fig
The dressed nonrelativistic electron in a magnetic field
International Nuclear Information System (INIS)
Amour, L.; Grebert, B.; Guillot, J.C.
2005-01-01
We consider a nonrelativistic electron interacting with a classical magnetic field pointing along the x 3 -axis and with a quantized electromagnetic field. Because of the translation invariance along the x 3 -axis, we consider the reduced Hamiltonian associated with the total momentum along the x 3 -axis and, after introducing an ultraviolet cutoff and an infrared regularization, we prove that the reduced Hamiltonian has a ground state if the coupling constant and the total momentum along the x 3 -axis are sufficiently small. Finally, we determine the absolutely continuous spectrum of the reduced Hamiltonian and we prove that the renormalized mass of the electron is greater than its bare one. (authors)
Dielectric laser acceleration of non-relativistic electrons at a photonic structure
Energy Technology Data Exchange (ETDEWEB)
Breuer, John
2013-08-29
This thesis reports on the observation of dielectric laser acceleration of non-relativistic electrons via the inverse Smith-Purcell effect in the optical regime. Evanescent modes in the vicinity of a periodic grating structure can travel at the same velocity as the electrons along the grating surface. A longitudinal electric field component is used to continuously impart momentum onto the electrons. This is only possible in the near-field of a suitable photonic structure, which means that the electron beam has to pass the structure within about one wavelength. In our experiment we exploit the third spatial harmonic of a single fused silica grating excited by laser pulses derived from a Titanium:sapphire oscillator and accelerate non-relativistic 28 keV electrons. We measure a maximum energy gain of 280 eV, corresponding to an acceleration gradient of 25 MeV/m, already comparable with state-of-the-art radio-frequency linear accelerators. To experience this acceleration gradient the electrons approach the grating closer than 100 nm. We present the theory behind grating-based particle acceleration and discuss simulation results of dielectric laser acceleration in the near-field of photonic grating structures, which is excited by near-infrared laser light. Our measurements show excellent agreement with our simulation results and therefore confirm the direct acceleration with the light field. We further discuss the acceleration inside double grating structures, dephasing effects of non-relativistic electrons as well as the space charge effect, which can limit the attainable peak currents of these novel accelerator structures. The photonic structures described in this work can be readily concatenated and therefore represent a scalable realization of dielectric laser acceleration. Furthermore, our structures are directly compatible with the microstructures used for the acceleration of relativistic electrons demonstrated in parallel to this work by our collaborators in
Lamb Shift in Nonrelativistic Quantum Electrodynamics.
Grotch, Howard
1981-01-01
The bound electron self-energy or Lamb shift is calculated in nonrelativistic quantum electrodynamics. Retardation is retained and also an interaction previously dropped in other nonrelativistic approaches is kept. Results are finite without introducing a cutoff and lead to a Lamb shift in hydrogen of 1030.9 MHz. (Author/JN)
International Nuclear Information System (INIS)
Mahmood, S.; Sadiq, Safeer; Haque, Q.
2013-01-01
Linear and nonlinear electrostatic waves in magnetized dense electron-ion plasmas are studied with nonrelativistic and ultra-relativistic degenerate and singly, doubly charged helium (He + , He ++ ) and hydrogen (H + ) ions, respectively. The dispersion relation of electrostatic waves in magnetized dense plasmas is obtained under both the energy limits of degenerate electrons. Using reductive perturbation method, the Zakharov-Kuznetsov equation for nonlinear propagation of electrostatic solitons in magnetized dense plasmas is derived for both nonrelativistic and ultra-relativistic degenerate electrons. It is found that variations in plasma density, magnetic field intensity, different mass, and charge number of ions play significant role in the formation of electrostatic solitons in magnetized dense plasmas. The numerical plots are also presented for illustration using the parameters of dense astrophysical plasma situations such as white dwarfs and neutron stars exist in the literature. The present investigation is important for understanding the electrostatic waves propagation in the outer periphery of compact stars which mostly consists of hydrogen and helium ions with degenerate electrons in dense magnetized plasmas
Injection and propagation of a nonrelativistic electron beam and spacecraft charging
International Nuclear Information System (INIS)
Okuda, H.; Berchem, J.
1987-05-01
Two-dimensional numerical simulations have been carried out in order to study the injection and propagation of a nonrelativistic electron beam from a spacecraft into a fully ionized plasma in a magnetic field. Contrary to the earlier results in one-dimension, a high density electron beam whose density is comparable to the ambient density can propagate into a plasma. A strong radial electric field resulting from the net charges in the beam causes the beam electrons to spread radially reducing the beam density. When the injection current exceeds the return current, significant charging of the spacecraft is observed along with the reflection of the injected electrons back to the spacecraft. Recent data on the electron beam injection from the Spacelab 1 (SEPAC) are discussed
Höfener, Sebastian; Ahlrichs, Reinhart; Knecht, Stefan; Visscher, Lucas
2012-12-07
We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga(2) to Br(2) , the 5p-block dimers In(2) to I(2) , and their atoms. Extended basis sets up to pentuple zeta are employed and energies extrapolated to the complete basis-set limit. Relativistic and non-relativistic results for the dissociation energy D(e) are in close agreement with each other and previously published data, provided non-relativistic or scalar-relativistic results are corrected for spin-orbit contributions taken from the literature. An exception is Te(2) where theoretical results scatter by 0.085 eV. By virtue of this agreement it is unexpected that comparison with the experimental D(0) or D(e) dissociation energies (zero-point vibrational effects are negligible in this context) reveal errors larger than 0.1 eV for Ga(2), Ge(2), and Sb(2). Only relativistic treatments are presented for the 6p-block cases Tl(2) to At(2). Sufficient agreement with experimental data is found only for Pb(2) and Bi(2), the deviation of the computed and experimental D(0) values for Po(2) is again larger than 0.1 eV. Deviations of 0.1 eV between the computed and experimental D(0) values are a major reason for concern and call for additional investigations in both fields to clarify the situation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Energy modulation of nonrelativistic electrons in an optical near field on a metal microslit
R., Ishikawa; Jongsuck, Bae; K., Mizuno
2001-01-01
Energy modulation of nonrelativistic electrons with a laser beam using a metal microslit as an interaction circuit has been investigated. An optical near field is induced in the proximity of the microslit by illumination of the laser beam. The electrons passing close to the slit are accelerated or decelerated by an evanescent wave contained in the near field whose phase velocity is equal to the velocity of the electrons. The electron-evanescent wave interaction in the microslit has been analy...
Energy modulation of nonrelativistic electrons in an optical near field on a metal microslit
Ishikawa, R.; Bae, J.; Mizuno, K.
2001-04-01
Energy modulation of nonrelativistic electrons with a laser beam using a metal microslit as an interaction circuit has been investigated. An optical near field is induced in the proximity of the microslit by illumination of the laser beam. The electrons passing close to the slit are accelerated or decelerated by an evanescent wave contained in the near field whose phase velocity is equal to the velocity of the electrons. The electron-evanescent wave interaction in the microslit has been analyzed theoretically and experimentally. The theory has predicted that electron energy can be modulated at optical frequencies. Experiments performed in the infrared region have verified theoretical predictions. The electron-energy changes of more than ±5 eV with a 10 kW CO2 laser pulse at the wavelength of 10.6 μm has been successfully observed for an electron beam with an energy of less than 80 keV.
Nonrelativistic Conformed Symmetry in 2 + 1 Dimensional Field Theory.
Bergman, Oren
This thesis is devoted to the study of conformal invariance and its breaking in non-relativistic field theories. It is a well known feature of relativistic field theory that theories which are conformally invariant at the classical level can acquire a conformal anomaly upon quantization and renormalization. The anomaly appears through the introduction of an arbitrary, but dimensionful, renormalization scale. One does not usually associate the concepts of renormalization and anomaly with nonrelativistic quantum mechanics, but there are a few examples where these concepts are useful. The most well known case is the two-dimensional delta -function potential. In two dimensions the delta-function scales like the kinetic term of the Hamiltonian, and therefore the problem is classically conformally invariant. Another example of classical conformal invariance is the famous Aharonov-Bohm (AB) problem. In that case each partial wave sees a 1/r^2 potential. We use the second quantized formulation of these problems, namely the nonrelativistic field theories, to compute Green's functions and derive the conformal anomaly. In the case of the AB problem we also solve an old puzzle, namely how to reproduce the result of Aharonov and Bohm in perturbation theory. The thesis is organized in the following manner. Chapter 1 is an introduction to nonrelativistic field theory, nonrelativistic conformal invariance, contact interactions and the AB problem. In Chapter 2 we discuss nonrelativistic scalar field theory, and how its quantization produces the anomaly. Chapter 3 is devoted to the AB problem, and the resolution of the perturbation puzzle. In Chapter 4 we generalize the discussion of Chapter 3 to particles carrying nonabelian charges. The structure of the nonabelian theory is much richer, and deserves a separate discussion. We also comment on the issues of forward scattering and single -valuedness of wavefunctions, which are important for Chapter 3 as well. (Copies available
Nonrelativistic superstring theories
International Nuclear Information System (INIS)
Kim, Bom Soo
2007-01-01
We construct a supersymmetric version of the critical nonrelativistic bosonic string theory [B. S. Kim, Phys. Rev. D 76, 106007 (2007).] with its manifest global symmetry. We introduce the anticommuting bc conformal field theory (CFT) which is the super partner of the βγ CFT. The conformal weights of the b and c fields are both 1/2. The action of the fermionic sector can be transformed into that of the relativistic superstring theory. We explicitly quantize the theory with manifest SO(8) symmetry and find that the spectrum is similar to that of type IIB superstring theory. There is one notable difference: the fermions are nonchiral. We further consider noncritical generalizations of the supersymmetric theory using the superspace formulation. There is an infinite range of possible string theories similar to the supercritical string theories. We comment on the connection between the critical nonrelativistic string theory and the lightlike linear dilaton theory
Propagation of a nonrelativistic electron beam in a plasma in a magnetic field
International Nuclear Information System (INIS)
Okuda, H.; Horton, R.; Ono, M.; Ashour-Abdalla, M.
1986-10-01
Propagation of a nonrelativistic electron beam in a plasma in a strong magnetic field has been studied using electrostatic one-dimensional particle simulation models. Electron beams of finite pulse length and of continuous injection are followed in time to study the effects of beam-plasma interaction on the beam propagation. For the case of pulsed beam propagation, it is found that the beam distribution rapidly spreads in velocity space generating a plateaulike distribution with a high energy tail extending beyond the initial beam velocity
The infrared problem for the dressed non-relativistic electron in a magnetic field
International Nuclear Information System (INIS)
Amour, L.; Faupin, J.; Grebert, B.; Guillot, J.C.
2008-01-01
We consider a non-relativistic electron interacting with a classical magnetic field pointing along the x 3 -axis and with a quantized electromagnetic field. The system is translation invariant in the x 3 -direction and the corresponding Hamiltonian has a decomposition H ≅∫ R + H(P 3 )dP 3 . For a fixed momentum P 3 sufficiently small, we prove that H(P 3 ) has a ground state in the Fock representation if and only if E'(P 3 )=0, where P 3 →E'(P 3 ) is the derivative of the map P 3 →E(P 3 )=infσ(H(P 3 )). If E'(P 3 )≠0, we obtain the existence of a ground state in a non-Fock representation. This result holds for sufficiently small values of the coupling constant. (authors)
Energy Technology Data Exchange (ETDEWEB)
Costescu, A [Department of Physics, University of Bucharest, MG11, Bucharest-Magurele 76900 (Romania); Spanulescu, S [Department of Physics, University of Bucharest, MG11, Bucharest-Magurele 76900 (Romania); Stoica, C [Department of Physics, University of Bucharest, MG11, Bucharest-Magurele 76900 (Romania)
2007-08-14
The right expressions of the nonrelativistic K-shell Rayleigh scattering amplitudes and cross-sections are obtained by using the Coulomb Green's function method. Our analytical result does not have the spurious poles that occur in the old nonrelativistic result with retardation (Gavrila and Costescu 1970 Phys. Rev. A 2 1752). Starting from the expression of the second-order S-matrix element for the case of the elastic scattering of photons by K-shell bound electrons, we obtain the correct nonrelativistic Rayleigh angular distribution (valid for photon energies {omega} up to {alpha}Zm) by removing the relativistic higher order terms in {alpha}Z and {omega}/m. The imaginary part of the Rayleigh amplitudes is obtained for any scattering angles in a closed form in terms of elementary functions. Thereby a simple formula for the exact nonrelativistic photoeffect total cross-section is obtained via the optical theorem, giving significantly better predictions than Fischer's nonrelativistic photoeffect formula. Comparing the predictions given by our formulae with the full relativistic numerical calculations of Kissel et al (Phys. Rev. 1980 A 22 1970), and with experimental results, a fairly good agreement within 10% is found for the angular distribution of Rayleigh scattering for photon energies up to 200 keV and both below and above the first resonance.
Gauging of 1D-space translations for nonrelativistic matter - Geometric bags
International Nuclear Information System (INIS)
Stichel, P.C.
2000-01-01
We develop in a systematic fashion the idea of gauging 1D-space translations with fixed Newtonian time for nonrelativistic matter (particles and fields). By starting with a nonrelativistic free theory we obtain its minimal gauge invariant extension by introducing two gauge fields with a Maxwellian self interaction. We fix the gauge so that the residual symmetry group is the Galilei group and construct a representation of the extended Galilei algebra. The reduced N-particle Lagrangian describes geodesic motion in a (N-1)-dimensional (Pseudo-) Riemannian space. The singularity of the metric for negative gauge coupling leads in classical dynamics to the formation of geometric bags in the case of two or three particles. The ordering problem within the quantization scheme for N-particles is solved by canonical quantization of a pseudoclassical Schroedinger theory obtained by adding to the continuum generalization of the point-particle Lagrangian an appropriate quantum correction. We solve the two-particle bound state problem for both signs of the gauge coupling. At the end we speculate on the possible physical relevance of the new interaction induced by the gauge fields
Nonrelativistic quantum electrodynamic approach to photoemission theory
International Nuclear Information System (INIS)
Fujikawa, Takashi; Arai, Hiroko
2005-01-01
A new nonrelativistic many-body theory to analyze X-ray photoelectron spectroscopy (XPS) spectra has been developed on the basis of quantum electrodynamic (QED) Keldysh Green's function approach. To obtain XPS current density we calculate electron Green's function g which partly includes electron-photon interactions. We first separate longitudinal and transverse parts of these Green's functions in the Coulomb gauge. The transverse electron selfenergy describes the electron-photon interaction, whereas the longitudinal electron selfenergy describes the electron-electron interaction. We derive the QED Hedin's equation from which we obtain systematic skeleton expansion in the power series of the screened Coulomb interaction W and the photon Green's function D kl . We show the present theory provides a sound theoretical tool to study complicated many-body processes such as the electron propagation damping, intrinsic, extrinsic losses and their interference, and furthermore, resonant photoemission processes. We have also found the importance of the mixed photon Green's functions D 0k and D k0 which have been supposed to be unimportant for the XPS analyses. They, however, directly describe the radiation field screening. In this work, photon field screening effects are discussed in one-step theory, where the electron-photon interaction operator Δ is proved to be replaced by ε -1 Δ beyond linear approximation. Beyond free photon Green's function approximation, photon scatterings from the electron density are incorporated within the present QED theory. These photon field effects can directly describe the microscopic photon field spatial variation specific to near the surface region and nanoparticle systems
Propagation of a nonrelativistic electron beam in a plasma in a magnetic field
International Nuclear Information System (INIS)
Okuda, H.; Horton, R.; Ono, M.; Ashour-Abdalla, M.
1987-01-01
Propagation of a nonrelativistic electron beam in a plasma in a strong magnetic field has been studied using electrostatic one-dimensional particle simulation models. Electron beams of finite pulse length and of continuous injection are followed in time to study the effects of beam--plasma interaction on the beam propagation. For the case of pulsed beam propagation, it is found that the beam distribution rapidly spreads in velocity space generating a plateaulike distribution with a high energy tail extending beyond the initial beam velocity. This rapid diffusion takes place within a several amplification length of the beam--plasma instability given by (ω/sub p/ω 2 /sub b/) -1 /sup // 3 V 0 , where ω/sub p/, ω/sub b/, and V 0 are the target plasma, beam--plasma frequencies, and the beam drift speed. This plateaulike distribution, however, becomes unstable as the high energy tail electrons free-stream, generating a secondary beam. A similar process is observed to take place for the case of continuous beam injection when the beam density is small compared with the total density n/sub b//n/sub t/<1. In particular, the electron velocity distribution is found monotonically decreasing in energy, having a high energy tail whose energy reaches twice the initial beam energy. Such an electron distribution is also seen in laboratory experiments and in computer simulations performed for a uniform, periodic system
Is nonrelativistic gravity possible?
International Nuclear Information System (INIS)
Kocharyan, A. A.
2009-01-01
We study nonrelativistic gravity using the Hamiltonian formalism. For the dynamics of general relativity (relativistic gravity) the formalism is well known and called the Arnowitt-Deser-Misner (ADM) formalism. We show that if the lapse function is constrained correctly, then nonrelativistic gravity is described by a consistent Hamiltonian system. Surprisingly, nonrelativistic gravity can have solutions identical to relativistic gravity ones. In particular, (anti-)de Sitter black holes of Einstein gravity and IR limit of Horava gravity are locally identical.
Virial Theorem for Nonrelativistic Quantum Fields in D Spatial Dimensions
International Nuclear Information System (INIS)
Lin, Chris L.; Ordóñez, Carlos R.
2015-01-01
The virial theorem for nonrelativistic complex fields in D spatial dimensions and with arbitrary many-body potential is derived, using path-integral methods and scaling arguments recently developed to analyze quantum anomalies in low-dimensional systems. The potential appearance of a Jacobian J due to a change of variables in the path-integral expression for the partition function of the system is pointed out, although in order to make contact with the literature most of the analysis deals with the J=1 case. The virial theorem is recast into a form that displays the effect of microscopic scales on the thermodynamics of the system. From the point of view of this paper the case usually considered, J=1, is not natural, and the generalization to the case J≠1 is briefly presented
The notion of nonrelativistic isoparticle
International Nuclear Information System (INIS)
Santilli, R.M.
1991-09-01
We introduce the notion of nonrelativistic isoparticle as a representation of a Galilei-isotopic symmetry studied in preceding works or, equivalently, as the generalization of the conventional notion of particle characterized by the isotopic liftings of the unit. We show that the lifting represents the transition from massive points moving in vacuum to extended-deformable particles moving within physical media. As explicit examples, we work out the cases of an extended-deformable particle: 1) in free conditions; 2) under external potential-selfadjoint interactions; and 3) under external potential-selfadjoint and nonhamiltonian-nonselfadjoint interactions. The emerging methods are applied to a first classical and nonrelativistic treatment of Rauch's experiments on the spinorial symmetry of thermal neutrons under external (magnetic and) nuclear fields. The notion nonrelativistic isoquark is submitted as a conceivable classical basis for future operator studies. (author). 12 refs, 1 fig
A unified treatment of the non-relativistic and relativistic hydrogen atom: Pt. 2
International Nuclear Information System (INIS)
Swainson, R.A.; Drake, G.W.F.
1991-01-01
This is the second in a series of three papers in which it is shown how the radial part of non-relativistic and relativistic hydrogenic bound-state calculations involving the Green functions can be presented in a unified manner. In this paper the non-relativistic Green function is examined in detail; new functional forms are presented and a clear mathematical progression is show to link these and most other known forms. A linear transformation of the four radial parts of the relativistic Green function is given which allows for the presentation of this function as a simple generalization of the non-relativistic Green function. Thus, many properties of the non-relativistic Green function are shown to have simple relativistic generalizations. In particular, new recursion relations of the radial parts of both the non-relativistic and relativistic Green functions are presented, along with new expressions for the double Laplace transforms and recursion relations between the radial matrix elements. (author)
Supersymmetric solutions for non-relativistic holography
International Nuclear Information System (INIS)
Donos, Aristomenis; Gauntlett, Jerome P.
2009-01-01
We construct families of supersymmetric solutions of type IIB and D=11 supergravity that are invariant under the non-relativistic conformal algebra for various values of dynamical exponent z≥4 and z≥3, respectively. The solutions are based on five- and seven-dimensional Sasaki-Einstein manifolds and generalise the known solutions with dynamical exponent z=4 for the type IIB case and z=3 for the D=11 case, respectively. (orig.)
OPE convergence in non-relativistic conformal field theories
Energy Technology Data Exchange (ETDEWEB)
Goldberger, Walter D.; Khandker, Zuhair University; Prabhu, Siddharth [Department of Physics, Yale University,New Haven, CT 06511 (United States); Physics Department, Boston University,Boston, MA 02215 (United States)
2015-12-09
Motivated by applications to the study of ultracold atomic gases near the unitarity limit, we investigate the structure of the operator product expansion (OPE) in non-relativistic conformal field theories (NRCFTs). The main tool used in our analysis is the representation theory of charged (i.e. non-zero particle number) operators in the NRCFT, in particular the mapping between operators and states in a non-relativistic “radial quantization” Hilbert space. Our results include: a determination of the OPE coefficients of descendant operators in terms of those of the underlying primary state, a demonstration of convergence of the (imaginary time) OPE in certain kinematic limits, and an estimate of the decay rate of the OPE tail inside matrix elements which, as in relativistic CFTs, depends exponentially on operator dimensions. To illustrate our results we consider several examples, including a strongly interacting field theory of bosons tuned to the unitarity limit, as well as a class of holographic models. Given the similarity with known statements about the OPE in SO(2,d) invariant field theories, our results suggest the existence of a bootstrap approach to constraining NRCFTs, with applications to bound state spectra and interactions. We briefly comment on a possible implementation of this non-relativistic conformal bootstrap program.
Non-relativistic AdS branes and Newton-Hooke superalgebra
International Nuclear Information System (INIS)
Sakaguchi, Makoto; Yoshida, Kentaroh
2006-01-01
We examine a non-relativistic limit of D-branes in AdS 5 x S 5 and M-branes in AdS 4/7 x S 7/4 . First, Newton-Hooke superalgebras for the AdS branes are derived from AdS x S superalgebras as Inoenue-Wigner contractions. It is shown that the directions along which the AdS-brane worldvolume extends are restricted by requiring that the isometry on the AdS-brane worldvolume and the Lorentz symmetry in the transverse space naturally extend to the super-isometry. We also derive Newton-Hooke superalgebras for pp-wave branes and show that the directions along which a brane worldvolume extends are restricted. Then the Wess-Zumino terms of the AdS branes are derived by using the Chevalley-Eilenberg cohomology on the super-AdS x S algebra, and the non-relativistic limit of the AdS-brane actions is considered. We show that the consistent limit is possible for the following branes: Dp (even,even) for p = 1 mod 4 and Dp (odd,odd) for p = 3 mod 4 in AdS 5 x S 5 , and M2 (0,3), M2 (2,1), M5 (1,5) and M5 (3,3) in AdS 4 x S 7 and S 4 x AdS 7 . We furthermore present non-relativistic actions for the AdS branes
Non-relativistic Limit of a Dirac Polaron in Relativistic Quantum Electrodynamics
Arai, A
2006-01-01
A quantum system of a Dirac particle interacting with the quantum radiation field is considered in the case where no external potentials exist. Then the total momentum of the system is conserved and the total Hamiltonian is unitarily equivalent to the direct integral $\\int_{{\\bf R}^3}^\\oplus\\overline{H({\\bf p})}d{\\bf p}$ of a family of self-adjoint operators $\\overline{H({\\bf p})}$ acting in the Hilbert space $\\oplus^4{\\cal F}_{\\rm rad}$, where ${\\cal F}_{\\rm rad}$ is the Hilbert space of the quantum radiation field. The fibre operator $\\overline{H({\\bf p})}$ is called the Hamiltonian of the Dirac polaron with total momentum ${\\bf p} \\in {\\bf R}^3$. The main result of this paper is concerned with the non-relativistic (scaling) limit of $\\overline{H({\\bf p})}$. It is proven that the non-relativistic limit of $\\overline{H({\\bf p})}$ yields a self-adjoint extension of a Hamiltonian of a polaron with spin $1/2$ in non-relativistic quantum electrodynamics.
Excited state electron affinity calculations for aluminum
Hussein, Adnan Yousif
2017-08-01
Excited states of negative aluminum ion are reviewed, and calculations of electron affinities of the states (3s^23p^2)^1D and (3s3p^3){^5}{S}° relative to the (3s^23p)^2P° and (3s3p^2)^4P respectively of the neutral aluminum atom are reported in the framework of nonrelativistic configuration interaction (CI) method. A priori selected CI (SCI) with truncation energy error (Bunge in J Chem Phys 125:014107, 2006) and CI by parts (Bunge and Carbó-Dorca in J Chem Phys 125:014108, 2006) are used to approximate the valence nonrelativistic energy. Systematic studies of convergence of electron affinity with respect to the CI excitation level are reported. The calculated value of the electron affinity for ^1D state is 78.675(3) meV. Detailed Calculations on the ^5S°c state reveals that is 1216.8166(3) meV below the ^4P state.
The hydrogen atom in D = 3 - 2ɛ dimensions
Adkins, Gregory S.
2018-06-01
The nonrelativistic hydrogen atom in D = 3 - 2 ɛ dimensions is the reference system for perturbative schemes used in dimensionally regularized nonrelativistic effective field theories to describe hydrogen-like atoms. Solutions to the D-dimensional Schrödinger-Coulomb equation are given in the form of a double power series. Energies and normalization integrals are obtained numerically and also perturbatively in terms of ɛ. The utility of the series expansion is demonstrated by the calculation of the divergent expectation value .
Acceleration-enlarged symmetries in nonrelativistic space-time with a cosmological constant TH1"-->
Lukierski, J.; Stichel, P. C.; Zakrzewski, W. J.
2008-05-01
By considering the nonrelativistic limit of de Sitter geometry one obtains the nonrelativistic space-time with a cosmological constant and Newton Hooke (NH) symmetries. We show that the NH symmetry algebra can be enlarged by the addition of the constant acceleration generators and endowed with central extensions (one in any dimension (D) and three in D=(2+1)). We present a classical Lagrangian and Hamiltonian framework for constructing models quasi-invariant under enlarged NH symmetries that depend on three parameters described by three nonvanishing central charges. The Hamiltonian dynamics then splits into external and internal sectors with new noncommutative structures of external and internal phase spaces. We show that in the limit of vanishing cosmological constant the system reduces to the one, which possesses acceleration-enlarged Galilean symmetries.
Energy Technology Data Exchange (ETDEWEB)
Dieckmann, M. E. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam (Germany); Department of Science and Technology, Linkoeping University, SE-60174 Norrkoeping (Sweden); Ahmed, H.; Sarri, G.; Doria, D.; Kourakis, I.; Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom); Romagnani, L. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Pohl, M. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam (Germany); DESY, D-15738 Zeuthen (Germany)
2013-04-15
Nonrelativistic electrostatic unmagnetized shocks are frequently observed in laboratory plasmas and they are likely to exist in astrophysical plasmas. Their maximum speed, expressed in units of the ion acoustic speed far upstream of the shock, depends only on the electron-to-ion temperature ratio if binary collisions are absent. The formation and evolution of such shocks is examined here for a wide range of shock speeds with particle-in-cell simulations. The initial temperatures of the electrons and the 400 times heavier ions are equal. Shocks form on electron time scales at Mach numbers between 1.7 and 2.2. Shocks with Mach numbers up to 2.5 form after tens of inverse ion plasma frequencies. The density of the shock-reflected ion beam increases and the number of ions crossing the shock thus decreases with an increasing Mach number, causing a slower expansion of the downstream region in its rest frame. The interval occupied by this ion beam is on a positive potential relative to the far upstream. This potential pre-heats the electrons ahead of the shock even in the absence of beam instabilities and decouples the electron temperature in the foreshock ahead of the shock from the one in the far upstream plasma. The effective Mach number of the shock is reduced by this electron heating. This effect can potentially stabilize nonrelativistic electrostatic shocks moving as fast as supernova remnant shocks.
International Nuclear Information System (INIS)
Dieckmann, M. E.; Ahmed, H.; Sarri, G.; Doria, D.; Kourakis, I.; Borghesi, M.; Romagnani, L.; Pohl, M.
2013-01-01
Nonrelativistic electrostatic unmagnetized shocks are frequently observed in laboratory plasmas and they are likely to exist in astrophysical plasmas. Their maximum speed, expressed in units of the ion acoustic speed far upstream of the shock, depends only on the electron-to-ion temperature ratio if binary collisions are absent. The formation and evolution of such shocks is examined here for a wide range of shock speeds with particle-in-cell simulations. The initial temperatures of the electrons and the 400 times heavier ions are equal. Shocks form on electron time scales at Mach numbers between 1.7 and 2.2. Shocks with Mach numbers up to 2.5 form after tens of inverse ion plasma frequencies. The density of the shock-reflected ion beam increases and the number of ions crossing the shock thus decreases with an increasing Mach number, causing a slower expansion of the downstream region in its rest frame. The interval occupied by this ion beam is on a positive potential relative to the far upstream. This potential pre-heats the electrons ahead of the shock even in the absence of beam instabilities and decouples the electron temperature in the foreshock ahead of the shock from the one in the far upstream plasma. The effective Mach number of the shock is reduced by this electron heating. This effect can potentially stabilize nonrelativistic electrostatic shocks moving as fast as supernova remnant shocks.
Non-relativistic conformal symmetries and Newton-Cartan structures
International Nuclear Information System (INIS)
Duval, C; Horvathy, P A
2009-01-01
This paper provides us with a unifying classification of the conformal infinitesimal symmetries of non-relativistic Newton-Cartan spacetime. The Lie algebras of non-relativistic conformal transformations are introduced via the Galilei structure. They form a family of infinite-dimensional Lie algebras labeled by a rational 'dynamical exponent', z. The Schroedinger-Virasoro algebra of Henkel et al corresponds to z = 2. Viewed as projective Newton-Cartan symmetries, they yield, for timelike geodesics, the usual Schroedinger Lie algebra, for which z = 2. For lightlike geodesics, they yield, in turn, the Conformal Galilean Algebra (CGA) of Lukierski, Stichel and Zakrzewski (alias 'alt' of Henkel), with z = 1. Physical systems realizing these symmetries include, e.g. classical systems of massive and massless non-relativistic particles, and also hydrodynamics, as well as Galilean electromagnetism.
Extended Galilean symmetries of non-relativistic strings
Energy Technology Data Exchange (ETDEWEB)
Batlle, Carles [Departament de Matemàtiques and IOC, Universitat Politècnica de Catalunya, EPSEVG,Av. V. Balaguer 1, E-08808 Vilanova i la Geltrú (Spain); Gomis, Joaquim; Not, Daniel [Departament de Física Quàntica i Astrofísica and Institut de Ciències del Cosmos (ICCUB),Universitat de Barcelona,Martí i Franquès 1, E-08028 Barcelona (Spain)
2017-02-09
We consider two non-relativistic strings and their Galilean symmetries. These strings are obtained as the two possible non-relativistic (NR) limits of a relativistic string. One of them is non-vibrating and represents a continuum of non-relativistic massless particles, and the other one is a non-relativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of non-relativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional space-time symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of non-central extensions.
On Secondary Electron Emission from Solid H2 and D2
DEFF Research Database (Denmark)
Schou, Jørgen; Sørensen, H.
1978-01-01
The emission of secondary electrons from solid hydrogen (H2 , D2, T2) is often considered to be of importance for the interaction between a fusion plasma and pellets of solid hydrogens. A set-up was therefore built for studies of interactions between energetic particles and solid hydrogens. Studies...... of secondary electron emission (SEE) from solid H2 and D2 were made for incidence of electrons up to 3 keV and for incidence of ions of hydrogen, deuterium, and helium up to 10 keV. The measurements were made for normal incidence, and in some cases also for oblique incidence. The SEE coefficients for solid H2...... is always 0.65-0.70 times that for solid D2. This difference is attributed to different losses to vibrational states in H2 and D2 for the low energy electrons. Measurements were also made on solid para-H2 with both electrons and hydrogen ions. There was no difference from the results for normal H2, which...
Radiation reaction in nonrelativistic quantum theory
International Nuclear Information System (INIS)
Sharp, D.H.
1979-01-01
Some recent work is reviewed on the quantum theory of radiation reaction. The starting point is the Heisenberg operator equation of motion for a nonrelativistic point electron coupled to the quantized electromagnetic field. It is shown that this equation, in contrast to its classical counterpart, leads to a finite value for the electrostatic self-energy of a point electron and, for values of the fine structure constant α approximately less than 1, admits neither runaway behavior nor noncausal motion. Furthermore, the correspondence limit of the solution to the quantum mechanical equation of motion agrees with that of the Lorentz--Dirac theory in the classical regime, but without the imposition of additional conditions and with no possibility of observable noncausality. Thus, a consistent picture of a classical point electron emerges in the correspondence limit of the quantum mechanical theory. 17 references
International Nuclear Information System (INIS)
Jayaraman, Jambunatha; Lima Rodrigues, R. de
1994-01-01
In the context of the 3 D generalized SUSY model oscillator Hamiltonian of Celka and Hussin (CH), a generalized Dirac oscillator interaction is studied, that leads, in the non-relativistic limit considered for both signs of energy, to the CH's generalized 3 D SUSY oscillator. The relevance of this interaction to the CH's SUSY model and the SUSY breaking dependent on the Wigner parameter is brought out. (author). 6 refs
Vibrational excitation of D2 by low energy electrons
International Nuclear Information System (INIS)
Buckman, S.J.; Phelps, A.V.
1985-01-01
Excitation coefficients for the production of vibrationally exicted D 2 by low energy electrons have been determined from measurements of the intensity of infrared emission from mixtures of D 2 and small concentrations of CO 2 or CO. The measurements were made using the electron drift tube technique and covered electric field to gas density ratios (E/n) from (5 to 80) x 10 -21 V m 2 , corresponding to mean electron energies between 0.45 and 4.5 eV. The CO 2 and CO concentrations were chosen to allow efficient excitation transfer from the D 2 to the carbon containing molecule, but to minimize direct excitation of the CO 2 or CO. The measured infrared intensities were normalized to predicted values for N 2 --CO 2 and N 2 --CO mixtures at E/n where the efficiency of vibrational excitation is known to be very close to 100%. The experimental excitation coefficients are in satisfactory agreement with predictions based on electron--D 2 cross sections at mean electron energies below 1 eV, but are about 50% too high at mean energies above about 2 eV. Application of the technique to H 2 did not yield useful vibrational excitation coefficients. The effective coefficients in H 2 --CO 2 mixtures were a factor of about 3 times the predicted values. For our H 2 --CO mixtures the excitation of CO via excitation transfer from H 2 is small compared to direct electron excitation of CO molecules. Published experiments and theories on electron--H 2 and electron--D 2 collisions are reviewed to obtain the cross sections used in the predictions
Energy Technology Data Exchange (ETDEWEB)
Amour, L. [Reims Univ., Lab. de Mathematiques EDPPM, FRE-CNRS 3111, 51 (France); Faupin, J. [Aarhus Univ., Institut for Matematiske Fag (Denmark); Grebert, B. [Nantes Univ, Lab. de Mathematiques Jean-Leray, UMR-CNRS 6629 (France); Guillot, J.C. [Ecole Polytechnique, Centre de Mathematiques Appliquees, UMR-CNRS 7641, 91 - Palaiseau (France)
2008-10-15
We consider a non-relativistic electron interacting with a classical magnetic field pointing along the x{sub 3}-axis and with a quantized electromagnetic field. The system is translation invariant in the x{sub 3}-direction and the corresponding Hamiltonian has a decomposition H {approx_equal}{integral}{sub R}{sup +}H(P{sub 3})dP{sub 3}. For a fixed momentum P{sub 3} sufficiently small, we prove that H(P{sub 3}) has a ground state in the Fock representation if and only if E'(P{sub 3})=0, where P{sub 3} {yields}E'(P{sub 3}) is the derivative of the map P{sub 3}{yields}E(P{sub 3})=inf{sigma}(H(P{sub 3})). If E'(P{sub 3}){ne}0, we obtain the existence of a ground state in a non-Fock representation. This result holds for sufficiently small values of the coupling constant. (authors)
Run-away electrons in relativistic spin (1) /(2) quantum electrodynamics
International Nuclear Information System (INIS)
Low, F.E.
1998-01-01
The existence of run-away solutions in classical and non-relativistic quantum electrodynamics is reviewed. It is shown that the less singular high energy behavior of relativistic spin (1) /(2) quantum electrodynamics precludes an analogous behavior in that theory. However, a Landau-like anomalous pole in the photon propagation function or in the electron-massive photon forward scattering amplitude would generate a new run-away, characterized by an energy scale ω∼m e thinspexp(1/α). This contrasts with the energy scale ω∼m e /α associated with the classical and non-relativistic quantum run-aways. copyright 1998 Academic Press, Inc
Effectively semi-relativistic Hamiltonians of nonrelativistic form
International Nuclear Information System (INIS)
Lucha, W.; Schoeberl, F.F.; Moser, M.
1993-12-01
We construct effective Hamiltonians which despite their apparently nonrelativistic form incorporate relativistic effects by involving parameters which depend on the relevant momentum. For some potentials the corresponding energy eigenvalues may be determined analytically. Applied to two-particle bound states, it turns out that in this way a nonrelativistic treatment may indeed be able to simulate relativistic effects. Within the framework of hadron spectroscopy, this lucky circumstance may be an explanation for the sometimes extremely good predictions of nonrelativistic potential models even in relativistic regions. (authors)
International Nuclear Information System (INIS)
March, N.H.
2009-08-01
In this Journal, March and Suhai have earlier set up a first-order Dirac idempotent density matrix theory for one- and two-level occupancy in which the only input required is the nonrelativistic ground-state electron density. Here, an analytic generalization is provided for the case of spherical electron densities for arbitrary level occupancy. Be-like atomic ions are referred to as an example, but 'almost spherical' molecules like SiH 4 and GeH 4 also become accessible. (author)
International Nuclear Information System (INIS)
Liljequist, D.; Ismail, M.
1987-01-01
This analysis is based on the similarity between multiple scattering and slowing down (random walk) processes described by the same transport mean-free-path function λ/sub tr/(s) (s = path length). We discuss the connection between λ/sub tr/(s) and the characteristic appearance and scale of the trajectory pattern. Straggling is considered by means by stochastically discontinuous λ/sub tr/(s) functions. In the application to electron penetration, we show that while nonrelativistic electron penetration is modeled by λ/sub tr/ = (r-s)/α, where r is the range and α is a material-dependent dimensionless constant, highly relativistic electron penetration is modeled by λ/sub tr/proportionalexp(-s/Λ), where Λ is a length characteristic for the penetrated material. The respective trajectory patterns are distinctly different. The effect of straggling on the trajectory pattern in the highly relativistic case is demonstrated by means of a simple model of the stochastic λ/sub tr/(s) behavior
Organic High Electron Mobility Transistors Realized by 2D Electron Gas.
Zhang, Panlong; Wang, Haibo; Yan, Donghang
2017-09-01
A key breakthrough in inorganic modern electronics is the energy-band engineering that plays important role to improve device performance or develop novel functional devices. A typical application is high electron mobility transistors (HEMTs), which utilizes 2D electron gas (2DEG) as transport channel and exhibits very high electron mobility over traditional field-effect transistors (FETs). Recently, organic electronics have made very rapid progress and the band transport model is demonstrated to be more suitable for explaining carrier behavior in high-mobility crystalline organic materials. Therefore, there emerges a chance for applying energy-band engineering in organic semiconductors to tailor their optoelectronic properties. Here, the idea of energy-band engineering is introduced and a novel device configuration is constructed, i.e., using quantum well structures as active layers in organic FETs, to realize organic 2DEG. Under the control of gate voltage, electron carriers are accumulated and confined at quantized energy levels, and show efficient 2D transport. The electron mobility is up to 10 cm 2 V -1 s -1 , and the operation mechanisms of organic HEMTs are also argued. Our results demonstrate the validity of tailoring optoelectronic properties of organic semiconductors by energy-band engineering, offering a promising way for the step forward of organic electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Nonrelativistic hyperfine splitting in muonic helium by adiabatic perturbation theory
International Nuclear Information System (INIS)
Drachman, R.J.
1980-01-01
Huang and Hughes have recently discussed the hyperfine splitting Δν of muonic helium (α ++ μ - e - ) using a variational approach. In this paper, the Born-Oppenheimer approximation is used to simplify the evaluation of Δν in the nonrelativistic limit. The first-order perturbed wave function of the electron is obtained in closed form by slightly modifying the method used by Dalgarno and Lynn. The result Δν=4450 MHz, is quite close to the published result of Huang and Hughes 4455.2 +- 1 MHz, which required a very large Hylleraas expansion as well as considerable extrapolation
Fermions in nonrelativistic AdS/CFT correspondence
International Nuclear Information System (INIS)
Akhavan, Amin; Alishahiha, Mohsen; Davody, Ali; Vahedi, Ali
2009-01-01
We extend the nonrelativistic AdS/CFT correspondence to the fermionic fields. In particular, we study the two point function of a fermionic operator in nonrelativistic CFTs by making use of a massive fermion propagating in geometries with Schroedinger group isometry. Although the boundary of the geometries with Schroedinger group isometry differ from that in AdS geometries where the dictionary of AdS/CFT is established, using the general procedure of AdS/CFT correspondence, we see that the resultant two point function has the expected form for fermionic operators in nonrelativistic CFTs, though a nontrivial regularization may be needed.
Relativistic energy-dispersion relations of 2D rectangular lattices
Ata, Engin; Demirhan, Doğan; Büyükkılıç, Fevzi
2017-04-01
An exactly solvable relativistic approach based on inseparable periodic well potentials is developed to obtain energy-dispersion relations of spin states of a single-electron in two-dimensional (2D) rectangular lattices. Commutation of axes transfer matrices is exploited to find energy dependencies of the wave vector components. From the trace of the lattice transfer matrix, energy-dispersion relations of conductance and valence states are obtained in transcendental form. Graphical solutions of relativistic and nonrelativistic transcendental energy-dispersion relations are plotted to compare how lattice parameters V0, core and interstitial size of the rectangular lattice affects to the energy-band structures in a situation core and interstitial diagonals are of equal slope.
Dual-mode operation of 2D material-base hot electron transistors
Lan, Yann-Wen; Jr., Carlos M. Torres,; Zhu, Xiaodan; Qasem, Hussam; Adleman, James R.; Lerner, Mitchell B.; Tsai, Shin-Hung; Shi, Yumeng; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L.
2016-01-01
Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (V-CB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (V-CB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.
Dual-mode operation of 2D material-base hot electron transistors
Lan, Yann-Wen
2016-09-01
Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (V-CB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (V-CB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.
International Nuclear Information System (INIS)
Ehvarestov, R.A.; Panin, A.I.; Bandura, A.V.
2008-01-01
Account of relativistic effects on the properties of uranium hexafluoride is testified. Detailed comparison of single electron energies spectrum revealed in nonrelativistic (by Hartree-Fock method), relativistic (by Dirac-Fock method), and scalar-relativistic (using relativistic potential of atomic uranium frame) has been conducted. Optimization procedures of atomic basis in LCAO calculations of molecules and crystals permissive taking into account distortion of atomic orbitals when chemical bonding are discussed, and optimization effect of atomic basis on the results of scalar-relativistic calculations of UF 6 molecule properties is analyzed. Calculations of electronic structure and properties of UO 2 crystal having relativistic and nonrelativistic pseudopotentials have been realized [ru
DEFF Research Database (Denmark)
Hofener, S.; Ahlrichs, R.; Knecht, S.
2012-01-01
We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga2 to Br2, the 5p-block dimers In2 to I2, and their atoms. Extended basis sets up...
Non-relativistic spinning particle in a Newton-Cartan background
Barducci, Andrea; Casalbuoni, Roberto; Gomis, Joaquim
2018-01-01
We construct the action of a non-relativistic spinning particle moving in a general torsionless Newton-Cartan background. The particle does not follow the geodesic equations, instead the motion is governed by the non-relativistic analog of Papapetrou equation. The spinning particle is described in terms of Grassmann variables. In the flat case the action is invariant under the non-relativistic analog of space-time vector supersymmetry.
Canonical analysis of non-relativistic particle and superparticle
Energy Technology Data Exchange (ETDEWEB)
Kluson, Josef [Masaryk University, Department of Theoretical Physics and Astrophysics, Faculty of Science, Brno (Czech Republic)
2018-02-15
We perform canonical analysis of non-relativistic particle in Newton-Cartan Background. Then we extend this analysis to the case of non-relativistic superparticle in the same background. We determine constraints structure of this theory and find generator of κ-symmetry. (orig.)
Non-relativistic supersymmetry
International Nuclear Information System (INIS)
Clark, T.E.; Love, S.T.
1984-01-01
The most general one- and two-body hamiltonian invariant under galilean supersymmetry is constructed in superspace. The corresponding Feynman rules are given for the superfield Green functions. As demonstrated by a simple example, it is straightforward to construct models in which the supersymmetry is spontaneously broken by the non-relativistic vacuum. (orig.)
Dual-mode operation of 2D material-base hot electron transistors.
Lan, Yann-Wen; Torres, Carlos M; Zhu, Xiaodan; Qasem, Hussam; Adleman, James R; Lerner, Mitchell B; Tsai, Shin-Hung; Shi, Yumeng; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L
2016-09-01
Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (VCB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (VCB transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.
Condensation for non-relativistic matter in Hořava–Lifshitz gravity
Directory of Open Access Journals (Sweden)
Jiliang Jing
2015-10-01
Full Text Available We study condensation for non-relativistic matter in a Hořava–Lifshitz black hole without the condition of the detailed balance. We show that, for the fixed non-relativistic parameter α2 (or the detailed balance parameter ϵ, it is easier for the scalar hair to form as the parameter ϵ (or α2 becomes larger, but the condensation is not affected by the non-relativistic parameter β2. We also find that the ratio of the gap frequency in conductivity to the critical temperature decreases with the increase of ϵ and α2, but increases with the increase of β2. The ratio can reduce to the Horowitz–Roberts relation ωg/Tc≈8 obtained in the Einstein gravity and Cai's result ωg/Tc≈13 found in a Hořava–Lifshitz gravity with the condition of the detailed balance for the relativistic matter. Especially, we note that the ratio can arrive at the value of the BCS theory ωg/Tc≈3.5 by taking proper values of the parameters.
2D scattering of unpolarized beams of electrons by charged nanomagnets
Energy Technology Data Exchange (ETDEWEB)
Senbeta, Teshome, E-mail: teshearada@yahoo.com [Department of Physics, Addis Ababa University, P.O. Box 1176, Addis Ababa (Ethiopia); Mal' nev, V.N., E-mail: vnmalnev@aau.edu.et [Department of Physics, Addis Ababa University, P.O. Box 1176, Addis Ababa (Ethiopia)
2012-07-15
2D spin-dependent scattering of slow unpolarized beams of electrons by charged nanomagnets is analyzed in the Born approximation. The obtained scattering lengths are larger than those from the neutral nanomagnets approximately by one order. It is shown that for particular parameters of the system it is possible to polarize completely the scattered electrons in a narrow range of scattering angles. The most suitable system for realization of these effects is 2D Si electron gas with immersed nanomagnets. - Highlights: Black-Right-Pointing-Pointer We study 2D spin dependent electron scattering by charged nanomagnets. Black-Right-Pointing-Pointer The applicability of the Born approximation to the problem is discussed. Black-Right-Pointing-Pointer Unpolarized incident beams used to obtain completely polarized scattered electrons. Black-Right-Pointing-Pointer The study shows peculiarities of 2D spin dependent scattering enhanced by Coulomb potential. Black-Right-Pointing-Pointer The result obtained can be used as one method of controlling spin currents.
Symmetries of nonrelativistic phase space and the structure of quark-lepton generation
International Nuclear Information System (INIS)
Zenczykowski, Piotr
2009-01-01
According to the Hamiltonian formalism, nonrelativistic phase space may be considered as an arena of physics, with momentum and position treated as independent variables. Invariance of x 2 + p 2 constitutes then a natural generalization of ordinary rotational invariance. We consider Dirac-like linearization of this form, with position and momentum satisfying standard commutation relations. This leads to the identification of a quantum-level structure from which some phase space properties might emerge. Genuine rotations and reflections in phase space are tied to the existence of new quantum numbers, unrelated to ordinary 3D space. Their properties allow their identification with the internal quantum numbers characterising the structure of a single quark-lepton generation in the Standard Model. In particular, the algebraic structure of the Harari-Shupe preon model of fundamental particles is reproduced exactly and without invoking any subparticles. Analysis of the Clifford algebra of nonrelativistic phase space singles out an element which might be associated with the concept of lepton mass. This element is transformed into a corresponding element for a single coloured quark, leading to a generalization of the concept of mass and a different starting point for the discussion of quark unobservability.
Nonrelativistic trace and diffeomorphism anomalies in particle number background
Auzzi, Roberto; Baiguera, Stefano; Nardelli, Giuseppe
2018-04-01
Using the heat kernel method, we compute nonrelativistic trace anomalies for Schrödinger theories in flat spacetime, with a generic background gauge field for the particle number symmetry, both for a free scalar and a free fermion. The result is genuinely nonrelativistic, and it has no counterpart in the relativistic case. Contrary to naive expectations, the anomaly is not gauge invariant; this is similar to the nongauge covariance of the non-Abelian relativistic anomaly. We also show that, in the same background, the gravitational anomaly for a nonrelativistic scalar vanishes.
Nonrelativistic closed string theory
International Nuclear Information System (INIS)
Gomis, Jaume; Ooguri, Hirosi
2001-01-01
We construct a Galilean invariant nongravitational closed string theory whose excitations satisfy a nonrelativistic dispersion relation. This theory can be obtained by taking a consistent low energy limit of any of the conventional string theories, including the heterotic string. We give a finite first order worldsheet Hamiltonian for this theory and show that this string theory has a sensible perturbative expansion, interesting high energy behavior of scattering amplitudes and a Hagedorn transition of the thermal ensemble. The strong coupling duals of the Galilean superstring theories are considered and are shown to be described by an eleven-dimensional Galilean invariant theory of light membrane fluctuations. A new class of Galilean invariant nongravitational theories of light-brane excitations are obtained. We exhibit dual formulations of the strong coupling limits of these Galilean invariant theories and show that they exhibit many of the conventional dualities of M theory in a nonrelativistic setting
Non-Relativistic Twistor Theory and Newton-Cartan Geometry
Dunajski, Maciej; Gundry, James
2016-03-01
We develop a non-relativistic twistor theory, in which Newton-Cartan structures of Newtonian gravity correspond to complex three-manifolds with a four-parameter family of rational curves with normal bundle O oplus O(2)}. We show that the Newton-Cartan space-times are unstable under the general Kodaira deformation of the twistor complex structure. The Newton-Cartan connections can nevertheless be reconstructed from Merkulov's generalisation of the Kodaira map augmented by a choice of a holomorphic line bundle over the twistor space trivial on twistor lines. The Coriolis force may be incorporated by holomorphic vector bundles, which in general are non-trivial on twistor lines. The resulting geometries agree with non-relativistic limits of anti-self-dual gravitational instantons.
Electronic and optical properties of 2D graphene-like ZnS: DFT calculations
International Nuclear Information System (INIS)
Lashgari, Hamed; Boochani, Arash; Shekaari, Ashkan; Solaymani, Shahram; Sartipi, Elmira; Mendi, Rohollah Taghavi
2016-01-01
Graphical abstract: - Highlights: • DFT has been applied to investigate the optical properties of 2D-ZnS and 3D-ZnS. • The electronic and the optical properties of 3D-ZnS and 2D-ZnS are compared. • At visible range of energies the transparency of 2D-ZnS is more than the 3D. - Abstract: Density-functional theory has been applied to investigate the electronic and optical properties of graphene-like two-dimensional ZnS in the (0001) direction of its Wurtzite phase. A comparison with 3D-ZnS has been carried out within the PBE- and EV-GGA. The electronic properties of 2D- and 3D-ZnS have been derived by the examination of the electronic band structures and density of states. The optical properties have been determined through the study of the dielectric function, reflectivity, electron loss function, refractive and extinction indices, the absorption index and optical conductivity. It is found that the transparency of 2D-ZnS is greater than the 3D over the visible range. A thorough study of the dielectric function has been performed so that the peaks and the transition bands have been specified. The electron loss function demonstrates that the plasmonic frequency for 2D- and 3D-ZnS is accrued at 11.22 and 19.93 eV within the PBE-GGA, respectively.
Phenomenological aspects of nonrelativistic potential models
International Nuclear Information System (INIS)
Lucha, W.; Schoeberl, F.F.
1989-01-01
This review reports on the description of hardrons as bound states of quarks by nonrelativistic potential models. It contains a brief sketch of the way in which information on the form of the inter-quark potential may be gained from quantum chromodynamics, proofs of some general theorems related to the potential-model approach, a discussion of the significance of the treatment of bound states consisting of relativistically-moving constituents by the nonrelativistic Schroedinger formalism, as well as a brief survey of the motivations for the various proposed potential models. Finally, it illustrates the application of the developed theoretical framework at a few selected examples. 60 refs., 8 figs., 17 tabs. (Authors)
First Principles Calculations of Electronic Excitations in 2D Materials
DEFF Research Database (Denmark)
Rasmussen, Filip Anselm
electronic transport, optical and chemical properties. On the other hand it has shown to be a great starting point for a systematic pertubation theory approach to obtain the so-called quasiparticle spectrum. In the GW approximation one considers the considers the potential from a charged excitation...... as if it is being screened by the electrons in the material. This method has been very successful for calculating quasiparticle energies of bulk materials but results have been more varying for 2D materials. The reason is that the 2D confined electrons are less able to screen the added charge and some...
Non-relativistic holography and singular black hole
International Nuclear Information System (INIS)
Lin Fengli; Wu Shangyu
2009-01-01
We provide a framework for non-relativistic holography so that a covariant action principle ensuring the Galilean symmetry for dual conformal field theory is given. This framework is based on the Bargmann lift of the Newton-Cartan gravity to the one-dimensional higher Einstein gravity, or reversely, the null-like Kaluza-Klein reduction. We reproduce the previous zero temperature results, and our framework provides a natural explanation about why the holography is co-dimension 2. We then construct the black hole solution dual to the thermal CFT, and find the horizon is curvature singular. However, we are able to derive the sensible thermodynamics for the dual non-relativistic CFT with correct thermodynamical relations. Besides, our construction admits a null Killing vector in the bulk such that the Galilean symmetry is preserved under the holographic RG flow. Finally, we evaluate the viscosity and find it zero if we neglect the back reaction of the singular horizon, otherwise, it could be non-zero.
Scattering of Non-Relativistic Charged Particles by Electromagnetic Radiation
Apostol, M.
2017-11-01
The cross-section is computed for non-relativistic charged particles (like electrons and ions) scattered by electromagnetic radiation confined to a finite region (like the focal region of optical laser beams). The cross-section exhibits maxima at scattering angles given by the energy and momentum conservation in multi-photon absorption or emission processes. For convenience, a potential scattering is included and a comparison is made with the well-known Kroll-Watson scattering formula. The scattering process addressed in this paper is distinct from the process dealt with in previous studies, where the scattering is immersed in the radiation field.
Nonrelativistic quantum X-ray physics
Hau-Riege, Stefan P
2015-01-01
Providing a solid theoretical background in photon-matter interaction, Nonrelativistic Quantum X-Ray Physics enables readers to understand experiments performed at XFEL-facilities and x-ray synchrotrons. As a result, after reading this book, scientists and students will be able to outline and perform calculations of some important x-ray-matter interaction processes. Key features of the contents are that the scope reaches beyond the dipole approximation when necessary and that it includes short-pulse interactions. To aid the reader in this transition, some relevant examples are discussed in detail, while non-relativistic quantum electrodynamics help readers to obtain an in-depth understanding of the formalisms and processes. The text presupposes a basic (undergraduate-level) understanding of mechanics, electrodynamics, and quantum mechanics. However, more specialized concepts in these fields are introduced and the reader is directed to appropriate references. While primarily benefiting users of x-ray light-sou...
Local supersymmetry in non-relativistic systems
International Nuclear Information System (INIS)
Urrutia, L.F.; Zanelli, J.
1989-10-01
Classical and quantum non-relativistic interacting systems invariant under local supersymmetry are constructed by the method of taking square roots of the bosonic constraints which generate timelike reparametrization, leaving the action unchanged. In particular, the square root of the Schroedinger constraint is shown to be the non-relativistic limit of the Dirac constraint. Contact is made with the standard models of Supersymmetric Quantum Mechanics through the reformulation of the locally invariant systems in terms of their true degrees of freedom. Contrary to the field theory case, it is shown that the locally invariant systems are completely equivalent to the corresponding globally invariant ones, the latter being the Heisenberg picture description of the former, with respect to some fermionic time. (author). 14 refs
International Nuclear Information System (INIS)
Toms, D.J.
1995-01-01
We consider the problem of Bose-Einstein condensation for a system of nonrelativistic spin-0 bosons in a space of arbitrary dimension D. A general static homogeneous magnetic field is imposed. The effective action approach and ζ-function regularization are used. If D=2δ or 2δ+1, a constant magnetic field is characterized by δ independent components. If p≤δ of these components are nonzero, the condition for Bose-Einstein condensation to occur is D-2p≥3. This means that if D=2δ, then Bose-Einstein condensation never occurs for p=δ-1 or δ. If D=2δ+1, Bose-Einstein condensation never occurs for p=δ. For D-2p≥3, Bose-Einstein condensation does occur, and we show how it may be interpreted as symmetry breaking to give a ground state which is not constant
Electric field effect on the electronic structure of 2D Y2C electride
Oh, Youngtek; Lee, Junsu; Park, Jongho; Kwon, Hyeokshin; Jeon, Insu; Wng Kim, Sung; Kim, Gunn; Park, Seongjun; Hwang, Sung Woo
2018-07-01
Electrides are ionic compounds in which electrons confined in the interstitial spaces serve as anions and are attractive owing to their exotic physical and chemical properties in terms of their low work function and efficient charge-transfer characteristics. Depending on the topology of the anionic electrons, the surface electronic structures of electrides can be significantly altered. In particular, the electronic structures of two-dimensional (2D) electride surfaces are of interest because the localized anionic electrons at the interlayer space can be naturally exposed to cleaved surfaces. In this paper, we report the electronic structure of 2D Y2C electride surface using scanning tunneling microscopy (STM) and first-principles calculations, which reveals that anionic electrons at a cleaved surface are absorbed by the surface and subsequently resurged onto the surface due to an applied electric field. We highlight that the estranged anionic electrons caused by the electric field occupy the slightly shifted crystallographic site compared with a bulk Y2C electride. We also measure the work function of the Y2C single crystal, and it shows a slightly lower value than the calculated one, which appears to be due to the electric field from the STM junction.
Rayleigh scattering of x-ray and {gamma}-ray by 1s and 2s electrons in ions and neutral atoms
Energy Technology Data Exchange (ETDEWEB)
Costescu, A; Karim, K; Stoica, C [Department of Physics, University of Bucharest, MG11, Bucharest-Magurele 077125 (Romania); Moldovan, M [Department of Physics, UMF Targu Mures, Targu Mures 540142 (Romania); Spanulescu, S, E-mail: severspa2004@yahoo.com [Department of Physics, Hyperion University of Bucharest, Bucharest 030629 (Romania)
2011-02-28
Using the Coulomb-Green function method and considering the nonrelativistic limit for the two-photon S-matrix element, the right nonrelativistic 2s Rayleigh scattering amplitudes are obtained. Our result takes into account all multipoles, retardation and relativistic kinematics contributions, and the old dipole approximation result of Costescu is retrieved as a limit case. The total photoeffect cross-section which is related to the imaginary part of the Rayleigh forward scattering amplitude through the optical theorem is also obtained. Our Coulombian formulae are used in the more realistic case of elastic scattering of photons by bound 1s and 2s electrons in ions and neutral atoms. Screening effects are considered in the independent particle approximation through the Hartree-Fock method. The effective charge Z{sub eff} is obtained by fitting the Hartree-Fock charge distribution by a Coulombian one. Good agreement (within 10%) is found when comparing the numerical predictions given by our nonrelativistic formulae with the full relativistic numerical results of Kissel in the case of elastic scattering of photons by 1s and 2s electrons and Scofield [3] in the case of K-shell and 2s subshell photoionization for neutral atoms with 18 {<=} Z {<=} 92 and photon energies {omega} {<=} {alpha}Zm.
Single-electron capture in He2+-D2 collisions
International Nuclear Information System (INIS)
Bordenave-Montesquieu, D.; Dagnac, R.
1994-01-01
Doubly differential cross sections of single-electron capture were measured for He 2+ impinging on a molecular deuterium target. The investigated collision energies are 4, 6 and 8 keV and the scattering angles range from 10' to 2 o 30' (laboratory frame). The exothermic capture leading to He + (1s) + D 2 +* was found to be the most important process at low energies and angles, whereas the endothermic channels leading to dissociative capture become the main processes at high scattering angles, i.e. at small impact parameters. (author)
2-D Imaging of Electron Temperature in Tokamak Plasmas
International Nuclear Information System (INIS)
Munsat, T.; Mazzucato, E.; Park, H.; Domier, C.W.; Johnson, M.; Luhmann, N.C. Jr.; Wang, J.; Xia, Z.; Classen, I.G.J.; Donne, A.J.H.; Pol, M.J. van de
2004-01-01
By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented
Short-time perturbation theory and nonrelativistic duality
International Nuclear Information System (INIS)
Whitenton, J.B.; Durand, B.; Durand, L.
1983-01-01
We give a simple proof of the nonrelativistic duality relation 2 sigma/sub bound/>roughly-equal 2 sigma/sub free/> for appropriate energy averages of the cross sections for e + e - →(qq-bar bound states) and e + e - →(free qq-bar pair), and calculate the corrections to the relation by relating W 2 sigma to the Fourier transform of the Feynman propagation function and developing a short-time perturbation series for that function. We illustrate our results in detail for simple power-law potentials and potentials which involve combinations of powers
Search for non-relativistic magnetic monopoles with IceCube
International Nuclear Information System (INIS)
Aartsen, M.G.; Hill, G.C.; Robertson, S.; Whelan, B.J.; Abbasi, R.; Ahlers, M.; Arguelles, C.; Baker, M.; BenZvi, S.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Eisch, J.; Fadiran, O.; Feintzeig, J.; Gladstone, L.; Halzen, F.; Hoshina, K.; Jacobsen, J.; Jero, K.; Karle, A.; Kauer, M.; Kelley, J.L.; Kopper, C.; Krasberg, M.; Kurahashi, N.; Landsman, H.; Maruyama, R.; McNally, F.; Merck, M.; Morse, R.; Riedel, B.; Rodrigues, J.P.; Santander, M.; Tobin, M.N.; Toscano, S.; Van Santen, J.; Weaver, C.; Wellons, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Ackermann, M.; Benabderrahmane, M.L.; Berghaus, P.; Bernardini, E.; Bretz, H.P.; Cruz Silva, A.H.; Gluesenkamp, T.; Jacobi, E.; Kaminsky, B.; Karg, T.; Middell, E.; Mohrmann, L.; Nahnhauer, R.; Schoenwald, A.; Shanidze, R.; Spiering, C.; Stoessl, A.; Yanez, J.P.; Adams, J.; Brown, A.M.; Hickford, S.; Macias, O.; Aguilar, J.A.; Christov, A.; Montaruli, T.; Rameez, M.; Vallecorsa, S.; Altmann, D.; Classen, L.; Gora, D.; Kappes, A.; Tselengidou, M.; Arlen, T.C.; De Andre, J.P.A.M.; DeYoung, T.; Dunkman, M.; Eagan, R.; Groh, J.C.; Huang, F.; Quinnan, M.; Smith, M.W.E.; Stanisha, N.A.; Tesic, G.; Auffenberg, J.; Bissok, M.; Blumenthal, J.; Gretskov, P.; Haack, C.; Hallen, P.; Heinen, D.; Jagielski, K.; Kriesten, A.; Krings, K.; Leuermann, M.; Paul, L.; Raedel, L.; Reimann, R.; Schoenen, S.; Schukraft, A.; Vehring, M.; Wallraff, M.; Wiebusch, C.H.; Zierke, S.; Bai, X.; Evenson, P.A.; Gaisser, T.K.; Gonzalez, J.G.; Hussain, S.; Kuwabara, T.; Ruzybayev, B.; Seckel, D.; Stanev, T.; Tamburro, A.; Tilav, S.; Barwick, S.W.; Yodh, G.; Baum, V.; Eberhardt, B.; Koepke, L.; Kroll, G.; Luenemann, J.; Sander, H.G.; Schatto, K.; Wiebe, K.; Bay, R.; Filimonov, K.; Price, P.B.; Woschnagg, K.; Beatty, J.J.; Becker Tjus, J.; Eichmann, B.; Fedynitch, A.; Saba, S.M.; Schoeneberg, S.; Unger, E.; Becker, K.H.; Bindig, D.; Fischer-Wasels, T.; Helbing, K.; Hoffmann, R.; Klaes, J.; Kopper, S.; Naumann, U.; Obertacke, A.; Omairat, A.; Posselt, J.; Soldin, D.; Tepe, A.; Berley, D.; Blaufuss, E.; Christy, B.; Goodman, J.A.; Hellauer, R.; Hoffman, K.D.; Huelsnitz, W.; Meagher, K.; Olivas, A.; Redl, P.; Richman, M.; Schmidt, T.; Sullivan, G.W.; Wissing, H.; Bernhard, A.; Coenders, S.; Gross, A.; Leute, J.; Resconi, E.; Schulz, O.; Sestayo, Y.; Besson, D.Z.; Binder, G.; Gerhardt, L.; Ha, C.; Klein, S.R.; Miarecki, S.; Boersma, D.J.; Botner, O.; Euler, S.; Hallgren, A.; Perez de los Heros, C.; Stroem, R.; Taavola, H.; Bohm, C.; Danninger, M.; Finley, C.; Flis, S.; Hulth, P.O.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M.; Bose, D.; Rott, C.
2014-01-01
The IceCube Neutrino Observatory is a large Cherenkov detector instrumenting 1 km 3 of Antarctic ice. The detector can be used to search for signatures of particle physics beyond the Standard Model. Here, we describe the search for non-relativistic, magnetic monopoles as remnants of the Grand Unified Theory (GUT) era shortly after the Big Bang. Depending on the underlying gauge group these monopoles may catalyze the decay of nucleons via the Rubakov-Callan effect with a cross section suggested to be in the range of 10 -27 to 10 -21 cm 2 . In IceCube, the Cherenkov light from nucleon decays along the monopole trajectory would produce a characteristic hit pattern. This paper presents the results of an analysis of first data taken from May 2011 until May 2012 with a dedicated slow particle trigger for DeepCore, a subdetector of IceCube. A second analysis provides better sensitivity for the brightest non-relativistic monopoles using data taken from May 2009 until May 2010. In both analyses no monopole signal was observed. For catalysis cross sections of 10 -22 (10 -24 ) cm 2 the flux of non-relativistic GUT monopoles is constrained up to a level of Φ 90 ≤ 10 -18 (10 -17 ) cm -2 s -1 sr -1 at a 90 % confidence level, which is three orders of magnitude below the Parker bound. The limits assume a dominant decay of the proton into a positron and a neutral pion. These results improve the current best experimental limits by one to two orders of magnitude, for a wide range of assumed speeds and catalysis cross sections. (orig.)
Bottomonium above Deconfinement in Lattice Nonrelativistic QCD
International Nuclear Information System (INIS)
Aarts, G.; Kim, S.; Lombardo, M. P.; Oktay, M. B.; Ryan, S. M.; Sinclair, D. K.; Skullerud, J.-I.
2011-01-01
We study the temperature dependence of bottomonium for temperatures in the range 0.4T c c , using nonrelativistic dynamics for the bottom quark and full relativistic lattice QCD simulations for N f =2 light flavors on a highly anisotropic lattice. We find that the Υ is insensitive to the temperature in this range, while the χ b propagators show a crossover from the exponential decay characterizing the hadronic phase to a power-law behavior consistent with nearly free dynamics at T≅2T c .
J-matrix method of scattering in one dimension: The nonrelativistic theory
International Nuclear Information System (INIS)
Alhaidari, A.D.; Bahlouli, H.; Abdelmonem, M.S.
2009-01-01
We formulate a theory of nonrelativistic scattering in one dimension based on the J-matrix method. The scattering potential is assumed to have a finite range such that it is well represented by its matrix elements in a finite subset of a basis that supports a tridiagonal matrix representation for the reference wave operator. Contrary to our expectation, the 1D formulation reveals a rich and highly nontrivial structure compared to the 3D formulation. Examples are given to demonstrate the utility and accuracy of the method. It is hoped that this formulation constitutes a viable alternative to the classical treatment of 1D scattering problem and that it will help unveil new and interesting applications.
XPS study of the Ln 5p,4f-electronic states of lanthanides in Ln2O3
International Nuclear Information System (INIS)
Teterin, Yu.A.; Teterin, A.Yu.; Utkin, I.O.; Ryzhkov, M.V.
2004-01-01
The present work analyses the fine structure of the low binding energy (E b , 0-50 eV) X-ray photoelectron spectra XPS of lanthanide (La through Lu excepted for Pm) oxides, and compares it with the non-relativistic X α -discrete variation calculation results for the clusters reflecting the close environment of lanthanides in oxides. The obtained results show that the Ln 4f n -electrons of lanthanides in oxides by their spectral parameters have much in common with the M 3d-electrons in oxides of the 3d-transition metals. According to these data, the Ln 4f shell of lanthanides is rather outer and can participate in the formation of molecular orbitals in compounds. The XPS data at least do not contradict the theoretical suggestion about the significant participation of the Ln 4f-electrons in formation of the molecular orbitals in the studied materials. The spectra in the Ln 5p-O 2s binding energy region of the studied lanthanide oxides were found to exhibit the complicated structure instead of separated peaks due to the electrons of the Ln 5p 3/2,5/2 and O 2s atomic shells. Taking into account the energy differences between the inner (Ln 3d) and outer (Ln 5p) electronic shells for some metallic lanthanides and their oxides, the Ln 5p atomic shells were shown to participate in the formation of the inner valence molecular orbitals (IVMO). That agrees qualitatively with the calculation results
Spin force and torque in non-relativistic Dirac oscillator on a sphere
Shikakhwa, M. S.
2018-03-01
The spin force operator on a non-relativistic Dirac oscillator (in the non-relativistic limit the Dirac oscillator is a spin one-half 3D harmonic oscillator with strong spin-orbit interaction) is derived using the Heisenberg equations of motion and is seen to be formally similar to the force by the electromagnetic field on a moving charged particle. When confined to a sphere of radius R, it is shown that the Hamiltonian of this non-relativistic oscillator can be expressed as a mere kinetic energy operator with an anomalous part. As a result, the power by the spin force and torque operators in this case are seen to vanish. The spin force operator on the sphere is calculated explicitly and its torque is shown to be equal to the rate of change of the kinetic orbital angular momentum operator, again with an anomalous part. This, along with the conservation of the total angular momentum, suggests that the spin force exerts a spin-dependent torque on the kinetic orbital angular momentum operator in order to conserve total angular momentum. The presence of an anomalous spin part in the kinetic orbital angular momentum operator gives rise to an oscillatory behavior similar to the Zitterbewegung. It is suggested that the underlying physics that gives rise to the spin force and the Zitterbewegung is one and the same in NRDO and in systems that manifest spin Hall effect.
Search for non-relativistic magnetic monopoles with IceCube
Energy Technology Data Exchange (ETDEWEB)
Aartsen, M.G.; Hill, G.C.; Robertson, S.; Whelan, B.J. [University of Adelaide, School of Chemistry and Physics, Adelaide, SA (Australia); Abbasi, R.; Ahlers, M.; Arguelles, C.; Baker, M.; BenZvi, S.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Eisch, J.; Fadiran, O.; Feintzeig, J.; Gladstone, L.; Halzen, F.; Hoshina, K.; Jacobsen, J.; Jero, K.; Karle, A.; Kauer, M.; Kelley, J.L.; Kopper, C.; Krasberg, M.; Kurahashi, N.; Landsman, H.; Maruyama, R.; McNally, F.; Merck, M.; Morse, R.; Riedel, B.; Rodrigues, J.P.; Santander, M.; Tobin, M.N.; Toscano, S.; Van Santen, J.; Weaver, C.; Wellons, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N. [University of Wisconsin, Department of Physics and Wisconsin IceCube Particle Astrophysics Center, Madison, WI (United States); Ackermann, M.; Benabderrahmane, M.L.; Berghaus, P.; Bernardini, E.; Bretz, H.P.; Cruz Silva, A.H.; Gluesenkamp, T.; Jacobi, E.; Kaminsky, B.; Karg, T.; Middell, E.; Mohrmann, L.; Nahnhauer, R.; Schoenwald, A.; Shanidze, R.; Spiering, C.; Stoessl, A.; Yanez, J.P. [DESY, Zeuthen (Germany); Adams, J.; Brown, A.M.; Hickford, S.; Macias, O. [University of Canterbury, Department of Physics and Astronomy, Private Bag 4800, Christchurch (New Zealand); Aguilar, J.A.; Christov, A.; Montaruli, T.; Rameez, M.; Vallecorsa, S. [Universite de Geneve, Departement de physique nucleaire et corpusculaire, Geneva (Switzerland); Altmann, D.; Classen, L.; Gora, D.; Kappes, A.; Tselengidou, M. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen Centre for Astroparticle Physics, Erlangen (Germany); Arlen, T.C.; De Andre, J.P.A.M.; DeYoung, T.; Dunkman, M.; Eagan, R.; Groh, J.C.; Huang, F.; Quinnan, M.; Smith, M.W.E.; Stanisha, N.A.; Tesic, G. [Pennsylvania State University, Department of Physics, University Park, PA (United States); Auffenberg, J.; Bissok, M.; Blumenthal, J.; Gretskov, P.; Haack, C.; Hallen, P.; Heinen, D.; Jagielski, K.; Kriesten, A.; Krings, K.; Leuermann, M.; Paul, L.; Raedel, L.; Reimann, R.; Schoenen, S.; Schukraft, A.; Vehring, M.; Wallraff, M.; Wiebusch, C.H.; Zierke, S. [RWTH Aachen University, III. Physikalisches Institut, Aachen (Germany); Bai, X.; Evenson, P.A.; Gaisser, T.K.; Gonzalez, J.G.; Hussain, S.; Kuwabara, T.; Ruzybayev, B.; Seckel, D.; Stanev, T.; Tamburro, A.; Tilav, S. [University of Delaware, Bartol Research Institute and Department of Physics and Astronomy, Newark, DE (United States); Barwick, S.W.; Yodh, G. [University of California, Department of Physics and Astronomy, Irvine, CA (United States); Baum, V.; Eberhardt, B.; Koepke, L.; Kroll, G.; Luenemann, J.; Sander, H.G.; Schatto, K.; Wiebe, K. [University of Mainz, Institute of Physics, Mainz (Germany); Bay, R.; Filimonov, K.; Price, P.B.; Woschnagg, K. [University of California, Department of Physics, Berkeley, CA (United States); Beatty, J.J. [Ohio State University, Department of Physics and Center for Cosmology and Astro-Particle Physics, Columbus, OH (United States); Ohio State University, Department of Astronomy, Columbus, OH (United States); Becker Tjus, J.; Eichmann, B.; Fedynitch, A.; Saba, S.M.; Schoeneberg, S.; Unger, E. [Ruhr-Universitaet Bochum, Fakultaet fuer Physik and Astronomie, Bochum (Germany); Becker, K.H.; Bindig, D.; Fischer-Wasels, T.; Helbing, K.; Hoffmann, R.; Klaes, J.; Kopper, S.; Naumann, U.; Obertacke, A.; Omairat, A.; Posselt, J.; Soldin, D.; Tepe, A. [University of Wuppertal, Department of Physics, Wuppertal (Germany); Berley, D.; Blaufuss, E.; Christy, B.; Goodman, J.A.; Hellauer, R.; Hoffman, K.D.; Huelsnitz, W.; Meagher, K.; Olivas, A.; Redl, P.; Richman, M.; Schmidt, T.; Sullivan, G.W.; Wissing, H. [University of Maryland, Department of Physics, College Park, MD (United States); Bernhard, A.; Coenders, S.; Gross, A.; Leute, J.; Resconi, E.; Schulz, O.; Sestayo, Y. [T.U. Munich, Garching (Germany); Besson, D.Z. [University of Kansas, Department of Physics and Astronomy, Lawrence, KS (United States); Binder, G.; Gerhardt, L.; Ha, C.; Klein, S.R.; Miarecki, S. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Boersma, D.J.; Botner, O.; Euler, S.; Hallgren, A.; Perez de los Heros, C.; Stroem, R.; Taavola, H. [Uppsala University, Department of Physics and Astronomy, Box 516, Uppsala (Sweden); Bohm, C.; Danninger, M.; Finley, C.; Flis, S.; Hulth, P.O.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M. [Stockholm University, Oskar Klein Centre and Department of Physics, Stockholm (Sweden); Bose, D.; Rott, C. [Sungkyunkwan University, Department of Physics, Suwon (Korea, Republic of); Collaboration: IceCube Collaboration; and others
2014-07-15
The IceCube Neutrino Observatory is a large Cherenkov detector instrumenting 1 km{sup 3} of Antarctic ice. The detector can be used to search for signatures of particle physics beyond the Standard Model. Here, we describe the search for non-relativistic, magnetic monopoles as remnants of the Grand Unified Theory (GUT) era shortly after the Big Bang. Depending on the underlying gauge group these monopoles may catalyze the decay of nucleons via the Rubakov-Callan effect with a cross section suggested to be in the range of 10{sup -27} to 10{sup -21} cm{sup 2}. In IceCube, the Cherenkov light from nucleon decays along the monopole trajectory would produce a characteristic hit pattern. This paper presents the results of an analysis of first data taken from May 2011 until May 2012 with a dedicated slow particle trigger for DeepCore, a subdetector of IceCube. A second analysis provides better sensitivity for the brightest non-relativistic monopoles using data taken from May 2009 until May 2010. In both analyses no monopole signal was observed. For catalysis cross sections of 10{sup -22} (10{sup -24}) cm{sup 2} the flux of non-relativistic GUT monopoles is constrained up to a level of Φ{sub 90} ≤ 10{sup -18} (10{sup -17}) cm{sup -2} s{sup -1} sr{sup -1} at a 90 % confidence level, which is three orders of magnitude below the Parker bound. The limits assume a dominant decay of the proton into a positron and a neutral pion. These results improve the current best experimental limits by one to two orders of magnitude, for a wide range of assumed speeds and catalysis cross sections. (orig.)
Physical stress, mass, and energy for non-relativistic matter
Geracie, Michael; Prabhu, Kartik; Roberts, Matthew M.
2017-06-01
For theories of relativistic matter fields there exist two possible definitions of the stress-energy tensor, one defined by a variation of the action with the coframes at fixed connection, and the other at fixed torsion. These two stress-energy tensors do not necessarily coincide and it is the latter that corresponds to the Cauchy stress measured in the lab. In this note we discuss the corresponding issue for non-relativistic matter theories. We point out that while the physical non-relativistic stress, momentum, and mass currents are defined by a variation of the action at fixed torsion, the energy current does not admit such a description and is naturally defined at fixed connection. Any attempt to define an energy current at fixed torsion results in an ambiguity which cannot be resolved from the background spacetime data or conservation laws. We also provide computations of these quantities for some simple non-relativistic actions.
Secondary electron emission from solid HD and a solid H2-D2 mixture
DEFF Research Database (Denmark)
Sørensen, H.; Børgesen, P.; Hao-Ming, Chen
1983-01-01
Secondary electron emission from solid HD and a solid 0.6 H2 + 0.4 D2 mixture has been studied for electron and hydrogen ion bombardment at primary energies from 0.5 to 3 keV and 2 to 10 keV/amu, respectively. The yield for solid HD is well explained by a simple stoichiometric model of the low...
Exact solution of nonrelativistic Schrodinger equation for certain central physical potential
International Nuclear Information System (INIS)
Bose, S.K.; Gupta, N.
1998-01-01
It is obtained here a class/classes of exact solution of the nonrelativistic Schrodinger equation for certain central potentials of physical interest by using proper ansatz/ansatze. The explicit expressions of energy eigenvalue and eigenfunction are obtained for each solution. These solutions are valid when for, in general, each solutions an interrelation between the parameters of the potential and the orbital-angular-momentum quantum number l is satisfied. These solutions, besides having an aesthetic appeal, can be used as benchmark to test the accuracy of nonperturbative methods, which sometimes yield wrong results, of solving the Schrodinger equation. The exact solution for the following central potentials, which are relevant in different areas of physics, have been obtained: 1) V(r)=ar 6 + br 4 + cr 2 ; 2) V(r)=ar 2 + br + c/r; 3) V(r)=r 2 + λr 2 /(1+gr 2 ); 4) V(r)= a/r + b/(r+λ); 5a) V(r)=a/r + b/r 2 +c/r 3 +d/r 4 ; 5)b V(r)=a/r 2 + b/r 2 + c/r 4 + d/r 6 ; 6a) V(r)=a/r 1/2 + b/r 3/2 ; 6b) V(r)=ar 2/3 + br -2/3 + cr -4/3
Hoefener, S.; Ahlrichs, R.; Knecht, S.; Visscher, L.
2012-01-01
We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga
Many-electron theory of x-ray photoelectron spectra: N-shell linewidths in the 46Pd to 92U range
International Nuclear Information System (INIS)
Ohno, M.; Wendin, G.
1985-01-01
The linewidths and energies of 4d holes (main lines in x-ray photoelectron spectra) are calculated for a number of elements in the range 70 Yb to 92 U, with use of nonrelativistic atomic many-body theory. The nonrelativistic Hartree-Fock frozen-core approximation for one-electron wave functions and Auger energies gives very good agreement with experiment. In the case of 4s and 4p holes, the Auger (in particular, super-Coster-Kronig) energies have to be calculated with inclusion of relaxation and relativistic effects. Combined with frozen-core, nonrelativistic one-electron wave functions, this gives good agreement with experimental energies and widths for 4s and 4p holes in 80 Hg. In conclusion, it is very important to include the effects of two final-state holes on the Auger electron, as well as the polarization response which screens the Auger emission matrix element. This latter effect is largely equivalent to the so-called exchange interaction between the Auger electron and the final-state holes
D-, O- and OD- desorption induced by low-energy (0-20 eV) electron impact on amorphous D2O films
International Nuclear Information System (INIS)
Pan Xiaoning; Abdoul-Carime, Hassan; Cloutier, Pierre; Bass, Andrew D.; Sanche, Leon
2005-01-01
We report measurements of low-energy electron stimulated desorption of D - , O - and OD - anions from multilayer amorphous D 2 O films physisorbed on a Pt substrate. The 0-20 eV incident energy dependence (i.e., the yield function) of the desorbed D - yield reveals the presence of a strong peak located at 7.2 eV with a shoulder near 9 eV, which are due to dissociation of the transient states 2 B 1 and 2 A 1 of D 2 O, respectively. The O - and OD - yield functions each exhibit a single broad structure between 5 and 12 eV which also result from dissociative electron attachment (DEA). Due to the weakness of the O - and OD - signals, three possible processes involving DEA must be considered to explain their yield functions, i.e., direct DEA, reactive scattering and DEA to a new product in the film synthesized by the electron beam. It is concluded that at large electron doses (>7.5x10 14 electrons/cm 2 ), these broad peaks arise from DEA to a new product, whereas at lower dose the possibility of direct DEA (i.e., e - +D 2 O→D 2 O - →O - +D 2 and OD - +D) cannot be entirely discounted. Above 15 eV, all anion yield functions exhibit a monotonic rise due to direct dipolar dissociation
Mosquera, Martín A.
2017-10-01
Provided the initial state, the Runge-Gross theorem establishes that the time-dependent (TD) external potential of a system of non-relativistic electrons determines uniquely their TD electronic density, and vice versa (up to a constant in the potential). This theorem requires the TD external potential and density to be Taylor-expandable around the initial time of the propagation. This paper presents an extension without this restriction. Given the initial state of the system and evolution of the density due to some TD scalar potential, we show that a perturbative (not necessarily weak) TD potential that induces a non-zero divergence of the external force-density, inside a small spatial subset and immediately after the initial propagation time, will cause a change in the density within that subset, implying that the TD potential uniquely determines the TD density. In this proof, we assume unitary evolution of wavefunctions and first-order differentiability (which does not imply analyticity) in time of the internal and external force-densities, electronic density, current density, and their spatial derivatives over the small spatial subset and short time interval.
Recent progress in printed 2/3D electronic devices
Klug, Andreas; Patter, Paul; Popovic, Karl; Blümel, Alexander; Sax, Stefan; Lenz, Martin; Glushko, Oleksandr; Cordill, Megan J.; List-Kratochvil, Emil J. W.
2015-09-01
New, energy-saving, efficient and cost-effective processing technologies such as 2D and 3D inkjet printing (IJP) for the production and integration of intelligent components will be opening up very interesting possibilities for industrial applications of molecular materials in the near future. Beyond the use of home and office based printers, "inkjet printing technology" allows for the additive structured deposition of photonic and electronic materials on a wide variety of substrates such as textiles, plastics, wood, stone, tiles or cardboard. Great interest also exists in applying IJP in industrial manufacturing such as the manufacturing of PCBs, of solar cells, printed organic electronics and medical products. In all these cases inkjet printing is a flexible (digital), additive, selective and cost-efficient material deposition method. Due to these advantages, there is the prospect that currently used standard patterning processes can be replaced through this innovative material deposition technique. A main issue in this research area is the formulation of novel functional inks or the adaptation of commercially available inks for specific industrial applications and/or processes. In this contribution we report on the design, realization and characterization of novel active and passive inkjet printed electronic devices including circuitry and sensors based on metal nanoparticle ink formulations and the heterogeneous integration into 2/3D printed demonstrators. The main emphasis of this paper will be on how to convert scientific inkjet knowledge into industrially relevant processes and applications.
Imaging the motion of electrons in 2D semiconductor heterostructures
Dani, Keshav
Technological progress since the late 20th century has centered on semiconductor devices, such as transistors, diodes, and solar cells. At the heart of these devices, is the internal motion of electrons through semiconductor materials due to applied electric fields or by the excitation of photocarriers. Imaging the motion of these electrons would provide unprecedented insight into this important phenomenon, but requires high spatial and temporal resolution. Current studies of electron dynamics in semiconductors are generally limited by the spatial resolution of optical probes, or by the temporal resolution of electronic probes. In this talk, we combine femtosecond pump-probe techniques with spectroscopic photoemission electron microscopy to image the motion of photoexcited electrons from high-energy to low-energy states in a 2D InSe/GaAs heterostructure exhibiting a type-II band alignment. At the instant of photoexcitation, energy-resolved photoelectron images reveal a highly non-equilibrium distribution of photocarriers in space and energy. Thereafter, in response to the out-of-equilibrium photocarriers, we observe the spatial redistribution of charges, thus forming internal electric fields, bending the semiconductor bands, and finally impeding further charge transfer. By assembling images taken at different time-delays, we make a movie lasting a few tens of picoseconds of the electron transfer process in the photoexcited type-II heterostructure - a fundamental phenomenon in semiconductor devices like solar cells. Quantitative analysis and theoretical modeling of spatial variations in the video provide insight into future solar cells, electron dynamics in 2D materials, and other semiconductor devices.
Spectral concentration in the nonrelativistic limit
International Nuclear Information System (INIS)
Gesztesy, F.; Grosse, H.; Thaller, B.
1982-01-01
First order relativistic corrections to the Schroedinger operator according to Foldy and Wouthuysen are rigorously discussed in the framework of singular perturbation theory. For Coulomb plus short-range interactions we investigate the corresponding spectral properties and prove spectral concentration and existence of first order pseudoeigenvalues in the nonrelativistic limit. (Author)
Nonrelativistic equations of motion for particles with arbitrary spin
International Nuclear Information System (INIS)
Fushchich, V.I.; Nikitin, A.G.
1981-01-01
First- and second-order Galileo-invariant systems of differential equations which describe the motion of nonrelativistic particles of arbitrary spin are derived. The equations can be derived from a Lagrangian and describe the dipole, quadrupole, and spin-orbit interaction of the particles with an external field; these interactions have traditionally been regarded as purely relativistic effects. The problem of the motion of a nonrelativistic particle of arbitrary spin in a homogeneous magnetic field is solved exactly on the basis of the obtained equations. The generators of all classes of irreducible representations of the Galileo group are found
Energy Technology Data Exchange (ETDEWEB)
Fujihashi, Yuta; Ishizaki, Akihito, E-mail: ishizaki@ims.ac.jp [Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585 (Japan); Fleming, Graham R. [Department of Chemistry, University of California, Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2015-06-07
Recently, nuclear vibrational contribution signatures in two-dimensional (2D) electronic spectroscopy have attracted considerable interest, in particular as regards interpretation of the oscillatory transients observed in light-harvesting complexes. These transients have dephasing times that persist for much longer than theoretically predicted electronic coherence lifetime. As a plausible explanation for this long-lived spectral beating in 2D electronic spectra, quantum-mechanically mixed electronic and vibrational states (vibronic excitons) were proposed by Christensson et al. [J. Phys. Chem. B 116, 7449 (2012)] and have since been explored. In this work, we address a dimer which produces little beating of electronic origin in the absence of vibronic contributions, and examine the impact of protein-induced fluctuations upon electronic-vibrational quantum mixtures by calculating the electronic energy transfer dynamics and 2D electronic spectra in a numerically accurate manner. It is found that, at cryogenic temperatures, the electronic-vibrational quantum mixtures are rather robust, even under the influence of the fluctuations and despite the small Huang-Rhys factors of the Franck-Condon active vibrational modes. This results in long-lasting beating behavior of vibrational origin in the 2D electronic spectra. At physiological temperatures, however, the fluctuations eradicate the mixing, and hence, the beating in the 2D spectra disappears. Further, it is demonstrated that such electronic-vibrational quantum mixtures do not necessarily play a significant role in electronic energy transfer dynamics, despite contributing to the enhancement of long-lived quantum beating in 2D electronic spectra, contrary to speculations in recent publications.
First-principles studies of electronic, transport and bulk properties of pyrite FeS2
Directory of Open Access Journals (Sweden)
Dipendra Banjara
2018-02-01
Full Text Available We present results from first principle, local density approximation (LDA calculations of electronic, transport, and bulk properties of iron pyrite (FeS2. Our non-relativistic computations employed the Ceperley and Alder LDA potential and the linear combination of atomic orbitals (LCAO formalism. The implementation of the LCAO formalism followed the Bagayoko, Zhao, and Williams (BZW method, as enhanced by Ekuma and Franklin (BZW-EF. We discuss the electronic energy bands, total and partial densities of states, electron effective masses, and the bulk modulus. Our calculated indirect band gap of 0.959 eV (0.96, using an experimental lattice constant of 5.4166 Å, at room temperature, is in agreement with the measured indirect values, for bulk samples, ranging from 0.84 eV to 1.03 ± 0.05 eV. Our calculated bulk modulus of 147 GPa is practically in agreement with the experimental value of 145 GPa. The calculated, partial densities of states reproduced the splitting of the Fe d bands to constitute the dominant upper most valence and lower most conduction bands, separated by the generally accepted, indirect, experimental band gap of 0.95 eV.
2D electron systems viewed through an RF spectrometer
International Nuclear Information System (INIS)
Andrei, E.Y.
1994-01-01
Electrons trapped at the liquid helium-vacuum interface are an almost ideal realization of a 2D electron system. I will describe experiments probing the in-plane as well as the out-of-plane motion of the electrons. The former have emphasized the dynamics and thermodynamics of the electronic motion within the plane to understand the nature of the liquid-solid transition and to outline its phase boundary. The latter have studied the escape out of the electron layer and provided an opportunity to observe tunneling in a clean and well-characterized system as well as to measure the effects of correlations on the tunneling process. More recently experiments in the presence of a magnetic field transverse to the direction of tunneling have revealed several novel phenomena associated with the magnetic coupling between the in-plane and the out-of-plane electronic motions. Together, these experiments helped uncover the multi-faceted physics that can be found in this system. (orig.)
The equation of motion of an electron
International Nuclear Information System (INIS)
Kim, K.-J.
1998-01-01
We review the current status of understanding of the equation of motion of an electron. Classically, a consistent linearized theory exists for an electron of finite extent, as long as the size of the electron is larger than the classical electron radius. Nonrelativistic quantum mechanics seems to offer a fine theory even in the point particle limit. Although there is as yet no convincing calculation, it is probable that a quantum electrodynamical result will be at least as well-behaved as is the nonrelativistic quantum mechanical results
Non-relativistic scalar field on the quantum plane
International Nuclear Information System (INIS)
Jahan, A.
2005-01-01
We apply the coherent state approach to the non-commutative plane to check the one-loop finiteness of the two-point and four-point functions of a non-relativistic scalar field theory in 2+1 dimensions. We show that the two-point and four-point functions of the model are finite at one-loop level and one recovers the divergent behavior of the model in the limit θ->0 + by appropriate redefinition of the non-commutativity parameter
Polarizational bremsstrahlung in non-relativistic collisions
International Nuclear Information System (INIS)
Korol, A.V.; Solov'yov, A.V.
2006-01-01
We review the developments made during the last decade in the theory of polarization bremsstrahlung in the non-relativistic domain. A literature survey covering the latest history of the phenomenon is given. The main features which distinguish the polarization bremsstrahlung from other mechanisms of radiation are discussed and illustrated by the results of numerical calculations
High accuracy results for the energy levels of the molecular ions H+2, D+2 and HD+, up to J = 2
International Nuclear Information System (INIS)
Karr, J Ph; Hilico, L
2006-01-01
We present a nonrelativistic calculation of the rotation-vibration levels of the molecular ions H + 2 , D + 2 and HD + , relying on the diagonalization of the exact three-body Hamiltonian in a variational basis. The J = 2 levels are obtained with a very high accuracy of 10 -14 au (for most levels) representing an improvement by five orders of magnitude over previous calculations. The accuracy is also improved for the J = 1 levels of H + 2 and D + 2 with respect to earlier works. Moreover, we have computed the sensitivities of the energy levels with respect to the mass ratios, allowing these levels to be used for metrological purposes
Nonrelativistic effective field theories of QED and QCD. Applications and automatic calculations
Energy Technology Data Exchange (ETDEWEB)
Shtabovenko, Vladyslav
2017-05-22
This thesis deals with the applications of nonrelativistic Effective Field Theories to electromagnetic and strong interactions. The main results of this work are divided into three parts. In the first part, we use potential Nonrelativistic Quantum Electrodynamics (pNRQED), an EFT of QED at energies much below m{sub e}α (with m{sub e} being the electron mass and α the fine-structure constant), to develop a consistent description of electromagnetic van der Waals forces between two hydrogen atoms at a separation R much larger than the Bohr radius. We consider the interactions at short (R<<1/m{sub e}α{sup 2}), long (R>>1/m{sub e}α{sup 2}) and intermediate (R∝1/m{sub e}α{sup 2}) distances and identify the relevant dynamical scales that characterize each of the three regimes. For each regime we construct a suitable van der Waals EFT, that provides the simplest description of the low-energy dynamics. In this framework, van der Waals potentials naturally arise from the matching coefficients of the corresponding EFTs. They can be computed in a systematic way, order by order in the relevant expansion parameters, as is done in this work. Furthermore, the potentials receive contributions from radiative corrections and have to be renormalized. The development of a consistent EFT framework to treat electromagnetic van der Waals interactions between hydrogen atoms and the renormalization of the corresponding van der Waals potentials are the novel features of this study. In the second part, we study relativistic O(α{sup 0}{sub s}υ{sup 2}) (with α{sub s} being the strong coupling constant) corrections to the exclusive electromagnetic production of the heavy quarkonium χ {sub cJ} and a hard photon in the framework of nonrelativistic Quantum Chromodynamics (NRQCD), an EFT of QCD that takes full advantage of the nonrelativistic nature of charmonia and bottomonia and exploits wide separation of the relevant dynamical scales. These scales are m{sub Q} >> m{sub Q}υ >> m{sub Q
Nonrelativistic effective field theories of QED and QCD. Applications and automatic calculations
International Nuclear Information System (INIS)
Shtabovenko, Vladyslav
2017-01-01
This thesis deals with the applications of nonrelativistic Effective Field Theories to electromagnetic and strong interactions. The main results of this work are divided into three parts. In the first part, we use potential Nonrelativistic Quantum Electrodynamics (pNRQED), an EFT of QED at energies much below m e α (with m e being the electron mass and α the fine-structure constant), to develop a consistent description of electromagnetic van der Waals forces between two hydrogen atoms at a separation R much larger than the Bohr radius. We consider the interactions at short (R<<1/m e α 2 ), long (R>>1/m e α 2 ) and intermediate (R∝1/m e α 2 ) distances and identify the relevant dynamical scales that characterize each of the three regimes. For each regime we construct a suitable van der Waals EFT, that provides the simplest description of the low-energy dynamics. In this framework, van der Waals potentials naturally arise from the matching coefficients of the corresponding EFTs. They can be computed in a systematic way, order by order in the relevant expansion parameters, as is done in this work. Furthermore, the potentials receive contributions from radiative corrections and have to be renormalized. The development of a consistent EFT framework to treat electromagnetic van der Waals interactions between hydrogen atoms and the renormalization of the corresponding van der Waals potentials are the novel features of this study. In the second part, we study relativistic O(α 0 s υ 2 ) (with α s being the strong coupling constant) corrections to the exclusive electromagnetic production of the heavy quarkonium χ cJ and a hard photon in the framework of nonrelativistic Quantum Chromodynamics (NRQCD), an EFT of QCD that takes full advantage of the nonrelativistic nature of charmonia and bottomonia and exploits wide separation of the relevant dynamical scales. These scales are m Q >> m Q υ >> m Q υ 2 , where m Q is the heavy quark mass and υ is the relative
Nonrelativistic fluids on scale covariant Newton-Cartan backgrounds
Mitra, Arpita
2017-12-01
The nonrelativistic covariant framework for fields is extended to investigate fields and fluids on scale covariant curved backgrounds. The scale covariant Newton-Cartan background is constructed using the localization of space-time symmetries of nonrelativistic fields in flat space. Following this, we provide a Weyl covariant formalism which can be used to study scale invariant fluids. By considering ideal fluids as an example, we describe its thermodynamic and hydrodynamic properties and explicitly demonstrate that it satisfies the local second law of thermodynamics. As a further application, we consider the low energy description of Hall fluids. Specifically, we find that the gauge fields for scale transformations lead to corrections of the Wen-Zee and Berry phase terms contained in the effective action.
Generalized dilatation operator method for non-relativistic holography
Energy Technology Data Exchange (ETDEWEB)
Chemissany, Wissam, E-mail: wissam@stanford.edu [Department of Physics and SITP, Stanford University, Stanford, CA 94305 (United States); Papadimitriou, Ioannis, E-mail: ioannis.papadimitriou@csic.es [Instituto de Física Teórica UAM/CSIC, Universidad Autónoma de Madrid, Madrid 28049 (Spain)
2014-10-07
We present a general algorithm for constructing the holographic dictionary for Lifshitz and hyperscaling violating Lifshitz backgrounds for any value of the dynamical exponent z and any value of the hyperscaling violation parameter θ compatible with the null energy condition. The objective of the algorithm is the construction of the general asymptotic solution of the radial Hamilton–Jacobi equation subject to the desired boundary conditions, from which the full dictionary can be subsequently derived. Contrary to the relativistic case, we find that a fully covariant construction of the asymptotic solution for running non-relativistic theories necessitates an expansion in the eigenfunctions of two commuting operators instead of one. This provides a covariant but non-relativistic grading of the expansion, according to the number of time derivatives.
Dissociative ionization of H2 and D2 by electron impact near threshold
Boesten, L.G.J.; Heideman, H.G.M.
We have studied the dissciative ionization of H2 and D2 by electron impact. It is found that in the vicinity of the 2Σ+g dissociation threshold of H+2 (18.08 eV) a significant fraction of the produced protons originates from the process e + H2 → H− + H+ + e (threshold at 17.34 eV). Similar results
Heavy-to-light form factors for non-relativistic bound states
International Nuclear Information System (INIS)
Bell, G.; Feldmann, Th.
2007-01-01
We investigate transition form factors between non-relativistic QCD bound states at large recoil energy. Assuming the decaying quark to be much heavier than its decay product, the relativistic dynamics can be treated according to the factorization formula for heavy-to-light form factors obtained from the heavy-quark expansion in QCD. The non-relativistic expansion determines the bound-state wave functions to be Coulomb-like. As a consequence, one can explicitly calculate the so-called 'soft-overlap' contribution to the transition form factor
International Nuclear Information System (INIS)
Moehlman, G.R.; Heer, F.J. de
1977-01-01
Absolute emission cross sections of Ly-α (H,D(2p → 1s)) radiation have been determined for 0 - 2000 eV electrons incident on H 2 , HD, HCl, H 2 O, NH 3 and CH 4 . By means of the application of electric quenching, the excitation cross sections of H,D(2s) could be obtained from the increase of the resulting Ly-α radiation for these molecules. Only in the case of electrons on H 2 , D 2 and HD was excitation of H,D(2s) found
Can positron 2D-ACAR resolve the electronic structure of high-Tc superconductors
International Nuclear Information System (INIS)
Chan, L.P.; Lynn, K.G.; Harshman, D.R.
1992-01-01
In this paper, the authors examine the ability of the positron Two-Dimensional Angular Correlation Annihilation Radiation (2D-ACAR) technique to resolve the electronic structures of high-T c cuprate superconductors. Following a short description of the technique, discussions of the theoretical assumptions, data analysis and experimental considerations, in relation to the high-T c superconductors, are given. The authors briefly review recent 2D-ACAR experiments on YBa 2 Cu 3 O 7-x , Bi 2 Sr 2 CaCuO 8+δ and La 2-x Sr x CuO 4 . The 2D-ACAR technique is useful in resolving the band crossings associated with the layers of the superconductors that are preferentially sampled by the positrons. Together with other Fermi surface measurements (namely angle-resolved photoemission), 2D-ACAR can resolve some of the electronic structures of high-T c cuprate superconductors
Holographic stress tensor for non-relativistic theories
International Nuclear Information System (INIS)
Ross, Simon F.; Saremi, Omid
2009-01-01
We discuss the calculation of the field theory stress tensor from the dual geometry for two recent proposals for gravity duals of non-relativistic conformal field theories. The first of these has a Schroedinger symmetry including Galilean boosts, while the second has just an anisotropic scale invariance (the Lifshitz case). For the Lifshitz case, we construct an appropriate action principle. We propose a definition of the non-relativistic stress tensor complex for the field theory as an appropriate variation of the action in both cases. In the Schroedinger case, we show that this gives physically reasonable results for a simple black hole solution and agrees with an earlier proposal to determine the stress tensor from the familiar AdS prescription. In the Lifshitz case, we solve the linearised equations of motion for a general perturbation around the background, showing that our stress tensor is finite on-shell.
Electron capture and excitation in collisions of O+(4S,2D,2P) with H2 molecules
International Nuclear Information System (INIS)
Pichl, Lukas; Li Yan; Liebermann, Heinz-Peter; Buenker, Robert J.; Kimura, Mineo
2004-01-01
Using an electronic-state close-coupling method, we treated the electron capture and excitation processes of O + ions both in ground state O + ( 4 S) and metastable states O +* ( 2 D) and O +* ( 2 P) in collisions with the H 2 molecule. In the ground-state projectile energy region considered (from 50 eV/amu to 10 keV/amu), the experimental data vary by orders of magnitude: our results smoothly connect to the data by Flesch and Ng [J. Chem. Phys. 94, 2372 (1991)] and Xu et al. [J. Phys. B 23, 1235 (1990)] at low energy and agree with Phaneuf et al. [Phys. Rev. A 17, 534 (1978)] in the high-energy region. The present values differ from Sieglaff et al. [Phys. Rev. A 59, 3538 (1999)] and Nutt et al. [J. Phys. B 12, L157 (1979)], especially in the energy region below 1 keV/amu. We provide the first calculated state-resolved cross sections of electron capture and target-projectile electronic excitations for the O + ( 4 S, 2 D, 2 P)-H 2 collision system
Spacetime coarse grainings in nonrelativistic quantum mechanics
International Nuclear Information System (INIS)
Hartle, J.B.
1991-01-01
Sum-over-histories generalizations of nonrelativistic quantum mechanics are explored in which probabilities are predicted, not just for alternatives defined on spacelike surfaces, but for alternatives defined by the behavior of spacetime histories with respect to spacetime regions. Closed, nonrelativistic systems are discussed whose histories are paths in a given configuration space. The action and the initial quantum state are assumed fixed and given. A formulation of quantum mechanics is used which assigns probabilities to members of sets of alternative coarse-grained histories of the system, that is, to the individual classes of a partition of its paths into exhaustive and exclusive classes. Probabilities are assigned to those sets which decohere, that is, whose probabilities are consistent with the sum rules of probability theory. Coarse graining by the behavior of paths with respect to regions of spacetime is described. For example, given a single region, the set of all paths may be partitioned into those which never pass through the region and those which pass through the region at least once. A sum-over-histories decoherence functional is defined for sets of alternative histories coarse-grained by spacetime regions. Techniques for the definition and effective computation of the relevant sums over histories by operator-product formulas are described and illustrated by examples. Methods based on Euclidean stochastic processes are also discussed and illustrated. Models of decoherence and measurement for spacetime coarse grainings are described. Issues of causality are investigated. Such spacetime generalizations of nonrelativistic quantum mechanics may be useful models for a generalized quantum mechanics of spacetime geometry
Non-local electron transport validation using 2D DRACO simulations
Cao, Duc; Chenhall, Jeff; Moll, Eli; Prochaska, Alex; Moses, Gregory; Delettrez, Jacques; Collins, Tim
2012-10-01
Comparison of 2D DRACO simulations, using a modified versionfootnotetextprivate communications with M. Marinak and G. Zimmerman, LLNL. of the Schurtz, Nicolai and Busquet (SNB) algorithmfootnotetextSchurtz, Nicolai and Busquet, ``A nonlocal electron conduction model for multidimensional radiation hydrodynamics codes,'' Phys. Plasmas 7, 4238(2000). for non-local electron transport, with direct drive shock timing experimentsfootnotetextT. Boehly, et. al., ``Multiple spherically converging shock waves in liquid deuterium,'' Phys. Plasmas 18, 092706(2011). and with the Goncharov non-local modelfootnotetextV. Goncharov, et. al., ``Early stage of implosion in inertial confinement fusion: Shock timing and perturbation evolution,'' Phys. Plasmas 13, 012702(2006). in 1D LILAC will be presented. Addition of an improved SNB non-local electron transport algorithm in DRACO allows direct drive simulations with no need for an electron conduction flux limiter. Validation with shock timing experiments that mimic the laser pulse profile of direct drive ignition targets gives a higher confidence level in the predictive capability of the DRACO code. This research was supported by the University of Rochester Laboratory for Laser Energetics.
On the question of symmetries in nonrelativistic diffeomorphism-invariant theories
Banerjee, Rabin; Gangopadhyay, Sunandan; Mukherjee, Pradip
2017-07-01
A novel algorithm is provided to couple a Galilean-invariant model with curved spatial background by taking nonrelativistic limit of a unique minimally coupled relativistic theory, which ensures Galilean symmetry in the flat limit and canonical transformation of the original fields. That the twin requirements are fulfilled is ensured by a new field, the existence of which was demonstrated recently from Galilean gauge theory. The ambiguities and anomalies concerning the recovery of Galilean symmetry in the flat limit of spatial nonrelativistic diffeomorphic theories, reported in the literature, are focused and resolved from a new angle.
International Nuclear Information System (INIS)
Gajnutdinov, R.Kh.
1983-01-01
Possibility is studied to build the nonrelativistic scattering theory on the base of the general physical principles: causality, superposition, and unitarity, making no use of the Schroedinger formalism. The suggested approach is shown to be more general than the nonrelativistic scattering theory based on the Schroedinger equation. The approach is applied to build a model ofthe scattering theory for a system which consists of heavy nonrelativistic particles and a light relativistic particle
Quantum theory of nonrelativistic particles interacting with gravity
International Nuclear Information System (INIS)
Anastopoulos, C.
1996-01-01
We investigate the effects of the gravitational field on the quantum dynamics of nonrelativistic particles. We consider N nonrelativistic particles, interacting with the linearized gravitational field. Using the Feynman-Vernon influence functional technique, we trace out the graviton field to obtain a master equation for the system of particles to first order in G. The effective interaction between the particles as well as the self-interaction is in general non-Markovian. We show that the gravitational self-interaction cannot be held responsible for decoherence of microscopic particles due to the fast vanishing of the diffusion function. For macroscopic particles though, it leads to diagonalization to the energy eigenstate basis, a desirable feature in gravity-induced collapse models. We finally comment on possible applications. copyright 1996 The American Physical Society
Deep processes in non-relativistic confining potentials
International Nuclear Information System (INIS)
Fishbane, P.M.; Grisaru, M.T.
1978-01-01
The authors study deep inelastic and hard scattering processes for non-relativistic particles confined in deep potentials. The mechanisms by which the effects of confinement disappear and the particles scatter as if free are useful in understanding the analogous results for a relativistic field theory. (Auth.)
X-versus y-scaling in non-relativistic deep inelastic scattering
Energy Technology Data Exchange (ETDEWEB)
Santos Padula, S. dos; Escobar, C.O.
1983-06-01
It is shown, in the context of non-relativistic potential scattering, that the appropriate scaling variable for the deep inelastic region is not the usual Bjorken one x sub(Bj) = Q/sup 2//2 M..nu.. but instead, the variable y=(2m..nu..-q/sup 2/ sup(..-->..))/2q. The y-scaling is shown to be obtained in a natural way by using the WKB approximation. Numerical results are presented comparing the approach to scaling in terms of x sub(Bj) and y.
X-versus y-scaling in non-relativistic deep inelastic scattering
International Nuclear Information System (INIS)
Santos Padula, S. dos; Escobar, C.O.
1983-01-01
It is shown, in the context of non-relativistic potential scattering, that the appropriate scaling variable for the deep inelastic region is not the usual Bjorken one x sub(Bj) = Q 2 /2 Mν but instead, the variable y=(2mν-q 2 sup(→))/2q. The y-scaling is shown to be obtained in a natural way by using the WKB approximation. Numerical results are presented comparing the approach to scaling in terms of x sub(Bj) and y. (Author) [pt
2D PIC simulations for an EN discharge with magnetized electrons and unmagnetized ions
Lieberman, Michael A.; Kawamura, Emi; Lichtenberg, Allan J.
2009-10-01
We conducted 2D particle-in-cell (PIC) simulations for an electronegative (EN) discharge with magnetized electrons and unmagnetized ions, and compared the results to a previously developed 1D (radial) analytical model of an EN plasma with strongly magnetized electrons and weakly magnetized ions [1]. In both cases, there is a static uniform applied magnetic field in the axial direction. The 1D radial model mimics the wall losses of the particles in the axial direction by introducing a bulk loss frequency term νL. A special (desired) solution was found in which only positive and negative ions but no electrons escaped radially. The 2D PIC results show good agreement with the 1D model over a range of parameters and indicate that the analytical form of νL employed in [1] is reasonably accurate. However, for the PIC simulations, there is always a finite flux of electrons to the radial wall which is about 10 to 30% of the negative ion flux.[4pt] [1] G. Leray, P. Chabert, A.J. Lichtenberg and M.A. Lieberman, J. Phys. D, accepted for publication 2009.
International Nuclear Information System (INIS)
Kolbun, N.; Lund, E.; Adolfsson, E.; Gustafsson, H.
2014-01-01
Electron paramagnetic resonance imaging (EPRI) was performed to visualise 2D dose distributions of homogeneously irradiated potassium dithionate tablets and to demonstrate determination of 1D dose profiles along the height of the tablets. Mathematical correction was applied for each relative dose profile in order to take into account the inhomogeneous response of the resonator using X-band EPRI. The dose profiles are presented with the spatial resolution of 0.6 mm from the acquired 2D images; this value is limited by pixel size, and 1D dose profiles from 1D imaging with spatial resolution of 0.3 mm limited by the intrinsic line-width of potassium dithionate. In this paper, dose profiles from 2D reconstructed electron paramagnetic resonance (EPR) images using the Xepr software package by Bruker are focussed. The conclusion is that using potassium dithionate, the resolution 0.3 mm is sufficient for mapping steep dose gradients if the dosemeters are covering only ±2 mm around the centre of the resonator. (authors)
Searching for beauty-fully bound tetraquarks using lattice nonrelativistic QCD
Hughes, Ciaran; Eichten, Estia; Davies, Christine T. H.
2018-03-01
Motivated by multiple phenomenological considerations, we perform the first search for the existence of a b ¯b ¯b b tetraquark bound state with a mass below the lowest noninteracting bottomonium-pair threshold using the first-principles lattice nonrelativistic QCD methodology. We use a full S -wave color/spin basis for the b ¯b ¯b b operators in the three 0++, 1+- and 2++ channels. We employ four gluon field ensembles at multiple lattice spacing values ranging from a =0.06 - 0.12 fm , all of which include u , d , s and c quarks in the sea, and one ensemble which has physical light-quark masses. Additionally, we perform novel exploratory work with the objective of highlighting any signal of a near threshold tetraquark, if it existed, by adding an auxiliary potential into the QCD interactions. With our results we find no evidence of a QCD bound tetraquark below the lowest noninteracting thresholds in the channels studied.
Dai, Zhenyu
2017-09-08
2D semiconductors are poised to revolutionize the future of electronics and photonics, much like transparent oxide conductors and semiconductors have revolutionized the display industry. Herein, these two types of materials are combined to realize fully transparent 2D electronic devices and circuits. Specifically, a large-area chemical vapor deposition process is developed to grow monolayer MoS2 continuous films, which are, for the first time, combined with transparent conducting oxide (TCO) contacts. Transparent conducting aluminum doped zinc oxide contacts are deposited by atomic layer deposition, with composition tuning to achieve optimal conductivity and band-offsets with MoS2. The optimized process gives fully transparent TCO/MoS2 2D electronics with average visible-range transmittance of 85%. The transistors show high mobility (4.2 cm2 V−1 s−1), fast switching speed (0.114 V dec−1), very low threshold voltage (0.69 V), and large switching ratio (4 × 108). To our knowledge, these are the lowest threshold voltage and subthreshold swing values reported for monolayer chemical vapor deposition MoS2 transistors. The transparent inverters show fast switching properties with a gain of 155 at a supply voltage of 10 V. The results demonstrate that transparent conducting oxides can be used as contact materials for 2D semiconductors, which opens new possibilities in 2D electronic and photonic applications.
Single-electron capture in He[sup 2+]-D[sub 2] collisions
Energy Technology Data Exchange (ETDEWEB)
Bordenave-Montesquieu, D.; Dagnac, R. (Toulouse-3 Univ., 31 (France))
1994-02-14
Doubly differential cross sections of single-electron capture were measured for He[sup 2+] impinging on a molecular deuterium target. The investigated collision energies are 4, 6 and 8 keV and the scattering angles range from 10' to 2[sup o]30' (laboratory frame). The exothermic capture leading to He[sup +] (1s) + D[sub 2][sup +*] was found to be the most important process at low energies and angles, whereas the endothermic channels leading to dissociative capture become the main processes at high scattering angles, i.e. at small impact parameters. (author).
Kwon, Oh-Hoon; Zewail, Ahmed H.
2010-06-01
Electron tomography provides three-dimensional (3D) imaging of noncrystalline and crystalline equilibrium structures, as well as elemental volume composition, of materials and biological specimens, including those of viruses and cells. We report the development of 4D electron tomography by integrating the fourth dimension (time resolution) with the 3D spatial resolution obtained from a complete tilt series of 2D projections of an object. The different time frames of tomograms constitute a movie of the object in motion, thus enabling studies of nonequilibrium structures and transient processes. The method was demonstrated using carbon nanotubes of a bracelet-like ring structure for which 4D tomograms display different modes of motion, such as breathing and wiggling, with resonance frequencies up to 30 megahertz. Applications can now make use of the full space-time range with the nanometer-femtosecond resolution of ultrafast electron tomography.
International Nuclear Information System (INIS)
Gomonaj, A.N.; Imre, A.I.
2005-01-01
Radiation transitions between 4d 9 ( 2 D 5/2,3/2 )5s 2 nl and 4d 10 5p( 2 P 1/2,3/2 0 )nl self-ionized states of Cd atom being dielectron satellites of λ325.0 nm (4d 9 5s 22 D 3/2 →4d 10 5p 2 P 1/2 0 ) and λ353.6 nm (4d 9 5s 22 D 3/2 → 4d 10 5p 2 P 3/2 0 ) laser lines of Cd + ion were detected for the first time at electron-ion collisions. One studied energy dependences of the effective cross sections of electron excitation of the satellite lines within 7-10 eV energy range. The effective cross sections of excitation of dielectron satellites constitutes ∼ 10 -17 cm 2 that is comparable with the efficiency of excitation of the laser lines [ru
1,3Do and 1,3Pe states of two electron atoms under Debye plasma screening
International Nuclear Information System (INIS)
Saha, Jayanta K.; Bhattacharyya, S.; Mukherjee, T.K.; Mukherjee, P.K.
2010-01-01
Extensive non-relativistic variational calculations for estimating the energy values of 2pnd( 1,3 D o ) states [n=3-6] of two electron atoms (He, Li + ,Be 2+ ) and 2pnp( 1 P e )[n=3-8] and 2pnp( 3 P e ) states [n=2-7] of Be 2+ under weakly coupled plasma screening have been performed using explicitly correlated Hylleraas type basis. The modified energy eigenvalues of 1,3 P e states arising from two p electrons of Be 2+ ion and 1,3 D o states due to 2pnd configuration of Li + and Be 2+ ion in the Debye plasma environment are being reported for the first time. The effect of plasma has been incorporated through the Debye screening model. The system tends towards gradual instability and the number of bound states reduces with increasing plasma coupling strength. The wavelengths for 2pn ' p( 1 P e )[n ' =3-8]→2pnd( 1 D o )[n=3-6] and 2pn ' p( 3 P e )[n ' =2-8]→2pnd( 3 D o )[n=3-6] transitions in plasma embedded two electron atoms have also been reported.
Weyl consistency conditions in non-relativistic quantum field theory
Energy Technology Data Exchange (ETDEWEB)
Pal, Sridip; Grinstein, Benjamín [Department of Physics, University of California,San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States)
2016-12-05
Weyl consistency conditions have been used in unitary relativistic quantum field theory to impose constraints on the renormalization group flow of certain quantities. We classify the Weyl anomalies and their renormalization scheme ambiguities for generic non-relativistic theories in 2+1 dimensions with anisotropic scaling exponent z=2; the extension to other values of z are discussed as well. We give the consistency conditions among these anomalies. As an application we find several candidates for a C-theorem. We comment on possible candidates for a C-theorem in higher dimensions.
International Nuclear Information System (INIS)
Bystritsky, V.M.; Bystritskii, Vit.M.; Dudkin, G.N.; Filipowicz, M.; Gazi, S.; Huran, J.; Kobzev, A.P.; Mesyats, G.A.; Nechaev, B.A.; Padalko, V.N.; Parzhitskii, S.S.; Pen'kov, F.M.; Philippov, A.V.; Kaminskii, V.L.; Tuleushev, Yu.Zh.; Wozniak, J.
2012-01-01
The present paper is devoted to the study of the electron screening effect influence on the rate of d(d,n) 3 He reaction in the ultralow deuteron collision energy range in the deuterated metals (ZrD 2 , TiD 2 and TaD 0.5 ). The ZrD 2 , TiD 2 and TaD0.5 targets were fabricated via magnetron sputtering of titanium, zirconium and tantalum in gas (deuterium) environment. The experiments have been carried out using the high-current pulsed Hall plasma accelerator (NSR TPU, Russia). The detection of neutrons with energy of 2.5 MeV from the dd reaction was done with plastic scintillation spectrometers. As a result of the experiments, the energy dependences of the astrophysical S-factor for the dd reaction in the deuteron collision energy range of 2-7 keV and the values of the electron screening potential U e of the interacting deuterons have been measured for the above targets: U e (ZrD 2 )=(205±35) eV; U e (TiD 2 )=(125±34) eV; U e (TaD 0.5 )=(313±58) eV. Our results are compared with the other published experimental and calculated data.
Predicting Electron Population Characteristics in 2-D Using Multispectral Ground-Based Imaging
Grubbs, Guy; Michell, Robert; Samara, Marilia; Hampton, Donald; Jahn, Jorg-Micha
2018-01-01
Ground-based imaging and in situ sounding rocket data are compared to electron transport modeling for an active inverted-V type auroral event. The Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment (GREECE) mission successfully launched from Poker Flat, Alaska, on 3 March 2014 at 11:09:50 UT and reached an apogee of approximately 335 km over the aurora. Multiple ground-based electron-multiplying charge-coupled device (EMCCD) imagers were positioned at Venetie, Alaska, and aimed toward magnetic zenith. The imagers observed the intensity of different auroral emission lines (427.8, 557.7, and 844.6 nm) at the magnetic foot point of the rocket payload. Emission line intensity data are correlated with electron characteristics measured by the GREECE onboard electron spectrometer. A modified version of the GLobal airglOW (GLOW) model is used to estimate precipitating electron characteristics based on optical emissions. GLOW predicted the electron population characteristics with 20% error given the observed spectral intensities within 10° of magnetic zenith. Predictions are within 30% of the actual values within 20° of magnetic zenith for inverted-V-type aurora. Therefore, it is argued that this technique can be used, at least in certain types of aurora, such as the inverted-V type presented here, to derive 2-D maps of electron characteristics. These can then be used to further derive 2-D maps of ionospheric parameters as a function of time, based solely on multispectral optical imaging data.
Relativistic and non-relativistic studies of nuclear matter
Banerjee, MK; Tjon, JA
2002-01-01
We point out that the differences between the results of the non-relativistic lowest order Brueckner theory (LOBT) and the relativistic Dirac-Brueckner analysis predominantly arise from two sources. Besides effects from a nucleon mass modification M* in nuclear medium we have in a relativistic
Numerically robust and efficient nonlocal electron transport in 2D DRACO simulations
Cao, Duc; Chenhall, Jeff; Moses, Greg; Delettrez, Jacques; Collins, Tim
2013-10-01
An improved implicit algorithm based on Schurtz, Nicolai and Busquet (SNB) algorithm for nonlocal electron transport is presented. Validation with direct drive shock timing experiments and verification with the Goncharov nonlocal model in 1D LILAC simulations demonstrate the viability of this efficient algorithm for producing 2D lagrangian radiation hydrodynamics direct drive simulations. Additionally, simulations provide strong incentive to further modify key parameters within the SNB theory, namely the ``mean free path.'' An example 2D polar drive simulation to study 2D effects of the nonlocal flux as well as mean free path modifications will also be presented. This research was supported by the University of Rochester Laboratory for Laser Energetics.
Electron excitation cross sections for some Ar I 5d (J = 2) levels
International Nuclear Information System (INIS)
Blanco, F.; Sanchez, J.A.; Campos, J.
1992-01-01
Absolute excitation cross sections by electron impact for some 5d levels with J = 2 of Ar I have been measured by the optical method. Excitation functions for electron energies in the range from the excitation threshold to 1000 eV are also reported. A delayed coincidence analysis of the de-excitation at 100 eV electron energy allowed for the subtraction of radiative cascades. The resulting excitation cross sections are between 7.3 and 12x10 -20 cm 2 . (author)
Non-relativistic supergravity in three space-time dimensions
Zojer, Thomas
2016-01-01
This year Einstein's theory of general relativity celebrates its one hundredth birthday. It supersedes the non-relativistic Newtonian theory of gravity in two aspects: i) there is a limiting velocity, nothing can move quicker than the speed of light and ii) the theory is valid in arbitrary
Absence of effects of an in-plane magnetic field in a quasi-two-dimensional electron system
Brandt, F. T.; Sánchez-Monroy, J. A.
2018-03-01
The dynamics of a quasi-two-dimensional electron system (q2DES) in the presence of a tilted magnetic field is reconsidered employing the thin-layer method. We derive the effective equations for relativistic and nonrelativistic q2DESs. Through a perturbative expansion, we show that while the magnetic length is much greater than the confinement width, the in-plane magnetic field only affects the particle dynamics through the spin. Therefore, effects due to an in-plane magnetic vector potential reported previously in the literature for 2D quantum rings, 2D quantum dots and graphene are fictitious. In particular, the so-called pseudo chiral magnetic effect recently proposed in graphene is not realistic.
Ni doping effect on the electronic and sensing properties of 2D SnO2
Patel, Anjali; Roondhe, Basant; Jha, Prafulla K.
2018-05-01
In the present work using state of art first principles calculations under the frame work of density functional theory the effect of Nickel (Ni) doping on electronic as well as sensing properties of most stable two dimensional (2D) T-SnO2 phase towards ethanol (C2H5OH) has been observed. It has been found that Ni atom when dope on T-SnO2 causes prominent decrement in the band gap from 2.26 eV to 1.48 eV and improves the sensing phenomena of pristine T-SnO2 towards C2H5OH by increasing the binding energy from -0.18eV to -0.93eV. The comparative analysis of binding energy shows that Ni improves the binding of C2H5OH by 5.16 times the values for pristine T-SnO2. The doping of Ni into 2D T-SnO2 reduces the band gap through lowering of the conduction band minimum, thereby increasing the electron affinity which increases the sensing performance of T-SnO2. The variation in the electronic properties after and before the exposure of ethanol reinforced to use Ni:SnO2 nano structure for sensing applications. The results indicate that the Ni doped T-SnO2 can be utilized in improved optoelectronic as well as sensor devices in the future.
Energy Technology Data Exchange (ETDEWEB)
Oria, M; Sorriaux, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1965-07-01
With a view to ease the work of research workers using 150 kV electrostatic accelerators, we have calculated the energy and the emission angle of particles emitted during the reactions {sub 1}{sup 3}T(d,n){sub 2}{sup 4}He, {sub 1}{sup 2}D(d,n){sub 2}{sup 3}He and {sub 1}{sup 2}D(d,p){sub 1}{sup 3}T. The results are classified in tables and arranged according to the acceleration energy of the deuterons. Since the energies considered are relatively low we have limited our study to the non-relativistic domain; this simplification results in a maximum energy variation with respect to the real energy values of 1 per cent. We give also two curves representing the variations in the total cross-sections for the reactions T (d,n){sub 2}{sup 4}He and D (d,n){sub 2}{sup 3}He. (authors) [French] De facon a faciliter la tache des experimentateurs utilisant des accelerateurs electrostatiques de 150 kV, nous avons calcule l'energie et l'angle d'emission des particules emises lors des reactions {sub 1}{sup 3}T(d,n){sub 2}{sup 4}He, {sub 1}{sup 2}D(d,n){sub 2}{sup 3}He and {sub 1}{sup 2}D(d,p){sub 1}{sup 3}T. Les resultats ont ete classes dans des tableaux, et ordonnes en fonction de l'energie d'acceleration des deuterons. Les energies considerees etant relativement peu elevees, nous avons limite notre etude au domaine non relativiste, cette simplification n'entraine qu'une variation maximale de 1 pour cent sur les valeurs reelles des energies. Nous avons joint a ce calcul deux courbes representant la variation des sections efficaces totales des reactions T (d,n){sub 2}{sup 4}He et D (d,n){sub 2}{sup 3}He. (auteurs)
Wibisono, C.; Sulaksono, A.
We study the stability of nonrelativistic polytropic stars within two modified gravity theories, i.e. beyond Horndeski gravity and Eddington-inspired Born-Infeld theories, using the configuration entropy method. We use the spatially localized bounded function of energy density as solutions from stellar effective equations to construct the corresponding configuration entropy. We use the same argument as the one used by Gleiser and coworkers [M. Gleiser and D. Sowinski, Phys. Lett. B 727 (2013) 272; M. Gleiser and N. Jiang, Phys. Rev. D 92 (2015) 044046] that the stars are stable if there is a peak in configuration entropy as a function of adiabatic index curve. Specifically, the boundary between stable and unstable regions which corresponds to Chandrasekhar stability bound is indicated from the existence of the maximum peak while the most stable polytropic stars are indicated by the minimum peak in the corresponding curve. We have found that the values of critical adiabatic indexes of Chandrasekhar stability bound and the most stable polytropic stars predicted by the nonrelativistic limits of beyond Horndeski gravity and Eddington-inspired Born-Infeld theories are different to those predicted by general relativity where the corresponding differences depend on the free parameters of both theories.
Two-electron photoionization cross sections at high energies
International Nuclear Information System (INIS)
Amusia, M.Ya.; Krivec, R.; Mandelzweig, V.B.
2003-01-01
Double and single electron photoionization cross sections and their ratios at high and ultra-relativistic energies are calculated for H - , He and helium-like ions in ground and excited states including triplet states. The ratios contain shake-off and quasi-free terms. A high precision non-variational wave function is used. The quasi-free mechanism increases the ratios impressively: for He we get 0.0762 instead of 0.0164 in the non-relativistic case. Ratios are inversely proportional to Z 2 , with a factor increasing from 0.094 in the nonrelativistic to 0.595 in the ultra-relativistic limit. (author)
Semiclassical and quantum-electrodynamical approaches in nonrelativistic radiation theory
International Nuclear Information System (INIS)
Milonni, P.W.
1976-01-01
Theoretical aspects of the interaction of atoms with the radiation field are reviewed with emphasis on those features of the interaction requiring field quantization. The approach is nonrelativistic, with special attention given to the theory of spontaneous emission. (Auth.)
Hydrodynamic model for 2D degenerate free-electron gas for arbitrary frequencies
Castillo, M D; Cocoletzi, G H
2003-01-01
Following Halevi's procedure for 3D degenerate free-electron gas (3D-DEG), we investigate the response function in the hydrodynamic model (HM) for 2D-DEG confined in low dimensional systems when collisions are included. For small wave vectors we found from the two- dimensional Boltzmann-Mermin model a useful expression for the HM complex stiffness parameter of the nonlocal dielectric function beta, which is beta = [((3 omega/ 4) + i(v/ 2)) / (w + iv)]v sub F , where omega and v are the circular and collisional frequencies and v sub F is the Fermi velocity. (Author)
Triggering of 178Hfm2 by photoinduced electron transition
Directory of Open Access Journals (Sweden)
A. Ya. Dzyublik
2013-03-01
Full Text Available We considered the NEET (nuclear excitation by electron transition as a possible triggering mechanism of the isomer 178Hfm2 during ionization of the L3 atomic shell by x-rays. This isomer is assumed to be excited into an intermediate state by E1 electronic transition between M5 and L3 shells. Simple nonrelativistic formulas are derived for the NEET probability. The estimations show the probability to be less than the experimental data of [1] by one order of magnitude. The intermediate level is found to decay bypassing the isomeric level 16+, if the nucleus attributes a triaxial shape in the state and, besides, there exists a level 13- shifted with respect to 15- by 400 keV. We have shown also that the NEET cross section as a function of the energy of x-ray photons , has to accept constant value above the L photoionization threshold in contrast to narrow peak observed by [1].
Lev, L. L.; Maiboroda, I. O.; Husanu, M. -A.; Grichuk, E. S.; Chumakov, N. K.; Ezubchenko, I. S.; Chernykh, I. A.; Wang, X.; Tobler, B.; Schmitt, T.; Zanaveskin, M. L.; Valeyev, V. G.; Strocov, V. N.
2018-01-01
Nanostructures based on buried interfaces and heterostructures are at the heart of modern semiconductor electronics as well as future devices utilizing spintronics, multiferroics, topological effects and other novel operational principles. Knowledge of electronic structure of these systems resolved in electron momentum k delivers unprecedented insights into their physics. Here, we explore 2D electron gas formed in GaN/AlGaN high-electron-mobility transistor (HEMT) heterostructures with an ult...
Electron spectroscopy of rubber and resin-based composites containing 2D carbon
International Nuclear Information System (INIS)
Kaciulis, S.; Mezzi, A.; Balijepalli, S.K.; Lavorgna, M.; Xia, H.S.
2015-01-01
Composite materials with 2D carbon (graphene and/or single wall carbon nanotubes) are very promising due to their extraordinary electrical and mechanical properties. Graphene and natural rubber composites, which may be used for the gaskets or sealants, were prepared by ultrasonically assisted latex-mixing exfoliation and in-situ reduction process, with two vulcanization approaches: roll-mixing and hot-pressing. Also the resin-based composites, filled with micro-particles of Ag and graphene or carbon nanotubes, have been studied. The standards for the compositional characterization of these materials still are not established. In addition to the mostly used techniques, such as Raman spectroscopy and electron microscopy, also Auger electron spectroscopy can be employed for the identification of graphene. In this study, the shape of C KVV peak, excited by electron beam and X-ray photons, has been investigated in different composite materials containing graphene and carbon nanotubes. A spectroscopic method for 2D carbon recognition, based on the D x parameter which is determined from C KVV signal excited by X-ray photons, was proposed and verified. Even a small content of graphene in different types of composites was sufficient for this recognition due to the dominating presence of graphene on the surface of composites. - Highlights: • Chemical composition of the rubber composites was determined by XPS. • Auger spectrum of carbon was used for graphene identification in composites. • Small content of graphene was sufficient for its recognition from the D parameter
Electron spectroscopy of rubber and resin-based composites containing 2D carbon
Energy Technology Data Exchange (ETDEWEB)
Kaciulis, S., E-mail: saulius.kaciulis@ismn.cnr.it [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Mezzi, A.; Balijepalli, S.K. [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Lavorgna, M. [Institute of Polymers, Composites and Biomaterials, IPCB-CNR, P.le Fermi, 80055 Napoli (Italy); Xia, H.S. [State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065 Sichuan (China)
2015-04-30
Composite materials with 2D carbon (graphene and/or single wall carbon nanotubes) are very promising due to their extraordinary electrical and mechanical properties. Graphene and natural rubber composites, which may be used for the gaskets or sealants, were prepared by ultrasonically assisted latex-mixing exfoliation and in-situ reduction process, with two vulcanization approaches: roll-mixing and hot-pressing. Also the resin-based composites, filled with micro-particles of Ag and graphene or carbon nanotubes, have been studied. The standards for the compositional characterization of these materials still are not established. In addition to the mostly used techniques, such as Raman spectroscopy and electron microscopy, also Auger electron spectroscopy can be employed for the identification of graphene. In this study, the shape of C KVV peak, excited by electron beam and X-ray photons, has been investigated in different composite materials containing graphene and carbon nanotubes. A spectroscopic method for 2D carbon recognition, based on the D{sub x} parameter which is determined from C KVV signal excited by X-ray photons, was proposed and verified. Even a small content of graphene in different types of composites was sufficient for this recognition due to the dominating presence of graphene on the surface of composites. - Highlights: • Chemical composition of the rubber composites was determined by XPS. • Auger spectrum of carbon was used for graphene identification in composites. • Small content of graphene was sufficient for its recognition from the D parameter.
Non-relativistic model of two-particle decay
International Nuclear Information System (INIS)
Dittrich, J.; Exner, P.
1986-01-01
A simple non-relativistic model of a spinless particle decaying into two lighter particles is treated in detail. It is similar to the Lee-model description of V-particle decay. Galilean covariance is formulated properly, by means of a unitary projective representation acting on the state space of the model. After separating the centre-of-mass motion the meromorphic structure of the reduced resolvent is deduced
Selected topics on the nonrelativistic diagram technique
International Nuclear Information System (INIS)
Blokhintsev, L.D.; Narodetskij, I.M.
1983-01-01
The construction of the diagrams describing various processes in the four-particle systems is considered. It is shown that these diagrams, in particular the diagrams corresponding to the simple mechanisms often used in nuclear and atomic reaction theory, are readily obtained from the Faddeev-Yakubovsky equations. The covariant four-dimensional formalism of nonrelativistic Feynman graphs and its connection to the three-dimensional graph technique are briefly discussed
Energy Technology Data Exchange (ETDEWEB)
Monahan, Daniele M.; Whaley-Mayda, Lukas; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States); Ishizaki, Akihito [Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585 (Japan)
2015-08-14
Coherence oscillations measured in two-dimensional (2D) electronic spectra of pigment-protein complexes may have electronic, vibrational, or mixed-character vibronic origins, which depend on the degree of electronic-vibrational mixing. Oscillations from intrapigment vibrations can obscure the inter-site coherence lifetime of interest in elucidating the mechanisms of energy transfer in photosynthetic light-harvesting. Huang-Rhys factors (S) for low-frequency vibrations in Chlorophyll and Bacteriochlorophyll are quite small (S ≤ 0.05), so it is often assumed that these vibrations influence neither 2D spectra nor inter-site coherence dynamics. In this work, we explore the influence of S within this range on the oscillatory signatures in simulated 2D spectra of a pigment heterodimer. To visualize the inter-site coherence dynamics underlying the 2D spectra, we introduce a formalism which we call the “site-probe response.” By comparing the calculated 2D spectra with the site-probe response, we show that an on-resonance vibration with Huang-Rhys factor as small as S = 0.005 and the most strongly coupled off-resonance vibrations (S = 0.05) give rise to long-lived, purely vibrational coherences at 77 K. We moreover calculate the correlation between optical pump interactions and subsequent entanglement between sites, as measured by the concurrence. At 77 K, greater long-lived inter-site coherence and entanglement appear with increasing S. This dependence all but vanishes at physiological temperature, as environmentally induced fluctuations destroy the vibronic mixing.
International Nuclear Information System (INIS)
Seccombe, D.P.; Collins, S.A.; Reddish, T.J.; Selles, P.; Malegat, L.; Huetz, A.; Kazansky, A.K.
2002-01-01
The mutual angular distributions of the two ejected electrons following direct photodouble ionization have been measured for D 2 at an excess energy (E) of 25 eV using linearly polarized light. These (γ, 2e) 'triple' differential cross sections (TDCSs) were obtained for asymmetric electron energy conditions with energy sharing ratios (R=E 2 /E 1 ) of R=24, 11.5, 4 and 2.57. In all cases the 'reference' electron (energy = E 1 ) was oriented along the direction of the electric field vector (ε) and detected in coincidence with a second electron (energy = E 2 ) coplanar with ε and the photon beam direction (kγ). For comparison, helium TDCSs were obtained for the same E and R values under nearly identical spectrometer conditions. These show very good agreement with the results of hyperspherical-R-matrix with semi-classical outgoing waves calculations, thus providing even more confidence in the D 2 TDCSs where there is as yet no accurate ab initio theory. The similarities and differences between the experimental results associated with the two targets are qualitatively discussed in terms of Feagin's model (Feagin J M 1998 J. Phys. B: At. Mol. Opt. Phys. 31 L729). (author)
Linear and nonlinear ion-acoustic waves in nonrelativistic quantum plasmas with arbitrary degeneracy
Haas, Fernando; Mahmood, Shahzad
2015-11-01
Linear and nonlinear ion-acoustic waves are studied in a fluid model for nonrelativistic, unmagnetized quantum plasma with electrons with an arbitrary degeneracy degree. The equation of state for electrons follows from a local Fermi-Dirac distribution function and applies equally well both to fully degenerate and classical, nondegenerate limits. Ions are assumed to be cold. Quantum diffraction effects through the Bohm potential are also taken into account. A general coupling parameter valid for dilute and dense plasmas is proposed. The linear dispersion relation of the ion-acoustic waves is obtained and the ion-acoustic speed is discussed for the limiting cases of extremely dense or dilute systems. In the long-wavelength limit, the results agree with quantum kinetic theory. Using the reductive perturbation method, the appropriate Korteweg-de Vries equation for weakly nonlinear solutions is obtained and the corresponding soliton propagation is analyzed. It is found that soliton hump and dip structures are formed depending on the value of the quantum parameter for the degenerate electrons, which affect the phase velocities in the dispersive medium.
Energy Technology Data Exchange (ETDEWEB)
Bystritsky, V.M., E-mail: bystvm@jinr.ru [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Bystritskii, Vit.M. [Department of Physics and Astronomy, University of California, Irvine (United States); Dudkin, G.N. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Filipowicz, M. [Faculty of Energy and Fuels, AGH, University of Science and Technology, Cracow (Poland); Gazi, S.; Huran, J. [Institute of Electrical Engineering, SAS, Bratislava (Slovakia); Kobzev, A.P. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Mesyats, G.A. [Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation); Nechaev, B.A.; Padalko, V.N. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Parzhitskii, S.S. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Pen' kov, F.M. [Institute of Nuclear Physics, NNC, Almaty (Kazakhstan); Philippov, A.V. [Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Kaminskii, V.L. [National Scientific Research Tomsk Polytechnical University, Tomsk (Russian Federation); Tuleushev, Yu.Zh. [Institute of Nuclear Physics, NNC, Almaty (Kazakhstan); Wozniak, J. [Faculty of Physics and Applied Computer Sciences, AGH, University of Science and Technology, Cracow (Poland)
2012-09-01
The present paper is devoted to the study of the electron screening effect influence on the rate of d(d,n){sup 3}He reaction in the ultralow deuteron collision energy range in the deuterated metals (ZrD{sub 2}, TiD{sub 2} and TaD{sub 0.5}). The ZrD{sub 2}, TiD{sub 2} and TaD0.5 targets were fabricated via magnetron sputtering of titanium, zirconium and tantalum in gas (deuterium) environment. The experiments have been carried out using the high-current pulsed Hall plasma accelerator (NSR TPU, Russia). The detection of neutrons with energy of 2.5 MeV from the dd reaction was done with plastic scintillation spectrometers. As a result of the experiments, the energy dependences of the astrophysical S-factor for the dd reaction in the deuteron collision energy range of 2-7 keV and the values of the electron screening potential U{sub e} of the interacting deuterons have been measured for the above targets: U{sub e}(ZrD{sub 2})=(205{+-}35) eV; U{sub e}(TiD{sub 2})=(125{+-}34) eV; U{sub e}(TaD{sub 0.5})=(313{+-}58) eV. Our results are compared with the other published experimental and calculated data.
Cyclotron Resonances in Electron Cloud Dynamics
International Nuclear Information System (INIS)
Celata, C.M.; Furman, M.A.; Vay, J.L.; Grote, D.P.; Ng, J.T.; Pivi, M.F.; Wang, L.F.
2009-01-01
A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where l b c , (l b = bunch duration, ω c = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor ∼ 3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined density 'stripes' of multipactoring found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations, the reason for the bunch-length dependence, and details of the dynamics will be discussed
High mobility 2D electron gas in CdTe/CdMgTe heterostructures
International Nuclear Information System (INIS)
Karczewski, G.; Jaroszynski, J.; Kurowski, M.; Barcz, A.; Wojtowicz, T.; Kossut, J.
1997-01-01
We report on iodine doping of molecular beam epitaxy (MBE)-grown Cd(Mn)Te quasi-bulk films and modulation-doped CdTe/Cd 1-y Mg y Te two-dimensional (2D) single quantum well structures. Modulation doping with iodine of CdTe/Cd 1-y Mg y Te structures resulted in fabrication of a 2D electron gas with mobility exceeding 10 5 cm 2 /(Vs). This is the highest mobility reported in wide-gap II-VI materials
Bremsstrahlung in electron-positronium scattering
International Nuclear Information System (INIS)
Amusia, M.Ya.; Korol, A.V.; Solovyov, A.V.
1986-01-01
The spectrum of radiation formed in the fast nonrelativistic electron scattering on positronium is calculated. It is shown that all the radiation proceeds via virtual positronium deformations during the collision. An essential difference of bremsstrahlung spectra in electron on positronium and electron on hydrogen scattering is demonstrated. (orig.)
Theory of a four-electron 2-D system in a strong magnetic field
International Nuclear Information System (INIS)
Yuandong Dai; Bingjian Ni; Fusui Liu.
1985-10-01
An orthogonal and complete set for relative motion of four-electron 2-D system in strong magnetic field is given, the energy of ground state of relative motion is calculated. This paper also calculates the energy of ground state whose maximum of single electron angular momentum is limited by the degeneracy under a given magnetic field, obtains the energy minimums corresponding to a fractional quantized Hall effect of 2/5, 2/7, and from it the physical meaning of 'magic number' is interpreted. (author)
Variable-range hopping in 2D quasi-1D electronic systems
International Nuclear Information System (INIS)
Teber, S.
2005-12-01
A semi-phenomenological theory of variable-range hopping (VRH) is developed for two-dimensional (2D) quasi-one-dimensional (quasi-1D) systems such as arrays of quantum wires in the Wigner crystal regime. The theory follows the phenomenology of Efros, Mott and Shklovskii allied with microscopic arguments. We first derive the Coulomb gap in the single-particle density of states, g(ε), where ε is the energy of the charge excitation. We then derive the main exponential dependence of the electron conductivity in the linear (L), i.e. σ(T) ∼ exp [-(T L /T) γL ], and current in the non-linear (NL), i.e. j(E) ∼ [-(E NL /E) γNL ], response regimes (E is the applied electric field). Due to the strong anisotropy of the system and its peculiar dielectric properties we show that unusual, with respect to known results, Coulomb gaps open followed by unusual VRH laws, i.e. with respect to the disorder-dependence of T L and E NL and the values of γ L and γ NL . (author)
Relativistic convergent close-coupling method applied to electron scattering from mercury
International Nuclear Information System (INIS)
Bostock, Christopher J.; Fursa, Dmitry V.; Bray, Igor
2010-01-01
We report on the extension of the recently formulated relativistic convergent close-coupling (RCCC) method to accommodate two-electron and quasi-two-electron targets. We apply the theory to electron scattering from mercury and obtain differential and integrated cross sections for elastic and inelastic scattering. We compared with previous nonrelativistic convergent close-coupling (CCC) calculations and for a number of transitions obtained significantly better agreement with the experiment. The RCCC method is able to resolve structure in the integrated cross sections for the energy regime in the vicinity of the excitation thresholds for the (6s6p) 3 P 0,1,2 states. These cross sections are associated with the formation of negative ion (Hg - ) resonances that could not be resolved with the nonrelativistic CCC method. The RCCC results are compared with the experiment and other relativistic theories.
Ef: Software for Nonrelativistic Beam Simulation by Particle-in-Cell Algorithm
Boytsov, A. Yu.; Bulychev, A. A.
2018-04-01
Understanding of particle dynamics is crucial in construction of electron guns, ion sources and other types of nonrelativistic beam devices. Apart from external guiding and focusing systems, a prominent role in evolution of such low-energy beams is played by particle-particle interaction. Numerical simulations taking into account these effects are typically accomplished by a well-known particle-in-cell method. In practice, for convenient work a simulation program should not only implement this method, but also support parallelization, provide integration with CAD systems and allow access to details of the simulation algorithm. To address the formulated requirements, development of a new open source code - Ef - has been started. It's current features and main functionality are presented. Comparison with several analytical models demonstrates good agreement between the numerical results and the theory. Further development plans are discussed.
Ef: Software for Nonrelativistic Beam Simulation by Particle-in-Cell Algorithm
Directory of Open Access Journals (Sweden)
Boytsov A. Yu.
2018-01-01
Full Text Available Understanding of particle dynamics is crucial in construction of electron guns, ion sources and other types of nonrelativistic beam devices. Apart from external guiding and focusing systems, a prominent role in evolution of such low-energy beams is played by particle-particle interaction. Numerical simulations taking into account these effects are typically accomplished by a well-known particle-in-cell method. In practice, for convenient work a simulation program should not only implement this method, but also support parallelization, provide integration with CAD systems and allow access to details of the simulation algorithm. To address the formulated requirements, development of a new open source code - Ef - has been started. It's current features and main functionality are presented. Comparison with several analytical models demonstrates good agreement between the numerical results and the theory. Further development plans are discussed.
Energy Technology Data Exchange (ETDEWEB)
Staehler, A.J.
2007-05-15
The present work investigates the electron transfer and solvation dynamics at the D{sub 2}O/Cu(111), D{sub 2}O/Ru(001), and NH{sub 3}/Cu(111) interfaces using femtosecond time-resolved two-photon photoelectron spectroscopy. Within this framework, the influence of the substrate, adsorbate structure and morphology, solvation site, coverage, temperature, and solvent on the electron dynamics are studied, yielding microscopic insight into the underlying fundamental processes. Transitions between different regimes of ET, substrate-dominated, barrier-determined, strong, and weak coupling are observed by systematic variation of the interfacial properties and development of empirical model descriptions. It is shown that the fundamental steps of the interfacial electron dynamics are similar for all investigated systems: Metal electrons are photoexcited to unoccupied metal states and transferred into the adlayer via the adsorbate's conduction band. The electrons localize at favorable sites and are stabilized by reorientations of the surrounding polar solvent molecules. Concurrently, they decay back two the metal substrate, as it offers a continuum of unoccupied states. However, the detailed characteristics vary for the different investigated interfaces: For amorphous ice-metal interfaces, the electron transfer is initially, right after photoinjection, dominated by the substrate's electronic surface band structure. With increasing solvation, a transient barrier evolves at the interface that increasingly screens the electrons from the substrate. Tunneling through this barrier becomes the rate-limiting step for ET. The competition of electron decay and solvation leads to lifetimes of the solvated electrons in the order of 100 fs. Furthermore, it is shown that the electrons bind in the bulk of the ice layers, but on the edges of adsorbed D{sub 2}O clusters and that the ice morphology strongly influences the electron dynamics. For the amorphous NH{sub 3}/Cu(111
Energy Technology Data Exchange (ETDEWEB)
Zhu, X. P. [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024 (China); Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zhang, Z. C.; Lei, M. K., E-mail: surfeng@dlut.edu.cn [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Pushkarev, A. I. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Laboratory of Beam and Plasma Technology, High Technologies Physics Institute, Tomsk Polytechnic University, 30, Lenin Ave, 634050 Tomsk (Russian Federation)
2016-01-15
High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200–300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.
2D electron density profile measurement in tokamak by laser-accelerated ion-beam probe.
Chen, Y H; Yang, X Y; Lin, C; Wang, L; Xu, M; Wang, X G; Xiao, C J
2014-11-01
A new concept of Heavy Ion Beam Probe (HIBP) diagnostic has been proposed, of which the key is to replace the electrostatic accelerator of traditional HIBP by a laser-driven ion accelerator. Due to the large energy spread of ions, the laser-accelerated HIBP can measure the two-dimensional (2D) electron density profile of tokamak plasma. In a preliminary simulation, a 2D density profile was reconstructed with a spatial resolution of about 2 cm, and with the error below 15% in the core region. Diagnostics of 2D density fluctuation is also discussed.
Differential cross sections for single-electron capture in He{sup 2+}-D collisions
Energy Technology Data Exchange (ETDEWEB)
Bordenave-Montesquieu, D.; Dagnac, R. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France)]|[Toulouse-3 Univ., 31 (France)
1995-06-14
A translational energy spectroscopy technique was used to study single-electron capture into the He{sup +} (n = 2) and He{sup +} (n 3) states in He{sup 2+}-D collisions. Differential cross sections were determined at 4, 6 and 8 keV in the angular range 5`-1{sup o}30` (laboratory frame). As expected, single-electron capture into the n = 2 state was found to be the dominant process; total cross sections for capture into the He{sup +} (n = 3) state were compared to other experimental and theoretical results. (author).
Formation of heavy d-electron quasiparticles in Sr3Ru2O7
International Nuclear Information System (INIS)
Allan, M P; Tamai, A; Rozbicki, E; King, P D C; Meevasana, W; Perry, R S; Mercure, J F; Mackenzie, A P; Fischer, M H; Wang, M A; Lee, Jinho; Kim, E-A; Lawler, M J; Shen, K M; Voss, J; Fennie, C J; Thirupathaiah, S; Rienks, E; Fink, J; Tennant, D A
2013-01-01
The phase diagram of Sr 3 Ru 2 O 7 shows hallmarks of strong electron correlations despite the modest Coulomb interaction in the Ru 4d shell. We use angle-resolved photoelectron spectroscopy measurements to provide microscopic insight into the formation of the strongly renormalized heavy d-electron liquid that controls the physics of Sr 3 Ru 2 O 7 . Our data reveal itinerant Ru 4d-states confined over large parts of the Brillouin zone to an energy range of <6 meV, nearly three orders of magnitude lower than the bare band width. We show that this energy scale agrees quantitatively with a characteristic thermodynamic energy scale associated with quantum criticality and illustrate how it arises from a combination of back-folding due to a structural distortion and the hybridization of light and strongly renormalized, heavy quasiparticle bands. The resulting heavy Fermi liquid has a marked k-dependence of the renormalization which we relate to orbital mixing along individual Fermi surface sheets. (paper)
Persistent spin helices in 2D electron systems
Kozulin, A. S.; Malyshev, A. I.; Konakov, A. A.
2017-03-01
We present a theoretical investigation of persistent spin helices in two-dimensional electron systems with spin-orbit coupling. For this purpose, we consider a single-particle effective mass Hamiltonian with a generalized linear-in- k spin-orbit coupling term corresponding to a quantum well grown in an arbitrary crystallographic direction, and derive the general condition for the formation of the persistent spin helix. This condition applied for the Hamiltonians describing quantum wells with different growth directions indicates the possibility of existence of the persistent spin helix in a wide class of 2D systems apart from the [001] model with equal Rashba and Dresselhaus spin-orbit coupling strengths and the [110] Dresselhaus model.
Interacting Electrons and Holes in Quasi-2D Quantum Dots in Strong Magnetic Fields
Hawrylak, P.; Sheng, W.; Cheng, S.-J.
2004-09-01
Theory of optical properties of interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields is discussed. In two dimensions and the lowest Landau level, hidden symmetries control the interaction of the interacting system with light. By confining electrons and holes into quantum dots hidden symmetries can be removed and the excitation spectrum of electrons and excitons can be observed. We discuss a theory electronic and of excitonic quantum Hall droplets at a filling factorν=2. For an excitonic quantum Hall droplet the characteristic emission spectra are predicted to be related to the total spin of electron and hole configurations. For the electronic droplet the excitation spectrum of the droplet can be mapped out by measuring the emission for increasing number of electrons.
Interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields
International Nuclear Information System (INIS)
Hawrylak, P.; Sheng, W.; Cheng, S.-J.
2004-01-01
Theory of optical properties of interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields is discussed. In two dimensions and the lowest Landau level, hidden symmetries control the interaction of the interacting system with light. By confining electrons and holes into quantum dots hidden symmetries can be removed and the excitation spectrum of electrons and excitons can be observed. We discuss a theory electronic and excitonic quantum Hall droplets at a filling factor υ = 2. For an excitonic quantum Hall droplet the characteristic emission spectra are predicted to be related to the total spin of electron and hole configurations. For the electronic droplet the excitation spectrum of the droplet can be mapped out by measuring the emission for increasing number of electrons. (author)
Connection of relativistic and nonrelativistic wave functions in the calculation of leptonic widths
International Nuclear Information System (INIS)
Durand, B.; Durand, L.
1984-01-01
We generalize our previous JWKB relations between the relativistic qq-bar wave function at the origin and (a) the inverse density of states of the qq-bar system and (b) the nonrelativistic qq-bar wave function at the origin, to the case of potentials with a Coulomb singularity. We show that the square of the Bethe-Salpeter wave function at the the origin is given approximately for 1 - states by for M/sub n/>2m/sub q/, where F(v) = (4πα/sub s//3v)[1-exp(-4πα /sub s//3v)] -1 is the usual Coulomb factor and g(v)approx. =1 is associated with the lowest-order gluonic radiative corrections. We present numerical evidence for the remarkable accuracy of these relations, which have important implications for the use of nonrelativistic potential models to describe quarkonium systems. We also discuss some subtleties in the v and α/sub s/ dependence of corrections to leptonic widths
Coupling constants and the nonrelativistic quark model with charmonium potential
International Nuclear Information System (INIS)
Chaichian, M.; Koegerler, R.
1978-01-01
Hadronic coupling constants of the vertices including charm mesons are calculated in a nonrelativistic quark model. The wave functions of the mesons which enter the corresponding overlap integrals are obtained from the charmonium picture as quark-antiquark bound state solutions of the Schroedinger equation. The model for the vertices takes into account in a dynamical way the SU 4 breakings through different masses of quarks and different wave functions in the overlap integrals. All hadronic vertices involving scalar, pseudoscalar, vector, pseudovector and tensor mesons are calculated up to an overall normalization constant. Regularities among the couplings of mesons and their radial excitations are observed: i) Couplings decrease with increasing order of radial excitations; ii) In general they change sign if a particle is replaced by its next radial excitation. The k-dependence of the vertices is studied. This has potential importance in explaining the unorthodox ratios in different decay channels. Having got the hadronic couplings radiative transitions are obtained with the current coupled to mesons and their recurrences. The resulting width values are smaller than those conventionally obtained in the naive quark model. The whole picture is only adequate for nonrelativistic configurations, as for the members of the charmonium- or of the UPSILON-family and most calculations have been done for transitions among charmed states. To see how far nonrelativistic concepts can be applied, couplings of light mesons are also considered. (author)
Differential regularization of a non-relativistic anyon model
International Nuclear Information System (INIS)
Freedman, D.Z.; Rius, N.
1993-07-01
Differential regularization is applied to a field theory of a non-relativistic charged boson field φ with λ(φ * φ) 2 self-interaction and coupling to a statistics-changing 0(1) Chern-Simons gauge field. Renormalized configuration-space amplitudes for all diagrams contributing to the φ * φ * φφ 4-point function, which is the only primitively divergent Green's function, are obtained up to 3-loop order. The renormalization group equations are explicitly checked, and the scheme dependence of the β-function is investigated. If the renormalization scheme is fixed to agree with a previous 1-loop calculation, the 2- and 3-loop contributions to β(λ, e) vanish, and β(λ, ε) itself vanishes when the ''self-dual'' condition relating λ to the gauge coupling e is imposed. (author). 12 refs, 1 fig
On the role of time in nonrelativistic quantum mechanics
International Nuclear Information System (INIS)
Chattaraj, P.K.; Sannigrahi, A.B.
1994-01-01
It has been didactically analysed that time appears as a parameter in nonrelativistic quantum mechanics. Corresponding Heisenberg's uncertainty principle is discussed. Dynamical behaviour of time and its operator equivalence are generally obtained from analogy and should not be treated at par with other dynamical observables, e.g. momentum. (author). 8 refs
Relativistic electronic dressing in laser-assisted ionization of atomic hydrogen by electron impact
International Nuclear Information System (INIS)
Attaourti, Y.; Taj, S.
2004-01-01
Within the framework of the coplanar binary geometry where it is justified to use plane wave solutions for the study of the (e,2e) reaction and in the presence of a circularly polarized laser field, we introduce as a first step the Dirac-Volkov plane wave Born approximation 1 where we take into account only the relativistic dressing of the incident and scattered electrons. Then, we introduce the Dirac-Volkov plane wave Born approximation 2 where we take totally into account the relativistic dressing of the incident, scattered, and ejected electrons. We then compare the corresponding triple differential cross sections for laser-assisted ionization of atomic hydrogen by electron impact both for the nonrelativistic and the relativistic regime
Binary and ternary recombination of D3+ ions with electrons in He-D2 plasma
International Nuclear Information System (INIS)
Glosik, J.; Korolov, I.; Plasil, R.; Kotrik, T.; Dohnal, P.; Novotny, O.; Varju, J.; Roucka, S.; Greene, Chris H.; Kokoouline, V.
2009-01-01
An experimental study is reported about the recombination of D 3 + ions with electrons in a low-temperature plasma (200-300 K) consisting of He with a small admixture of D 2 . At several temperatures, the pressure dependence of the apparent binary recombination rate coefficient (α eff ) was measured over a broad range of helium pressures (200-2000 Pa). The binary and ternary recombination rate coefficients were obtained from measured pressure dependences of α eff . The binary recombination rate coefficient obtained α bin (300 K)=(2.7±0.9)x10 -8 cm 3 s -1 is in agreement with recent theory. The ternary recombination rate coefficient obtained is K He (300 K)=(1.8±0.6)x10 -25 cm 6 s -1 . In analogy with the recently described process of helium-assisted ternary recombination of H 3 + ions, it is suggested that the ternary helium-assisted recombination of D 3 + ions proceeds through the formation of a neutral long-lived highly excited Rydberg molecule D 3 followed by a collision with a He atom.
Binary and ternary recombination of D3+ ions with electrons in He-D2 plasma
Glosík, J.; Korolov, I.; Plašil, R.; Kotrík, T.; Dohnal, P.; Novotný, O.; Varju, J.; Roučka, Š.; Greene, Chris H.; Kokoouline, V.
2009-10-01
An experimental study is reported about the recombination of D3+ ions with electrons in a low-temperature plasma (200-300 K) consisting of He with a small admixture of D2 . At several temperatures, the pressure dependence of the apparent binary recombination rate coefficient (αeff) was measured over a broad range of helium pressures (200-2000 Pa). The binary and ternary recombination rate coefficients were obtained from measured pressure dependences of αeff . The binary recombination rate coefficient obtained αbin(300K)=(2.7±0.9)×10-8cm3s-1 is in agreement with recent theory. The ternary recombination rate coefficient obtained is KHe(300K)=(1.8±0.6)×10-25cm6s-1 . In analogy with the recently described process of helium-assisted ternary recombination of H3+ ions, it is suggested that the ternary helium-assisted recombination of D3+ ions proceeds through the formation of a neutral long-lived highly excited Rydberg molecule D3 followed by a collision with a He atom.
Production of H, D (2s, 2p) by electron impact (0-2000 eV) on simple hydrogen containing molecules
International Nuclear Information System (INIS)
Moehlmann, G.R.; Shima, K.H.; Heer, F.J. de
1978-01-01
Absolute emission cross sections of Ly-α (H, D (2p → 1s)) radiation have been determined for 0-2000 eV electrons incident on H 2 , HD, D 2 , HCl, H 2 O, NH 3 and CH 4 . By means of the application of electric quenching the excitation cross sections of H, D (2s) could be obtained from the increase of the resulting Ly-α radiation for these molecules. It was found that only for H 2 , HD and D 2 fragments in the H (2s) state are formed. (Auth.)
Ginsberg, Naomi S.; Davis, Jeffrey A.; Ballottari, Matteo; Cheng, Yuan-Chung; Bassi, Roberto; Fleming, Graham R.
2011-01-01
The CP29 light harvesting complex from green plants is a pigment-protein complex believed to collect, conduct, and quench electronic excitation energy in photosynthesis. We have spectroscopically determined the relative angle between electronic transition dipole moments of its chlorophyll excitation energy transfer pairs in their local protein environments without relying on simulations or an X-ray crystal structure. To do so, we measure a basis set of polarized 2D electronic spectra and isolate their absorptive components on account of the tensor relation between the light polarization sequences used to obtain them. This broadly applicable advance further enhances the acuity of polarized 2D electronic spectroscopy and provides a general means to initiate or feed back on the structural modeling of electronically-coupled chromophores in condensed phase systems, tightening the inferred relations between the spatial and electronic landscapes of ultrafast energy flow. We also discuss the pigment composition of CP29 in the context of light harvesting, energy channeling, and photoprotection within photosystem II. PMID:21321222
Energy Technology Data Exchange (ETDEWEB)
Leroy, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Prelec, K [Institut Rudjer Boskovic, Zagreb (Croatia)
1960-07-01
The secondary electron yield {gamma}-bar due to primary positive ions D{sup +} and D{sup +}{sub 2} has been measured in the 70 keV to 300 keV ion energy range. Several metallic targets have been used. The variation of this yield with the angle of incidence is proportional to sec {theta} where {theta} is the angle between the beam of primary ions and the normal to the target surface. The values {gamma}-bar decrease for increasing energy ions. At a given energy all the targets tried gave approximately the same electron yield. (author) [French] Le facteur d'emission secondaire a ete mesure pour des ions positifs D{sup +} et D{sup +}{sub 2} ayant une energie comprise entre 70 keV et 300 keV, sur differentes cibles metalliques. La variation de ce facteur avec l'angle d'incidence suit une loi de la forme {gamma}{sub 0} sec {theta}, {theta} etant l'angle entre le faisceau et la normale a la cible. Les valeurs de {gamma}-bar trouvees decroissent lorsque l'energie des ions incidents augmente, mais sont assez voisines les unes des autres, a une energie donnee, pour les differentes cibles essayees. (auteur)
Energy Technology Data Exchange (ETDEWEB)
Long, Andrew J.; Lunardini, Cecilia; Sabancilar, Eray, E-mail: andrewjlong@asu.edu, E-mail: Cecilia.Lunardini@asu.edu, E-mail: Eray.Sabancilar@asu.edu [Physics Department, Arizona State University, Tempe, Arizona 85287 (United States)
2014-08-01
We study the physics potential of the detection of the Cosmic Neutrino Background via neutrino capture on tritium, taking the proposed PTOLEMY experiment as a case study. With the projected energy resolution of Δ ∼ 0.15 eV, the experiment will be sensitive to neutrino masses with degenerate spectrum, m{sub 1} ≅ m{sub 2} ≅ m{sub 3} = m{sub ν} ∼> 0.1 eV. These neutrinos are non-relativistic today; detecting them would be a unique opportunity to probe this unexplored kinematical regime. The signature of neutrino capture is a peak in the electron spectrum that is displaced by 2 m{sub ν} above the beta decay endpoint. The signal would exceed the background from beta decay if the energy resolution is Δ ∼< 0.7 m{sub ν} . Interestingly, the total capture rate depends on the origin of the neutrino mass, being Γ{sup D} ≅ 4 and Γ{sup M} ≅ 8 events per year (for a 100 g tritium target) for unclustered Dirac and Majorana neutrinos, respectively. An enhancement of the rate of up to O(1) is expected due to gravitational clustering, with the unique potential to probe the local overdensity of neutrinos. Turning to more exotic neutrino physics, PTOLEMY could be sensitive to a lepton asymmetry, and reveal the eV-scale sterile neutrino that is favored by short baseline oscillation searches. The experiment would also be sensitive to a neutrino lifetime on the order of the age of the universe and break the degeneracy between neutrino mass and lifetime which affects existing bounds.
Fragments of reminiscences and exactly solvable nonrelativistic quantum models
International Nuclear Information System (INIS)
Zakhariev, B.N.
1994-01-01
Some exactly solvable nonrelativistic quantum models are discussed. Special attention is paid to the quantum inverse problem. It is pointed out that by analyzing the inverse problem pictures one can get a deeper insight into the laws of the microworld and acquire the ability to make the qualitative predictions without computers and formulae. 5 refs
Experimental Route to Scanning Probe Hot Electron Nanoscopy (HENs) Applied to 2D Material
Giugni, Andrea; Torre, Bruno; Allione, Marco; Das, Gobind; Wang, Zhenwei; He, Xin; Alshareef, Husam N.; Di Fabrizio, Enzo M.
2017-01-01
for applications in electronics: 2D MoS2 single crystal and a p-type SnO layer. Results are supported by complementary scanning Kelvin probe microscopy, traditional conductive AFM, and Raman measurements. New features highlighted by HEN technique reveal details
On causal nonrelativistic classical electrodynamics
International Nuclear Information System (INIS)
Goedecke, G.H.
1984-01-01
The differential-difference (DD) motion equations of the causal nonrelativistic classical electrodynamics developed by the author in 1975 are shown to possess only nonrunaway, causal solutions with no discontinuities in particle velocity or position. As an example, the DD equation solution for the problem of an electromagnetic shock incident on an initially stationary charged particle is contrasted with the standard Abraham-Lorentz equation solution. The general Cauchy problem for these DD motion equations is discussed. In general, in order to uniquely determine a solution, the initial data must be more detailed than the standard Cauchy data of initial position and velocity. Conditions are given under which the standard Cauchy data will determine the DD equation solutions to sufficient practical accuracy
Electronic and magnetic properties of SnS2 monolayer doped with 4d transition metals
Xiao, Wen-Zhi; Xiao, Gang; Rong, Qing-Yan; Chen, Qiao; Wang, Ling-Ling
2017-09-01
We investigate the electronic structures and magnetic properties of SnS2 monolayers substitutionally doped with 4-d transition-metal through systematic first principles calculations. The doped complexes exhibit interesting electronic and magnetic behaviors, depending on the interplay between crystal field splitting, Hund's rule, and 4d levels. The system doped with Y is nonmagnetic metal. Both the Zr- and Pd-doped systems remain nonmagnetic semiconductors. Doping results in half-metallic states for Nb-, Ru-, Rh-, Ag, and Cd doped cases, and magnetic semiconductors for systems with Mo and Tc dopants. In particular, the Nb- and Mo-doped systems display long-ranged ferromagnetic ordering with Curie temperature above room temperature, which are primarily attributable to the double-exchange mechanism, and the p-d/p-p hybridizations, respectively. Moreover, The Mo-doped system has excellent energetic stability and flexible mechanical stability, and also possesses remarkable dynamic and thermal (500 K) stability. Our studies demonstrate that Nb- and Mo-doped SnS2 monolayers are promising candidates for preparing 2D diluted magnetic semiconductors, and hence will be a helpful clue for experimentalists.
Electron-electron attractive interaction in Maxwell-Chern-Simons QED3 at zero temperature
International Nuclear Information System (INIS)
Belich, H.; Ferreira Junior, M.M.; Helayel-Neto, J.A.; Ferreira Junior, M.M.
2001-04-01
One discusses the issue of low-energy electron-electron bound states in the Maxwell-Chern-Simons model coupled to QED 3 with spontaneous breaking of a local U(1)-symmetry. The scattering potential, in the non-relativistic limit, steaming from the electron-electron Moeller scattering, mediated by the Maxwell-Chern-Simons-Proca gauge field and the Higgs scalar, might be attractive by fine-tuning properly the physical parameters of the model. (author)
Hall-Effect Thruster Simulations with 2-D Electron Transport and Hydrodynamic Ions
Mikellides, Ioannis G.; Katz, Ira; Hofer, Richard H.; Goebel, Dan M.
2009-01-01
A computational approach that has been used extensively in the last two decades for Hall thruster simulations is to solve a diffusion equation and energy conservation law for the electrons in a direction that is perpendicular to the magnetic field, and use discrete-particle methods for the heavy species. This "hybrid" approach has allowed for the capture of bulk plasma phenomena inside these thrusters within reasonable computational times. Regions of the thruster with complex magnetic field arrangements (such as those near eroded walls and magnets) and/or reduced Hall parameter (such as those near the anode and the cathode plume) challenge the validity of the quasi-one-dimensional assumption for the electrons. This paper reports on the development of a computer code that solves numerically the 2-D axisymmetric vector form of Ohm's law, with no assumptions regarding the rate of electron transport in the parallel and perpendicular directions. The numerical challenges related to the large disparity of the transport coefficients in the two directions are met by solving the equations in a computational mesh that is aligned with the magnetic field. The fully-2D approach allows for a large physical domain that extends more than five times the thruster channel length in the axial direction, and encompasses the cathode boundary. Ions are treated as an isothermal, cold (relative to the electrons) fluid, accounting for charge-exchange and multiple-ionization collisions in the momentum equations. A first series of simulations of two Hall thrusters, namely the BPT-4000 and a 6-kW laboratory thruster, quantifies the significance of ion diffusion in the anode region and the importance of the extended physical domain on studies related to the impact of the transport coefficients on the electron flow field.
Some no-go theorems for string duals of non-relativistic Lifshitz-like theories
International Nuclear Information System (INIS)
Li Wei; Takayanagi, Tadashi; Nishioka, Tatsuma
2009-01-01
We study possibilities of string theory embeddings of the gravity duals for non-relativistic Lifshitz-like theories with anisotropic scale invariance. We search classical solutions in type IIA and eleven-dimensional supergravities which are expected to be dual to (2+1)-dimensional Lifshitz-like theories. Under reasonable ansaetze, we prove that such gravity duals in the supergravities are not possible. We also discuss a possible physical reason behind this.
Non-relativistic Bondi-Metzner-Sachs algebra
Batlle, Carles; Delmastro, Diego; Gomis, Joaquim
2017-09-01
We construct two possible candidates for non-relativistic bms4 algebra in four space-time dimensions by contracting the original relativistic bms4 algebra. bms4 algebra is infinite-dimensional and it contains the generators of the Poincaré algebra, together with the so-called super-translations. Similarly, the proposed nrbms4 algebras can be regarded as two infinite-dimensional extensions of the Bargmann algebra. We also study a canonical realization of one of these algebras in terms of the Fourier modes of a free Schrödinger field, mimicking the canonical realization of relativistic bms4 algebra using a free Klein-Gordon field.
International Nuclear Information System (INIS)
Hiroshima, Fumio
2002-01-01
Scaling limits of the Hamiltonian H of a system of N charged particles coupled to a quantized radiation field are considered. Ultraviolet cutoffs, λ 1 ,...,λ N , are imposed on the radiation field and the Coulomb gauge is taken. It is the so-called Pauli-Fierz model in nonrelativistic quantum electrodynamics. We mainly consider two cases: (i) all the ultraviolet cutoffs are identical, λ 1 =···=λ N , (ii) supports of ultraviolet cutoffs have no intersection, supp λ i intersection supp λ j = null-set , i≠j. The Hamiltonian acts on L 2 (R dN )(multiply-in-circle sign)F, where F is a symmetric Fock space, and has the form H=H el (multiply-in-circle sign)1+B+1(multiply-in-circle sign)H quad . Here H el denotes a particle Hamiltonian, H quad a quadratic field operator, and B an interaction term. The scaling is introduced as H(κ)=H el (multiply-in-circle sign)1+κ l B+κ 2 1(multiply-in-circle sign)H quad , where κ is a scaling parameter and l≤2 a parameter of the scaling. Performing a mass renormalization we consider the scaling limit of H(κ) as κ→∞ in the strong resolvent sense. Then effective Hamiltonians H eff in L 2 (R dN ) infected with reaction of effect of the radiation field is derived. In particular (1) effective Hamiltonians with an effective potential for l=2, and (2) effective Hamiltonians with an observed mass for l=1, are obtained
Energy Technology Data Exchange (ETDEWEB)
Cannoni, Mirco [Universidad de Huelva, Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Huelva (Spain)
2016-03-15
We find an exact formula for the thermally averaged cross section times the relative velocity left angle σv{sub rel} right angle with relativistic Maxwell-Boltzmann statistics. The formula is valid in the effective field theory approach when the masses of the annihilation products can be neglected compared with the dark matter mass and cut-off scale. The expansion at x = m/T >> 1 directly gives the nonrelativistic limit of left angle σv{sub rel} right angle, which is usually used to compute the relic abundance for heavy particles that decouple when they are nonrelativistic. We compare this expansion with the one obtained by expanding the total cross section σ(s) in powers of the nonrelativistic relative velocity vr. We show the correct invariant procedure that gives the nonrelativistic average left angle σv{sub rel} right angle {sub nr} coinciding with the large x expansion of left angle σv{sub rel} right angle in the comoving frame. We explicitly formulate flux, cross section, thermal average, collision integral of the Boltzmann equation in an invariant way using the true relativistic relative v{sub rel}, showing the uselessness of the Moeller velocity and further elucidating the conceptual and numerical inconsistencies related with its use. (orig.)
International Nuclear Information System (INIS)
Cannoni, Mirco
2016-01-01
We find an exact formula for the thermally averaged cross section times the relative velocity left angle σv rel right angle with relativistic Maxwell-Boltzmann statistics. The formula is valid in the effective field theory approach when the masses of the annihilation products can be neglected compared with the dark matter mass and cut-off scale. The expansion at x = m/T >> 1 directly gives the nonrelativistic limit of left angle σv rel right angle, which is usually used to compute the relic abundance for heavy particles that decouple when they are nonrelativistic. We compare this expansion with the one obtained by expanding the total cross section σ(s) in powers of the nonrelativistic relative velocity vr. We show the correct invariant procedure that gives the nonrelativistic average left angle σv rel right angle nr coinciding with the large x expansion of left angle σv rel right angle in the comoving frame. We explicitly formulate flux, cross section, thermal average, collision integral of the Boltzmann equation in an invariant way using the true relativistic relative v rel , showing the uselessness of the Moeller velocity and further elucidating the conceptual and numerical inconsistencies related with its use. (orig.)
Quantum-Dynamical Theory of Electron Exchange Correlation
Directory of Open Access Journals (Sweden)
Burke Ritchie
2013-01-01
aggregate, is elucidated. The relationship depends on the use of spin-dependent quantum trajectories (SDQT to evaluate Coulomb’s law between any two electrons as an instantaneous interaction in space and time rather than as a quantum-mean interaction in the form of screening and exchange potentials. Hence FDS depends in an ab initio sense on the inference of SDQT from Dirac’s equation, which provides for relativistic Lorentz invariance and a permanent magnetic moment (or spin in the electron’s equation of motion. Schroedinger’s time-dependent equation can be used to evaluate the SDQT in the nonrelativistic regime of electron velocity. Remarkably FDS is a relativistic property of an ensemble of electron, even though it is of order c0 in the nonrelativistic limit, in agreement with experimental observation. Finally it is shown that covalent versus separated-atoms limits can be characterized by the SDQT. As an example of the use of SDQT in a canonical structure problem, the energies of the 1Σg and 3Σu states of H2 are calculated and compared with the accurate variational energies of Kolos and Wolniewitz.
International Nuclear Information System (INIS)
Samardzic, O.; Hurn, J.A.; Weigold, E.; Brunger, M.J.
1994-01-01
The electron impact excitation of the (2s 2 ) 1 S, (2p 2 ) 1 D and (2s2p) 1 P autoionising states of helium and their subsequent radiationless decay was studied by observation of the ejected electrons. The present work was carried out at an incident energy of 94.6 eV and for ejected electron scattering angles in the range 25-135 deg C. The lineshapes observed in the present ejected electron spectra are analysed using the Shore-Balashov parametrisation. As part of the analysis procedure, numerically rigorous confidence limits were determined for the derived parameters. No previous experimental or theoretical work has been undertaken at the incident energy of the present investigation but, where possible, the resulting parameters are qualitatively compared against the 80 eV results of other experiments and theory. 37 refs., 4 figs
Assembling phosphorene flexagons for 2D electron-density-guided nanopatterning and nanofabrication.
Kang, Kisung; Jang, Woosun; Soon, Aloysius
2017-07-27
To build upon the rich structural diversity in the ever-increasing polymorphic phases of two-dimensional phosphorene, we propose different assembly methods (namely, the "bottom-up" and "top-down" approaches) that involve four commonly reported parent phases (i.e. the α-, β-, γ-, and δ-phosphorene) in combination with the lately reported remarkably low-energy one-dimensional defects in α-phosphorene. In doing so, we generate various periodically repeated phosphorene patterns in these so-called phosphorene flexagons and present their local electron density (via simulated scanning tunneling microscopy (STM) images). These interesting electron density patterns seen in the flexagons (mimicking symmetry patterns that one may typically see in a kaleidoscope) may assist as potential 2D templates where electron-density-guided nanopatterning and nanofabrication in complex organized nanoarchitectures are important.
Electron-electron attractive interaction in Maxwell-Chern-Simons QED{sub 3} at zero temperature
Energy Technology Data Exchange (ETDEWEB)
Belich, H.; Ferreira Junior, M.M.; Helayel-Neto, J.A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). E-mail: belich@cbpf.br; manojr@cbpf.br; helayel@gft.ucp.br; Ferreira Junior, M.M. [Universidade Catolica de Petropolis, RJ (Brazil). Grupo de Fisica Teorica. E-mail: delcima@gft.ucp.br
2001-04-01
One discusses the issue of low-energy electron-electron bound states in the Maxwell-Chern-Simons model coupled to QED{sub 3} with spontaneous breaking of a local U(1)-symmetry. The scattering potential, in the non-relativistic limit, steaming from the electron-electron Moeller scattering, mediated by the Maxwell-Chern-Simons-Proca gauge field and the Higgs scalar, might be attractive by fine-tuning properly the physical parameters of the model. (author)
Nonlinear de Broglie waves and the relation between relativistic and nonrelativistic solitons
International Nuclear Information System (INIS)
Barut, A.O.; Baby, B.V.
1988-07-01
It is shown that the well-known envelope soliton and kink solutions of the nonlinear Schroedinger equation are the nonrelativistic limit of the corresponding solutions of the nonlinear Klein-Gordon equation. 34 refs
Song, Zhibo; Schultz, Thorsten; Ding, Zijing; Lei, Bo; Han, Cheng; Amsalem, Patrick; Lin, Tingting; Chi, Dongzhi; Wong, Swee Liang; Zheng, Yu Jie; Li, Ming-yang; Li, Lain-Jong; Chen, Wei; Koch, Norbert; Huang, Yu Li; Wee, Andrew Thye Shen
2017-01-01
Two-dimensional (2D) semiconductors offer a convenient platform to study 2D physics, for example, to understand doping in an atomically thin semiconductor. Here, we demonstrate the fabrication and unravel the electronic properties of a lateral doped/intrinsic heterojunction in a single-layer (SL) tungsten diselenide (WSe2), a prototype semiconducting transition metal dichalcogenide (TMD), partially covered with a molecular acceptor layer, on a graphite substrate. With combined experiments and theoretical modeling, we reveal the fundamental acceptor-induced p-doping mechanism for SL-WSe2. At the 1D border between the doped and undoped SL-WSe2 regions, we observe band bending and explain it by Thomas-Fermi screening. Using atomically resolved scanning tunneling microscopy and spectroscopy, the screening length is determined to be in the few nanometer range, and we assess the carrier density of intrinsic SL-WSe2. These findings are of fundamental and technological importance for understanding and employing surface doping, for example, in designing lateral organic TMD heterostructures for future devices.
Song, Zhibo
2017-07-28
Two-dimensional (2D) semiconductors offer a convenient platform to study 2D physics, for example, to understand doping in an atomically thin semiconductor. Here, we demonstrate the fabrication and unravel the electronic properties of a lateral doped/intrinsic heterojunction in a single-layer (SL) tungsten diselenide (WSe2), a prototype semiconducting transition metal dichalcogenide (TMD), partially covered with a molecular acceptor layer, on a graphite substrate. With combined experiments and theoretical modeling, we reveal the fundamental acceptor-induced p-doping mechanism for SL-WSe2. At the 1D border between the doped and undoped SL-WSe2 regions, we observe band bending and explain it by Thomas-Fermi screening. Using atomically resolved scanning tunneling microscopy and spectroscopy, the screening length is determined to be in the few nanometer range, and we assess the carrier density of intrinsic SL-WSe2. These findings are of fundamental and technological importance for understanding and employing surface doping, for example, in designing lateral organic TMD heterostructures for future devices.
A new formulation of non-relativistic diffeomorphism invariance
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Rabin, E-mail: rabin@bose.res.in [S.N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake City, Kolkata-700 098 (India); Mitra, Arpita, E-mail: arpita12t@bose.res.in [S.N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake City, Kolkata-700 098 (India); Mukherjee, Pradip, E-mail: mukhpradip@gmail.com [Department of Physics, Barasat Government College, Barasat, West Bengal (India)
2014-10-07
We provide a new formulation of non-relativistic diffeomorphism invariance. It is generated by localising the usual global Galilean symmetry. The correspondence with the type of diffeomorphism invariant models currently in vogue in the theory of fractional quantum Hall effect has been discussed. Our construction is shown to open up a general approach of model building in theoretical condensed matter physics. Also, this formulation has the capacity of obtaining Newton–Cartan geometry from the gauge procedure.
Pipa, Viktor; Vasko, Fedor; Mitin, Vladimir
1997-03-01
The low temperature energy and momentum relaxation rates of 2D electron gas placed near the free or clamped surface of a semi-infinit sample are calculated. To describe the electron-acoustic phonon interaction with allowance of the surface effect the method of elasticity theory Green functions was used. This method allows to take into account the reflection of acoustic waves from the surface and related mutual conversion of LA and TA waves. It is shown that the strength of the deformation potential scattering at low temperatures substantially depends on the mechanical conditions at the surface: relaxation rates are suppressed for the free surface while for the rigid one the rates are enhanced. The dependence of the conductivity on the distance between the 2D layer and the surface is discussed. The effect is most pronounced in the range of temperatures 2 sl pF < T < (2 hbar s_l)/d, where pF is the Fermi momentum, sl is the velocity of LA waves, d is the width of the quantum well.
Electron correlation within the relativistic no-pair approximation
Energy Technology Data Exchange (ETDEWEB)
Almoukhalalati, Adel; Saue, Trond, E-mail: trond.saue@irsamc.ups-tlse.fr [Laboratoire de Chimie et Physique Quantique, UMR 5626 CNRS — Université Toulouse III-Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse (France); Knecht, Stefan [ETH Zürich, Laboratorium für Physikalische Chemie, Vladimir-Prelog-Weg 2, 8093 Zürich (Switzerland); Jensen, Hans Jørgen Aa. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Dyall, Kenneth G. [Dirac Solutions, 10527 NW Lost Park Drive, Portland, Oregon 97229 (United States)
2016-08-21
This paper addresses the definition of correlation energy within 4-component relativistic atomic and molecular calculations. In the nonrelativistic domain the correlation energy is defined as the difference between the exact eigenvalue of the electronic Hamiltonian and the Hartree-Fock energy. In practice, what is reported is the basis set correlation energy, where the “exact” value is provided by a full Configuration Interaction (CI) calculation with some specified one-particle basis. The extension of this definition to the relativistic domain is not straightforward since the corresponding electronic Hamiltonian, the Dirac-Coulomb Hamiltonian, has no bound solutions. Present-day relativistic calculations are carried out within the no-pair approximation, where the Dirac-Coulomb Hamiltonian is embedded by projectors eliminating the troublesome negative-energy solutions. Hartree-Fock calculations are carried out with the implicit use of such projectors and only positive-energy orbitals are retained at the correlated level, meaning that the Hartree-Fock projectors are frozen at the correlated level. We argue that the projection operators should be optimized also at the correlated level and that this is possible by full Multiconfigurational Self-Consistent Field (MCSCF) calculations, that is, MCSCF calculations using a no-pair full CI expansion, but including orbital relaxation from the negative-energy orbitals. We show by variational perturbation theory that the MCSCF correlation energy is a pure MP2-like correlation expression, whereas the corresponding CI correlation energy contains an additional relaxation term. We explore numerically our theoretical analysis by carrying out variational and perturbative calculations on the two-electron rare gas atoms with specially tailored basis sets. In particular, we show that the correlation energy obtained by the suggested MCSCF procedure is smaller than the no-pair full CI correlation energy, in accordance with the
On some solvable models in non-relativistic quantum mechanics
International Nuclear Information System (INIS)
Shabani, J.; Shayo, L.K.
1985-11-01
The theory of self-adjoint extensions is employed to generalize some previous results in non-relativistic quantum interactions. In particular, the Hamiltonian H=-Δ+V, where Δ is the Laplacian and the potential V consists of a strongly singular interaction, a Coulomb and a delta-shell interaction is studied. The spectral properties are discussed and phase shifts as well as low energy parameters are obtained. (author)
Patil, Prasanna Dnyaneshwar
Investigations performed in order to understand the electronic and optoelectronic properties of field effect transistors based on few layers of 2D Copper Indium Selenide (CuIn7Se11) are reported. In general, field effect transistors (FETs), electric double layer field effect transistors (EDL-FETs), and photodetectors are crucial part of several electronics based applications such as tele-communication, bio-sensing, and opto-electronic industry. After the discovery of graphene, several 2D semiconductor materials like TMDs (MoS2, WS2, and MoSe2 etc.), group III-VI materials (InSe, GaSe, and SnS2 etc.) are being studied rigorously in order to develop them as components in next generation FETs. Traditionally, thin films of ternary system of Copper Indium Selenide have been extensively studied and used in optoelectronics industry as photoactive component in solar cells. Thus, it is expected that atomically thin 2D layered structure of Copper Indium Selenide can have optical properties that could potentially be more advantageous than its thin film counterpart and could find use for developing next generation nano devices with utility in opto/nano electronics. Field effect transistors were fabricated using few-layers of CuIn7Se11 flakes, which were mechanically exfoliated from bulk crystals grown using chemical vapor transport technique. Our FET transport characterization measurements indicate n-type behavior with electron field effect mobility microFE ≈ 36 cm2 V-1 s-1 at room temperature when Silicon dioxide (SiO2) is used as a back gate. We found that in such back gated field effect transistor an on/off ratio of 104 and a subthreshold swing ≈ 1 V/dec can be obtained. Our investigations further indicate that Electronic performance of these materials can be increased significantly when gated from top using an ionic liquid electrolyte [1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)]. We found that electron field effect mobility microFE can be increased from
Excitation of the (2p2)1D and (2s2p)1P autoionizing states of helium by 200 eV electron impact
International Nuclear Information System (INIS)
Godunov, A.L.; McGuire, J.H.; Schipakov, V.S.; Crowe, A.
2002-01-01
We report full second Born calculations with inclusion of post-collision interactions for excitation of the (2p 2 ) 1 D and (2s2p) 1 P autoionizing states of helium by 200 eV electron impact. The calculations are compared to (e, 2e) measurements of McDonald and Crowe (McDonald D G and Crowe A 1993 J. Phys. B: At. Mol. Opt. Phys. 26 2887-97) and Lower and Weigold (Lower J and Weigold E 1990 J. Phys. B: At. Mol. Opt. Phys. 23 2819-45). It is shown that post-collision interactions or Coulomb interactions in the final state between the scattered particle, the ejected electron and the recoil ion have a strong influence on both the direct ionization and resonance profiles around the binary lobe. The second-order terms in the amplitude of double electron excitation also play an observable role under these kinematic conditions. Reasonable agreement is found between the full-scale calculations and the experimental data. (author). Letter-to-the-editor
Particle production in high energy collisions and the non-relativistic quark model
International Nuclear Information System (INIS)
Anisovich, V.V.; Nyiri, J.
1981-07-01
The present review deals with multiparticle production processes at high energies using ideas which originate in the non-relativistic quark model. Consequences of the approach are considered and they are compared with experimental data. (author)
Bhatia, A. K.
2014-01-01
In previous papers [A. K. Bhatia, Phys. Rev. A 85, 052708 (2012); 86, 032709 (2012); 87, 042705 (2013)] electron-H, -He+, and -Li2+ P-wave scattering phase shifts were calculated using the variational polarized orbital theory. This method is now extended to the singlet and triplet D-wave scattering in the elastic region. The long-range correlations are included in the Schrodinger equation by using the method of polarized orbitals variationally. Phase shifts are compared to those obtained by other methods. The present calculation provides results which are rigorous lower bonds to the exact phase shifts. Using the presently calculated D-wave and previously calculated S-wave continuum functions, photoionization of singlet and triplet P states of He and Li+ are also calculated, along with the radiative recombination rate coefficients at various electron temperatures.
Electron correlation effects on the d-d excitations in NiO
de Graaf, C; Broer, R.; Nieuwpoort, WC
1996-01-01
The partly filled 3d shell in solid transition metal compounds is quite localized on the transition metal ion and gives rise to large electron correlation effects. With the recently developed CASSCF/CASPT2 approach electron correlation effects can be accounted for efficiently. The CASSCF step
DEFF Research Database (Denmark)
Schou, Jørgen; Sørensen, H.
1982-01-01
at the largest angles. The results agree well with the existing qualitative tendencies described in the literature. The variation with the angle of incidence shows a fair agreement with an estimate based on data for the angular distribution of electrons ejected from ionized hydrogen molecules. In addition......Electron emission, i.e. electron reflection (ER) and secondary electron emission (SEE), was studied for solid H2 and D2 for oblique incidence of 1-3 keV electrons up to an angle of incidence θ of 83°. The ER coefficient η was small at low angles, and rose rapidly with increasing θ above 60......, an ionization cascade treatment leads to an expression for the behavior of the yield of those secondary electrons that are generated directly by the primaries. The agreement with experimental data is good...
Acceleration of particles by electron plasma waves in a moderate magnetic field
International Nuclear Information System (INIS)
Smith, D.F.
1976-01-01
A general scheme is established to examine any magnetohydrodynamic (MHD) configuration for its acceleration potential including the effects of various types of plasma waves. The analysis is restricted to plasma waves in a magnetic field with electron cyclotron frequency less than, but comparable to, the electron plasma frequency (moderate field). The general role of electron plasma waves is examined in this paper independent of a specific MHD configuration or generating mechanism in the weak turbulence limit. The evolution of arbitrary wave spectra in a non-relativistic plasma is examined, and it is shown that the nonlinear process of induced scattering on the polarization clouds of ions leads to the collapse of the waves to an almost one-dimensional spectrum directed along the magnetic field. The subsequent acceleration of non-relativistic and relativistic particles is considered. It is shown for non-relativistic particles that when the wave distribution has a negative slope the acceleration is retarded for lower velocities and enhanced for higher velocities compared to acceleration by an isotropic distribution of electron plasma waves in a magnetic field. This change in behaviour is expected to affect the development of wave spectra and the subsequent acceleration spectrum. (Auth.)
Electronic transport properties of 1D-defects in graphene and other 2D-systems
Energy Technology Data Exchange (ETDEWEB)
Willke, P.; Wenderoth, M. [IV. Physical Institute, Solids and Nanostructures, Georg-August-University Goettingen (Germany); Schneider, M.A. [Lehrstuhl fuer Festkoerperphysik, Universitaet Erlangen-Nuernberg, Erlangen (Germany)
2017-11-15
The continuous progress in device miniaturization demands a thorough understanding of the electron transport processes involved. The influence of defects - discontinuities in the perfect and translational invariant crystal lattice - plays a crucial role here. For graphene in particular, they limit the carrier mobility often demanded for applications by contributing additional sources of scattering to the sample. Due to its two-dimensional nature graphene serves as an ideal system to study electron transport in the presence of defects, because one-dimensional defects like steps, grain boundaries and interfaces are easy to characterize and have profound effects on the transport properties. While their contribution to the resistance of a sample can be extracted by carefully conducted transport experiments, scanning probe methods are excellent tools to study the influence of defects locally. In this letter, the authors review the results of scattering at local defects in graphene and other 2D systems by scanning tunneling potentiometry, 4-point-probe microscopy, Kelvin probe force microscopy and conventional transport measurements. Besides the comparison of the different defect resistances important for device fabrication, the underlying scattering mechanisms are discussed giving insight into the general physics of electron scattering at defects. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Dai, Zhenyu; Wang, Zhenwei; He, Xin; Zhang, Xixiang; Alshareef, Husam N.
2017-01-01
2D semiconductors are poised to revolutionize the future of electronics and photonics, much like transparent oxide conductors and semiconductors have revolutionized the display industry. Herein, these two types of materials are combined to realize
Nonrelativistic electron bunch train for coherently enhanced terahertz radiation sources
International Nuclear Information System (INIS)
Li Yuelin; Kim, Kwang-Je
2008-01-01
We propose to generate a train of prebunched electron beams for producing coherently enhanced Smith-Purcell radiation [S. J. Smith and E. M. Purcell, Phys. Rev. 92, 1069 (1953)] in the terahertz wavelength range. In this scheme, a train of picosecond laser pulses is produced to drive a photoemission gun to generate a train of 50 keV electron pulses. The parameters are chosen so that the space-charge effect does not destroy the pulse time structure. Smith-Purcell radiation from the electron pulse train is enhanced due both to the short length of the individual electron bunch and to the repetitive structure of the beam. Example systems producing coherent terahertz power at about 1 mW are described
Yu, Nengjie; Li Qing Feng; Tang, Chuan-Xiang; Zheng, Shuxin
2005-01-01
A new method for low energy electron beam profile measurement is advanced, which presents a full 2-D beam profile distribution other than the traditional 2-D beam profile distribution given by 1-D vertical and horizontal beam profiles. The method is based on the CT (Computer Tomography) algorithm. Multi-sets of data about the 1-D beam profile projections are attained by rotating the multi-wire scanner. Then a 2-D beam profile is reconstructed from these projections with CT algorithm. The principle of this method is presented. The simulation and the experiment results are compared and analyzed in detail.
New singularities in nonrelativistic coupled channel scattering. II. Fourth order
International Nuclear Information System (INIS)
Khuri, N.N.; Tsun Wu, T.
1997-01-01
We consider a two-channel nonrelativistic potential scattering problem, and study perturbation theory in fourth order for the forward amplitude. The main result is that the new singularity demonstrated in second order in the preceding paper I also occurs at the same point in fourth order. Its strength is again that of a pole. copyright 1997 The American Physical Society
Infinite stochastic acceleration of charged particles from non-relativistic initial energies
International Nuclear Information System (INIS)
Buts, V.A.; Manujlenko, O.V.; Turkin, Yu.A.
1997-01-01
Stochastic charged particle acceleration by electro-magnetic field due to overlapping of non-linear cyclotron resonances is considered. It was shown that non-relativistic charged particles are involved in infinitive stochastic acceleration regime. This effect can be used for stochastic acceleration or for plasma heating by regular electro-magnetic fields
Low-energy collisions between electrons and BeD+
Niyonzima, S.; Pop, N.; Iacob, F.; Larson, Å; Orel, A. E.; Mezei, J. Zs; Chakrabarti, K.; Laporta, V.; Hassouni, K.; Benredjem, D.; Bultel, A.; Tennyson, J.; Reiter, D.; Schneider, I. F.
2018-02-01
Multichannel quantum defect theory is applied in the treatment of the dissociative recombination and vibrational excitation processes for the BeD+ ion in the 24 vibrational levels of its ground electronic state ({{X}}{}1{{{Σ }}}+,{v}{{i}}+=0\\ldots 23). Three electronic symmetries of BeD** states ({}2{{\\Pi }}, {}2{{{Σ }}}+, and {}2{{Δ }}) are considered in the calculation of cross sections and the corresponding rate coefficients. The incident electron energy range is 10-5-2.7 eV and the electron temperature range is 100-5000 K. The vibrational dependence of these collisional processes is highlighted. The resulting data are useful in magnetic confinement fusion edge plasma modeling and spectroscopy, in devices with beryllium based main chamber materials, such as ITER and JET, and operating with the deuterium-tritium fuel mix. An extensive rate coefficients database is presented in graphical form and also by analytic fit functions whose parameters are tabulated in the supplementary material.
Non-relativistic electron transport in metals: a Monte Carlo approach
International Nuclear Information System (INIS)
Rahimi, F.; Ghal eh, N.
2001-01-01
A simple Monte Carlo procedure is described for simulating the multiple scattering and absorption of electrons with the incident energy in the range 1-50 keV moving through a slab of uniformly distributed material of given atomic number, density and thickness. The simulation is based on a screened Rutherford cross-section and Bethe continuous energy-loss equation. A FORTRAN program is written to determine backscattering, transmission and absorption coefficients, providing the user with a graphical output of the electron trajectories. The results of several simulations are presented by using various numbers of electrons, showing a good agreement with the experiment. The program is used to analyze the relation between the energy and the range of electron in the slab, the backscattering, absorption, transmission coefficients and the angular distribution
Radiative electron capture studied in relativistic heavy-ion--atom collisions
International Nuclear Information System (INIS)
Stoehlker, T.; Kozhuharov, C.; Mokler, P.H.; Warczak, A.; Bosch, F.; Geissel, H.; Moshammer, R.; Scheidenberger, C.; Eichler, J.; Ichihara, A.; Shirai, T.; Stachura, Z.; Rymuza, P.
1995-01-01
The process of radiative electron capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed x-ray spectra are analyzed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well reproduced by exact relativistic calculations which yield significant deviations from standard sin 2 θ distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a nonrelativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the nonrelativistic approach for practical purposes
H-particle stability in the nonrelativistic quark model
International Nuclear Information System (INIS)
Silvestre-Brac, B.; Carbonell, J.; Gignoux, C.
1987-01-01
The H particle with quark content (uuddss) is presented as a good candidate to be stable with respect to strong interactions. In the framework of a nonrelativistic potential model, the binding energy is calculated by a full dynamical approach using a resonating group trial wave function. The center-of-mass motion and the Pauli principle are correctly treated. Sophisticated baryon wave functions are employed and the equation of motion is solved with six coupled channels including radial excited baryon states. The effect of breaking SU(3)-flavor symmetry is discussed in detail
International Nuclear Information System (INIS)
Maulois, Melissa; Ribière, Maxime; Eichwald, Olivier; Yousfi, Mohammed; Azaïs, Bruno
2016-01-01
The comprehension of electromagnetic perturbations of electronic devices, due to air plasma-induced electromagnetic field, requires a thorough study on air plasma. In the aim to understand the phenomena at the origin of the formation of non-equilibrium air plasma, we simulate, using a volume average chemical kinetics model (0D model), the time evolution of a non-equilibrium air plasma generated by an energetic X-ray flash. The simulation is undertaken in synthetic air (80% N_2 and 20% O_2) at ambient temperature and atmospheric pressure. When the X-ray flash crosses the gas, non-relativistic Compton electrons (low energy) and a relativistic Compton electron beam (high energy) are simultaneously generated and interact with the gas. The considered chemical kinetics scheme involves 26 influent species (electrons, positive ions, negative ions, and neutral atoms and molecules in their ground or metastable excited states) reacting following 164 selected reactions. The kinetics model describing the plasma chemistry was coupled to the conservation equation of the electron mean energy, in order to calculate at each time step of the non-equilibrium plasma evolution, the coefficients of reactions involving electrons while the energy of the heavy species (positive and negative ions and neutral atoms and molecules) is assumed remaining close to ambient temperature. It has been shown that it is the relativistic Compton electron beam directly created by the X-ray flash which is mainly responsible for the non-equilibrium plasma formation. Indeed, the low energy electrons (i.e., the non-relativistic ones) directly ejected from molecules by Compton collisions contribute to less than 1% on the creation of electrons in the plasma. In our simulation conditions, a non-equilibrium plasma with a low electron mean energy close to 1 eV and a concentration of charged species close to 10"1"3" cm"−"3 is formed a few nanoseconds after the peak of X-ray flash intensity. 200 ns after the
An analytic approach to 2D electronic PE spectra of molecular systems
International Nuclear Information System (INIS)
Szoecs, V.
2011-01-01
Graphical abstract: The three-pulse photon echo (3P-PE) spectra of finite molecular systems using direct calculation from electronic Hamiltonians allows peak classification from 3P-PE spectra dynamics. Display Omitted Highlights: → RWA approach to electronic photon echo. → A straightforward calculation of 2D electronic spectrograms in finite molecular systems. → Importance of population time dynamics in relation to inter-site coherent coupling. - Abstract: The three-pulse photon echo (3P-PE) spectra of finite molecular systems and simplified line broadening models is presented. The Fourier picture of a heterodyne detected three-pulse rephasing PE signal in the δ-pulse limit of the external field is derived in analytic form. The method includes contributions of one and two-excitonic states and allows direct calculation of Fourier PE spectrogram from corresponding Hamiltonian. As an illustration, the proposed treatment is applied to simple systems, e.g. 2-site two-level system (TLS) and n-site TLS model of photosynthetic unit. The importance of relation between Fourier picture of 3P-PE dynamics (corresponding to nonzero population time, T) and coherent inter-state coupling is emphasized.
Energy Technology Data Exchange (ETDEWEB)
Wenk, H.R.; Hu Meisheng (California Univ., Berkeley, CA (United States). Dept. of Geology and Geophysics); Downing, K.H. (Lawrence Berkeley Lab., CA (United States). Donner Lab.); O' Keefe, M.A. (Lawrence Berkeley Lab., CA (United States). National Center for Electron Microscopy)
1992-09-01
Resolution of better than 2 A has been obtained in many crystals by high-resolution electron microscopy. Although this resolution is sufficient to resolve interatomic spacings, structures are traditionally interpreted by comparing experimental images with contrast calculations. A drawback of this method is that images are 2D projections in which information is invariably obscured by overlap of atoms. 3D electron crystallography, developed by biophysicists to study proteins, has been used to investigate the crystal structure of staurolite. Amplitudes and phases of structure factors are obtained experimentally from high-resolution images (JEOL ARM 1000 at the National Center for Electron Microscopy at LBL), taken in different directions from thin regions where dynamic scattering is minimal. From images in five orientations (containing 59 independent reflections to a resolution of 1.38 A), a 3D electron potential map is constructed which resolves clearly all cations (Al, Si, Fe, including those with partial occupancy) and all O atoms. This method has great potential in crystal structure determinations of small domains in heterogeneous crystals which are inaccessible to X-ray analysis. It is estimated that 3D structure determinations should be possible on regions only about ten unit cells wide and should resolve not only atom positions but also site occupancies. The method is also applicable to space-group determination. (orig.).
International Nuclear Information System (INIS)
PETTY, CC; LAHAYE, LA; LUCE, TC; HUMPHREYS, DA; HYATT, AW; PRATER, R; STRAIT, EJ; WADE, MR
2003-01-01
A271 COMPLETE SUPPRESSION OF THE M=2/N-1 NEOCLASSICAL TEARING MODE USING ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D. The first suppression of the important and deleterious m=2/n=1 neoclassical tearing mode (NTM) is reported using electron cyclotron current drive (ECCD) to replace the ''missing'' bootstrap current in the island O-point. Experiments on the DIII-D tokamak verify the maximum shrinkage of the m=2/n=1 island occurs when the ECCD location coincides with the q = 2 surface. The DIII-D plasma control system is put into search and suppress mode to make small changes in the toroidal field to find and lock onto the optimum position, based on real time measurements of dB θ /dt, for complete m=2/n=1 NTM suppression by ECCD. The requirements on the ECCD for complete island suppression are well modeled by the modified Rutherford equation for the DIII-D plasma conditions
Directory of Open Access Journals (Sweden)
Scholes Gregory D.
2013-03-01
Full Text Available The study of LH2 protein of purple bacteria by broadband 2D electronic spectroscopy is presented. The dark 1Bu- carotenoid state is directly observed in 2D spectra and its role in carotenoid-bacteriochlorophyll interaction is discussed.
Zuo, M.; Smith, Steven J.; Chutjian, A.; Williams, I. D.; Tayal, S. S.; Mclaughlin, Brendan M.
1995-01-01
Experimental and theoretical excitation cross sections are reported for the first forbidden transition 4S(O) -- 2S(2)2p(3) 2D(O) (lambda-lambda 3726, 3729) and the first allowed (resonance) transition 4S(O) -- 2s2p(4) 4P(lambda-833) in O II. Use is made of electron energy loss and merged-beams methods. The electron energy range covered is 3.33 (threshold) to 15 eV for the S -- D transition, and 14.9 (threshold) to 40 eV for the S -- P transition. Care was taken to assess and minimize the metastable fraction of the O II beam. An electron mirror was designed and tested to reflect inelastically backscattered electrons into the forward direction to account for the full range of polar scattering angles. Comparisons are made between present experiments and 11-state R-matrix calculations. Calculations are also presented for the 4S(O) -- 2s(2)2p(3)2P(O) (lambda-2470) transition.
Nonlinear bound on unstable field energy in relativistic electron beams and plasmas
International Nuclear Information System (INIS)
Davidson, R.C.; Yoon, P.H.
1989-01-01
This paper makes use of Fowler's method [J. Math Phys. 4, 559 (1963)] to determine the nonlinear thermodynamic bound on field energy in unstable plasmas or electron beams in which the electrons are relativistic. Treating the electrons as the only active plasma component, the nonlinear Vlasov--Maxwell equations and the associated global conservation constraints are used to calculate the lowest upper bound on the field energy [ΔE-script/sub F/]/sub max/ that can evolve for the general initial electron distribution function f/sub b//sub / 0 equivalentf/sub b/(x,p,0). The results are applied to three choices of the initial distribution function f/sub b//sub / 0 . Two of the distribution functions have an inverted population in momentum p/sub perpendicular/ perpendicular to the magnetic field B 0 e/sub z/, and the third distribution function reduces to a bi-Maxwellian in the nonrelativistic limit. The lowest upper bound on the efficiency of radiation generation, eta/sub max/ = [ΔE-script/sub F/]/sub max//[V -1 ∫ d 3 x∫ d 3 p(γ-1)mc 2 f/sub b//sub / 0 ], is calculated numerically over a wide range of system parameters for varying degrees of initial anisotropy
Electronic structure robustness and design rules for 2D colloidal heterostructures
Chu, Audrey; Livache, Clément; Ithurria, Sandrine; Lhuillier, Emmanuel
2018-01-01
Among the colloidal quantum dots, 2D nanoplatelets present exceptionally narrow optical features. Rationalizing the design of heterostructures of these objects is of utmost interest; however, very little work has been focused on the investigation of their electronic properties. This work is organized into two main parts. In the first part, we use 1D solving of the Schrödinger equation to extract the effective masses for nanoplatelets (NPLs) of CdSe, CdS, and CdTe and the valence band offset for NPL core/shell of CdSe/CdS. In the second part, using the determined parameters, we quantize how the spectra of the CdSe/CdS heterostructure get affected by (i) the application of an electric field and (ii) by the presence of a dull interface. We also propose design strategies to make the heterostructure even more robust.
Comparison between relativistic, semirelativistic, and nonrelativistic approaches of quarkonium
International Nuclear Information System (INIS)
Semay, C.; Silvestre-Brac, B.
1992-01-01
We study the connections existing between relativistic, semirelativistic, and nonrelativistic potential models of quarkonium using an interaction composed of an attractive Coulomb potential and a confining power-law term. We show that the spectra of these very different models become nearly similar provided specific relations exist between the dimensionless parameters peculiar to each model. As our analysis is carried out by taking advantage of scaling laws, our results are applicable for a wide range of physical parameters
Interactions in 2D electron and hole systems in the intermediate and ballistic regimes
International Nuclear Information System (INIS)
Proskuryakov, Y Y; Savchenko, A K; Safonov, S S; Li, L; Pepper, M; Simmons, M Y; Ritchie, D A; Linfield, E H; Kvon, Z D
2003-01-01
In different 2D semiconductor systems we study the interaction correction to the Drude conductivity in the intermediate and ballistic regimes, where the parameter k B Tτ/ h-bar changes from 0.1 to 10 (τ is momentum relaxation time). The temperature dependence of the resistance and magnetoresistance in parallel and perpendicular magnetic fields is analysed in terms of the recent theories of electron-electron interactions in systems with different degree of disorder and different character of the fluctuation potential. Generally, good agreement is found between the experiments and the theories
Nonrelativistic Schroedinger equation in quasi-classical theory
International Nuclear Information System (INIS)
Wignall, J.W.G.
1987-01-01
The author has recently proposed a quasi-classical theory of particles and interactions in which particles are pictured as extended periodic disturbances in a universal field chi(x,t), interacting with each other via nonlinearity in the equation of motion for chi. The present paper explores the relationship of this theory to nonrelativistic quantum mechanics; as a first step, it is shown how it is possible to construct from chi a configuration-space wave function Psi(x 1 , X 2 , t), and that the theory requires that Psi satisfy the two-particle Schroedinger equation in the case where the two particles are well separated from each other. This suggests that the multiparticle Schroedinger equation can be obtained as a direct consequence of the quasi-classical theory without any use of the usual formalism (Hilbert space, quantization rules, etc.) of conventional quantum theory and in particular without using the classical canonical treatment of a system as a crutch theory which has subsequently to be quantized. The quasi-classical theory also suggests the existence of a preferred absolute gauge for the electromagnetic potentials
Electronic structure effects on stability and quantum conductance in 2D gold nanowires
International Nuclear Information System (INIS)
Kashid, Vikas; Shah, Vaishali; Salunke, H. G.
2011-01-01
In this study, we have investigated the stability and conductivity of unsupported, two-dimensional infinite gold nanowires using ab initio density functional theory (DFT). Two-dimensional ribbon-like nanowires with 1–5 rows of gold atoms in the non-periodic direction and with different possible structures have been considered. The nanowires with >2 rows of atoms exhibit dimerization, similar to finite wires, along the non-periodic direction. Our results show that in these zero thickness nanowires, the parallelogram motif is the most stable. A comparison between parallelogram- and rectangular-shaped nanowires of increasing width indicates that zero thickness (111) oriented wires have a higher stability over (100). A detailed analysis of the electronic structure, reveals that the (111) oriented structures show increased delocalization of s and p electrons in addition to a stronger delocalization of the d electrons and hence are the most stable. The density of states show that the nanowires are metallic and conducting except for the double zigzag structure, which is semiconducting. Conductance calculations show transmission for a wide range of energies in all the stable nanowires with more than two rows of atoms. The conductance channels are not purely s and have strong contributions from the d levels, and weak contributions from the p levels.
Angular distributions of autoionization electrons from Ne(2p43s2) 1D in Li+-Ne collisions
International Nuclear Information System (INIS)
Oud, M.; Pas, S.F. te; Westerveld, W.B.; Niehaus, A.
1993-01-01
Angular distributions of autoionization electrons from Ne(2p 4 3s 2 ) 1 D due to Li + -Ne collisions measured in coincidence with the scattered projectile ions are presented. The measurements are performed at four different collision energies between 1.0 keV and 3.0 keV, and the complex population amplitudes for the excited 1 D state are determined. A nearly pure M = O sublevel population is found with respect to an axis coinciding with the direction of the angular distribution. The direction of the angular distribution is found to deviate from the final direction of the asymptotic internuclear axis. (author)
Theoretical foundations of electron spin resonance
Harriman, John E
2013-01-01
Theoretical Foundations of Electron Spin Resonance deals with the theoretical approach to electron paramagnetic resonance. The book discusses electron spin resonance in applications related to polyatomic, probably organic, free radicals in condensed phases. The book also focuses on essentially static phenomena, that is, the description and determination of stationary-state energy levels. The author reviews the Dirac theory of the electron in which a four-component wave function is responsible for the behavior of the electron. The author then connects this theory with the nonrelativistic wave f
Conservation of energy and momentum in nonrelativistic plasmas
International Nuclear Information System (INIS)
Sugama, H.; Watanabe, T.-H.; Nunami, M.
2013-01-01
Conservation laws of energy and momentum for nonrelativistic plasmas are derived from applying Noether's theorem to the action integral for the Vlasov-Poisson-Ampère system [Sugama, Phys. Plasmas 7, 466 (2000)]. The symmetric pressure tensor is obtained from modifying the asymmetric canonical pressure tensor with using the rotational symmetry of the action integral. Differences between the resultant conservation laws and those for the Vlasov-Maxwell system including the Maxwell displacement current are clarified. These results provide a useful basis for gyrokinetic conservation laws because gyrokinetic equations are derived as an approximation of the Vlasov-Poisson-Ampère system.
Electron-electron bound states in parity-preserving QED3
International Nuclear Information System (INIS)
Belich, H.; Helayel-Neto, J.A.; Centro Brasileiro de Pesquisas Fisicas; Cima, O.M. del; Ferreira Junior, M.M.; Maranhao Univ., Sao Luis, MA
2002-04-01
By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may dominate. The e - e - interaction potential emerges as the non-relativistic limit of the Moeller scattering amplitude and it results attractive with a suitable choice of parameters. Numerically values of the e - e - binding energy are obtained by solving the two-dimensional Schroedinger equation. The existence of bound states is a strong indicative that this model may be adopted to address the pairing mechanism of high-T c superconductivity. (author)
Relativistic form factors for clusters with nonrelativistic wave functions
International Nuclear Information System (INIS)
Mitra, A.N.; Kumari, I.
1977-01-01
Using a simple variant of an argument employed by Licht and Pagnamenta (LP) on the effect of Lorentz contraction on the elastic form factors of clusters with nonrelativistic wave functions, it is shown how their result can be generalized to inelastic form factors so as to produce (i) a symmetrical appearance of Lorentz contraction effects in the initial and final states, and (ii) asymptotic behavior in accord with dimensional scaling theories. A comparison of this result with a closely analogous parametric form obtained by Brodsky and Chertok from a propagator chain model leads, with plausible arguments, to the conclusion of an effective mass M for the cluster, with M 2 varying as the number n of the quark constituents, instead of as n 2 . A further generalization of the LP formula is obtained for an arbitrary duality-diagram vertex, again with asymptotic behavior in conformity with dimensional scaling. The practical usefulness of this approach is emphasized as a complementary tool to those of high-energy physics for phenomenological fits to data up to moderate values of q 2
Relativistic theory of electron-impact ionization
International Nuclear Information System (INIS)
Rosenberg, Leonard
2010-01-01
A relativistic version of an earlier, non-relativistic, formulation of the theory of ionization of an atomic system by electron impact is presented. With a time-independent resolvent operator taken as the basis for the dynamics, a wave equation is derived for a system with open channels consisting of two positive-energy electrons in an external field generated by the residual ion. Virtual intermediate states can be accounted for by the effective Hamiltonian that appears in the wave equation and which in principle may be constructed perturbatively. The asymptotic form of the wavefunction, modified by the effects of the long-range Coulomb interactions of the two electrons in the external field, is derived. These electrons are constrained, by projection operators which appear naturally in the theory, to propagate in positive-energy states only. The long-range Coulomb effects take the form of phase factors similar to those that are found in the non-relativistic version of the theory. With the boundary conditions established, an integral identity for the ionization amplitude is derived, and used to set up a distorted-wave Born expansion for the transition amplitude involving Coulomb-modified propagating waves.
Radiative electron capture studied in relativistic heavy-ion atom collisions
International Nuclear Information System (INIS)
Stoehlker, T.; Kozhuharov, C.; Mokler, P.H.; Warczak, A.; Bosch, F.; Geissel, H.; Moshammer, R.; Scheidenberger, C.; Eichler, J.; Shirai, T.; Stachura, Z.; Rymuza, P.
1994-08-01
The process of Radiative Electron Capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed X-ray spectra are analysed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well-reproduced by exact relativistic calculations which yield significant deviations from standard sin 2 θ distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a non-relativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the non-relativistic approach for practical purposes. (orig.)
Reaction (γ,2e) and (e,3e) as probe of electron correlation in atoms
International Nuclear Information System (INIS)
Amusia, M.Y.
1995-01-01
Cross sections of the (γ,2e) and (e,3e) reactions contain information about the two vacancy-energy spectrum and electron-pair correlations in initial and final states of the target atom. Physical pictures of these processes are presented for two- and many-electron atoms. The simplest mechanisms are discussed, demonstrating some features which await experimental confirmation. Attention is given to high photon energy and the relativistic energy region of these reactions. The energy distribution of outgoing relativistic electrons is qualitatively different from the nonrelativistic case. The origin and types of corrections to the simplest mechanisms, and possible means of their detection, are discussed. In addition, the role of different resonances: shape, giant, autoionizational, and Feshbach-type are considered. Results of calculations are compared with experimental data, mainly on double photoionization cross sections. Different possible objects as targets for the reactions are considered, including negative ions, excited atoms, molecules, and clusters. The modification of these reactions due to photon emission is discussed. The future of the domain is outlined
Reactions (γ,2e) and (e,3e) as probes of electronic correlations in atoms
International Nuclear Information System (INIS)
Amusia, M.Ya.
1993-01-01
Cross sections of the (γ,2e) and (e,3e) reactions carry information on two vacancy energy spectrum and on electron pair correlations in initial and final states of the target atom. Physical pictures of these processes are presented for two- and many-electron atoms. Simplest mechanisms of them are discussed, demonstrating some features which are waiting for experimental confirmation. Attention is given to high photon energy and even to relativistic energy region of these reactions. The energy distribution of outgoing relativistic electrons is qualitatively different from what it is for the nonrelativistic case. Origin and types of corrections to the simplest mechanisms and possible means of their detection are discussed. Role of different resonances: shape, giant, autoionizational, and Feschbach-type are considered. Results of calculations are compared with experimental data, mainly on double photoionization cross sections. Different possible objects as targets for the reactions are mentioned, including negative ions, excited atoms, molecules and clusters. Modification of the type of these reactions due to rather probable emission of the photon is discussed. Future of the domain is outlined. (orig.)
International Nuclear Information System (INIS)
Ghanbari Adivi, E.; Kanjuri, F.; Bolorizadeh, M.
2006-01-01
The positronium formation differential cross sections in collision of the high-energy but non-relativistic electrons with anti-hydrogen atoms are calculated by using the three-body Faddeev-Watson-Lovelace formalism. In a second-order approximation, the inter-nuclear and nuclear-electronic partial amplitudes therein the Faddeev-Watson series are calculated, analytically, in the range of 0-180 degrees of the scattering angles. The presence of the T homas peak a t 45 d egree i s investigated. The results are discussed for 1 and 10 keV impact energies and for electron transition from anti-hydrogen ground state into the different states therein the K-, L- and M- shells of the positronium atoms.
Design of the 2D electron cyclotron emission imaging instrument for the J-TEXT tokamak.
Pan, X M; Yang, Z J; Ma, X D; Zhu, Y L; Luhmann, N C; Domier, C W; Ruan, B W; Zhuang, G
2016-11-01
A new 2D Electron Cyclotron Emission Imaging (ECEI) diagnostic is being developed for the J-TEXT tokamak. It will provide the 2D electron temperature information with high spatial, temporal, and temperature resolution. The new ECEI instrument is being designed to support fundamental physics investigations on J-TEXT including MHD, disruption prediction, and energy transport. The diagnostic contains two dual dipole antenna arrays corresponding to F band (90-140 GHz) and W band (75-110 GHz), respectively, and comprises a total of 256 channels. The system can observe the same magnetic surface at both the high field side and low field side simultaneously. An advanced optical system has been designed which permits the two arrays to focus on a wide continuous region or two radially separate regions with high imaging spatial resolution. It also incorporates excellent field curvature correction with field curvature adjustment lenses. An overview of the diagnostic and the technical progress including the new remote control technique are presented.
Design of the 2D electron cyclotron emission imaging instrument for the J-TEXT tokamak
Energy Technology Data Exchange (ETDEWEB)
Pan, X. M.; Yang, Z. J., E-mail: yangzj@hust.edu.cn; Ma, X. D.; Ruan, B. W.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Zhu, Y. L. [School of Physics, University of Science and Technology of China, Anhui 230026 (China); Luhmann, N. C.; Domier, C. W. [Davis Millimeter Wave Research Center, University of California, Davis, California 95616 (United States)
2016-11-15
A new 2D Electron Cyclotron Emission Imaging (ECEI) diagnostic is being developed for the J-TEXT tokamak. It will provide the 2D electron temperature information with high spatial, temporal, and temperature resolution. The new ECEI instrument is being designed to support fundamental physics investigations on J-TEXT including MHD, disruption prediction, and energy transport. The diagnostic contains two dual dipole antenna arrays corresponding to F band (90-140 GHz) and W band (75-110 GHz), respectively, and comprises a total of 256 channels. The system can observe the same magnetic surface at both the high field side and low field side simultaneously. An advanced optical system has been designed which permits the two arrays to focus on a wide continuous region or two radially separate regions with high imaging spatial resolution. It also incorporates excellent field curvature correction with field curvature adjustment lenses. An overview of the diagnostic and the technical progress including the new remote control technique are presented.
Is MoS2 a robust material for 2D electronics?
International Nuclear Information System (INIS)
Lorenz, Tommy; Joswig, Jan-Ole; Seifert, Gotthard; Ghorbani-Asl, Mahdi; Heine, Thomas
2014-01-01
A nanoindentation computer experiment has been carried out by means of Born–Oppenheimer molecular-dynamics simulations employing the density-functional based tight-binding method. A free-standing MoS 2 sheet, fixed at a circular support, was indented by a stiff, sharp tip. During this process, the strain on the nanolayer is locally different, with maximum values in the vicinity of the tip. All studied electronic properties—the band gap, the projected density of states, the atomic charges and the quantum conductance through the layer—vary only slightly before they change significantly when the MoS 2 sheet finally is pierced. After strong local deformation due to the indentation process, the electronic conductance in our model still is 80% of its original value. Thus, the electronic structure of single-layer MoS 2 is rather robust upon local deformation. (paper)
Energy Technology Data Exchange (ETDEWEB)
Bangert, U., E-mail: Ursel.Bangert@ul.ie [Department of Physics, School of Sciences & Bernal Institute, University of Limerick, Limerick (Ireland); Stewart, A.; O’Connell, E.; Courtney, E. [Department of Physics, School of Sciences & Bernal Institute, University of Limerick, Limerick (Ireland); Ramasse, Q.; Kepaptsoglou, D. [SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury WA4 4AD (United Kingdom); Hofsäss, H.; Amani, J. [II. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-PLatz 1, 37077 Göttingen (Germany); Tu, J.-S.; Kardynal, B. [Peter Grünberg Institut 9, Forschungszentrum Jülich, 52425 Jülich (Germany)
2017-05-15
Functionalisation of two-dimensional (2-D) materials via low energy ion implantation could open possibilities for fabrication of devices based on such materials. Nanoscale patterning and/or electronically doping can thus be achieved, compatible with large scale integrated semiconductor technologies. Using atomic resolution High Angle Annular Dark Field (HAADF) scanning transmission electron microscopy supported by image simulation, we show that sites and chemical nature of individual implants/ dopants in graphene, as well as impurities in hBN, can uniquely and directly be identified on grounds of their position and their image intensity in accordance with predictions from Z-contrast theories. Dopants in graphene (e.g., N) are predominantly substitutional. In other 2-Ds, e.g. dichalcogenides, the situation is more complicated since implants can be embedded in different layers and substitute for different elements. Possible configurations of Se-implants in MoS{sub 2} are discussed and image contrast calculations performed. Implants substituting for S in the top or bottom layer can undoubtedly be identified. We show, for the first time, using HAADF contrast measurement that successful Se-integration into MoS{sub 2} can be achieved via ion implantation, and we demonstrate the possibility of HAADF image contrast measurements for identifying impurities and dopants introduced into in 2-Ds. - Highlights: • Ion implantation of 2-dimensional materials. • Targeted and controlled functionalisation of graphene and 2-D dichalcocenides. • Atomic resolution High Angle Dark Field scanning transmission electron microscopy. • Determination of atomic site and elemental nature of dopants in 2-D materials. • Quantitative information from Z-contrast images.
Models of non-relativistic quantum gravity: the good, the bad and the healthy
Blas, Diego; Sibiryakov, Sergey
2011-01-01
Horava's proposal for non-relativistic quantum gravity introduces a preferred time foliation of space-time which violates the local Lorentz invariance. The foliation is encoded in a dynamical scalar field which we call `khronon'. The dynamics of the khronon field is sensitive to the symmetries and other details of the particular implementations of the proposal. In this paper we examine several consistency issues present in three non-relativistic gravity theories: Horava's projectable theory, the healthy non-projectable extension, and a new extension related to ghost condensation. We find that the only model which is free from instabilities and strong coupling is the non-projectable one. We elaborate on the phenomenology of the latter model including a discussion of the couplings of the khronon to matter. In particular, we obtain the parameters of the post-Newtonian expansion in this model and show that they are compatible with current observations.
2d axisymmetric "beam-bulk" modelling of the generation of runaway electrons by streamers.
Chanrion, Olivier; Bonaventura, Zdenek; Bourdon, Anne; Neubert, Torsten
2017-04-01
We present results from a 2d axisymmetric numerical model of streamers based on a "beam-bulk" approach which describes cold electrons with a fluid model and high energy electrons with a particle model. The interest is motivated by the generation of runaway electrons by streamers which may participate in the recently observed TGFs and which challenge the modelling. Runaway electrons are known to be generated from streamers when the electric field in its negative tip is of sufficient magnitude. After overtaking the streamer tip, runaways can affect the streamer propagation ahead and may produce high energy photons through the bremsstrahlung process. In conventional model of streamers, the evolution of the streamer discharge is mostly governed by cold electrons. By including runaway electrons, we model their production, their impact on the discharge propagation and can address their role in TGFs. Results of streamer propagation in leader electric field show that the runaway electrons accelerate the streamers, reduce the electric field in its tip and enlarge its radius by pre-ionizing the gas ahead. We observed that if we increase the electric field, the discharge is getting more diffuse, with a pattern driven by the increase in runaway induced ionisation.
Corrections to O(α7(lnα)mc2) fine-structure splittings and O(α6(lnα)mc2) energy levels in helium
International Nuclear Information System (INIS)
Zhang, T.
1996-01-01
Fully relativistic formulas for the energy-level shifts arising from no-pair exchange diagrams of two transverse photons plus an arbitrary number of Coulomb photons are derived in closed form within the external potential Bethe-Salpeter formalism. O(α 7 (lnα)mc 2 ) corrections to the fine-structure splittings of helium are obtained and expressed in terms of expectation values of nonrelativistic operators. O(α 7 mc 2 ) operators from exchange diagrams are found in nonrelativistic approximation. O(α 6 m 2 c 2 /M) nucleus-electron operators contributing to the fine-structure splittings are derived. Nonrelativistic operators of O(α 6 mc 2 ) corrections to the triplet levels of helium are presented. Nonrelativistic operators of O(α 6 (lnα)mc 2 ) corrections to the helium singlet levels and to positronium S levels are derived. O(α 6 m 2 c 2 /M) hydrogen and O(α 6 mc 2 ) positronium P levels, and O(α 6 (lnα)mc 2 ) corrections of first order to positronium S levels, are calculated using the derived operators for helium, in agreement with those obtained previously by others, except for one term in corrections to positronium P levels. In addition, the O(α 6 mc 2 ) Dirac energies for hydrogenic non-S levels are exactly reproduced in a perturbative calculation. copyright 1996 The American Physical Society
To the theory of the Pierce instability of neutralized electron flows
International Nuclear Information System (INIS)
Ignatov, A.M.; Rukhadze, A.A.
1984-01-01
The Pierce instability of a nonrelativistic electron beam in an exernal fi inite magnetic field is investigated. Analytical expressions for a critical electron density in limiting cases of strong or weak magnetic field have been fo ound. The critical electron density is shown to increase with a decrease in the magnetic field strength
Satou, Yoshinori; Komine, Shigeki; Shimizu, Sumera
2017-09-01
Cathode materials for lithium-ion batteries containing Ni2+ have attracted much interest because of their high theoretical capacity. However, the precise electronic structures of these cathode materials have not yet been clearly observed, especially the energy positions of the O2p and Ni3d orbitals and the shape of the density of states. The aim of this study was to investigate the relative energy positions and shape of the density of states of O2p and Ni3d for LiNi0.5Mn0.5O2 experimentally. We cleaved a LiNi0.5Mn0.5O2 pellet in an Ar-filled glove box and performed synchrotron ultraviolet photoelectron spectroscopy for different photon energies, which enabled us to investigate the relative cross-section intensity of O2p and Ni3d. As a result, the valence-band structure was determined. We found that O2p electrons are itinerant and exist in the vicinity of the Fermi energy more than Ni3d electrons. Ni3d electrons are more localized and spread mainly from 1.2-1.5 eV below the Fermi energy. To validate the electronic structure, we measured the synchrotron O K-edge X-ray absorption fine structure of electrochemically lithium-extracted LiNi0.5Mn0.5O2. The electronic structure demonstrated that ligand holes in the oxygen atoms form below the Fermi level during the initial stage of Li extraction and that the formation rate of the holes decreases with Li extraction.
Energy Technology Data Exchange (ETDEWEB)
Fernandez, Jorge; MartIn, Fernando [Departamento de Quimica C-9, Universidad Autonoma de Madrid, 28049 Madrid (Spain)], E-mail: fernando.martin@uam.es
2009-04-15
We have evaluated fully differential electron angular distributions in H{sub 2} and D{sub 2} dissociative photoionization by using linearly polarized light of 20, 27 and 33 eV. At 20 eV, the distributions exhibit simple p-wave patterns, which is the signature of direct ionization through the X{sup 2}{sigma}{sub g}{sup +}(1s{sigma}{sub g}) channel. At 27 eV, where the Q{sub 1} autoionizing states are populated, we observe a similar pattern, except when the molecule is oriented perpendicularly to the polarization direction and the energy of the ejected electron is small. In contrast, at 33 eV, autoionization from the Q{sub 1} and Q{sub 2} states leads to interferences between the X{sup 2}{sigma}{sub g}{sup +}(1s{sigma}{sub g}) and {sup 2}{sigma}{sub u}{sup +}(2p{sigma}{sub u}) ionization channels that result in a strong asymmetry of the electron angular distributions along the molecular axis. This asymmetry changes rapidly with the energy of the ejected electron. Electron angular distributions integrated over all possible molecular orientations or ion angular distributions integrated over electron emission angle show no reminiscence of the above phenomena, but the corresponding asymmetry parameters dramatically change with electron and ion energies in the region of autoionizing states.
Octet dominance of nonleptonic hyperon decays in a nonrelativistic quark model
International Nuclear Information System (INIS)
Riazuddin; Fayyazuddin
1978-01-01
Extracting an effective Hamiltonian by taking the nonrelativistic limit of quark-quark scattering through W-boson exchange, it is shown that we obtain octet dominance for the matrix elements , where B/sub r/,B/sub s/ denote ordinary baryons. Further, it is shown that the above matrix elements are enhanced so as to compensate the Cabibbo suppression factor sintheta/sub C/ to some extent
Rowley-Neale, Samuel J.; Fearn, Jamie M.; Brownson, Dale A. C.; Smith, Graham C.; Ji, Xiaobo; Banks, Craig E.
2016-08-01
Two-dimensional molybdenum disulphide nanosheets (2D-MoS2) have proven to be an effective electrocatalyst, with particular attention being focused on their use towards increasing the efficiency of the reactions associated with hydrogen fuel cells. Whilst the majority of research has focused on the Hydrogen Evolution Reaction (HER), herein we explore the use of 2D-MoS2 as a potential electrocatalyst for the much less researched Oxygen Reduction Reaction (ORR). We stray from literature conventions and perform experiments in 0.1 M H2SO4 acidic electrolyte for the first time, evaluating the electrochemical performance of the ORR with 2D-MoS2 electrically wired/immobilised upon several carbon based electrodes (namely; Boron Doped Diamond (BDD), Edge Plane Pyrolytic Graphite (EPPG), Glassy Carbon (GC) and Screen-Printed Electrodes (SPE)) whilst exploring a range of 2D-MoS2 coverages/masses. Consequently, the findings of this study are highly applicable to real world fuel cell applications. We show that significant improvements in ORR activity can be achieved through the careful selection of the underlying/supporting carbon materials that electrically wire the 2D-MoS2 and utilisation of an optimal mass of 2D-MoS2. The ORR onset is observed to be reduced to ca. +0.10 V for EPPG, GC and SPEs at 2D-MoS2 (1524 ng cm-2 modification), which is far closer to Pt at +0.46 V compared to bare/unmodified EPPG, GC and SPE counterparts. This report is the first to demonstrate such beneficial electrochemical responses in acidic conditions using a 2D-MoS2 based electrocatalyst material on a carbon-based substrate (SPEs in this case). Investigation of the beneficial reaction mechanism reveals the ORR to occur via a 4 electron process in specific conditions; elsewhere a 2 electron process is observed. This work offers valuable insights for those wishing to design, fabricate and/or electrochemically test 2D-nanosheet materials towards the ORR.Two-dimensional molybdenum disulphide nanosheets
International Nuclear Information System (INIS)
Speliotopoulos, A.D.; Chiao, Raymond Y.
2004-01-01
The coupling of gravity to matter is explored in the linearized gravity limit. The usual derivation of gravity-matter couplings within the quantum-field-theoretic framework is reviewed. A number of inconsistencies between this derivation of the couplings and the known results of tidal effects on test particles according to classical general relativity are pointed out. As a step towards resolving these inconsistencies, a general laboratory frame fixed on the worldline of an observer is constructed. In this frame, the dynamics of nonrelativistic test particles in the linearized gravity limit is studied, and their Hamiltonian dynamics is derived. It is shown that for stationary metrics this Hamiltonian reduces to the usual Hamiltonian for nonrelativistic particles undergoing geodesic motion. For nonstationary metrics with long-wavelength gravitational waves present (GWs), it reduces to the Hamiltonian for a nonrelativistic particle undergoing geodesic deviation motion. Arbitrary-wavelength GWs couple to the test particle through a vector-potential-like field N a , the net result of the tidal forces that the GW induces in the system, namely, a local velocity field on the system induced by tidal effects, as seen by an observer in the general laboratory frame. Effective electric and magnetic fields, which are related to the electric and magnetic parts of the Weyl tensor, are constructed from N a that obey equations of the same form as Maxwell's equations. A gedankin gravitational Aharonov-Bohm-type experiment using N a to measure the interference of quantum test particles is presented
Energy Technology Data Exchange (ETDEWEB)
Suparmi, A., E-mail: soeparmi@staff.uns.ac.id; Cari, C., E-mail: cari@staff.uns.ac.id; Pratiwi, B. N., E-mail: namakubetanurpratiwi@gmail.com [Physics Department, Faculty of Mathematics and Science, Sebelas Maret University, Jl. Ir. Sutami 36A Kentingan Surakarta 57126 (Indonesia); Deta, U. A. [Physics Department, Faculty of Science and Mathematics Education and Teacher Training, Surabaya State University, Surabaya (Indonesia)
2016-02-08
The analytical solution of D-dimensional Dirac equation for hyperbolic tangent potential is investigated using Nikiforov-Uvarov method. In the case of spin symmetry the D dimensional Dirac equation reduces to the D dimensional Schrodinger equation. The D dimensional relativistic energy spectra are obtained from D dimensional relativistic energy eigen value equation by using Mat Lab software. The corresponding D dimensional radial wave functions are formulated in the form of generalized Jacobi polynomials. The thermodynamically properties of materials are generated from the non-relativistic energy eigen-values in the classical limit. In the non-relativistic limit, the relativistic energy equation reduces to the non-relativistic energy. The thermal quantities of the system, partition function and specific heat, are expressed in terms of error function and imaginary error function which are numerically calculated using Mat Lab software.
International Nuclear Information System (INIS)
Woesler, Richard
2007-01-01
The computations of the present text with non-relativistic quantum teleportation equations and special relativity are totally speculative, physically correct computations can be done using quantum field theory, which remain to be done in future. Proposals for what might be called statistical time loop experiments with, e.g., photon polarization states are described when assuming the simplified non-relativistic quantum teleportation equations and special relativity. However, a closed time loop would usually not occur due to phase incompatibilities of the quantum states. Histories with such phase incompatibilities are called inconsistent ones in the present text, and it is assumed that only consistent histories would occur. This is called an exclusion principle for inconsistent histories, and it would yield that probabilities for certain measurement results change. Extended multiple parallel experiments are proposed to use this statistically for transmission of classical information over distances, and regarding time. Experiments might be testable in near future. However, first a deeper analysis, including quantum field theory, remains to be done in future
Directory of Open Access Journals (Sweden)
Yoshinori Satou
2017-09-01
Full Text Available Cathode materials for lithium-ion batteries containing Ni2+ have attracted much interest because of their high theoretical capacity. However, the precise electronic structures of these cathode materials have not yet been clearly observed, especially the energy positions of the O2p and Ni3d orbitals and the shape of the density of states. The aim of this study was to investigate the relative energy positions and shape of the density of states of O2p and Ni3d for LiNi0.5Mn0.5O2 experimentally. We cleaved a LiNi0.5Mn0.5O2 pellet in an Ar-filled glove box and performed synchrotron ultraviolet photoelectron spectroscopy for different photon energies, which enabled us to investigate the relative cross-section intensity of O2p and Ni3d. As a result, the valence-band structure was determined. We found that O2p electrons are itinerant and exist in the vicinity of the Fermi energy more than Ni3d electrons. Ni3d electrons are more localized and spread mainly from 1.2–1.5 eV below the Fermi energy. To validate the electronic structure, we measured the synchrotron O K-edge X-ray absorption fine structure of electrochemically lithium-extracted LiNi0.5Mn0.5O2. The electronic structure demonstrated that ligand holes in the oxygen atoms form below the Fermi level during the initial stage of Li extraction and that the formation rate of the holes decreases with Li extraction.
Confinement of acoustical modes due to the electron-phonon interaction within 2D-electron gas
International Nuclear Information System (INIS)
Kochelap, V.A.; Gulseren, O.
1992-09-01
We study the confinement of acoustical modes within 2DEG due only to the electron-phonon interaction. The confined modes split out from the bulk phonons even at uniform lattice parameters, when the 2DEG is created by means of modulation doping. The effect is more pronounced when the wave vector q of the modes increases and is maximum at q = 2 k F (k F is the Fermi wave vector). In the case of several electron sheets the additional features of the confinement effect appear. In the limit of the strong electron-phonon coupling and high surface concentration of the electrons the considered system can suffer Peierls-type phase transition. In this case periodical deformation of the lattice and charge density wave are confined within the electron sheet. (author). 18 refs, 2 figs
Wang, Zhuo; Samaraweera, R L; Reichl, C; Wegscheider, W; Mani, R G
2016-12-07
Electron-heating induced by a tunable, supplementary dc-current (I dc ) helps to vary the observed magnetoresistance in the high mobility GaAs/AlGaAs 2D electron system. The magnetoresistance at B = 0.3 T is shown to progressively change from positive to negative with increasing I dc , yielding negative giant-magnetoresistance at the lowest temperature and highest I dc . A two-term Drude model successfully fits the data at all I dc and T. The results indicate that carrier heating modifies a conductivity correction σ 1 , which undergoes sign reversal from positive to negative with increasing I dc , and this is responsible for the observed crossover from positive- to negative- magnetoresistance, respectively, at the highest B.
Weak coupling theory of the ripplon limited mobility of a 2-D electron lattice
International Nuclear Information System (INIS)
Dahm, A.J.; Mehrotra, R.
1981-01-01
The one ripplon-n phonon scattering contribution to the mobility of a 2D electron lattice supported by a liquid helium substrate is calculated in first order perturbation theory to all orders of n in the weak coupling limit. The Debye Waller factor is shown to limit the momentum transfer at large ripplon wave-vectors and high temperatures causing a minimum in the mobility as a function of temperature. (orig.)
Experimental Route to Scanning Probe Hot Electron Nanoscopy (HENs) Applied to 2D Material
Giugni, Andrea
2017-06-09
This paper presents details on a new experimental apparatus implementing the hot electron nanoscopy (HENs) technique introduced for advanced spectroscopies on structure and chemistry in few molecules and interface problems. A detailed description of the architecture used for the laser excitation of surface plasmons at an atomic force microscope (AFM) tip is provided. The photogenerated current from the tip to the sample is detected during the AFM scan. The technique is applied to innovative semiconductors for applications in electronics: 2D MoS2 single crystal and a p-type SnO layer. Results are supported by complementary scanning Kelvin probe microscopy, traditional conductive AFM, and Raman measurements. New features highlighted by HEN technique reveal details of local complexity in MoS2 and polycrystalline structure of SnO at nanometric scale otherwise undetected. The technique set in this paper is promising for future studies in nanojunctions and innovative multilayered materials, with new insight on interfaces.
Study of interactions of a electron beam of 10 MeV energy and matter
International Nuclear Information System (INIS)
Askri, Boubaker
2002-01-01
In this work, we tried to extend the algorithm of the Monte Carlo method to the case of relativistic electrons of energy 10 MeV through the material, after appropriate to the simple case of non-relativistic electrons of energy 20 keV. It was determined the coefficients of reflection, transmission and absorption of electrons through the middle in both cases. As the energy and angular distributions of electrons transmitted. The results show a fairly good precision on the determination of the three coefficients. For the non-relativistic case, it was in 1000 simulations of 1000 lots electrons for gold and aluminum, it has reached an accuracy of about 0.5 pour cent. For the relativistic case, it was 20 lots of simulations for 500 electrons carbon and aluminum. we reached an accuracy of about 2, 5 pour cent determining the coefficients. The energy and angular distributions of electrons transmitted, are close those derived from the program GEANT, taken as a reference and as comparison tool. It hopes to increase the accuracy by increasing the number of lots and the size of each batch of electrons. However, the process took six days to simulate ten miles electrons under normal conditions on the HP9000 machine calculation takes a greatest time of execution for a statistical sample of smaller great. Several criteria are necessary to optimize the study. About improving the theoretical model and the algorithm, and implementation the procedure on a machine more powerful computing. (Author)
Electron-electron bound states in parity-preserving QED{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Belich, H.; Helayel-Neto, J.A. [Universidade Catolica do Petropolis, RJ (Brazil). Grupo de Fisica Teorica]|[Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas; Cima, O.M. del [Universidade Catolica do Petropolis, RJ (Brazil). Grupo de Fisica Teorica; Ferreira Junior, M.M. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas]|[Maranhao Univ., Sao Luis, MA (Brazil). Dept. de Fisica
2002-04-01
By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may dominate. The e{sup -}e{sup -} interaction potential emerges as the non-relativistic limit of the Moeller scattering amplitude and it results attractive with a suitable choice of parameters. Numerically values of the e{sup -}e{sup -} binding energy are obtained by solving the two-dimensional Schroedinger equation. The existence of bound states is a strong indicative that this model may be adopted to address the pairing mechanism of high-T{sub c} superconductivity. (author)
Identities for the electron forms 2 and their 3D representation
International Nuclear Information System (INIS)
Minogin, Vladimir G.
2012-01-01
New type of identities for products of the electron forms 2 (Fs2) and the bilinear forms (BFs) are derived. The identities are found for both temporal Fs2 describing the electron energy and quasi energy densities and spatial Fs2 describing the linear momentum and quasi linear momentum densities. The identities allow one to transform the quasi energy densities into the energy densities as well as the quasi linear momentum densities into the linear momentum densities. It is shown that by choosing any one of the 16 electron temporal or spatial Fs2 one can represent the remaining 15 temporal or spatial Fs2 as combinations of a chosen form 2 (F2) and the derivatives of a number of BFs. Any one of such 16 sets of identities can be considered as a specific form of an irreducible representation for the temporal or spatial Fs2. Similar to the bilinear identities for BFs the derived identities can be used for reduction different physical quantities describing the electron to the forms defined by the basic physical observables. As an example we consider transformation of the electron energy density to a new fundamental form that presents the energy density through the linear momentum density. - Highlights: ► New type of identities connecting electron forms 2 and bilinear forms is derived.► Identities are found for temporal and spatial forms 2. ► Irreducible representation of the identities is derived. ► New forms of the electron energy density are presented.
Reconstruction of 3D structures of MET antibodies from electron microscopy 2D class averages.
Directory of Open Access Journals (Sweden)
Qi Chen
Full Text Available Dynamics of three MET antibody constructs (IgG1, IgG2, and IgG4 and the IgG4-MET antigen complex was investigated by creating their atomic models with an integrative experimental and computational approach. In particular, we used two-dimensional (2D Electron Microscopy (EM images, image class averaging, homology modeling, Rapidly exploring Random Tree (RRT structure sampling, and fitting of models to images, to find the relative orientations of antibody domains that are consistent with the EM images. We revealed that the conformational preferences of the constructs depend on the extent of the hinge flexibility. We also quantified how the MET antigen impacts on the conformational dynamics of IgG4. These observations allow to create testable hypothesis to investigate MET biology. Our protocol may also help describe structural diversity of other antigen systems at approximately 5 Å precision, as quantified by Root-Mean-Square Deviation (RMSD among good-scoring models.
Mahmood, S.; Sadiq, Safeer; Haque, Q.; Ali, Munazza Z.
2016-06-01
The obliquely propagating arbitrary amplitude electrostatic wave is studied in a dense magnetized plasma having singly and doubly charged helium ions with nonrelativistic and ultrarelativistic degenerate electrons pressures. The Fermi temperature for ultrarelativistic degenerate electrons described by N. M. Vernet [(Cambridge University Press, Cambridge, 2007), p. 57] is used to define ion acoustic speed in ultra-dense plasmas. The pseudo-potential approach is used to solve the fully nonlinear set of dynamic equations for obliquely propagating electrostatic waves in a dense magnetized plasma containing helium ions. The upper and lower Mach number ranges for the existence of electrostatic solitons are found which depends on the obliqueness of the wave propagation with respect to applied magnetic field and charge number of the helium ions. It is found that only compressive (hump) soliton structures are formed in all the cases and only subsonic solitons are formed for a singly charged helium ions plasma case with nonrelativistic degenerate electrons. Both subsonic and supersonic soliton hump structures are formed for doubly charged helium ions with nonrelativistic degenerate electrons and ultrarelativistic degenerate electrons plasma case containing singly as well as doubly charged helium ions. The effect of propagation direction on the soliton amplitude and width of the electrostatic waves is also presented. The numerical plots are also shown for illustration using dense plasma parameters of a compact star (white dwarf) from literature.
Corrosion of electron-irradiated Zr-2.5Nb and Zircaloy-2
International Nuclear Information System (INIS)
Woo, O.-T.; McDougall, G.M.; Hutcheon, R.M.; Urbanic, V.F.; Griffiths, M.; Coleman, C.E.
2000-01-01
We used 10-MeV electrons to rapidly produce radiation damage in zirconium alloys, investigated whether electrons produced the same microstructural changes as neutrons, then performed post-irradiation corrosion tests to determine whether electron-irradiated materials displayed similar corrosion behavior to neutron-irradiated materials. Two irradiations were completed using 10-MeV electrons with the beam normal to thin disks of material of 4 diameter slightly larger than the beam. The beam distribution. and disk cooling were designed to produce radial temperature and dose distributions having maxima at the disk center. A high-temperature irradiation was performed on annealed Zr-2.5Nb disks, achieving a central dose of 1.3 dpa and at a central temperature of ∼450 deg C. After irradiation, the samples contained needle-like β-Nb precipitates in the α-Zr matrix similar to those produced by neutrons. A low-temperature irradiation was performed on half-moon disks of Zr-2.5Nb and Zircaloy-2 pressure tube materials at 310 deg C central temperature and 1.3-dpa central dose. Dislocation loops were observed, again similar to those produced in neutron-irradiated materials. Some of the high-temperature electron-irradiated disks were exposed to 300 deg C moist air (saturated with D 2 O), and in separate tests, high- and low-temperature irradiated disks were corroded in 300 deg C D 2 0 (11.0 pD at room temperature) in an autoclave. Measurements of oxide thickness by Fourier Transform Infrared Reflectance (FTIR) spectroscopy showed that electron irradiation reduced the corrosion rate of Zr-2.5Nb compared with that of unirradiated material, as observed for neutron irradiation. For exposures to moist air and to D 2 O, the theoretical deuterium uptakes for the electron-irradiated materials were, respectively, about 4 times and 1.5 to 2 times those for the unirradiated materials. This is also in good agreement with results for neutron-irradiated pressure tube materials. Thus, 10-Me
The equation of motion of an electron: a debate in classical and quantum physics
International Nuclear Information System (INIS)
Kim, K.-J.
1999-01-01
The current status of understanding of the equation of motion of an electron is summarized. Classically, a consistent, linearized theory exists for an electron of finite extent, as long as the size of the electron is larger than the classical electron radius. Nonrelativistic quantum mechanics seems to offer a tine theory even in the point-particle limit
Crossover from 2d to 3d in anisotropic Kondo lattices
International Nuclear Information System (INIS)
Reyes, D.; Continentino, M.A.
2008-01-01
We study the crossover from two to three dimensions in Kondo lattices (KLM) using the Kondo necklace model (KNM). In order to diagonalize the KNM, we use a representation for the localized and conduction electron spins in terms of bond operators and a decoupling for the relevant Green's functions. Both models have a quantum critical point at a finite value of the ratio (J/t) between the Kondo coupling (J) and the hopping (t). In 2d there is no line of finite temperature antiferromagnetic (AF) transitions while for d≥3 this line is given by, T N ∝|g| 1/(d-1) [D. Reyes, M.A. Continentino, Phys. Rev. B 76 (2007) 075114]. The crossover from 2d to 3d is investigated by turning on the electronic hopping (t -perpendicular ) of conduction electrons between different planes. The phase diagram as a function of temperature T, J/t -parallel and ξ=t -perpendicular /t -parallel , where t -parallel is the hopping within the planes is calculated
Piñeiro Orioli, Asier; Boguslavski, Kirill; Berges, Jürgen
2015-07-01
We investigate universal behavior of isolated many-body systems far from equilibrium, which is relevant for a wide range of applications from ultracold quantum gases to high-energy particle physics. The universality is based on the existence of nonthermal fixed points, which represent nonequilibrium attractor solutions with self-similar scaling behavior. The corresponding dynamic universality classes turn out to be remarkably large, encompassing both relativistic as well as nonrelativistic quantum and classical systems. For the examples of nonrelativistic (Gross-Pitaevskii) and relativistic scalar field theory with quartic self-interactions, we demonstrate that infrared scaling exponents as well as scaling functions agree. We perform two independent nonperturbative calculations, first by using classical-statistical lattice simulation techniques and second by applying a vertex-resummed kinetic theory. The latter extends kinetic descriptions to the nonperturbative regime of overoccupied modes. Our results open new perspectives to learn from experiments with cold atoms aspects about the dynamics during the early stages of our universe.
D-Zero muon readout electronics design
International Nuclear Information System (INIS)
Baldin, B.; Hansen, S.; Los, S.; Matveev, M.; Vaniev, V.
1996-11-01
The readout electronics designed for the D null Muon Upgrade are described. These electronics serve three detector subsystems and one trigger system. The front-ends and readout hardware are synchronized by means of timing signals broadcast from the D null Trigger Framework. The front-end electronics have continuously running digitizers and two levels of buffering resulting in nearly deadtimeless operation. The raw data is corrected and formatted by 16- bit fixed point DSP processors. These processors also perform control of the data buffering. The data transfer from the front-end electronics located on the detector platform is performed by serial links running at 160 Mbit/s. The design and test results of the subsystem readout electronics and system interface are discussed
Towards atomically precise manipulation of 2D nanostructures in the electron microscope
Susi, Toma; Kepaptsoglou, Demie; Lin, Yung-Chang; Ramasse, Quentin M.; Meyer, Jannik C.; Suenaga, Kazu; Kotakoski, Jani
2017-12-01
Despite decades of research, the ultimate goal of nanotechnology—top-down manipulation of individual atoms—has been directly achieved with only one technique: scanning probe microscopy. In this review, we demonstrate that scanning transmission electron microscopy (STEM) is emerging as an alternative method for the direct assembly of nanostructures, with possible applications in plasmonics, quantum technologies, and materials science. Atomically precise manipulation with STEM relies on recent advances in instrumentation that have enabled non-destructive atomic-resolution imaging at lower electron energies. While momentum transfer from highly energetic electrons often leads to atom ejection, interesting dynamics can be induced when the transferable kinetic energies are comparable to bond strengths in the material. Operating in this regime, very recent experiments have revealed the potential for single-atom manipulation using the Ångström-sized electron beam. To truly enable control, however, it is vital to understand the relevant atomic-scale phenomena through accurate dynamical simulations. Although excellent agreement between experiment and theory for the specific case of atomic displacements from graphene has been recently achieved using density functional theory molecular dynamics, in many other cases quantitative accuracy remains a challenge. We provide a comprehensive reanalysis of available experimental data on beam-driven dynamics in light of the state-of-the-art in simulations, and identify important targets for improvement. Overall, the modern electron microscope has great potential to become an atom-scale fabrication platform, especially for covalently bonded 2D nanostructures. We review the developments that have made this possible, argue that graphene is an ideal starting material, and assess the main challenges moving forward.
Spin rotation function in a microscopic non-relativistic optical model
International Nuclear Information System (INIS)
Bauhoff, W.
1984-01-01
A microscopic optical potential, which is calculated non-relativistically with a density-dependent effective force, is used to calculate cross-section, polarization and spin-rotation function for elastic proton scattering from 40 Ca at 160 MeV and 497 MeV. At 160 MeV, the agreement to the data is comparable to phenomenological fits, and the spin-rotation can be used to distinguish between microscopic and Woods-Saxon potentials. A good fit to the spin-rotation function results at 497 MeV, whereas the polarization data are not well reproduced
ICF target 2D modeling using Monte Carlo SNB electron thermal transport in DRACO
Chenhall, Jeffrey; Cao, Duc; Moses, Gregory
2016-10-01
The iSNB (implicit Schurtz Nicolai Busquet multigroup diffusion electron thermal transport method is adapted into a Monte Carlo (MC) transport method to better model angular and long mean free path non-local effects. The MC model was first implemented in the 1D LILAC code to verify consistency with the iSNB model. Implementation of the MC SNB model in the 2D DRACO code enables higher fidelity non-local thermal transport modeling in 2D implosions such as polar drive experiments on NIF. The final step is to optimize the MC model by hybridizing it with a MC version of the iSNB diffusion method. The hybrid method will combine the efficiency of a diffusion method in intermediate mean free path regions with the accuracy of a transport method in long mean free path regions allowing for improved computational efficiency while maintaining accuracy. Work to date on the method will be presented. This work was supported by Sandia National Laboratories and the Univ. of Rochester Laboratory for Laser Energetics.
International Nuclear Information System (INIS)
Arnold, R.G.; Chertok, B.T.; Dally, E.B.; Grigorian, A.; Jordan, C.L.; Schuetz, W.P.; Zdarko, R.; Martin, F.; Mecking, B.A.
1975-06-01
Preliminary results of elastic eD scattering at large momentum transfer performed at the Stanford Linear Accelerator Center using two high resolution spectrometers in coincidence are reported. The deuteron structure function A(q 2 ) is deduced at 9 values of q 2 from a comparison of elastic eD and eP coincident yields and the world's eP cross sections. These measurements extend the range of q 2 by 4.5 over previous work, and in this new range A(q 2 ) is observed to approach 1/q 20 momentum dependence. Results are in sharp disagreement with the meson exchange calculations, and they are in rough agreement with the nonrelativistic potential models, and they are in agreement with the predictions of the quark dimensional scaling model which pictures the deuteron as a bound state of 6 quarks at large momentum transfer
The anomalous magnetic moment of the electron
International Nuclear Information System (INIS)
Awobode, A.M.
2002-05-01
The gyromagnetic ratio g of an electron is calculated by taking the non-relativistic limit of a newly proposed extension of the Dirac Hamiltonian coupled to a magnetic field. It is observed that the calculated g is greater than 2; the Dirac theory had predicted that g=2 in sharp contradiction with accurate experimental observations. The additional quantity (g-2)/2≡δ∼(1.6x10 -3 ) is shown here to be due to an extra term which appears in the reduced Hamiltonian, as a consequence of the modification of the rest energy. No divergences are encountered in the calculations described. (author)
Classical particle limit of non-relativistic quantum mechanics
International Nuclear Information System (INIS)
Zucchini, R.
1984-01-01
We study the classical particle limit of non-relativistic quantum mechanics. We show that the unitary group describing the evolution of the quantum fluctuation around any classical phase orbit has a classical limit as h → 0 in the strong operator topology for a very large class of time independent scalar and vector potentials, which in practice covers all physically interesting cases. We also show that the mean values of the quantum mechanical position and velocity operators on suitable states, obtained by time evolution of the product of a Weyl operator centred around the large coordinates and momenta and a fixed n-independent wave function, converge to the solution of the classical equations with initial data as h → 0 for a broad class of repulsive interactions
Recent investigations on electronic capture in atomic collisions
International Nuclear Information System (INIS)
Rivarola, R.D.
1988-01-01
In this work, electron capture processes in ion-atom collisions at various impact energy ranges are dicussed: i) intermediate non-relativistic energy; ii) high energy; iii) high relativistic energy. Much attention is given to the development and use of distorted wave models. (A.C.A.S.) [pt
On 2D electron cloud dynamics in high-current plasma lens for ion beam focusing
International Nuclear Information System (INIS)
Goncharov, A. A.; Litovko, I. V.; Onishchenko, I. N.; Zadorozhny, V. F.
1997-01-01
In this paper we are dealing with the appear the stable existence and dynamics of 2-D electron vortical structures in crossed electric and magnetic fields. The collective interactions in which the electron motion is nonlinear and ion motion is linear, is concerned. By using of the kinetic equation and the catastrophe theory approach we deduce an origin of the vortical structures. The nonlinear differential equation for the electric potential in a hydrodynamical approximation is obtained. It describes a drift motion of the electrons in oscillating electric fields of the high-current plasma lens(PL), arising due to presence the principal unremoval radical gradient of the axical component of the magnetic field. It was shown that the considered equations have contained the solutions in the form of the single vortical structures. The stability of the structures are given
International Nuclear Information System (INIS)
Onufrieva, F.; Pfeuty, P.
1999-01-01
A new microscopic scenario for high T c cuprates based on the existence of an electronic topological transition (ETT) in a strongly correlated 2D electron system has been developed recently. We first briefly sketch the principal results concerning the behaviour of a 2D fermion system on a square lattice close to an ETT and the main consequences for a strongly correlated system: d-wave superconductivity and SDW (CDW) quantum liquid state above T SC . We then illustrate how this theory can explain several crucial experimental facts (observed by NMR, angle resolved photoemission spectroscopy (ARPES), tunneling spectroscopy, inelastic neutron scattering) which reveal anomalous behavior in the SC state and in the metallic state above T s c. (orig.)
Positron-Electron Annihilation Process in (2,2)-Difluoropropane Molecule
Liu, Yang; Ma, Xiao-Guang; Zhu, Ying-Hao
2016-04-01
The positron-electron annihilation process in (2,2)-difluoropropane molecule and the corresponding gamma-ray spectra are studied by quantum chemistry method. The positrophilic electrons in (2,2)-difluoropropane molecule are found for the first time. The theoretical predictions show that the outermost 2s electrons of fluoride atoms play an important role in positron-electron annihilation process of (2,2)-difiuoropropane. In the present scheme, the correlation coefficient between the theoretical gamma-ray spectra and the experiments can be 99%. The present study gives an alternative annihilation model for positron-electron pair in larger molecules. Supported by the National Natural Science Foundation of China under Grant No. 11347011 and the Natural Science Foundation Project of Shandong Province under Grant No. ZR2011AM010 and 2014 Technology Innovation Fund of Ludong University under Grant Nos. 1d151007 and ld15l016
Exact diagonalization of the interacting propagator for the 2D-electron gas in a magnetic field
International Nuclear Information System (INIS)
Burke, A.; Cabo, A.
1990-07-01
The spatial dependence of the exact one electron propagator for an interacting 2D-electron gas in a magnetic field is shown to be the same as for a non-interacting gas. This happens whenever the translational symmetry is unbroken in the ground state. The result may be extended to a more general class of systems. The translational symmetry also implies that the density of states has the same kind of discrete character as in the non-interacting case. This is shown explicitly in the Hartree-Fock approximation by solving the Dyson equation. (author). 10 refs
Corrosion of electron-irradiated Zr-2.5Nb and Zircaloy-2
Energy Technology Data Exchange (ETDEWEB)
Woo, O.-T.; McDougall, G.M.; Hutcheon, R.M.; Urbanic, V.F.; Griffiths, M.; Coleman, C.E
2000-07-01
We used 10-MeV electrons to rapidly produce radiation damage in zirconium alloys, investigated whether electrons produced the same microstructural changes as neutrons, then performed post-irradiation corrosion tests to determine whether electron-irradiated materials displayed similar corrosion behavior to neutron-irradiated materials. Two irradiations were completed using 10-MeV electrons with the beam normal to thin disks of material of 4 diameter slightly larger than the beam. The beam distribution. and disk cooling were designed to produce radial temperature and dose distributions having maxima at the disk center. A high-temperature irradiation was performed on annealed Zr-2.5Nb disks, achieving a central dose of 1.3 dpa and at a central temperature of {approx}450 deg C. After irradiation, the samples contained needle-like {beta}-Nb precipitates in the {alpha}-Zr matrix similar to those produced by neutrons. A low-temperature irradiation was performed on half-moon disks of Zr-2.5Nb and Zircaloy-2 pressure tube materials at 310 deg C central temperature and 1.3-dpa central dose. Dislocation loops were observed, again similar to those produced in neutron-irradiated materials. Some of the high-temperature electron-irradiated disks were exposed to 300 deg C moist air (saturated with D{sub 2}O), and in separate tests, high- and low-temperature irradiated disks were corroded in 300 deg C D{sub 2}0 (11.0 pD at room temperature) in an autoclave. Measurements of oxide thickness by Fourier Transform Infrared Reflectance (FTIR) spectroscopy showed that electron irradiation reduced the corrosion rate of Zr-2.5Nb compared with that of unirradiated material, as observed for neutron irradiation. For exposures to moist air and to D{sub 2}O, the theoretical deuterium uptakes for the electron-irradiated materials were, respectively, about 4 times and 1.5 to 2 times those for the unirradiated materials. This is also in good agreement with results for neutron-irradiated pressure
International Nuclear Information System (INIS)
Tsuji, Masaharu; Matsuzaki, Toshinori; Tsuji, Takeshi
2002-01-01
The Ar + /2e - collisional radiative recombination has been studied by observing UV and visible emissions of Ar* in an Ar flowing afterglow. In order to clarify recombination mechanism, the Ar + ( 2 P 3/2 ) spin-orbit component was selected by using a filter gas of the Ar + ( 2 P 1/2 ) component. Spectral analysis indicated that 34 Ar*(4p, 4d, 5p, 5d, 6s, 6p, 6d, 4p ' , 4d ' , 5p ' , 5d ' , 6s ' ) states in the 13.08-15.33 eV range are produced. The electronic-state distribution decreased with an increase in the excitation energy of Ar*, which was expressed by a Boltzmann electronic temperature of 0.54 eV. The formation ratios of the 4p: 4d + 5p + 5d + 6s + 6p + 6d: 4p ' : 4d ' + 5p ' + 5d ' + 6s ' states were 43%, 2.8%, 54%, and 0.31%, respectively. The high formation ratio of the 4p ' state having an Ar + ( 2 P 1/2 ) ion core in the Ar + ( 2 P 3/2 )/2e - recombination indicated that such a two-electron process as an electron transfer to an inner 3p orbital followed by excitation of a 3p electron to an outer 4p orbital occurs significantly. The higher formation ratios of 4d + 5p + 5d + 6s + 6p + 6d than those of 4d ' + 5p ' + 5d ' + 6s ' led us to conclude the formation of these upper states dominantly proceeds through one electron transfer to an outer nl orbital of Ar + ( 2 P 3/2 )
NONTHERMALLY DOMINATED ELECTRON ACCELERATION DURING MAGNETIC RECONNECTION IN A LOW-β PLASMA
International Nuclear Information System (INIS)
Li, Xiaocan; Li, Gang; Guo, Fan; Li, Hui
2015-01-01
By means of fully kinetic simulations, we investigate electron acceleration during magnetic reconnection in a nonrelativistic proton–electron plasma with conditions similar to solar corona and flares. We demonstrate that reconnection leads to a nonthermally dominated electron acceleration with a power-law energy distribution in the nonrelativistic low-β regime but not in the high-β regime, where β is the ratio of the plasma thermal pressure and the magnetic pressure. The accelerated electrons contain most of the dissipated magnetic energy in the low-β regime. A guiding-center current description is used to reveal the role of electron drift motions during the bulk nonthermal energization. We find that the main acceleration mechanism is a Fermi-type acceleration accomplished by the particle curvature drift motion along the electric field induced by the reconnection outflows. Although the acceleration mechanism is similar for different plasma β, low-β reconnection drives fast acceleration on Alfvénic timescales and develops power laws out of thermal distribution. The nonthermally dominated acceleration resulting from magnetic reconnection in low-β plasma may have strong implications for the highly efficient electron acceleration in solar flares and other astrophysical systems
International Nuclear Information System (INIS)
Cari, C; Suparmi, A; Yunianto, M; Pratiwi, B N
2016-01-01
The Dirac equation of q-deformed hyperbolic Manning Rosen potential in D dimension was solved by using Supersymmetric Quantum Mechanics (SUSY QM). The D dimensional relativistic energy spectra were obtained by using SUSY QM and shape invariant properties and D dimensional wave functions of q-deformed hyperbolic Manning Rosen potential were obtained by using the SUSY raising and lowering operators. In the nonrelativistic limit, the relativistic energy spectra for exact spin symmetry case reduced into nonrelativistic energy spectra and so for the wave functions. In the classical regime, the partition function, the vibrational specific heat, and the vibrational mean energy of some diatomic molecules were calculated from the non-relativistic energy spectra with the help of error function and imaginary error function. (paper)
Absorption of resonant electromagnetic radiation in electron-atom collisions
International Nuclear Information System (INIS)
Arslanbekov, T.U.; Pazdzerskii, V.A.; Usachenko, V.I.
1986-01-01
Nonrelativistic quantum theory is used to study the possibility of amplification of electromagnetic radiation in forced braking scattering of an electron beam on atoms. The interaction of the atom with the electromagnetic field is considered in the resonant approximation. Cases of large and small detuning from resonance are considered. It is shown that for any orientation of the electron beam relative to the field polarization vector, absorption of radiation occurs, with the major contribution being produced by atomic electrons
Khazanov, George V.; Sibeck, David G.
2013-01-01
The interaction of electrons with coherent chorus waves in the random phase approximation can be described as quasi-linear diffusion for waves with amplitudes below some limit. The limit is calculated for relativistic and non-relativistic electrons. For stronger waves, the friction force should be taken into account.
Fernandez, Eduardo; Borelli, Noah; Cappelli, Mark; Gascon, Nicolas
2003-10-01
Most current Hall thruster simulation efforts employ either 1D (axial), or 2D (axial and radial) codes. These descriptions crucially depend on the use of an ad-hoc perpendicular electron mobility. Several models for the mobility are typically invoked: classical, Bohm, empirically based, wall-induced, as well as combinations of the above. Experimentally, it is observed that fluctuations and electron transport depend on axial distance and operating parameters. Theoretically, linear stability analyses have predicted a number of unstable modes; yet the nonlinear character of the fluctuations and/or their contribution to electron transport remains poorly understood. Motivated by these observations, a 2D code in the azimuthal and axial coordinates has been written. In particular, the simulation self-consistently calculates the azimuthal disturbances resulting in fluctuating drifts, which in turn (if properly correlated with plasma density disturbances) result in fluctuation-driven electron transport. The characterization of the turbulence at various operating parameters and across the channel length is also the object of this study. A description of the hybrid code used in the simulation as well as the initial results will be presented.
ηc production at the LHC challenges nonrelativistic-QCD factorization
International Nuclear Information System (INIS)
Butenschoen, Mathias; He, Zhi-Guo; Kniehl, Bernd A.
2014-11-01
We analyze the first measurement of η c production, performed by the LHCb Collaboration, in the nonrelativistic-QCD (NRQCD) factorization framework at next-to-leading order (NLO) in the strong-coupling constant α s and the relative velocity v of the bound quarks including the feeddown from h c mesons. Converting the long-distance matrix elements (LDMEs) extracted by various groups from J/ψ yield and polarization data to the η c case using heavy-quark spin symmetry, we find that the resulting NLO NRQCD predictions greatly overshoot the LHCb data, while the color-singlet model provides an excellent description.
International Nuclear Information System (INIS)
Rangelov, J.M.
1986-01-01
An electron model is proposed explaining the physical reasons for its nonrelativistic quantum-mechanical behaviour, the origin of its own mechanical and magnetic momentum and field energy. As an example the main electron state in hydrogen atom is obtained
Reactive collisions of electrons with H2+ , HD+, BeH+, BeD+ and SH+
Pop, Nicolina; Iacob, Felix; Mezei, János Zsolt; Motapon, Ousmanou; Niyonzima, Sebastien; Kashinski, David O.; Talbi, Dahbia; Hickman, Albert Peet; Schneider, Ioan F.
2017-12-01
In numerous cold ionized gases the dissociative recombination (DR), the elastic collisions (EC), the vibrational excitation (VE) (inelastic collisions) and the vibrational de-excitation (VdE) (super-elastic collisions) of molecular cations with electrons are major elementary processes. Using a stepwise method based on the Multichannel Quantum Defect Theory (MQDT), cross sections and rate coefficients have been obtained for reactions induced on HD+, H2+, BeH+, BeD+ and SH+. Moreover, the relative importance of the different reaction mechanisms, direct vs. indirect and rotational vs. non-rotational, have been studied for these molecular systems.
Protein 3D Structure and Electron Microscopy Map Retrieval Using 3D-SURFER2.0 and EM-SURFER.
Han, Xusi; Wei, Qing; Kihara, Daisuke
2017-12-08
With the rapid growth in the number of solved protein structures stored in the Protein Data Bank (PDB) and the Electron Microscopy Data Bank (EMDB), it is essential to develop tools to perform real-time structure similarity searches against the entire structure database. Since conventional structure alignment methods need to sample different orientations of proteins in the three-dimensional space, they are time consuming and unsuitable for rapid, real-time database searches. To this end, we have developed 3D-SURFER and EM-SURFER, which utilize 3D Zernike descriptors (3DZD) to conduct high-throughput protein structure comparison, visualization, and analysis. Taking an atomic structure or an electron microscopy map of a protein or a protein complex as input, the 3DZD of a query protein is computed and compared with the 3DZD of all other proteins in PDB or EMDB. In addition, local geometrical characteristics of a query protein can be analyzed using VisGrid and LIGSITE CSC in 3D-SURFER. This article describes how to use 3D-SURFER and EM-SURFER to carry out protein surface shape similarity searches, local geometric feature analysis, and interpretation of the search results. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.
On the Electronic Structure of [Cu(H2O)6]2+
DEFF Research Database (Denmark)
Tanaka, Kiyoshi; Johansen, Helge
1997-01-01
The electronic structure of the ground state and doublet excited states due to d-d transitions and charge transfer transitions from ligand to copper of [Cu(H2O)6]2+ are investigated by ab initio calculations. The excited states corresponding to the the d-d transitions are calculated to be 1.1 - 1...... on the description of these excited states. The chargetransfer excitations are predicted to start around 6.5 eV for [Cu(H2O)6]2+....
International Nuclear Information System (INIS)
Kukhtin, V.V.; Kuzmenko, M.V.
2000-01-01
Complete text of publication follows. Recent studies (1) have shown that the Schroedinger nonrelativistic wave equation for a system of interacting particles is not a rigorously nonrelativistic one since it is based on the implicit assumption that the interaction propagation velocity is a finite value, which implies commutativity of the operators of coordinates and momenta of different particles. The refusal from this assumption implies their noncommutativity, which allows one to construct a truly nonrelativistic nonlinear self-consistent wave equation for a system of interacting particles. In the frame of the advanced wave equation, we investigate the spectrum of bound states for the two-body problem with the Yukawa potential V(r) = -V 0 a exp(-r/a)/r as a function of parameters of the potential. A peculiar feature of the spectrum is the presence of a critical value of V 0 (with the fixed parameter a), above which the given bound state cannot exist. In the ground state with l = 0 at a critical value of V 0 , the mean distance between particles takes the least value equal to the Compton wavelength of the particle with reduced mass. We estimate the parameter of noncommutativity ε for the operators of the coordinate of one particle and of the momentum of other one ([χ 1 , p 2x ] = i(h/2π)m 2 /M x ε) for the bound state of a deuteron, for which we consider the lowest state with l = 0 as its ground state. The parameter a of the Yukawa potential is taken to be equal to the Compton wavelength of a pion, 1.41 fm. In order to obtain the binding energy of a deuteron E = -2.22452 MeV, the parameter V 0 has to equal 51.23 MeV. In this case, the parameter of noncommutativity ε for the operators of the coordinate of one particle and of the momentum of other one ε = 0.0011, i.e., the commutator is nonzero even for such a weakly bound system as a deuteron where particles are located outside the region of action of nuclear forces for a significant fraction of time. Moreover
Borelli, M. E. S.; Kleinert, H.; Schakel, Adriaan M. J.
2000-03-01
The effect of quantum fluctuations on a nearly flat, nonrelativistic two-dimensional membrane with extrinsic curvature stiffness and tension is investigated. The renormalization group analysis is carried out in first-order perturbative theory. In contrast to thermal fluctuations, which soften the membrane at large scales and turn it into a crumpled surface, quantum fluctuations are found to stiffen the membrane, so that it exhibits a Hausdorff dimension equal to two. The large-scale behavior of the membrane is further studied at finite temperature, where a nontrivial fixed point is found, signaling a crumpling transition.
Flexible 2D layered material junctions
Balabai, R.; Solomenko, A.
2018-03-01
Within the framework of the methods of the electron density functional and the ab initio pseudopotential, we have obtained the valence electron density spatial distribution, the densities of electron states, the widths of band gaps, the charges on combined regions, and the Coulomb potentials for graphene-based flexible 2D layered junctions, using author program complex. It is determined that the bending of the 2D layered junctions on the angle α leads to changes in the electronic properties of these junctions. In the graphene/graphane junction, there is clear charge redistribution with different signs in the regions of junctions. The presence in the heterojunctions of charge regions with different signs leads to the formation of potential barriers. The greatest potential jump is in the graphene/fluorographene junction. The greatest value of the band gap width is in the graphene/graphane junction.
Satellite structure of the xenon valence shell by electron momentum spectroscopy
International Nuclear Information System (INIS)
Braidwood, S.; Brunger, M.; Weigold, E.
1992-05-01
Momentum distributions and spectroscopic factors are obtained in a high resolution electron momentum spectroscopy (EMS) study of xenon at 1000 eV. The shapes and relative magnitudes of the momentum profiles are in excellent agreement with distorted-wave impulse approximations using the target Dirac-Fock approximation. The DWDF approximation accurately describes the relative magnitudes of the 5p and 5s manifold cross sections as well as the shape of the 5s cross section. The use of nonrelativistic Hartree-Fock wavefunctions gives significantly poorer fits to the data. Spectroscopic factors for transitions belonging to the 2 S e 1/2 ,P 0 1/2,3/2 , and 2 D 3 3/2,5/2 manifolds are assigned up to a separation energy of 45 eV. The spectroscopic strength for the lowest 5s transition is 0.345 ± 0.010 whereas that for the ground state 5p transition is 0.96 ± 0.02. The 5s strength in the continuum above 33.1 eV is 0.115 ± 0.025 and that for the 5p manifold is only 0.03± 0.01. The first momentum profiles belong to excited 2 P o and 2 D e manifolds are obtained. The latter, which must be entirely due to d-wave correlations in the xenon ground state, are in good agreement with DF 5d momentum profiles. Comparison is made with several many-body calculations and agreement with the latest relativistic calculation is very good. 26 refs., 3 tabs., 5 figs
Dissociative resonance electron capture in methylmercaptane and methylmercaptane-d3
International Nuclear Information System (INIS)
Sugiura, Toshio; Arakawa, Kazuo.
1975-01-01
The formation of negative ions by electron impact of methylmercaptane and methylmercaptane-3 3 has been investigated as a function of the electron energy. Appearance potentials, energies of resonance peaks, full widths of half maxima in resonance peak and relative formation cross sections have been determined about the negative ions of H - , D - , CH 3 S - , CD 3 S - , SH - , S - , CH 2 - , CD 2 - , Ch - and CD - . The dissociation energy of S-H bond and an electron affinity of CH 3 S radical have been determined as 4.7 +- 0.1 and 3.18 +- 0.2 eV, respectively. (auth.)
3D shaping of electron beams using amplitude masks
Energy Technology Data Exchange (ETDEWEB)
Shiloh, Roy, E-mail: royshilo@post.tau.ac.il; Arie, Ady
2017-06-15
Highlights: • Electron beams are shaped in 3D with examples of curves and lattices. • Computer generated holograms are manifested as binary amplitude masks. • Applications in electron-optical particle trapping, manipulation, and synthesis. • Electron beam lithography fabrication scheme explained in detail. • Measurement paradigms of 3D shaped beams are discussed. - Abstract: Shaping the electron wavefunction in three dimensions may prove to be an indispensable tool for research involving atomic-sized particle trapping, manipulation, and synthesis. We utilize computer-generated holograms to sculpt electron wavefunctions in a standard transmission electron microscope in 3D, and demonstrate the formation of electron beams exhibiting high intensity along specific trajectories as well as shaping the beam into a 3D lattice of hot-spots. The concepts presented here are similar to those used in light optics for trapping and tweezing of particles, but at atomic scale resolutions.
Suparmi, A.; Cari, C.; Pratiwi, B. N.
2016-04-01
D-dimensional Dirac equation of q-deformed modified Poschl-Teller plus Manning Rosen non-central potential was solved using supersymmetric quantum mechanics (SUSY QM). The relativistic energy spectra were analyzed by using SUSY QM and shape invariant properties from radial part of D dimensional Dirac equation and the angular quantum numbers were obtained from angular part of D dimensional Dirac equation. The SUSY operators was used to generate the D dimensional relativistic wave functions both for radial and angular parts. In the non-relativistic limit, the relativistic energy equation was reduced to the non-relativistic energy. In the classical limit, the partition function of vibrational, the specific heat of vibrational, and the mean energy of vibrational of some diatomic molecules were calculated from the equation of non-relativistic energy with the help of error function and Mat-lab 2011.
International Nuclear Information System (INIS)
Seguatni, A.; Fakhfakh, M.; Smiri, L.S.; Gressier, P.; Boucher, F.; Jouini, N.
2012-01-01
A new inorganic-organic compound [Cu(O 2 C–CH 2 –CO 2 H) 2 ·2H 2 O] ([Cumal]) was hydrothermally synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray diffraction. [Cumal] is the first three-dimensional compound existing in the system Cu(II)–malonic acid–H 2 O. Its framework is built up through carboxyl bridged copper where CuO 6 octahedra are elongated with an almost D 4h symmetry (4+2) due to the Jahn–Teller effect. The magnetic properties were studied by measuring its magnetic susceptibility in the temperature range of 2–300 K indicating the existence of weak ferromagnetic interactions. The electronic structure of [Cumal] was calculated within the density functional theory (DFT) framework. Structural features are well reproduced using DFT structural optimizations and the optical spectra, calculated within the dielectric formalism, explain very well the light blue colour of the compound. It is shown that a GGA+U approach with a U eff value of about 6 eV is necessary for a better correlation with the experiment. - Graphical abstract: [Cu(O 2 C–CH 2 –CO 2 H) 2 ·2H 2 O]: the first 3D hybrid organic–inorganic compound built up carboxyl groups. The network presents a diamond-like structure achieved via carboxyl. Highlights: ► A new organic–inorganic material with an unprecedented topology is synthesized. ► Crystallographic structure is determined using single crystal X-ray diffraction. ► Electronic structure is obtained from DFT, GGA+U calculation. ► Framework can be described as formed from CuC 4 tetrahedron sharing four corners. ► This structure can be classified as an extended diamond structure.
Anasori, Babak
2016-02-24
In this study, a transition from metallic to semiconducting-like behavior has been demonstrated in two-dimensional (2D) transition metal carbides by replacing titanium with molybdenum in the outer transition metal (M) layers of M3C2 and M4C3 MXenes. The MXene structure consists of n + 1 layers of near-close packed M layers with C or N occupying the octahedral site between them in an [MX]nM arrangement. Recently, two new families of ordered 2D double transition metal carbides MXenes were discovered, M′2M′′C2 and M′2M′′2C3 – where M′ and M′′ are two different early transition metals, such as Mo, Cr, Ta, Nb, V, and Ti. The M′ atoms only occupy the outer layers and the M′′ atoms fill the middle layers. In other words, M′ atomic layers sandwich the middle M′′–C layers. Using X-ray atomic pair distribution function (PDF) analysis on Mo2TiC2 and Mo2Ti2C3 MXenes, we present the first quantitative analysis of structures of these novel materials and experimentally confirm that Mo atoms are in the outer layers of the [MC]nM structures. The electronic properties of these Mo-containing MXenes are compared with their Ti3C2 counterparts, and are found to be no longer metallic-like conductors; instead the resistance increases mildly with decreasing temperatures. Density functional theory (DFT) calculations suggest that OH terminated Mo–Ti MXenes are semiconductors with narrow band gaps. Measurements of the temperature dependencies of conductivities and magnetoresistances have confirmed that Mo2TiC2Tx exhibits semiconductor-like transport behavior, while Ti3C2Tx is a metal. This finding opens new avenues for the control of the electronic and optical applications of MXenes and for exploring new applications, in which semiconducting properties are required.
Campos, Cesar T; Jorge, Francisco E; Alves, Júlia M A
2012-09-01
Recently, segmented all-electron contracted double, triple, quadruple, quintuple, and sextuple zeta valence plus polarization function (XZP, X = D, T, Q, 5, and 6) basis sets for the elements from H to Ar were constructed for use in conjunction with nonrelativistic and Douglas-Kroll-Hess Hamiltonians. In this work, in order to obtain a better description of some molecular properties, the XZP sets for the second-row elements were augmented with high-exponent d "inner polarization functions," which were optimized in the molecular environment at the second-order Møller-Plesset level. At the coupled cluster level of theory, the inclusion of tight d functions for these elements was found to be essential to improve the agreement between theoretical and experimental zero-point vibrational energies (ZPVEs) and atomization energies. For all of the molecules studied, the ZPVE errors were always smaller than 0.5 %. The atomization energies were also improved by applying corrections due to core/valence correlation and atomic spin-orbit effects. This led to estimates for the atomization energies of various compounds in the gaseous phase. The largest error (1.2 kcal mol(-1)) was found for SiH(4).
Allen, S. James; Ouellette, Daniel G.; Moetakef, Pouya; Cain, Tyler; Chen, Ru; Balents, Leon; Stemmer, Susanne
2013-03-01
By reducing the number of SrO planes in a GdTiO3 /SrTiO3/ GdTiO3 quantum well heterostructure, an electron gas with ~ fixed 2D electron density can be driven close to the Mott metal insulator transition - a quantum critical point at ~1 electron per unit cell. A single interface between the Mott insulator GdTiO3 and band insulator SrTiO3 has been shown to introduce ~ 1/2 electron per interface unit cell. Two interfaces produce a quantum well with ~ 7 1014 cm-2 electrons: at the limit of a single SrO layer it may produce a 2D magnetic Mott insulator. We use temperature and frequency dependent (DC - 3eV) conductivity and temperature dependent magneto-transport to understand the relative importance of electron-electron interactions, electron-phonon interactions, and surface roughness scattering as the electron gas is compressed toward the quantum critical point. Terahertz time-domain and FTIR spectroscopies, measure the frequency dependent carrier mass and scattering rate, and the mid-IR polaron absorption as a function of quantum well thickness. At the extreme limit of a single SrO plane, we observe insulating behavior with an optical gap substantially less than that of the surrounding GdTiO3, suggesting a novel 2D Mott insulator. MURI program of the Army Research Office - Grant No. W911-NF-09-1-0398
A universal equation for the electronic stopping of ions in solids
International Nuclear Information System (INIS)
Montenegro, E.C.; Cruz, S.A.; Vargas-Aburto, C.
1982-09-01
An analytical equation for the electronic stopping of ions in solids for non-relativistic velocities, that has no adjustable parameters, is obtained in a semi-phenomenological manner. The very good agreement with experiment gives support to the physical arguments used in its derivation. (Author) [pt
2D Dirac electrons in 3D materials
Ramankutty, S.V.
2018-01-01
Quantum materials pack the spooky properties of quantum mechanics into real-life materials you can make, pick up with tweezers and study in the lab. Those of interest to us show special electronic properties of great fundamental interest and have applications potential for future computer and
Quasiparticle interference in unconventional 2D systems.
Chen, Lan; Cheng, Peng; Wu, Kehui
2017-03-15
At present, research of 2D systems mainly focuses on two kinds of materials: graphene-like materials and transition-metal dichalcogenides (TMDs). Both of them host unconventional 2D electronic properties: pseudospin and the associated chirality of electrons in graphene-like materials, and spin-valley-coupled electronic structures in the TMDs. These exotic electronic properties have attracted tremendous interest for possible applications in nanodevices in the future. Investigation on the quasiparticle interference (QPI) in 2D systems is an effective way to uncover these properties. In this review, we will begin with a brief introduction to 2D systems, including their atomic structures and electronic bands. Then, we will discuss the formation of Friedel oscillation due to QPI in constant energy contours of electron bands, and show the basic concept of Fourier-transform scanning tunneling microscopy/spectroscopy (FT-STM/STS), which can resolve Friedel oscillation patterns in real space and consequently obtain the QPI patterns in reciprocal space. In the next two parts, we will summarize some pivotal results in the investigation of QPI in graphene and silicene, in which systems the low-energy quasiparticles are described by the massless Dirac equation. The FT-STM experiments show there are two different interference channels (intervalley and intravalley scattering) and backscattering suppression, which associate with the Dirac cones and the chirality of quasiparticles. The monolayer and bilayer graphene on different substrates (SiC and metal surfaces), and the monolayer and multilayer silicene on a Ag(1 1 1) surface will be addressed. The fifth part will introduce the FT-STM research on QPI in TMDs (monolayer and bilayer of WSe 2 ), which allow us to infer the spin texture of both conduction and valence bands, and present spin-valley coupling by tracking allowed and forbidden scattering channels.
International Nuclear Information System (INIS)
Skoblin, A.A.
1994-01-01
Free nonrelativistic electrons in both a static magnetic field and an electromagnetic wave are considered. A plane-polarized wave propagates along a magnetic field, its frequency is close to the electron rotation frequency in a magnetic field. Electron spin is taken into account. An electron quasi energy spectrum and steady states (quasi energy states) are constructed. 6 refs
International Nuclear Information System (INIS)
Jakiel, J.; Olkhovsky, V.S.
1998-01-01
It is known that, under certain conditions, the tunnelling time becomes independent of barrier width (the Hartman and Fletcher effect). Here, the generality of this effect is shown for mean tunnelling times in all known nonrelativistic approaches, in the cases of rectangular potential barriers without absorption and dissipation. On the base of this effect and the reshaping phenomenon, taking the analogy between nonrelativistic-particle and photon tunnelling into, account, one can self-consistently explain the observed superluminal effective (group) velocities in various photon tunnelling experiments without violation of the Einstein causality
Seeing in 4D with electrons: development of ultrafast electron microscopy at Caltech
International Nuclear Information System (INIS)
Baskin, J.S.; Zewail, A.H.
2014-01-01
The vision to develop 4D electron microscopy, a union of the capabilities of electron microscopy with ultrafast techniques to capture clearly defined images of the nano-scale structure of a material at each step in the course of its chemical or physical transformations, has been pursued at Caltech for the last decade. In this contribution, we will give a brief overview of the capabilities of three currently active Caltech 4D microscopy laboratories. Ongoing work is illustrated by a description of the most recent application of photon-induced near-field electron microscopy (PINEM), a field made possible only by the development of the 4D ultrafast electron microscopy (UEM). An appendix gives the various applications made so far and the historic roots of the development at Caltech. (authors)
International Nuclear Information System (INIS)
Nakamura, Shin
2005-01-01
We propose a new method to describe a recoiling D-brane that is elastically scattered by closed strings in the nonrelativistic region. We utilize the low-energy effective field theory on the worldvolume of the D-brane, and the velocity of the D-brane is described by the time derivative of the expectation values of the massless scalar fields on the worldvolume. The effects of the closed strings are represented by a source term for the massless fields in this method. The momentum conservation condition between the closed strings and the D-brane is derived up to the relative sign of the momentum of the D-brane
Electron cyclotron maser instability (ECMI in strong magnetic guide field reconnection
Directory of Open Access Journals (Sweden)
R. A. Treumann
2017-08-01
Full Text Available The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is
Electron cyclotron maser instability (ECMI) in strong magnetic guide field reconnection
Treumann, Rudolf A.; Baumjohann, Wolfgang
2017-08-01
The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales) electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR) in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects) involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is of particular
Directory of Open Access Journals (Sweden)
Changyong Liu
2018-06-01
Full Text Available 3D printing has attracted a lot of attention in recent years. Over the past three decades, various 3D printing technologies have been developed including photopolymerization-based, materials extrusion-based, sheet lamination-based, binder jetting-based, power bed fusion-based and direct energy deposition-based processes. 3D printing offers unparalleled flexibility and simplicity in the fabrication of highly complex 3D objects. Tactile sensors that emulate human tactile perceptions are used to translate mechanical signals such as force, pressure, strain, shear, torsion, bend, vibration, etc. into electrical signals and play a crucial role toward the realization of wearable electronics and electronic skin. To date, many types of 3D printing technologies have been applied in the manufacturing of various types of tactile sensors including piezoresistive, capacitive and piezoelectric sensors. This review attempts to summarize the current state-of-the-art 3D printing technologies and their applications in tactile sensors for wearable electronics and electronic skin. The applications are categorized into five aspects: 3D-printed molds for microstructuring substrate, electrodes and sensing element; 3D-printed flexible sensor substrate and sensor body for tactile sensors; 3D-printed sensing element; 3D-printed flexible and stretchable electrodes for tactile sensors; and fully 3D-printed tactile sensors. Latest advances in the fabrication of tactile sensors by 3D printing are reviewed and the advantages and limitations of various 3D printing technologies and printable materials are discussed. Finally, future development of 3D-printed tactile sensors is discussed.
Computational 2D Materials Database
DEFF Research Database (Denmark)
Rasmussen, Filip Anselm; Thygesen, Kristian Sommer
2015-01-01
We present a comprehensive first-principles study of the electronic structure of 51 semiconducting monolayer transition-metal dichalcogenides and -oxides in the 2H and 1T hexagonal phases. The quasiparticle (QP) band structures with spin-orbit coupling are calculated in the G(0)W(0) approximation...... and used as input to a 2D hydrogenic model to estimate exciton binding energies. Throughout the paper we focus on trends and correlations in the electronic structure rather than detailed analysis of specific materials. All the computed data is available in an open database......., and comparison is made with different density functional theory descriptions. Pitfalls related to the convergence of GW calculations for two-dimensional (2D) materials are discussed together with possible solutions. The monolayer band edge positions relative to vacuum are used to estimate the band alignment...
Directory of Open Access Journals (Sweden)
Radhakrishna Bettadapura
2015-10-01
Full Text Available There continue to be increasing occurrences of both atomistic structure models in the PDB (possibly reconstructed from X-ray diffraction or NMR data, and 3D reconstructed cryo-electron microscopy (3D EM maps (albeit at coarser resolution of the same or homologous molecule or molecular assembly, deposited in the EMDB. To obtain the best possible structural model of the molecule at the best achievable resolution, and without any missing gaps, one typically aligns (match and fits the atomistic structure model with the 3D EM map. We discuss a new algorithm and generalized framework, named PF(2 fit (Polar Fast Fourier Fitting for the best possible structural alignment of atomistic structures with 3D EM. While PF(2 fit enables only a rigid, six dimensional (6D alignment method, it augments prior work on 6D X-ray structure and 3D EM alignment in multiple ways: Scoring. PF(2 fit includes a new scoring scheme that, in addition to rewarding overlaps between the volumes occupied by the atomistic structure and 3D EM map, rewards overlaps between the volumes complementary to them. We quantitatively demonstrate how this new complementary scoring scheme improves upon existing approaches. PF(2 fit also includes two scoring functions, the non-uniform exterior penalty and the skeleton-secondary structure score, and implements the scattering potential score as an alternative to traditional Gaussian blurring. Search. PF(2 fit utilizes a fast polar Fourier search scheme, whose main advantage is the ability to search over uniformly and adaptively sampled subsets of the space of rigid-body motions. PF(2 fit also implements a new reranking search and scoring methodology that considerably improves alignment metrics in results obtained from the initial search.
Electron impact excitation and ionization of laser-excited sodium atoms Na*(7d)
International Nuclear Information System (INIS)
Nienhaus, J.; Dorn, A.; Mehlhorn, W.; Zatsarinny, O.I.
1997-01-01
We have investigated the ejected-electron spectrum following impact excitation and ionization of laser-excited Na * (nl) atoms by 1.5 keV electrons. By means of two-laser excitation 3s → 3p 3/2 → 7d and subsequent cascading transitions about 8% (4%) of the target atoms were in excited states with n > 3 (7d). The experimental ejected-electron spectrum due to the decay of Auger and autoionization states of laser-excited atoms Na * (nl) with n = 4-7 has been fully interpreted by comprehensive calculations of the energies, cross sections and decay probabilities of the corresponding states. The various processes contributing to the ejected-electron spectrum are with decreasing magnitude: 2s ionization leading to 2s2p 6 nl Auger states, 2p → 3s excitation leading to 2p 5 3s( 1 P)nl autoionization states and 2s → 3l' excitation leading to 2s2p 6 3l'( 1 L)nl autoionization states. (Author)
DROPOUT OF DIRECTIONAL ELECTRON INTENSITIES IN LARGE SOLAR ENERGETIC PARTICLE EVENTS
Energy Technology Data Exchange (ETDEWEB)
Tan, Lun C. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Reames, Donald V., E-mail: ltan@umd.edu [Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States)
2016-01-10
In the “gradual” solar energetic particle (SEP) event during solar cycle 23 we have observed the dispersionless modulation (“dropout”) in directional intensities of nonrelativistic electrons. The average duration of dropout periods is ∼0.8 hr, which is consistent with the correlation scale of solar wind turbulence. During the dropout period electrons could display scatter-free transport in an intermittent way. Also, we have observed a decrease in the anisotropic index of incident electrons with increasing electron energy (E{sub e}), while the index of scattered/reflected electrons is nearly independent of E{sub e}. We hence perform an observational examination of the correlation between the anisotropic index of low-energy scattered/reflected electrons and the signature of the locally measured solar wind turbulence in the dissipation range, which is responsible for resonant scattering of nonrelativistic electrons. Since during the dropout period the slab turbulence fraction is dominant (0.8 ± 0.1), we pay close attention to the effect of slab fraction on the correlation examined. Our observation is consistent with the simulation result that in the dominance of the slab turbulence component there should exist a dispatched structure of magnetic flux tubes, along which electrons could be transported in a scatter-free manner. Since a similar phenomenon is exhibited in the “impulsive” SEP event, electron dropout should be a transport effect. Therefore, being different from most ion dropout events, which are due to a compact flare source, the dropout of directional electron intensities should be caused by the change of turbulence status in the solar wind.
DROPOUT OF DIRECTIONAL ELECTRON INTENSITIES IN LARGE SOLAR ENERGETIC PARTICLE EVENTS
International Nuclear Information System (INIS)
Tan, Lun C.; Reames, Donald V.
2016-01-01
In the “gradual” solar energetic particle (SEP) event during solar cycle 23 we have observed the dispersionless modulation (“dropout”) in directional intensities of nonrelativistic electrons. The average duration of dropout periods is ∼0.8 hr, which is consistent with the correlation scale of solar wind turbulence. During the dropout period electrons could display scatter-free transport in an intermittent way. Also, we have observed a decrease in the anisotropic index of incident electrons with increasing electron energy (E e ), while the index of scattered/reflected electrons is nearly independent of E e . We hence perform an observational examination of the correlation between the anisotropic index of low-energy scattered/reflected electrons and the signature of the locally measured solar wind turbulence in the dissipation range, which is responsible for resonant scattering of nonrelativistic electrons. Since during the dropout period the slab turbulence fraction is dominant (0.8 ± 0.1), we pay close attention to the effect of slab fraction on the correlation examined. Our observation is consistent with the simulation result that in the dominance of the slab turbulence component there should exist a dispatched structure of magnetic flux tubes, along which electrons could be transported in a scatter-free manner. Since a similar phenomenon is exhibited in the “impulsive” SEP event, electron dropout should be a transport effect. Therefore, being different from most ion dropout events, which are due to a compact flare source, the dropout of directional electron intensities should be caused by the change of turbulence status in the solar wind
International Nuclear Information System (INIS)
Johnson, D.L.
1979-01-01
Relative total scattering cross sections for nH 2 + nH 2 , pH 2 + pH 2 , nD 2 + nD 2 , oD 2 + oD 2 , and HD + HD were measured with inclined nozzle beams derived from nozzle sources and intersecting at 21 0 . Both nozzles could be varied in temperature from 4.2K to 300K to provide the velocity range for the cross sections. The use of a parahydrogen converter allowed the measurement of the pH 2 + pH 2 and oD 2 + oD 2 cross sections. Cross sections for the H 2 + H 2 were measured over a relative velocity range of 200 m/s to 1450 m/s. The nH 2 + nH 2 results show an undulation in the velocity range between 350 m/s and 400 m/s that corresponds to a l = 3 orbiting resonance. Analysis of the pH 2 + pH 2 cross section indicates a l = 4 orbiting resonance near 586 m/s. This resonance has a peak energy of 1.79 meV and a measured energy width of 1.05 meV, both which agree well with theoretical predictions. The D 2 + D 2 cross sections have been measured in the velocity range between 190 m/s and 1000 m/s. No orbiting resonances have been observed, but in the oD 2 + oD 2 cross section a deep minimum between the l = 4 and the l = 5 resonances at low velocities is clearly suggested. Initial measurements of the HD + HD cross section suggests the presence of the l = 4 orbiting resonance near a relative velocity of 300 m/s. The experimental results for each system were normalized to the total cross sections, which were convoluted to account for experimental velocity and angular dispersions. Three different potentials were considered, but a chi-square fit of the data indicates that the Schaefer and Meyer potential, which has been theoretically obtained from first principles, provides the best overall description of the hydrogen systems in the low collisional energy range
Saha-Dasgupta, Tanusri; Baidya, Santu; Waghmare, Umesh; Paramekanti, Arun
Using density functional theory calculations, we establish that the half-metallicity of bulk Ba2FeReO6 survives down i to 1 nm thickness in BaTiO3/Ba2FeReO6/BaTiO3 heterostructures grown along the (001) and (111) directions. The confinement of the two-dimensional (2D) electron gas in this quantum well structure arises from the suppressed hybridization between Re/Fe d states and unoccupied Ti d states, and it is further strengthened by polar fields for the (111) direction. This mechanism, distinct from the polar catastrophe, leads to an order of magnitude stronger confinement of the 2D electron gas than that at the LaAlO3/SrTiO3 interface. We further show low-energy bands of (111) heterostructure display nontrivial topological character. Our work opens up the possibility of realizing ultra-thin spintronic devices. Journal Ref: Phys. Rev. B 92, 161106(R) (2015) S.B. and T.S.D thank Department of Science and Technology, India for the support through Thematic Unit of Excellence. AP was supported by NSERC (Canada).
Three-hair relations for rotating stars: Nonrelativistic limit
Energy Technology Data Exchange (ETDEWEB)
Stein, Leo C. [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States); Yagi, Kent; Yunes, Nicolás, E-mail: leostein@astro.cornell.edu [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)
2014-06-10
The gravitational field outside of astrophysical black holes is completely described by their mass and spin frequency, as expressed by the no-hair theorems. These theorems assume vacuum spacetimes, and thus they apply only to black holes and not to stars. Despite this, we analytically find that the gravitational potential of arbitrarily rapid, rigidly rotating stars can still be described completely by only their mass, spin angular momentum, and quadrupole moment. Although these results are obtained in the nonrelativistic limit (to leading order in a weak-field expansion of general relativity, GR), they are also consistent with fully relativistic numerical calculations of rotating neutron stars. This description of the gravitational potential outside the source in terms of just three quantities is approximately universal (independent of equation of state). Such universality may be used to break degeneracies in pulsar and future gravitational wave observations to extract more physics and test GR in the strong-field regime.
Bottom mass from nonrelativistic sum rules at NNLL
Energy Technology Data Exchange (ETDEWEB)
Stahlhofen, Maximilian
2013-01-15
We report on a recent determination of the bottom quark mass from nonrelativistic (large-n) {Upsilon} sum rules with renormalization group improvement (RGI) at next-to-next-to-leading logarithmic (NNLL) order. The comparison to previous fixed-order analyses shows that the RGI computed in the vNRQCD framework leads to a substantial stabilization of the theoretical sum rule moments with respect to scale variations. A single moment fit (n=10) to the available experimental data yields M{sub b}{sup 1S}=4.755{+-}0.057{sub pert}{+-}0.009{sub {alpha}{sub s}}{+-}0.003{sub exp} GeV for the bottom 1S mass and anti m{sub b}(anti m{sub b})=4.235{+-}0.055{sub pert}{+-}0.003{sub exp} GeV for the bottom MS mass. The quoted uncertainties refer to the perturbative error and the uncertainties associated with the strong coupling and the experimental input.
Energy Technology Data Exchange (ETDEWEB)
Roudjane, M
2007-12-15
The aim of this thesis is to carry out an experimental study of the absorption and emission spectra of the D{sub 2} and HD isotopes, with high resolution, in the VUV domain and to supplement it by a theoretical study of the excited electronic states involved in the observed transitions. The emission spectra of HD and D{sub 2} are produced by Penning discharge source operating under low pressure and are recorded in the spectral range 78 - 170 nm. The recorded spectra contains more than 20.000 lines. The analysis of the spectrum consists in identifying and assigning the lines to the electronic transitions between energy levels of the molecule. The present analysis is based on our theoretical calculations of the ro-vibrational energy levels of the excited electronic states and the transition probabilities from these states towards the energy levels of the fundamental state. The theoretical results are obtained by resolving the coupled equations between the excited electronic states B{sup 1}{sigma}{sub u}{sup 1}, B'{sup 1}{sigma}{sub u}{sup 1}, C{sup 1}{pi}{sub u}{sup 1} and D{sup 1}{pi}{sub u}{sup 1}, taking into account the nonadiabatic couplings between these states, and they are obtained in the adiabatic approximation for the excited electronic states B''B-bar{sup 1}{sigma}{sub u}{sup +}, D'{sup 1}{pi}{sub u}{sup 1} and D''{sup 1}{pi}{sub u}{sup 1}. The equations are resolved using a modern method based on the discretization variables representation method. In addition, we have carried out a study of the absorption spectra of the HD and D{sub 2} molecules.
Energy Technology Data Exchange (ETDEWEB)
Celik, Ozlem; Tiras, Engin; Ardali, Sukru [Department of Physics, Faculty of Science, Anadolu University, Yunus Emre Campus, 26470 Eskisehir (Turkey); Lisesivdin, Sefer Bora [Department of Physics, Faculty of Science and Arts, Gazi University, Teknikokullar, 06500 Ankara (Turkey); Ozbay, Ekmel [Nanotechnology Research Center, Department of Physics, and Department of Electrical and Electronics Engineering, Bilkent University, Ankara (Turkey)
2011-05-15
Magnetoresistance and Hall resistance measurements have been used to investigate the electronic transport properties of AlGaN/GaN based HEMTs. The Shubnikov-de Haas (SdH) oscillations from magnetoresistance, is obtained by fitting the nonoscillatory component to a polynomial of second degree, and then subtracting it from the raw experimental data. It is shown that only first subband is occupied with electrons. The two-dimensional (2D) carrier density and the Fermi energy with respect to subband energy (E{sub F}-E{sub 1}) have been determined from the periods of the SdH oscillations. The in-plane effective mass (m*) and the quantum lifetime ({tau}{sub q}) of electrons have been obtained from the temperature and magnetic field dependencies of the SdH amplitude, respectively. The in-plane effective mass of 2D electrons is in the range between 0.19 m{sub 0} and 0.22 m{sub 0}. Our results for in-plane effective mass are in good agreement with those reported in the literature (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Exact solutions of the dirac equation for an electron in magnetic field with shape invariant method
International Nuclear Information System (INIS)
Setare, M.R.; Hatami, O.
2008-01-01
Based on the shape invariance property we obtain exact solutions of the Virac equation for an electron moving in the presence of a certain varying magnetic Geld, then we also show its non-relativistic limit. (authors)
Electron emission following collisions between multi-charged ions and D2 molecules
International Nuclear Information System (INIS)
Laurent, G.
2004-05-01
Dissociative ionisation mechanisms induced in collisions involving a highly charged ion (S 15+ , 13.6 MeV/u) and a molecular deuterium target, have been studied through momentum vector correlations of both the D + fragments and the electrons produced. An experimental apparatus has been developed in order to detect in coincidence all the charged particles produced during the collision. The measurement of their momentum vectors, which allows one to determine both their kinetic energy and direction of emission with respect to the projectile one, combines Time of Flight, Position Sensitive Detection, and multi-coincidence techniques. The correlation of the fragment and electron kinetic energies enables not only to determine branching ratios between the dissociative ionisation pathways, but also to separate unambiguously kinetic energy distributions of fragments associated to each process. Finally, the angular distributions of ejected electrons, as a function of the orientation of the molecular axis with respect to the projectile direction, are deduced from the spatial correlation. Measurements are compared to theoretical angular distributions obtained using the CDW-EIS (Continuum Distorted Wave-Eikonal Initial State) method. (author)
Electronic structure of the 3d metals. An investigation by L-shell-photoionisation
Energy Technology Data Exchange (ETDEWEB)
Richter, T.S.
2007-12-03
The 3d transition metal elements from Sc to Cu have been investigated by both photo electron emission and photo absorption. Experimental spectra in the 2p energy range are discussed based on atomic multiplet models and Hartree- Fock calculations. The samples have been evaporated from an electron bombardment crucible and excited/ionized by monochromatized synchrotron radiation. Fundamental effects and the main interactions which govern the electronic structure of the 3d metal atoms are covered. Common spectral features and trends in the series are discussed as well as the importance of many body electron correlation effects. (orig.)
Directory of Open Access Journals (Sweden)
N. Xu
2013-01-01
Full Text Available We report an investigation with angle-resolved photoemission spectroscopy of the Fermi surface and electronic band structure of BaCo_{2}As_{2}. Although its quasinesting-free Fermi surface differs drastically from that of its Fe-pnictide cousins, we show that the BaCo_{2}As_{2} system can be used as an approximation to the bare unoccupied band structure of the related BaFe_{2-x}Co_{x}As_{2} and Ba_{1-x}K_{x}Fe_{2}As_{2} compounds. However, our experimental results, in agreement with dynamical-mean-field-theory calculations, indicate that electronic correlations are much less important in BaCo_{2}As_{2} than in the ferropnictides. Our findings suggest that this effect is due to the increased filling of the electronic 3d shell in the presence of significant Hund’s exchange coupling.
Bosonization of non-relativistic fermions and W-infinity algebra
International Nuclear Information System (INIS)
Das, S.R.; Dhar, A.; Mandal, G.; Wadia, S.R.
1992-01-01
In this paper the authors discuss the bosonization of non-relativistic fermions in one-space dimension in terms of bilocal operators which are naturally related to the generators of W-infinity algebra. The resulting system is analogous to the problem of a spin in a magnetic field for the group W-infinity. The new dynamical variables turn out to be W-infinity group elements valued in the coset W-infinity/H where H is a Cartan subalgebra. A classical action with an H gauge invariance is presented. This action is three-dimensional. It turns out to be similar to the action that describes the color degrees of freedom of a Yang-Mills particle in a fixed external field. The authors also discuss the relation of this action with the one recently arrived at in the Euclidean continuation of the theory using different coordinates
Voltammetric Studies on Vitamins D2 and D3 in Organic Solvents
International Nuclear Information System (INIS)
Chan, Ya Yun; Yue, Yanni; Webster, Richard D.
2014-01-01
Highlights: • Vitamins D 2 and D 3 undergo a chemically irreversible oxidation process. • The electrochemical oxidation occurs via one-electron on short (CV) time-scales. • On long time scales (electrolysis) the oxidation occurs via two-electrons. • Chemical oxidation was performed using two molar equivalents of NO + . • Oxidation occurs at the triene moiety. - Abstract: The electrochemical behavior of vitamins D 2 and D 3 were examined by performing cyclic voltammetry (CV), rotating disk electrode voltammetry, controlled potential electrolysis and chemical oxidation in aprotic organic solvents. Both vitamins were electrochemically oxidized in dichloromethane and acetonitrile (E p ox ∼ +0.8 vs. (Fc/Fc + )/V, where E p ox is the anodic peak potential and Fc = ferrocene) via a one-electron chemically irreversible process on the short voltammetric time scale (≤ seconds). Varying the scan rate (0.1 V s −1 to 20 V s −1 ) and temperature (233 K to 293 K) did not strongly affect the voltammetric response recorded on platinum and glassy carbon electrode surfaces with the oxidation process remaining chemically irreversible over the range of scan rates and temperatures tested, indicating that the initially formed cation radical was not long-lived. Repetitive CV experiments indicated that the oxidized product partially adsorbed onto the electrode surface, resulting in diminishing peak currents with multiple scans. Bulk controlled potential electrolysis of the vitamin D compounds performed by alternating several cycles of oxidative electrolysis and reductive pulsed stripping proved to be effective in stripping the adsorbed species off the electrode surfaces. Longer time scale bulk electrolysis experiments led to the detection of a new oxidation peak appearing at less positive potentials as the electrolysis progressed, suggesting that the compounds underwent oxidation on long time scales (minutes to hours) via a two electron process. The vitamins were most
Impurity and quaternions in nonrelativistic scattering from a quantum memory
International Nuclear Information System (INIS)
Margetis, Dionisios; Grillakis, Manoussos G
2008-01-01
Models of quantum computing rely on transformations of the states of a quantum memory. We study mathematical aspects of a model proposed by Wu in which the memory state is changed via the scattering of incoming particles. This operation causes the memory content to deviate from a pure state, i.e. induces impurity. For nonrelativistic particles scattered from a two-state memory and sufficiently general interaction potentials in (1+1) dimensions, we express impurity in terms of quaternionic commutators. In this context, pure memory states correspond to null hyperbolic quaternions. In the case with point interactions, the scattering process amounts to appropriate rotations of quaternions in the frequency domain. Our work complements previous analyses by Margetis and Myers (2006 J. Phys. A 39 11567)
Blocage de Coulomb dans une boite quantique laterale contenant un faible nombre d'electrons
Gould, Charles
Dans ce travail on utilise une nouvelle geometrie pour augmenter le controle sur le nombre d'electrons contenus dans une boite quantique laterale, et ainsi atteindre un regime de petit nombre d'electrons. Ces echantillons permettent une etude du blocage de Coulomb quand les electrons sont injectes a partir d'un gaz electronique a deux dimensions (2DEG). Les mesures a faible champ magnetique demontrent la grande flexibilite des echantillons et montrent que l'on peut faire varier le nombre d'electrons dans une boite quantique a partir de plus de 40 electrons jusqu'a un seul electron, ce qui est assez courant dans les boites quantiques verticales, mais ce qui n'avait jamais ete reussi dans une boite quantique laterale. Nos resultats montrent egalement que dans les boites quantiques laterales il est possible de determiner le spin du niveau qui participe au transport a l'aide du phenomene de blocage de spin. De plus, dans certaines circonstances il est meme possible de determiner le spin total de la boite quantique, ce qui peut avoir des applications pratiques dans des domaines tels l'informatique quantique. Les mesures dans le regime de renversement de spin a un champ magnetique plus eleve montrent l'importance des correlations electrons---electrons dans ces boites quantiques, qui menent a des depolarisations et a des structures de spins qui ont un effet sur le transport. En particulier, ces correlations menent a l'existence de niveaux excites de basse energie qui causent une dependance anormale de l'amplitude des pics de blocage de Coulomb en fonction de la temperature. Nos experiences demontrent egalement la possibilite d'utiliser ces boites quantiques comme sondes pour etudier les proprietes du bord d'un 2DEG. Une voie de recherche a etre exploree.
Relativistic electron drift in overdense plasma produced by a superintense femtosecond laser pulse
International Nuclear Information System (INIS)
Rastunkov, V.S.; Krainov, V.P.
2004-01-01
The general peculiarities of electron motion in the skin layer at the irradiation of overdense plasma by a superintense linearly polarized laser pulse of femtosecond duration are considered. The quiver electron energy is assumed to be a relativistic quantity. Relativistic electron drift along the propagation of laser radiation produced by a magnetic part of a laser field remains after the end of the laser pulse, unlike the relativistic drift of a free electron in underdense plasma. As a result, the penetration depth is much larger than the classical skin depth. The conclusion has been made that the drift velocity is a nonrelativistic quantity even at the peak laser intensity of 10 21 W/cm 2 . The time at which an electron penetrates into field-free matter from the skin layer is much less than the pulse duration
International Nuclear Information System (INIS)
Shakhazizyan, S.R.
1987-01-01
The problem of nonrelativistic dependence of unit length and unit time on the position in the space is considered on the basis of centre-containing spiral-geometric structure of the space-time. The experimental results of variation of the unit time are analyzed which well agree with the requirements of the model proposed. 13 refs.; 12 figs
2D and 3D organisation of nano-particles: synthesis and specific properties
International Nuclear Information System (INIS)
Taleb, Abdelhafed
1998-01-01
The first part of this research thesis addresses the synthesis of nano-particles of silver and cobalt in the inverse micellar system, and highlights the feasibility of two- and three-dimensional structures of these particles. The author first presents the micellar system (micro-emulsions, surfactant, properties of inverse micelles, functionalized inverse micelles, application to the synthesis of nano-particles), and then reports the study of the synthesis and organisation of colloids in 2D and 3D. He also reports the study of optical properties of metallic colloids: free electron approximation, optical properties of electron gases, optical properties of colloids, optical response of two-dimensional and three-dimensional nano-structures. The magnetic properties of colloids are then studied: magnetism of the massive metallic state, magnetic properties of nano-particles (influence of size, interactions and field, notions of magnetic order and disorder), effect of organisation. The second part of this thesis is made of a set of published articles: Synthesis of highly mono-disperse silver nano-particles from AOT reverse micelles (a way to 2D and 3D self-organisation), Optical properties of self-assembled 2D and 3D super-lattices of silver nano-particles, Collective optical properties of silver nano-particles organised in 2D super-lattices, Self assembled in 2D cobalt nano-sized particles, Self organisation of magnetic nano-sized cobalt particles, Organisation in 2D cobalt nano-particles (synthesis, characterization and magnetic properties) [fr
Sevilla, Galo T.; Cordero, Marlon D.; Nassar, Joanna M.; Hanna, Amir; Kutbee, Arwa T.; Carreno, Armando Arpys Arevalo; Hussain, Muhammad Mustafa
2016-01-01
High-performance complementary metal oxide semiconductor electronics are flexed, packaged using 3D printing as decal electronics, and then printed in roll-to-roll fashion for highly manufacturable printed flexible high-performance electronic systems.
Sevilla, Galo T.
2016-10-14
High-performance complementary metal oxide semiconductor electronics are flexed, packaged using 3D printing as decal electronics, and then printed in roll-to-roll fashion for highly manufacturable printed flexible high-performance electronic systems.
Energy Technology Data Exchange (ETDEWEB)
Berdiyorov, G.R., E-mail: gberdiyorov@qf.org.qa; Madjet, M.E., E-mail: mmadjet@qf.org.qa
2016-12-30
Highlights: • Effect of surface termination on the optoelectronic properties of TiC{sub 2} is studied. • Fluorinated, oxidized and hydroxylated surfaces are considered. • Partial charges are calculated. • Absorption of the system increases by surface passivation. • Electronic transport reduces considerably due to the termination. - Abstract: Using the first-principles density functional theory, we study the effect of surface functionalization on the structural and optoelectronic properties of recently proposed quasi-two-dimensional material TiC{sub 2} [T. Zhao, S. Zhang, Y. Guo, Q. Wang, Nanoscale 8 (2016) 233]. Hydrogenated, fluorinated, oxidized and hydroxylated surfaces are considered. Significant changes in the lattice parameters and partial charge distributions are found due to the surface termination. Direct contribution of the adatoms to the system density of states near the Fermi level is obtained, which has a major impact on the optoelectronic properties of the material. For example, surface termination results in larger absorption in the visible range of the spectrum. The electronic transport is also affected by the surface functionalization: the current in the system can be reduced by an order of magnitude. These findings indicate the importance of the effects of surface passivation on optoelectronic properties of this quasi-2D material.
Holographic energy loss in non-relativistic backgrounds
Energy Technology Data Exchange (ETDEWEB)
Atashi, Mahdi; Fadafan, Kazem Bitaghsir; Farahbodnia, Mitra [Shahrood University of Technology, Physics Department, P.O. Box 3619995161, Shahrood (Iran, Islamic Republic of)
2017-03-15
In this paper, we study some aspects of energy loss in non-relativistic theories from holography. We analyze the energy lost by a rotating heavy point particle along a circle of radius l with angular velocity ω in theories with general dynamical exponent z and hyperscaling violation exponent θ. It is shown that this problem provides a novel perspective on the energy loss in such theories. A general computation at zero and finite temperature is done and it is shown how the total energy loss rate depends non-trivially on two characteristic exponents (z,θ). We find that at zero temperature there is a special radius l{sub c} where the energy loss is independent of different values of (θ,z). Also at zero temperature, there is a crossover between a regime in which the energy loss is dominated by the linear drag force and by the radiation because of the acceleration of the rotating particle. We find that the energy loss of the particle decreases by increasing θ and z. We note that, unlike in the zero temperature, there is no special radius l{sub c} at finite temperature case. (orig.)
Dynamics of electron emission in double photoionization processes near the krypton 3d threshold
International Nuclear Information System (INIS)
Penent, F; Sheinerman, S; Andric, L; Lablanquie, P; Palaudoux, J; Becker, U; Braune, M; Viefhaus, J; Eland, J H D
2008-01-01
Two-electron emission following photoabsorption near the Kr 3d threshold is investigated both experimentally and theoretically. On the experimental side, electron/electron coincidences using a magnetic bottle time-of-flight spectrometer allow us to observe the complete double photo ionization (DPI) continua of selected Kr 2+ final states, and to see how these continua are affected by resonant processes in the vicinity of the Kr 3d threshold. The analysis is based on a quantum mechanical approach that takes into account the contribution of three different processes: (A) Auger decay of the inner 3d vacancy with the associated post-collision interaction (PCI) effects, (B) capture of slow photoelectrons into discrete states followed by valence multiplet decay (VMD) of the excited ionic states and (C) valence shell DPI. The dominant process for each Kr 2+ (4p -2 ) final state is the photoionization of the inner shell followed by Auger decay of the 3d vacancies. Moreover, for the 4p -2 ( 3 P) and 4p -2 ( 1 D) final ionic states an important contribution comes from the processes of slow photoelectron capture followed by VMD as well as from double ionization of the outer shell involving also VMD
Koo, Jaseung; Park, Jaehong; Tronin, Andrey; Zhang, Ruili; Krishnan, Venkata; Strzalka, Joseph; Kuzmenko, Ivan; Fry, H Christopher; Therien, Michael J; Blasie, J Kent
2012-02-14
We show that simply designed amphiphilic 4-helix bundle peptides can be utilized to vectorially orient a linearly extended donor-bridge-acceptor (D-br-A) electron transfer (ET) chromophore within its core. The bundle's interior is shown to provide a unique solvation environment for the D-br-A assembly not accessible in conventional solvents and thereby control the magnitudes of both light-induced ET and thermal charge recombination rate constants. The amphiphilicity of the bundle's exterior was employed to vectorially orient the peptide-chromophore complex at a liquid-gas interface, and its ends were tailored for subsequent covalent attachment to an inorganic surface, via a "directed assembly" approach. Structural data, combined with evaluation of the excited state dynamics exhibited by these peptide-chromophore complexes, demonstrate that densely packed, acentrically ordered 2-D monolayer ensembles of such complexes at high in-plane chromophore densities approaching 1/200 Å(2) offer unique potential as active layers in binary heterojunction photovoltaic devices.
Spectral density of electron concentration fluctuations in ionospheric D region
International Nuclear Information System (INIS)
Martynenko, S.I.
1989-01-01
Expression for spectral density of electron concentration fluctuations in D-region with regard to the effect of ionization-recombination proceses and negative ions is obtained in terms of atmospheric turbulence model which obeys Kolmogorov-Obukhov 2/3 law
Electron correlation energy in confined two-electron systems
Energy Technology Data Exchange (ETDEWEB)
Wilson, C.L. [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Montgomery, H.E., E-mail: ed.montgomery@centre.ed [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Sen, K.D. [School of Chemistry, University of Hyderabad, Hyderabad 500 046 (India); Thompson, D.C. [Chemistry Systems and High Performance Computing, Boehringer Ingelheim Pharamaceuticals Inc., 900 Ridgebury Road, Ridgefield, CT 06877 (United States)
2010-09-27
Radial, angular and total correlation energies are calculated for four two-electron systems with atomic numbers Z=0-3 confined within an impenetrable sphere of radius R. We report accurate results for the non-relativistic, restricted Hartree-Fock and radial limit energies over a range of confinement radii from 0.05-10a{sub 0}. At small R, the correlation energies approach limiting values that are independent of Z while at intermediate R, systems with Z{>=}1 exhibit a characteristic maximum in the correlation energy resulting from an increase in the angular correlation energy which is offset by a decrease in the radial correlation energy.
D-state Rydberg electrons interacting with ultracold atoms
Energy Technology Data Exchange (ETDEWEB)
Krupp, Alexander Thorsten
2014-10-02
This thesis was established in the field of ultracold atoms where the interaction of highly excited D-state electrons with rubidium atoms was examined. This work is divided into two main parts: In the first part we study D-state Rydberg molecules resulting from the binding of a D-state Rydberg electron to a ground state rubidium atom. We show that we can address specific rovibrational molecular states by changing our laser detuning and thus create perfectly aligned axial or antialigned toroidal molecules, in good agreement with our theoretical calculations. Furthermore the influence of the electric field on the Rydberg molecules was investigated, creating novel states which show a different angular dependence and alignment. In the second part of this thesis we excite single D-state Rydberg electrons in a Bose-Einstein condensate. We study the lifetime of these Rydberg electrons, the change of the shape of our condensate and the atom losses in the condensate due to this process. Moreover, we observe quadrupolar shape oscillations of the whole condensate created by the consecutive excitation of Rydberg atoms and compare all results to previous S-state measurements. In the outlook we propose a wide range of further experiments including the proposal of imaging a single electron wavefunction by the imprint of its orbit into the Bose-Einstein condensate.
Electron correlation within the relativistic no-pair approximation
DEFF Research Database (Denmark)
Almoukhalalati, Adel; Knecht, Stefan; Jensen, Hans Jørgen Aa
2016-01-01
and that this is possible by full Multiconfigurational Self-Consistent Field (MCSCF) calculations, that is, MCSCF calculations using a no-pair full CI expansion, but including orbital relaxation from the negative-energy orbitals. We show by variational perturbation theory that the MCSCF correlation energy is a pure MP2....... The well-known 1/Z- expansion in nonrelativistic atomic theory follows from coordinate scaling. We point out that coordinate scaling for consistency should be accompanied by velocity scaling. In the nonrelativistic domain this comes about automatically, whereas in the relativistic domain an explicit...... scaling of the speed of light is required. This in turn explains why the relativistic correlation energy to the lowest order is not independent of nuclear charge, in contrast to nonrelativistic theory....
Analysis of the electronic structures of 3d transition metals doped CuGaS2 based on DFT calculations
International Nuclear Information System (INIS)
Zhao Zongyan; Zhou Dacheng; Yi Juan
2014-01-01
3d transition metals doped CuGaS 2 are considered as possible absorbing material candidates for intermediated band thin film solar cells. The electronic structure and optical properties of 3d transition metals doped CuGaS 2 are investigated by using density functional theory calculations with the GGA + U method in the present work. The doping with 3d transition metals does not obviously change the crystal structure, band gap, and optical absorption edge of the CuGaS 2 host. However, in the case of CuGa 1−x TM x S 2 (TM = Ti, V, Cr, Fe, and Ni), there is at least one distinct isolated impurity energy level in the band gap, and the optical absorption is enhanced in the ultraviolet-light region. Therefore, these materials are ideal absorber material candidates for intermediated band thin film solar cells. The calculated results are very well consistent with experimental observations, and could better explain them. (semiconductor materials)
Optimization of FIBMOS Through 2D Silvaco ATLAS and 2D Monte Carlo Particle-based Device Simulations
Kang, J.; He, X.; Vasileska, D.; Schroder, D. K.
2001-01-01
Focused Ion Beam MOSFETs (FIBMOS) demonstrate large enhancements in core device performance areas such as output resistance, hot electron reliability and voltage stability upon channel length or drain voltage variation. In this work, we describe an optimization technique for FIBMOS threshold voltage characterization using the 2D Silvaco ATLAS simulator. Both ATLAS and 2D Monte Carlo particle-based simulations were used to show that FIBMOS devices exhibit enhanced current drive ...
Energy Technology Data Exchange (ETDEWEB)
Golowacz, H; Degras, D A [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires, Deptartement de Physique des Plasmas et de la Fusion Controlee, Service de Physique Appliquee, Service de Physique des Interractions Electroniques, Section d' Etude des Interactions Gaz-Solides
1967-07-01
The geometry and the technology of a cell used for investigations on electron-adsorbed gas interactions are described. The resonance frequencies of the surface ions which are created by the electron impact on the adsorbed gas are predicted by simplified calculations. The experimental data relative to carbon monoxide and neon are in good agreement with these predictions. (authors) [French] Les caracteristiques geometriques et technologiques generales d'une cellule d'etude des interactions entre un faisceau d'electrons et un gaz adsorbe sont donnees. Un calcul simplifie permet de prevoir les frequences de resonance des ions de surface crees par l'impact des electrons sur le gaz adsorbe. Les donnees experimentales sur l'oxyde de carbone et le neon confirment les previsions du calcul. (auteurs)
International Nuclear Information System (INIS)
Serva, M.
1986-01-01
In this paper we give probabilistic solutions to the equations describing non-relativistic quantum electrodynamical systems. These solutions involve, besides the usual diffusion processes, also birth and death processes corresponding to the 'photons number' variables. We state some inequalities and in particular we establish bounds to the ground state energy of systems composed by a non relativistic particle interacting with a field. The result is general and it is applied as an example to the polaron problem. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Cho, Donghwan; Ji, Sanggyu; Hwang, Junghyu; Lee, Byungchul [Kumoh National Institute of Technology, Gumi (Korea, Republic of)
2011-07-01
The purpose of this research is to improve the interfacial adhesion between natural jute fibers and PlA and the mechanical and thermal properties of jute/PLA green composites by means of electron beam irradiation under optimal conditions for the modification of sustainable and naturally calculably natural fibers. In ths present study, randomly aligned jute fiber/PLA and 2-directionally aligned jute fabric/PLA green composites with jute treated with electron beam at different dosages were fabricated by compression molding method and the effect of electron beam treatment on their mechanical, impact and thermal properties and fracture surfaces was extensively investigated. It was clearly concluded that electron beam irradiation to jute fibers and jute fabrics at 10 kGy was surely improved the tensile, flexural, impact, dynamic mechanical properties, thermal expansion, heat deflection temperature and thermal stability of random jute fiber/PLA and 2-D jute fabric/PLA green composites, All the results were consistent with each other, supporting the positive role of electron beam irradiation on the improved properties of their green composites.
Čenčariková, Hana; Strečka, Jozef; Gendiar, Andrej; Tomašovičová, Natália
2018-05-01
An exhaustive ground-state analysis of extended two-dimensional (2D) correlated spin-electron model consisting of the Ising spins localized on nodal lattice sites and mobile electrons delocalized over pairs of decorating sites is performed within the framework of rigorous analytical calculations. The investigated model, defined on an arbitrary 2D doubly decorated lattice, takes into account the kinetic energy of mobile electrons, the nearest-neighbor Ising coupling between the localized spins and mobile electrons, the further-neighbor Ising coupling between the localized spins and the Zeeman energy. The ground-state phase diagrams are examined for a wide range of model parameters for both ferromagnetic as well as antiferromagnetic interaction between the nodal Ising spins and non-zero value of external magnetic field. It is found that non-zero values of further-neighbor interaction leads to a formation of new quantum states as a consequence of competition between all considered interaction terms. Moreover, the new quantum states are accompanied with different magnetic features and thus, several kinds of field-driven phase transitions are observed.
The incompressible non-relativistic Navier-Stokes equation from gravity
International Nuclear Information System (INIS)
Bhattacharyya, Sayantani; Minwalla, Shiraz; Wadia, Spenta R.
2009-01-01
We note that the equations of relativistic hydrodynamics reduce to the incompressible Navier-Stokes equations in a particular scaling limit. In this limit boundary metric fluctuations of the underlying relativistic system turn into a forcing function identical to the action of a background electromagnetic field on the effectively charged fluid. We demonstrate that special conformal symmetries of the parent relativistic theory descend to 'accelerated boost' symmetries of the Navier-Stokes equations, uncovering a conformal symmetry structure of these equations. Applying our scaling limit to holographically induced fluid dynamics, we find gravity dual descriptions of an arbitrary solution of the forced non-relativistic incompressible Navier-Stokes equations. In the holographic context we also find a simple forced steady state shear solution to the Navier-Stokes equations, and demonstrate that this solution turns unstable at high enough Reynolds numbers, indicating a possible eventual transition to turbulence.
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
International Nuclear Information System (INIS)
Lin Lin; Chao Yang; Jiangfeng Lu; Lexing Ying; Weinan, E.
2009-01-01
We present an efficient parallel algorithm and its implementation for computing the diagonal of H -1 where H is a 2D Kohn-Sham Hamiltonian discretized on a rectangular domain using a standard second order finite difference scheme. This type of calculation can be used to obtain an accurate approximation to the diagonal of a Fermi-Dirac function of H through a recently developed pole-expansion technique LinLuYingE2009. The diagonal elements are needed in electronic structure calculations for quantum mechanical systems HohenbergKohn1964, KohnSham 1965,DreizlerGross1990. We show how elimination tree is used to organize the parallel computation and how synchronization overhead is reduced by passing data level by level along this tree using the technique of local buffers and relative indices. We analyze the performance of our implementation by examining its load balance and communication overhead. We show that our implementation exhibits an excellent weak scaling on a large-scale high performance distributed parallel machine. When compared with standard approach for evaluating the diagonal a Fermi-Dirac function of a Kohn-Sham Hamiltonian associated a 2D electron quantum dot, the new pole-expansion technique that uses our algorithm to compute the diagonal of (H-z i I) -1 for a small number of poles z i is much faster, especially when the quantum dot contains many electrons.
Energy Technology Data Exchange (ETDEWEB)
Lin, Lin; Yang, Chao; Lu, Jiangfeng; Ying, Lexing; E, Weinan
2009-09-25
We present an efficient parallel algorithm and its implementation for computing the diagonal of $H^-1$ where $H$ is a 2D Kohn-Sham Hamiltonian discretized on a rectangular domain using a standard second order finite difference scheme. This type of calculation can be used to obtain an accurate approximation to the diagonal of a Fermi-Dirac function of $H$ through a recently developed pole-expansion technique \\cite{LinLuYingE2009}. The diagonal elements are needed in electronic structure calculations for quantum mechanical systems \\citeHohenbergKohn1964, KohnSham 1965,DreizlerGross1990. We show how elimination tree is used to organize the parallel computation and how synchronization overhead is reduced by passing data level by level along this tree using the technique of local buffers and relative indices. We analyze the performance of our implementation by examining its load balance and communication overhead. We show that our implementation exhibits an excellent weak scaling on a large-scale high performance distributed parallel machine. When compared with standard approach for evaluating the diagonal a Fermi-Dirac function of a Kohn-Sham Hamiltonian associated a 2D electron quantum dot, the new pole-expansion technique that uses our algorithm to compute the diagonal of $(H-z_i I)^-1$ for a small number of poles $z_i$ is much faster, especially when the quantum dot contains many electrons.
Ran, Jingrun; Guo, Weiwei; Wang, Hailong; Zhu, Bicheng; Yu, Jiaguo; Qiao, Shi-Zhang
2018-04-30
The generation of green hydrogen (H 2 ) energy using sunlight is of great significance to solve the worldwide energy and environmental issues. Particularly, photocatalytic H 2 production is a highly promising strategy for solar-to-H 2 conversion. Recently, various heterostructured photocatalysts with high efficiency and good stability have been fabricated. Among them, 2D/2D van der Waals (VDW) heterojunctions have received tremendous attention, since this architecture can promote the interfacial charge separation and transfer and provide massive reactive centers. On the other hand, currently, most photocatalysts are composed of metal elements with high cost, limited reserves, and hazardous environmental impact. Hence, the development of metal-free photocatalysts is desirable. Here, a novel 2D/2D VDW heterostructure of metal-free phosphorene/graphitic carbon nitride (g-C 3 N 4 ) is fabricated. The phosphorene/g-C 3 N 4 nanocomposite shows an enhanced visible-light photocatalytic H 2 production activity of 571 µmol h -1 g -1 in 18 v% lactic acid aqueous solution. This improved performance arises from the intimate electronic coupling at the 2D/2D interface, corroborated by the advanced characterizations techniques, e.g., synchrotron-based X-ray absorption near-edge structure, and theoretical calculations. This work not only reports a new metal-free phosphorene/g-C 3 N 4 photocatalyst but also sheds lights on the design and fabrication of 2D/2D VDW heterojunction for applications in catalysis, electronics, and optoelectronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
3D Observation of GEMS by Electron Tomography
Matsuno, Junya; Miyake, Akira; Tsuchiyama, Akira; Nakamura-Messenger, Keiko; Messenger, Scott
2014-01-01
Amorphous silicates in chondritic porous interplanetary dust particles (CP-IDPs) coming from comets are dominated by glass with embedded metal and sulfides (GEMS). GEMS grains are submicron-sized rounded objects (typically 100-500) nm in diameter) with anaometer-sized (10-50 nm) Fe-Ni metal and sulfide grains embedded in an amorphous silicate matrix. Several formation processes for GEMS grains have been proposed so far, but these models are still being debated [2-5]. Bradley et al. proposed that GEMS grains are interstellar silicate dust that survived various metamorphism or alteration processes in the protoplanetary disk and that they are amorphiation products of crystalline silicates in the interstellar medium by sputter-deposition of cosmic ray irradiation, similar to space weathering [2,4]. This consideration is based on the observation of nano-sized crystals (approximately 10 nm) called relict grains in GEMS grains and their shapes are pseudomorphs to the host GEMS grains. On the other hand, Keller and Messenger proposed that most GEMS formed in the protoplanetary disk as condensates from high temperature gas [3,5]. This model is based on the fact that most GEMS grains have solar isotopic compositions and have extremely heterogeneous and non-solar elemental compositions. Keller and Messenger (2011) also reported that amorphous silicates in GEMS grains are surrounded by sulfide grains, which formed as sulfidization of metallic iron grains located on the GEMS surface. The previous studies were performed with 2D observation by using transmission electron microscopy (TEM) or scanning TEM (STEM). In order to understand the structure of GEMS grains described above more clearly, we observed 3D structure of GEMS grains by electron tomography using a TEM/STEM (JEM-2100F, JEOL) at Kyoto University. Electron tomography gives not only 3D structures but also gives higher spatial resolution (approximately a few nm) than that in conventional 2D image, which is restricted by
Probing collective oscillation of d-orbital electrons at the nanoscale
Dhall, Rohan; Vigil-Fowler, Derek; Houston Dycus, J.; Kirste, Ronny; Mita, Seiji; Sitar, Zlatko; Collazo, Ramon; LeBeau, James M.
2018-02-01
Here, we demonstrate that high energy electrons can be used to explore the collective oscillation of s, p, and d orbital electrons at the nanometer length scale. Using epitaxial AlGaN/AlN quantum wells as a test system, we observe the emergence of additional features in the loss spectrum with the increasing Ga content. A comparison of the observed spectra with ab-initio theory reveals that the origin of these spectral features lies in excitations of 3d-electrons contributed by Ga. We find that these modes differ in energy from the valence electron plasmons in Al1-xGaxN due to the different polarizabilities of the d electrons. Finally, we study the dependence of observed spectral features on the Ga content, lending insights into the origin of these spectral features, and their coupling with electron-hole excitations.
International Nuclear Information System (INIS)
Wu Xiao-Rui; Shen Li; Zhang Kai; Dai Chang-Jian; Yang Yu-Na
2016-01-01
The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f 7 6p 1/2 n d auto-ionizing states are investigated with the velocity-map-imaging technique. To populate the above auto-ionizing states, the relevant bound Rydberg states have to be detected first. Two new bound Rydberg states are identified in the region between 41150 cm −1 and 44580 cm −1 , from which auto-ionization spectra of the Eu 4f 7 6p 1/2 n d states are observed with isolated core excitation method. With all preparations above, the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically. Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed, followed by a qualitative interpretation. (paper)
Electron-beam-induced welding of 3D nano-objects from beneath
International Nuclear Information System (INIS)
Moskalenko, A V; Burbridge, D J; Viau, G; Gordeev, S N
2007-01-01
Exposure of a sample to the electron beam in a scanning electron microscope (SEM) results in the growth of a film of amorphous carbon due to decomposition of hydrocarbon molecules, which are always present in small quantities in the SEM chamber. This growth is induced mainly by secondary electrons backscattered by atoms of both the sample and substrate. We show that, because the secondary electrons are spread beyond the exposed area, this deposit can be grown in areas of geometric shadow and therefore can be used for bonding of different complex 3D nano-objects to a substrate. This is demonstrated by welding 100 nm Fe-Co-Ni nanoparticles to the surface of 2D graphite. The tip of an atomic force microscope was used to probe the mechanical properties of the formed nanostructures. We observed that, for layers thicker than 25 nm, the nanoparticle is bonded so strongly that it is easier to break the particle than to separate it from the substrate
Angular momentum in non-relativistic QED and photon contribution to spin of hydrogen atom
International Nuclear Information System (INIS)
Chen Panying; Ji Xiangdong; Xu Yang; Zhang Yue
2010-01-01
We study angular momentum in non-relativistic quantum electrodynamics (NRQED). We construct the effective total angular momentum operator by applying Noether's theorem to the NRQED lagrangian. We calculate the NRQED matching for the individual components of the QED angular momentum up to one loop. We illustrate an application of our results by the first calculation of the angular momentum of the ground state hydrogen atom carried in radiative photons, α em 3 /18π, which might be measurable in future atomic experiments.
Regulating the electrical behaviors of 2D inorganic nanomaterials for energy applications.
Feng, Feng; Wu, Junchi; Wu, Changzheng; Xie, Yi
2015-02-11
Recent years have witnessed great developments in inorganic 2D nanomaterials for their unique dimensional confinement and diverse electronic energy bands. Precisely regulating their intrinsic electrical behaviors would bring superior electrical conductivity, rendering 2D nanomaterials ideal candidates for active materials in electrochemical applications when combined with the excellent reaction activity from the inorganic lattice. This Concept focuses on highly conducting inorganic 2D nanomaterials, including intrinsic metallic 2D nanomaterials and artificial highly conductive 2D nanomaterials. The intrinsic metallicity of 2D nanomaterials is derived from their closely packed atomic structures that ensure maximum overlapping of electron orbitals, while artificial highly conductive 2D nanomaterials could be achieved by designed methodologies of surface modification, intralayer ion doping, and lattice strain, in which atomic-scale structural modulation plays a vital role in realizing conducting behaviors. Benefiting from fast electron transfer, high reaction activity, as well as large surface areas arising from the 2D inorganic lattice, highly conducting 2D nanomaterials open up prospects for enhancing performance in electrochemical catalysis and electrochemical capacitors. Conductive 2D inorganic nanomaterials promise higher efficiency for electrochemical applications of energy conversion and storage. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology
Directory of Open Access Journals (Sweden)
Kateryna Shavanova
2016-02-01
Full Text Available The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D materials. After considerable research effort, a distinct “beyond graphene” domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered, most of the research efforts are concentrated on material synthesis and the investigation of the properties of the material. Applications of 2D non-graphene materials are still at the embryonic stage, and the integration of 2D non-graphene materials into devices is scarcely reported. However, in recent years, numerous reports have blossomed about 2D material-based biosensors, evidencing the growing potential of 2D non-graphene materials for biosensing applications. This review highlights the recent progress in research on the potential of using 2D non-graphene materials and similar oxide nanostructures for different types of biosensors (optical and electrochemical. A wide range of biological targets, such as glucose, dopamine, cortisol, DNA, IgG, bisphenol, ascorbic acid, cytochrome and estradiol, has been reported to be successfully detected by biosensors with transducers made of 2D non-graphene materials.
International Nuclear Information System (INIS)
Accioly, Antonio; Helayël-Neto, José; Barone, F E; Herdy, Wallace
2015-01-01
A straightforward prescription for computing the D-dimensional potential energy of gravitational models, which is strongly based on the Feynman path integral, is built up. Using this method, the static potential energy for the interaction of two masses is found in the context of D-dimensional higher-derivative gravity models, and its behavior is analyzed afterwards in both ultraviolet and infrared regimes. As a consequence, two new gravity systems in which the potential energy is finite at the origin, respectively, in D = 5 and D = 6, are found. Since the aforementioned prescription is equivalent to that based on the marriage between quantum mechanics (to leading order, i.e., in the first Born approximation) and the nonrelativistic limit of quantum field theory, and bearing in mind that the latter relies basically on the calculation of the nonrelativistic Feynman amplitude (M NR ), a trivial expression for computing M NR is obtained from our prescription as an added bonus. (paper)
Electronic structure and optical absorption spectra of Y2 and Zr2 dimers
International Nuclear Information System (INIS)
Gutsev, G.L.
1989-01-01
The electron structure, ionization potentials from valent levels and energies of optic transitions of Y 2 and Zr 2 dimers are calculated within the framework of discrete-variatin X α -method. It is shown that the symmetry state 1 Σ g + is the main state of Y 2 and Zr 2 dimers, and the atoms in dimers have high-spin 4d n+1 5s 1 configuration. The chemical binding in Y 2 has the dominating 5s-5s nature which is revealed in a considerable interatomic distance; binding of 4d-electrons brings about a significant decrease in the bond length in Zr 2 dimer. The theoretical spectrum of optical absorption of Zr 2 agrees well with the obtained experimental spectrum of this molecule isolated in the organ matrix
QCD leading order study of the J/ψ leptoproduction at HERA within the nonrelativistic QCD framework
Energy Technology Data Exchange (ETDEWEB)
Sun, Zhan [Guizhou Minzu University, School of Science, Guiyang (China); Zhang, Hong-Fei [Third Military Medical University, Department of Physics, School of Biomedical Engineering, Chongqing (China)
2017-11-15
As indicated in our previous paper (Zhang and Sun in Phys. Rev. D 96:034002, 2017), the existing literature studying the J/ψ production in deeply inelastic scattering (DIS) in collinear factorisation is on the basis of a formalism that will lead to wrong results when the ranges of the transverse momentum or the rapidity of the J/ψ in the laboratory frame do not cover all values possible for them. In this paper, we present the renewed results for the J/ψ production in DIS at HERA within the nonrelativistic QCD framework at QCD leading order (LO). Three different sets of the long-distance matrix elements are employed for comparison. The predictions via the colour-singlet (CS) model at QCD LO are generally below the experimental data especially in the regions where perturbation theory are expected to work well, while the colour-octet contributions are of the same order of magnitude as the CS ones, however, in general make the agreement between theory and experiment better. (orig.)
Spectroscopie du Furanne et du Thiophene Par Diffusion Inelastique D'electrons
Lotfi, Said
Nous avons etudie les molecules de furanne ( rm C_4H_4O) et de thiophene (rm C_4H_4O) au moyen de la spectroscopie de diffusion inelastique d'electrons. Pour (rm C_4H_4O), les spectres realises dans differentes conditions d'energie d'impact et d'angle de diffusion contiennent des singularites ou des families de pics correspondant a: (1) des vibrations de l'etat fondamental dans le domaine 0-0.5 eV, (2) des etats triplets ^3 B_1 et ^3 A_1 qui dominent la region 3-5.5 eV, (3) des etats de valences, entre 5 et 10 eV, dont certains son accompagnes de progressions vibrationnelles, soit ~ A _1B_2, ~ B ^1A_1 et ~ C ^1A_1, (4) toujours entre 5 et 10 eV, deux series de Ryhdberg (rm 1a_2to nda_2 et rm 1a_2to npb_2) qui convergent vers la premiere limite d'ionisation de la molecule, avec une progression vibrationnelle associee au mdoe nu_4 pour la seconde, et une troisieme serie (rm 2b_1to nsa_1 ) convergent vers la seconde limite d'ionisation accompagnee de la progression de mode nu _1. Pour rm C_4H_4S, nos spectres presentent les memes etats de vibration et les memes etats triplets que pour rm C_4H _4O. Nous avons releve egalement, dans la region de 5 a 10 eV, des etats de valence ~ A ^1A_1 (ou ~ A ^1B_2), ~ B ^1A_1 (ou ~ B ^1B _2) et ~ C ^1A_1 (ou ~ C ^1B_2). Pour la premiere fois, par la spectroscopie de diffusion inelastique d'electrons, de nombreux pics ont ete identifies et attribues, dans le cadre de ce travail. Il s'agit, notamment, des etats de vibration de l'etat electronique fondamental de ces molecules et egalement de certains etats de Rydberg dans le cas du furanne.
International Nuclear Information System (INIS)
Begović, Nebojša N.; Blagojević, Vladimir A.; Ostojić, Sanja B.; Radulović, Aleksandra M.; Poleti, Dejan; Minić, Dragica M.
2015-01-01
Thermally activated 3D to 2D structural transformation of the binuclear [Ni 2 (en) 2 (H 2 O) 6 (pyr)]·4H 2 O complex was investigated using a combination of theoretical and experimental methods. Step-wise thermal degradation (dehydration followed by release of ethylene diamine) results in two layered flexible coordination polymer structures. Dehydration process around 365 K results in a conjugated 2D structure with weak interlayer connectivity. It was shown to be a reversible 3D to 2D framework transformation by a guest molecule, and rehydration of the dehydration product occurs at room temperature in saturated water vapor. Rehydrated complex exhibits lower dehydration temperature, due to decreased average crystalline size, with higher surface area resulting in easier release and diffusion of water during dehydration. Thermal degradation of dehydration around 570 K, results in loss of ethylene diamine, producing a related 2D layered polymer structure, without interconnectivity between individual polymer layers. - Highlights: • Reversible 3D to 2D framework topochemical transformation on dehydration around 365 K. • Resulting polymer exhibits 2D layered structure with weak interlayer connectivity. • Dehydration is fully reversible in saturated water vapor at room temperature. • Further degradation around 570 K yields 2D polymer without interlayer connectivity. • 2D polymer exhibits conjugated electronic system
Electron - atom bremsstrahlung
International Nuclear Information System (INIS)
Kim, L.
1986-01-01
Features of bremsstrahlung radiation from neutral atoms and atoms in hot dense plasmas are studied. Predictions for the distributions of electron-atom bremsstrahlung radiation for both the point-Coulomb potential and screened potentials are obtained using a classical numerical method. Results agree with exact quantum-mechanical partial-wave results for low incident electron energies in both the point-Coulomb and screened potentials. In the screened potential, the asymmetry parameter of a spectrum is reduced from the Coulomb values. The difference increases with decreasing energy and begins to oscillate at very low energies. The scaling properties of bremsstrahlung spectra and energy losses were also studied. It was found that the ratio of the radiative energy loss for positrons to that for electrons obeys a simple scaling law, being expressible fairly accurately as a function only of the quantity T 1 /Z 2 . This scaling is exact in the case of the point-Coulomb potential, both for classical bremsstrahlung and for the nonrelativistic dipole Sommerfeld formula. Bremsstrahlung from atoms in hot dense plasmas were also studied describing the atomic potentials by the temperature-and-density dependent Thomas-Fermi mode. Gaunt factors were obtained with the relativistic partial-wave method for atoms in plasmas of various densities and temperatures
Pressure effects on the 2D electron system in LaAlO{sub 3}/SrTiO{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Borisov, Vladislav; Jeschke, Harald O.; Valenti, Roser [Institute of Theoretical Physics, Goethe University, D-60438 Frankfurt am Main (Germany); Zabaleta, Jone [Max Planck Institute for Solid State Research, D-70569 Stuttgart (Germany); Kopp, Thilo [Center for Electronic Correlations and Magnetism, Experimental Physics VI, Institute of Physics, University of Augsburg, D-86135 Augsburg (Germany)
2016-07-01
We present a theoretical study of pressure effects on the electronic properties of the LaAlO{sub 3}/SrTiO{sub 3} (001) interface. Lattice relaxation plays a crucial role for the formation of the 2D electron system (2DES), in agreement with previous reports. We observe that the carrier density of the 2DES at zero pressure is much lower than the ''polar catastrophe'' estimate of 0.5 e{sup -} per two-dimensional unit cell, which agrees with most experimental works. Under hydrostatic pressure, structural distortions in LaAlO{sub 3} (LAO) are largely suppressed, whereas they increase in SrTiO{sub 3} (STO), and the carrier density of the 2DES is enhanced by almost 45% using a moderate pressure of 4.1 GPa. The origin of this behavior as well as the explanation for the low carrier density at the interface at ambient pressure are discussed in terms of the lattice polarization and electronic Berry phase in the LAO oxide. Reduction of the calculated static dielectric constants of LAO and STO under pressure might account for the recent experimental findings regarding the carrier mobility.
Kearns, Nicholas M; Mehlenbacher, Randy D; Jones, Andrew C; Zanni, Martin T
2017-04-03
We have developed a broad bandwidth two-dimensional electronic spectrometer that operates shot-to-shot at repetition rates up to 100 kHz using an acousto-optic pulse shaper. It is called a two-dimensional white-light (2D-WL) spectrometer because the input is white-light supercontinuum. Methods for 100 kHz data collection are studied to understand how laser noise is incorporated into 2D spectra during measurement. At 100 kHz, shot-to-shot scanning of the delays and phases of the pulses in the pulse sequence produces a 2D spectrum 13-times faster and with the same signal-to-noise as using mechanical stages and a chopper. Comparing 100 to 1 kHz repetition rates, data acquisition time is decreased by a factor of 200, which is beyond the improvement expected by the repetition rates alone due to reduction in 1/f noise. These improvements arise because shot-to-shot readout and modulation of the pulse train at 100 kHz enables the electronic coherences to be measured faster than the decay in correlation between laser intensities. Using white light supercontinuum for the pump and probe pulses produces high signal-to-noise spectra on samples with optical densities 200 nm bandwidth.
A signed particle formulation of non-relativistic quantum mechanics
Energy Technology Data Exchange (ETDEWEB)
Sellier, Jean Michel, E-mail: jeanmichel.sellier@parallel.bas.bg
2015-09-15
A formulation of non-relativistic quantum mechanics in terms of Newtonian particles is presented in the shape of a set of three postulates. In this new theory, quantum systems are described by ensembles of signed particles which behave as field-less classical objects which carry a negative or positive sign and interact with an external potential by means of creation and annihilation events only. This approach is shown to be a generalization of the signed particle Wigner Monte Carlo method which reconstructs the time-dependent Wigner quasi-distribution function of a system and, therefore, the corresponding Schrödinger time-dependent wave-function. Its classical limit is discussed and a physical interpretation, based on experimental evidences coming from quantum tomography, is suggested. Moreover, in order to show the advantages brought by this novel formulation, a straightforward extension to relativistic effects is discussed. To conclude, quantum tunnelling numerical experiments are performed to show the validity of the suggested approach.
Production of electronically excited NO via DEA to NO2
Gope, Krishnendu; Tadsare, Vishvesh; Prabhudesai, Vaibhav S.; Krishnakumar, E.
2017-12-01
Dissociative electron attachment (DEA) to NO2 in the 7-11 eV range is studied using velocity slice imaging technique. Two distinct channels are observed in the DEA corresponding to O- + NO(A 2Σ+) and O- + NO(C 2Π and/or D 2Σ+). While NO(A 2Σ+) is found to be formed only in very high vibrational levels, NO(C 2Π and/or D 2Σ+) is found to be formed with vibrational distribution starting from v = 0. From the angular distribution of the O- ions leading to the NO(C 2Π and/or D 2Σ+) channel, we obtain the symmetry of the negative ion resonance to be dominantly B1 with small contribution from B2. Contribution to the Topical Issue: "Low Energy Positron and Electron Interactions", edited by James Sullivan, Ron White, Michael Bromley, Ilya Fabrikant, and David Cassidy.
High Thermoelectric Power Factor of High-Mobility 2D Electron Gas.
Ohta, Hiromichi; Kim, Sung Wng; Kaneki, Shota; Yamamoto, Atsushi; Hashizume, Tamotsu
2018-01-01
Thermoelectric conversion is an energy harvesting technology that directly converts waste heat from various sources into electricity by the Seebeck effect of thermoelectric materials with a large thermopower ( S ), high electrical conductivity (σ), and low thermal conductivity (κ). State-of-the-art nanostructuring techniques that significantly reduce κ have realized high-performance thermoelectric materials with a figure of merit ( ZT = S 2 ∙σ∙ T ∙κ -1 ) between 1.5 and 2. Although the power factor (PF = S 2 ∙σ) must also be enhanced to further improve ZT , the maximum PF remains near 1.5-4 mW m -1 K -2 due to the well-known trade-off relationship between S and σ. At a maximized PF, σ is much lower than the ideal value since impurity doping suppresses the carrier mobility. A metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT) structure on an AlGaN/GaN heterostructure is prepared. Applying a gate electric field to the MOS-HEMT simultaneously modulates S and σ of the high-mobility electron gas from -490 µV K -1 and ≈10 -1 S cm -1 to -90 µV K -1 and ≈10 4 S cm -1 , while maintaining a high carrier mobility (≈1500 cm 2 V -1 s -1 ). The maximized PF of the high-mobility electron gas is ≈9 mW m -1 K -2 , which is a two- to sixfold increase compared to state-of-the-art practical thermoelectric materials.
2D Spin-Dependent Diffraction of Electrons From Periodical Chains of Nanomagnets
Directory of Open Access Journals (Sweden)
Teshome Senbeta
2012-03-01
Full Text Available The scattering of the unpolarized beams of electrons by nanomagnets in the vicinity of some scattering angles leads to complete spin polarized electrons. This result is obtained with the help of the perturbation theory. The dipole-dipole interaction between the magnetic moment of the nanomagnet and the magnetic moment of electron is treated as perturbation. This interaction is not spherically symmetric. Rather it depends on the electron spin variables. It in turn results in spinor character of the scattering amplitudes. Due to the smallness of the magnetic interactions, the scattering length of this process is very small to be proved experimentally. To enhance the relevant scattering lengths, we considered the diffraction of unpolarized beams of electrons by linear chains of nanomagnets. By tuning the distance between the scatterers it is possible to obtain the diffraction maximum of the scattered electrons at scattering angles which corresponds to complete spin polarization of electrons. It is shown that the total differential scattering length is proportional to N2 (N is a number of scatterers. Even small number of nanomagnets in the chain helps to obtain experimentally visible enhancement of spin polarization of the scattered electrons.
Analysis of the reaction 3He + p → p + p + d at 2,5 GeV/c 3He nucleus momentum
International Nuclear Information System (INIS)
Blinov, A.V.; Chuvilo, I.V.; Drobot, V.V.
1984-01-01
The experimental data on the reaction 3 He+p → p+p+d obtained by the exposition of an 80 cm liquid hydrogen bubble chamber to the 3 He nucleus beam at 2.5 GeV/c momentum are considered. The angular, momentum and invariant mass distributions, which have been measured, are compared with theoretical calculations performed using the pole model. On the whole a satisfactory agreement between theoretical and experimental data is found in the kinematical region, where pd- rescattering effects are negligible. It is concluded, that 3 He nuclear wave function calculated by means of nonrelativistic potential models falls too sharply with the spectator momenta as compared with the data
3D Modeling Activity for Novel High Power Electron Guns at SLAC
International Nuclear Information System (INIS)
Krasnykh, Anatoly
2003-01-01
The next generation of powerful electronic devices requires new approaches to overcome the known limitations of existing tube technology. Multi-beam and sheet beam approaches are novel concepts for the high power microwave devices. Direct and indirect modeling methods are being developed at SLAC to meet the new requirements in the 3D modeling. The direct method of solving of Poisson's equations for the multi-beam and sheet beam guns is employed in the TOPAZ 3D tool. The combination of TOPAZ 2D and EGUN (in the beginning) with MAFIA 3D and MAGIC 3D (at the end) is used in an indirect method to model the high power electron guns. Both methods complement each other to get reliable representation of the beam trajectories. Several gun ideas are under consideration at the present time. The collected results of these simulations are discussed
3D Modeling Activity for Novel High Power Electron Guns at SLAC
Krasnykh, Anatoly K
2003-01-01
The next generation of powerful electronic devices requires new approaches to overcome the known limitations of existing tube technology. Multi-beam and sheet beam approaches are novel concepts for the high power microwave devices. Direct and indirect modeling methods are being developed at SLAC to meet the new requirements in the 3D modeling. The direct method of solving of Poisson's equations for the multi-beam and sheet beam guns is employed in the TOPAZ 3D tool. The combination of TOPAZ 2D and EGUN (in the beginning) with MAFIA 3D and MAGIC 3D (at the end) is used in an indirect method to model the high power electron guns. Both methods complement each other to get reliable representation of the beam trajectories. Several gun ideas are under consideration at the present time. The collected results of these simulations are discussed.
Electronic structure of the [MNH2]+ (M = Sc-Cu) complexes.
Hendrickx, Marc F A; Clima, Sergiu
2006-11-23
B3LYP geometry optimizations for the [MNH2]+ complexes of the first-row transition metal cations (Sc+-Cu+) were performed. Without any exception the ground states of these unsaturated amide complexes were calculated to possess planar geometries. CASPT2 binding energies that were corrected for zero-point energies and including relativistic effects show a qualitative trend across the series that closely resembles the experimental observations. The electronic structures for the complexes of the early and middle transition metal cations (Sc+-Co+) differ from the electronic structures derived for the complexes of the late transition metal cations (Ni+ and Cu+). For the former complexes the relative higher position of the 3d orbitals above the singly occupied 2p(pi) HOMO of the uncoordinated NH2 induces an electron transfer from the 3d shell to 2p(pi). The stabilization of the 3d orbitals from the left to the right along the first-row transition metal series causes these orbitals to become situated below the HOMO of the NH2 ligand for Ni+ and Cu+, preventing a transfer from occurring in the [MNH2]+ complexes of these metal cations. Analysis of the low-lying states of the amide complexes revealed a rather unique characteristic of their electronic structures that was found across the entire series. Rather exceptionally for the whole of chemistry, pi-type interactions were calculated to be stronger than the corresponding sigma-type interactions. The origin of this extraordinary behavior can be ascribed to the low-lying sp2 lone pair orbital of the NH2 ligand with respect to the 3d level.
Energy Technology Data Exchange (ETDEWEB)
Seguatni, A., E-mail: seguatni@gmail.com [LBPC-INSERM U 698, Institut Galilee, Universite Paris XIII, 99, avenue J. B. Clement 93430, Villetaneuse (France); Fakhfakh, M. [Unite de recherche UR 12-30, Synthese et Structure de Materiaux Inorganiques, Faculte des Sciences de Bizerte, 7021 Zarzouna (Tunisia); Departement de Chimie, Universite du Quebec a Montreal, C.P. 8888, Succ. Centre-ville, Montreal, Que., H3C 3P8 (Canada); Smiri, L.S. [Unite de recherche UR 12-30, Synthese et Structure de Materiaux Inorganiques, Faculte des Sciences de Bizerte, 7021 Zarzouna (Tunisia); Gressier, P.; Boucher, F. [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 3 (France); Jouini, N. [Departement de Chimie, Universite du Quebec a Montreal, C.P. 8888, Succ. Centre-ville, Montreal, Que., H3C 3P8 (Canada)
2012-03-15
A new inorganic-organic compound [Cu(O{sub 2}C-CH{sub 2}-CO{sub 2}H){sub 2}{center_dot}2H{sub 2}O] ([Cumal]) was hydrothermally synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray diffraction. [Cumal] is the first three-dimensional compound existing in the system Cu(II)-malonic acid-H{sub 2}O. Its framework is built up through carboxyl bridged copper where CuO{sub 6} octahedra are elongated with an almost D{sub 4h} symmetry (4+2) due to the Jahn-Teller effect. The magnetic properties were studied by measuring its magnetic susceptibility in the temperature range of 2-300 K indicating the existence of weak ferromagnetic interactions. The electronic structure of [Cumal] was calculated within the density functional theory (DFT) framework. Structural features are well reproduced using DFT structural optimizations and the optical spectra, calculated within the dielectric formalism, explain very well the light blue colour of the compound. It is shown that a GGA+U approach with a U{sub eff} value of about 6 eV is necessary for a better correlation with the experiment. - Graphical abstract: [Cu(O{sub 2}C-CH{sub 2}-CO{sub 2}H){sub 2}{center_dot}2H{sub 2}O]: the first 3D hybrid organic-inorganic compound built up carboxyl groups. The network presents a diamond-like structure achieved via carboxyl. Highlights: Black-Right-Pointing-Pointer A new organic-inorganic material with an unprecedented topology is synthesized. Black-Right-Pointing-Pointer Crystallographic structure is determined using single crystal X-ray diffraction. Black-Right-Pointing-Pointer Electronic structure is obtained from DFT, GGA+U calculation. Black-Right-Pointing-Pointer Framework can be described as formed from CuC{sub 4} tetrahedron sharing four corners. Black-Right-Pointing-Pointer This structure can be classified as an extended diamond structure.
Theoretical prediction of high electron mobility in multilayer MoS2 heterostructured with MoSe2
Ji, Liping; Shi, Juan; Zhang, Z. Y.; Wang, Jun; Zhang, Jiachi; Tao, Chunlan; Cao, Haining
2018-01-01
Two-dimensional (2D) MoS2 has been considered to be one of the most promising semiconducting materials with the potential to be used in novel nanoelectronic devices. High carrier mobility in the semiconductor is necessary to guarantee a low power dissipation and a high switch speed of the corresponding electronic device. Strain engineering in 2D materials acts as an important approach to tailor and design their electronic and carrier transport properties. In this work, strain is introduced to MoS2 through perpendicularly building van der Waals heterostructures MoSe2-MoS2. Our first-principles calculations demonstrate that acoustic-phonon-limited electron mobility can be significantly enhanced in the heterostructures compared with that in pure multilayer MoS2. It is found that the effective electron mass and the deformation potential constant are relatively smaller in the heterostructures, which is responsible for the enhancement in the electron mobility. Overall, the electron mobility in the heterostructures is about 1.5 times or more of that in pure multilayer MoS2 with the same number of layers for the studied structures. These results indicate that MoSe2 is an excellent material to be heterostructured with multilayer MoS2 to improve the charge transport property.
PHYSICS OF ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D
International Nuclear Information System (INIS)
PETTY, C.C.; PRATER, R.; LUCE, T.C.; ELLIS, R.A.; HARVEY, R.W.; KINSEY, J.E.; LAO, L.L.; LOHR, J.; MAKOWSKI, M.A.
2002-01-01
OAK A271 PHYSICS OF ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D. Recent experiments on the DIII-D tokamak have focused on determining the effect of trapped particles on the electron cyclotron current drive (ECCD) efficiency. The measured ECCD efficiency increases as the deposition location is moved towards the inboard midplane or towards smaller minor radius for both co and counter injection. The measured ECCD efficiency also increases with increasing electron density and/or temperature. The experimental ECCD is compared to both the linear theory (Toray-GA) as well as a quasilinear Fokker-Planck model (CQL3D). The experimental ECCD is found to be in better agreement with the more complete Fokker-Planck calculation, especially for cases of high rf power density and/or loop voltage
Recombination of H3+ and D3+ ions with electrons in low temperature plasma
International Nuclear Information System (INIS)
Glosik, J; Plasil, R.; Pysanenko, A.; Poterya, V.; Kudrna, P.; Zakouril, P.
2002-01-01
From the decaying plasma (stationary afterglow) in the mixture of He, Ar and H 2 (or D 2 ) we determined the overall recombination rate constant (α eff ) of the recombination of H 3 + and D 3 + ions with electrons at thermal energies. We observed dependence of recombination rate coefficients on partial pressure of hydrogen (and deuterium), which indicates that observed recombination is the three-body process proceeding most probably via formation of long lived intermediate state. From the obtained data we conclude that binary dissociative recombination of H 3 + and D 3 + ions with electrons is very slow with rate coefficient α DR -9 cm 3 s -1 and α DR -9 cm 3 s -1 , respectively. (author)
Impulse electron gun with plasma cathode for realization of large diameter tube-shaped beams
International Nuclear Information System (INIS)
Antipov, V.S.; Karpukhin, V.I.; Kornilov, E.A.
1999-01-01
There are presented the results of investigations of a plasma electron source based on the gas discharge in a coaxial system of electrodes with longitudinal magnetic field. The examination is fulfilled from the viewpoint of applying the source as a plasma cathode for hybrid plasma-waveguide slow-wave structures on the basis of a disk-loaded coaxial. The source is optimized in order to get a powerful (up to 100 kW) nonrelativistic electron beam with the annular cross-section of a large diameter in the regime of relatively long current pulses (up to 0.2 ms) under the gas pressure ∼ 5 centre dot 10 -4 mm Hg in the area of the discharge burning
Effect of high pN2 and high pD2 on NH3 production, H2 evolution, and HD formation by nitrogenases
International Nuclear Information System (INIS)
Jensen, B.B.; Burris, R.H.
1985-01-01
We have investigated the effect of the partial pressure of N2 and D2 on HD formation, H2 evolution, and NH3 production by nitrogenase from Klebsiella pneumoniae and Clostridium pasteurianum. By using pressures up to 4 atm, we have been able to extend the concentration range of N2 and D2 in our investigations beyond that used in previous studies. The pN2 dependence of HD formation with constant pD2 ideally shows no HD formation under zero pN2, reaches a peak which depends on the pD2, and then decreases to zero at very high pN2. K. pneumoniae and C. pasteurianum nitrogenases differ in their Ki(D2) for nitrogen fixation. C. pasteurianum nitrogenase had the lower activity for formation of HD. With K. pneumoniae nitrogenase, D2 enhanced H2 evolution from 31% of the electron flux partitioned to H2 in the absence of D2 to 51% of the electron flux partitioned to H2 at 400 kPa of D2. With C. pasteurianum nitrogenase, the equivalent values were 33% and 48% of the total electron flux. Our results support previou findings on the mechanism for nitrogenase-catalyzed reductions proposed by W. W. Cleland
Energy Technology Data Exchange (ETDEWEB)
Pinsker, R. I.; Jackson, G. L.; Luce, T. C.; Politzer, P. A. [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Austin, M. E. [University of Texas at Austin, Austin, Texas 78712 (United States); Diem, S. J.; Kaufman, M. C.; Ryan, P. M. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Doyle, E. J.; Zeng, L. [University of California Los Angeles, Los Angeles, California 90095 (United States); Grierson, B. A.; Hosea, J. C.; Nagy, A.; Perkins, R.; Solomon, W. M.; Taylor, G. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Maggiora, R.; Milanesio, D. [Politecnico di Torino, Dipartimento di Elettronica, Torino (Italy); Porkolab, M. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Turco, F. [Columbia University, New York, New York 10027 (United States)
2014-02-12
Fast Wave (FW) heating and electron cyclotron heating (ECH) are used in the DIII-D tokamak to study plasmas with low applied torque and dominant electron heating characteristic of burning plasmas. FW heating via direct electron damping has reached the 2.5 MW level in high performance ELMy H-mode plasmas. In Advanced Inductive (AI) plasmas, core FW heating was found to be comparable to that of ECH, consistent with the excellent first-pass absorption of FWs predicted by ray-tracing models at high electron beta. FW heating at the ∼2 MW level to ELMy H-mode discharges in the ITER Baseline Scenario (IBS) showed unexpectedly strong absorption of FW power by injected neutral beam (NB) ions, indicated by significant enhancement of the D-D neutron rate, while the intended absorption on core electrons appeared rather weak. The AI and IBS discharges are compared in an effort to identify the causes of the different response to FWs.
Energy Technology Data Exchange (ETDEWEB)
Okunishi, Takuma; Clark, Richard; Takeda, Kyozaburo [Waseda University, Tokyo 169-8555 (Japan); Kusakabe, Kouichi [Osaka University, Osaka 560-8531 (Japan); Tomita, Norikazu [Yamagata University, Yamagata 960-8560 (Japan)
2013-12-04
We extend the static multi-reference description (resonant UHF) to the dynamic system in order to include the correlation effect over time, and simplify the TD Schrödinger equation (TD-CI) into a time-developed rate equation where the TD external field Ĥ′(t) is then incorporated directly in the Hamiltonian without any approximations. We apply this TD-CI method to the two-electron ground state of a 2D quantum dot (QD) under photon injection and study the resulting two-electron Rabi oscillation.
Bera, Ashok
2015-12-28
Integrating nanomaterials with different dimensionalities and properties is a versatile approach toward realizing new functionalities in advanced devices. Here, a novel diode-type heterostructure is reported consisting of 1D semiconducting ZnO nanorods and 2D metallic LaAlO3-SrTiO3 interface. Tunable insulator-to-metal transitions, absent in the individual components, are observed as a result of the competing temperature-dependent conduction mechanisms. Detailed transport analysis reveals direct tunneling at low bias, Fowler-Nordheim tunneling at high forward bias, and Zener breakdown at high reverse bias. Our results highlight the rich electronic properties of such artificial diodes with hybrid dimensionalities, and the design principle may be generalized to other nanomaterials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Bera, Ashok; Lin, Weinan; Yao, Yingbang; Ding, Junfeng; Lourembam, James; Wu, Tao
2015-01-01
Integrating nanomaterials with different dimensionalities and properties is a versatile approach toward realizing new functionalities in advanced devices. Here, a novel diode-type heterostructure is reported consisting of 1D semiconducting ZnO nanorods and 2D metallic LaAlO3-SrTiO3 interface. Tunable insulator-to-metal transitions, absent in the individual components, are observed as a result of the competing temperature-dependent conduction mechanisms. Detailed transport analysis reveals direct tunneling at low bias, Fowler-Nordheim tunneling at high forward bias, and Zener breakdown at high reverse bias. Our results highlight the rich electronic properties of such artificial diodes with hybrid dimensionalities, and the design principle may be generalized to other nanomaterials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
2D nanomaterials assembled from sequence-defined molecules
International Nuclear Information System (INIS)
Mu, Peng; State University of New York; Zhou, Guangwen; Chen, Chun-Long
2017-01-01
Two dimensional (2D) nanomaterials have attracted broad interest owing to their unique physical and chemical properties with potential applications in electronics, chemistry, biology, medicine and pharmaceutics. Due to the current limitations of traditional 2D nanomaterials (e.g., graphene and graphene oxide) in tuning surface chemistry and compositions, 2D nanomaterials assembled from sequence-defined molecules (e.g., DNAs, proteins, peptides and peptoids) have recently been developed. They represent an emerging class of 2D nanomaterials with attractive physical and chemical properties. Here, we summarize the recent progress in the synthesis and applications of this type of sequence-defined 2D nanomaterials. We also discuss the challenges and opportunities in this new field.
Non-dipole effects in spin polarization of photoelectrons from 3d electrons of Xe, Cs and Ba
Energy Technology Data Exchange (ETDEWEB)
Amusia, M Ya [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Cherepkov, N A [State University of Aerospace Instrumentation, St. Petersburg 190000 (Russian Federation); Chernysheva, L V [A F Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation); Felfli, Z [Department of Physics and Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta GA 30314 (United States); Msezane, A Z [Department of Physics and Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta GA 30314 (United States)
2005-04-28
The non-dipole contribution to spin polarization of photoelectrons from Xe, Cs and Ba 3d{sub 5/2} and 3d{sub 3/2} levels is calculated. The calculation is carried out within the framework of a modified version of the spin-polarized random phase approximation with exchange. The effects of relaxation of excited electrons due to the 3d-vacancy creation are also accounted for. It is demonstrated that the parameters that characterize the photoelectron angular distribution as functions of the incoming photon energy, although being predictably small, acquire additional peculiarities when the interaction between electrons that belong to the 3d{sub 5/2} and 3d{sub 3/2} components of the spin-orbit doublet is taken into account.
Determination of electric dipole transitions in heavy quarkonia using potential non-relativistic QCD
Segovia, Jorge; Steinbeißer, Sebastian
2018-05-01
The electric dipole transitions {χ }bJ(1P)\\to γ \\Upsilon (1S) with J = 0, 1, 2 and {h}b(1P)\\to γ {η }b(1S) are computed using the weak-coupling version of a low-energy effective field theory named potential non-relativistic QCD (pNRQCD). In order to improve convergence and thus give firm predictions for the studied reactions, the full static potential is incorporated into the leading order Hamiltonian; moreover, we must handle properly renormalon effects and re-summation of large logarithms. The precision we reach is {k}γ 3/{(mv)}2× O({v}2), where kγ is the photon energy, m is the mass of the heavy quark and v its velocity. Our analysis separates those relativistic contributions that account for the electromagnetic interaction terms in the pNRQCD Lagrangian which are v 2 suppressed and those that account for wave function corrections of relative order v 2. Among the last ones, corrections from 1/m and 1/m2 potentials are computed, but not those coming from higher Fock states since they demand non-perturbative input and are {{{Λ }}}{{QCD}}2/{(mv)}2 or {{{Λ }}}{{QCD}}3/({m}3{v}4) suppressed, at least, in the strict weak coupling regime. These proceedings are based on the forthcoming publication [1].
Guo, Yuqiao; Deng, Haitao; Sun, Xu; Li, Xiuling; Zhao, Jiyin; Wu, Junchi; Chu, Wangsheng; Zhang, Sijia; Pan, Haibin; Zheng, Xusheng; Wu, Xiaojun; Jin, Changqing; Wu, Changzheng; Xie, Yi
2017-08-01
2D transition-metal dichalcogenides (TMDCs) are currently the key to the development of nanoelectronics. However, TMDCs are predominantly nonmagnetic, greatly hindering the advancement of their spintronic applications. Here, an experimental realization of intrinsic magnetic ordering in a pristine TMDC lattice is reported, bringing a new class of ferromagnetic semiconductors among TMDCs. Through van der Waals (vdW) interaction engineering of 2D vanadium disulfide (VS 2 ), dual regulation of spin properties and bandgap brings about intrinsic ferromagnetism along with a small bandgap, unravelling the decisive role of vdW gaps in determining the electronic states in 2D VS 2 . An overall control of the electronic states of VS 2 is also demonstrated: bond-enlarging triggering a metal-to-semiconductor electronic transition and bond-compression inducing metallization in 2D VS 2 . The pristine VS 2 lattice thus provides a new platform for precise manipulation of both charge and spin degrees of freedom in 2D TMDCs availing spintronic applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Strain-Gated Field Effect Transistor of a MoS2-ZnO 2D-1D Hybrid Structure.
Chen, Libo; Xue, Fei; Li, Xiaohui; Huang, Xin; Wang, Longfei; Kou, Jinzong; Wang, Zhong Lin
2016-01-26
Two-dimensional (2D) molybdenum disulfide (MoS2) is an exciting material due to its unique electrical, optical, and piezoelectric properties. Owing to an intrinsic band gap of 1.2-1.9 eV, monolayer or a-few-layer MoS2 is used for fabricating field effect transistors (FETs) with high electron mobility and on/off ratio. However, the traditional FETs are controlled by an externally supplied gate voltage, which may not be sensitive enough to directly interface with a mechanical stimulus for applications in electronic skin. Here we report a type of top-pressure/force-gated field effect transistors (PGFETs) based on a hybrid structure of a 2D MoS2 flake and 1D ZnO nanowire (NW) array. Once an external pressure is applied, the piezoelectric polarization charges created at the tips of ZnO NWs grown on MoS2 act as a gate voltage to tune/control the source-drain transport property in MoS2. At a 6.25 MPa applied stimulus on a packaged device, the source-drain current can be tuned for ∼25%, equivalent to the results of applying an extra -5 V back gate voltage. Another type of PGFET with a dielectric layer (Al2O3) sandwiched between MoS2 and ZnO also shows consistent results. A theoretical model is proposed to interpret the received data. This study sets the foundation for applying the 2D material-based FETs in the field of artificial intelligence.
Energy Technology Data Exchange (ETDEWEB)
Alonso, E.V.; Baragiola, R.A.; Ferron, J.; Jakas, M.M.; Oliva-Florio, A.
1980-07-01
We have measured the electron emission yields ..gamma.. of clean aluminum under bombardment with H/sup +/, H/sub 2/ /sup +/, D/sup +/, D/sub 2/ /sup +/, He/sup +/, B/sup +/, C/sup +/, N/sup +/, N/sub 2/ /sup +/, O/sup +/, O/sub 2/ /sup +/, F/sup +/, Ne/sup +/, S/sup +/, Cl/sup +/, Ar/sup +/, Kr/sup +/, and Xe/sup +/ in the energy range 1.2--50 keV. The clean surfaces were prepared by in situ evaporation of high-purity Al under ultra-high-vacuum conditions. It is found that kinetic electron emission yields ..gamma../sub k/, obtained after subtracting from the measured ..gamma.. a contribution due to potential emission, are roughly proportional to the electronic stopping powers, for projectiles lighter than Al. For heavier projectiles there is a sizable contribution to electron emission from collisions involving rapidly recoiling target atoms, which increases with the mass of the projectile, and which dominates the threshold and near-threshold behavior of kinetic emission. The results, together with recently reported data on Auger electron emission from ion-bombarded Al show that the mechanism proposed by Parilis and Kishinevskii of inner-shell excitation and subsequent Auger decay is negligible for light ions and probably small for heavy ions on Al and in our energy range. We thus conclude that kinetic electron emission under bombardment by low-energy ions results mainly from the escape of excited valence electrons.
International Nuclear Information System (INIS)
Li, Dan; Niu, Yuan; Zhao, Hongmin; Liang, Chunjun; He, Zhiqun
2014-01-01
Utilizing first-principle calculations, the structural, electronic, and magnetic properties of monolayer MoS 2 doped with 3d transition-metal (TM) atoms and 3d-metal trioxides (TMO 3 ) superhalogen clusters are investigated. 3d-metal TMO 3 superhalogen cluster-doped monolayers MoS 2 almost have negative formation energies except CoO 3 and NiO 3 doped monolayer MoS 2 , which are much lower than those of 3d TM-doped structures. 3d-metal TMO 3 superhalogen clusters are more easily embedded in monolayer MoS 2 than 3d-metal atoms. MnO 3 , FeO 3 , CoO 3 , and NiO 3 incorporated into monolayer MoS 2 are magnetic, and the total magnetic moments are approximately 1.0, 2.0, 3.0, and 4.0 μB per supercell, respectively. MnO 3 and FeO 3 incorporated into monolayer MoS 2 become semiconductors, whereas CoO 3 and NiO 3 incorporated into monolayer MoS 2 become half-metallic. Our studies demonstrate that the half-metallic ferromagnetic nature of 3d-metal TMO 3 superhalogen clusters-doped monolayer MoS 2 has a great potential for MoS 2 -based spintronic device applications. -- Highlights: •TMO 3 superhalogen clusters incorporated into monolayer MoS 2 were investigated. •TMO 3 doped structures have much lower formation energies than TM doped structures. •TMO 3 cluster-doped MoS 2 are thermodynamically favored. •Significant charge transfers between O atoms and Mo atoms in TMO 3 doped structures. •MnO 3 , FeO 3 , CoO 3 , and NiO 3 incorporated into monolayer MoS 2 are magnetic.
Fast-electron-impact study on excitations of 4p, 4s, and 3d electrons of krypton
International Nuclear Information System (INIS)
Yuan Zhensheng; Zhu Linfan; Liu Xiaojing; Li Wenbin; Cheng Huadong; Xu Kezun; Zhong Zhiping
2002-01-01
Absolute optical oscillator strength densities for the excitations of the electrons 4p, 4s, and 3d have been measured. Their absolute optical oscillator strengths have also been obtained. An enhancement above the 4p ionization threshold in the photoabsorption spectrum was assigned as a delayed maximum which arises from the photoionization process of 4p→εd according to present Dirac-Slater calculation. In the energy region of 4s autoionization, we have observed several features that are absent in previous fast-electron-impact work, but exist in optical measurements. We clarify this discrepancy here. Two Rydberg series of optically forbidden transitions, i.e., 4s -1 ns( 1 S) (n=5,6,7) and 4s -1 nd( 1 D) (n=4,5,6,7) have been observed when the spectrometer worked at conditions with larger momentum transfers, namely, K 2 =0.23 a.u. and 0.67 a.u. Furthermore, the absolute optical oscillator strengths for the 3d excitation have been obtained
Nearly perpendicular wave propagation at the fundamental electron-cyclotron resonance
International Nuclear Information System (INIS)
Imre, K.; Weitzner, H.
1985-01-01
Waves propagating nearly perpendicular to the equilibrium magnetic field across the fundamental cyclotron resonance layer are studied by a boundary layer analysis for a weakly relativistic, inhomogeneous Vlasov plasma. The plasma is assumed to be perpendicularly stratified. It is found that the wave energy associated with the ordinary mode transmitted through the layer is independent of the relativistic corrections and is given by a geometrical optics formula. It is also found that there is no reflected energy associated with this mode when it is incident from the high-field side. These results are the same as the nonrelativistic case with purely perpendicular propagation. Relativistic effects produce a significant reduction of the reflection coefficient for low-field side incidence from the nonrelativistic value. Correspondingly, for this mode there is a considerable increase in the absorption rate for sufficiently high, but moderate, electron density and temperature
Duality of two-point functions for confined non-relativistic quark-antiquark systems
International Nuclear Information System (INIS)
Fishbane, P.M.; Gasiorowicz, S.G.; Kaus, P.
1985-01-01
An analog to the scattering matrix describes the spectrum and high-energy behavior of confined systems. We show that for non-relativistic systems this S-matrix is identical to a two-point function which transparently describes the bound states for all angular momenta. Confined systems can thus be described in a dual fashion. This result makes it possible to study the modification of linear trajectories (originating in a long-range confining potential) due to short range forces which are unknown except for the way in which they modify the asymptotic behavior of the two point function. A type of effective range expansion is one way to calculate the energy shifts. 9 refs
Structure, magnetism and electronic properties in 3d-5d based double perovskite (Sr1-xYx)2FeIrO6.
Kharkwal, Kishor Chandra; Pramanik, Ashim Kumar
2017-10-17
The 3$d$-5$d$ based double perovskites are of current interest as they provide model system to study the interplay between electronic correlation ($U$) and spin-orbit coupling (SOC). Here we report detailed structural, magnetic and transport properties of doped double perovskite material (Sr$_{1-x}$Y$_x$)$_2$FeIrO$_6$ with $x$ $\\leq$ 0.2. With substitution of Y, system retains its original crystal structure but structural parameters modify with $x$ in nonmonotonic fashion. The magnetization data for Sr$_2$FeIrO$_6$ show antiferromagnetic type magnetic transition around 45 K, however, a close inspection in data indicates a weak magnetic phase transition around 120 K. No change of structural symmetry has been observed down to low temperature, although the lattice parameters show sudden changes around the magnetic transitions. Sr$_2$FeIrO$_6$ shows an insulating behavior over the whole temperature range which yet does not change with Y substitution. Nature of charge conduction is found to follow thermally activated Mott's variable range hopping and power law behavior for parent and doped samples, respectively. Interestingly, evolution of structural, magnetic and transport behavior in (Sr$_{1-x}$Y$_x$)$_2$FeIrO$_6$ is observed to reverse with $x$ $>$ 0.1 which is believed to arise due to change in transition metal ionic state. © 2017 IOP Publishing Ltd.
Electron and photon identification in the D0 experiment
Energy Technology Data Exchange (ETDEWEB)
Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Agnew, J. P.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Borysova, M.; Brandt, A.; Brandt, O.; Brock, R.; Bross, A.; Brown, D.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Buszello, C. P.; Camacho-Pérez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Déliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dubey, A.; Dudko, L. V.; Duperrina, A.; Dutt, S.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, V. N.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garbincius, P. H.; Garcia-Bellido, A.; García-González, J. A.; Gavrilov, V.; Geng, W.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph.; Grivaz, J. -F.; Grohsjean, A.; Grünendahl, S.; Grünewald, M. W.; Guillemin, T.; Gutierrez, G.; Gutierrez, P.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hogan, J.; Hohlfeld, M.; Holzbauer, J. L.; Howley, I.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffré, M.; Jayasinghe, A.; Jeong, M. S.; Jesik, R.; Jiang, P.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kajfasz, E.; Karmanov, D.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kiselevich, I.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kumar, A.; Kupco, A.; Kurča, T.; Kuzmin, V. A.; Lammers, S.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lei, X.; Lellouch, J.; Li, D.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; Lopes de Sa, R.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magaña-Villalba, R.; Malik, S.; Malyshev, V. L.; Mansour, J.; Martínez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Miconi, F.; Mondal, N. K.; Mulhearn, M.; Nagy, E.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Nguyen, H. T.; Nunnemann, T.; Orduna, J.; Osman, N.; Osta, J.; Pal, A.; Parashar, N.; Parihar, V.; Park, S. K.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, Y.; Petridis, K.; Petrillo, G.; Pétroff, P.; Pleier, M. -A.; Podstavkov, V. M.; Popov, A. V.; Prewitt, M.; Price, D.; Prokopenko, N.; Qian, J.; Quadt, A.; Quinn, B.; Raja, R.; Ratoff, P. N.; Razumov, I.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Ross, A.; Royon, C.; Rubinov, P.; Ruchti, R.; Sajot, G.; Sánchez-Hernández, A.; Sanders, M. P.; Santos, A. S.; Savage, G.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shaw, S.; Shchukin, A. A.; Simak, V.; Skubic, P.; Slattery, P.; Smirnov, D.; Snow, G. R.; Snow, J.; Snyder, S.; Söldner-Rembold, S.; Sonnenschein, L.; Soustruznik, K.; Stark, J.; Stoyanova, D. A.; Strauss, M.; Suter, L.; Svoisky, P.; Titov, M.; Tokmenin, V. V.; Tsai, Y. -T.; Tsybychev, D.; Tuchming, B.; Tully, C.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Van Kooten, R.; van Leeuwen, W. M.; Varelas, N.; Varnes, E. W.; Vasilyev, I. A.; Verkheev, A. Y.; Vertogradov, L. S.; Verzocchi, M.; Vesterinen, M.; Vilanova, D.; Vokac, P.; Wahl, H. D.; Wang, M. H. L. S.; Warchol, J.; Watts, G.; Wayne, M.; Weichert, J.; Welty-Rieger, L.; Williams, M. R. J.; Wilson, G. W.; Wobisch, M.; Wood, D. R.; Wyatt, T. R.; Xie, Y.; Yamada, R.; Yang, S.; Yasuda, T.; Yatsunenko, Y. A.; Ye, W.; Ye, Z.; Yin, H.; Yip, K.; Youn, S. W.; Yu, J. M.; Zennamo, J.; Zhao, T. G.; Zhou, B.; Zhu, J.; Zielinski, M.; Zieminska, D.; Zivkovic, L.
2014-06-01
The electron and photon reconstruction and identification algorithms used by the D0 Collaboration at the Fermilab Tevatron collider are described. The determination of the electron energy scale and resolution is presented. Studies of the performance of the electron and photon reconstruction and identification are summarized.
Raman enhancement by graphene-Ga2O3 2D bilayer film.
Zhu, Yun; Yu, Qing-Kai; Ding, Gu-Qiao; Xu, Xu-Guang; Wu, Tian-Ru; Gong, Qian; Yuan, Ning-Yi; Ding, Jian-Ning; Wang, Shu-Min; Xie, Xiao-Ming; Jiang, Mian-Heng
2014-01-28
2D β-Ga2O3 flakes on a continuous 2D graphene film were prepared by a one-step chemical vapor deposition on liquid gallium surface. The composite was characterized by optical microscopy, scanning electron microscopy, Raman spectroscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy (XPS). The experimental results indicate that Ga2O3 flakes grew on the surface of graphene film during the cooling process. In particular, tenfold enhancement of graphene Raman scattering signal was detected on Ga2O3 flakes, and XPS indicates the C-O bonding between graphene and Ga2O3. The mechanism of Raman enhancement was discussed. The 2D Ga2O3-2D graphene structure may possess potential applications.
Growth of 2D Materials and Application in Electrochemical Energy Conversion
Ye, Gonglan
The discovery of graphene in 2004 has generated numerous interests among scientists for graphene's versatile potentials. The enthusiasm for graphene has recently been extended to other members of two-dimensional (2D) materials for applications in electronics, optoelectronics, and catalysis. Different from graphene, atomically-thin transition metal dichalcogenides (TMDs) have varied band gaps and would benefit for applications in the semiconductor industry. One of the promising applications of 2D TMDs is for 2D integrated circuits to replace current Si based electronics. In addition to electronic applications, 2D materials are also good candidates for electrochemical energy storage and conversion due to their large surface area and atomic thickness. This thesis mainly focuses on the synthesis of 2D materials and their application in energy conversion. Firstly, we focus on the synthesis of two-dimensional Tin Disulfide (SnS2). SnS2 is considered to be a novel material in 2D family. 2D SnS2 has a large band gap ( 2.8 eV) and high carrier mobility, which makes it a potential applicant for electronics. Monolayer SnS2 with large scale and high crystal quality was successfully synthesized by chemical vapor deposition (CVD), and its performance as a photodetector was examined. The next chapter demonstrated a generic method for growing millimeter-scale single crystals as well as wafer-scale thin films of TMDs. This generic method was obtained by studying the precursors' behavior and the flow dynamics during the CVD process of growing MoSe2, and was extended to other TMD layers such as millimeter-scale WSe2 single crystals. Understanding the growth processes of high quality large area monolayers of TMDs is crucial for further fundamental research as well as future development for scalable complex electronics. Besides the synthesis of 2D materials with high qualities, we further explored the relationship between defects and electrochemical properties. By directly observing
Electronic structures and superconductivity in LuTE2Si2 phases (TE = d-electron transition metal)
Samsel-Czekała, M.; Chajewski, G.; Wiśniewski, P.; Romanova, T.; Hackemer, A.; Gorzelniak, R.; Pikul, A. P.; Kaczorowski, D.
2018-05-01
In the course of our search for unconventional superconductors amidst the 1:2:2 phases, we have re-investigated the LuTE2Si2 compounds with TE = Fe, Co, Ni, Ru, Pd and Pt. In this paper, we present the results of our fully relativistic ab initio calculations of the band structures, performed using the full-potential local-orbital code. The theoretical data are supplemented by the results of low-temperature electrical transport and specific heat measurements performed down to 0.35 K. All the materials studied but LuPt2Si2 crystallize with the body-centered tetragonal ThCr2Si2-type structure (space group I4/mmm). Their Fermi surfaces exhibit a three-dimensional multi-band character. In turn, the Pt-bearing compound adopts the primitive tetragonal CaBe2Ge2-type structure (space group P4/nmm), and its Fermi surface consists of predominantly quasi-two-dimensional sheets. Bulk superconductivity was found only in LuPd2Si2 and LuPt2Si2 (independent of the structure type and dimensionality of the Fermi surface). The key superconducting characteristics indicate a fully-gapped BCS type character. Though the electronic structure of LuFe2Si2 closely resembles that of the unconventional superconductor YFe2Ge2, this Lu-based silicide exhibits neither superconductivity nor spin fluctuations at least down to 0.35 K.
Structural and electronic properties of LaPd2As2 superconductor: First-principle calculations
Singh, Birender; Kumar, Pradeep
2017-05-01
In present work we have studied electronic and structural properties of superconducting LaPd2As2 compound having collapsed tetragonal structure using first-principle calculations. The band structure calculations show that the LaPd2As2 is metallic consistent with the reported experimental observation, and the density of states plots clearly shows that at the Fermi level major contribution to density of states arises from Pd 4d and As 4p states, unlike the Fe-based superconductors where major contribution at the Fermi level comes from Fe 3d states. The estimated value of electron-phonon coupling is found to be 0.37, which gives the upper bound of superconducting transition temperature of 5K, suggesting the conventional nature of this superconductor.
International Nuclear Information System (INIS)
Ermler, W.C.; Lee, Y.S.; Pitzer, K.S.; Winter, N.W.
1978-01-01
Potential energy curves for the ground 1 Σ + /sub g/ state of Xe 2 , the first four states of the Xe + 2 ions, and the eight Xe* 2 excimer states corresponding to the addition of a 6ssigma/sub g/ Rydberg electron to these ion cores have been computed using averaged relativistic effective core potentials (AREP) and the self-consistent field approximation for the valence electrons. The calculations were carried out using the LS-coupling scheme with the effects of spin--orbit coupling included in the resulting potential energy curves using an empirical procedure. A comparison of nonrelativistic and averaged relativistic EP's and subsequent molecular calculations indicates that relativistic effects arising from the mass--velocity and Darwin terms are not important for these properties of Xe 2 molecules. Spectroscopic constants for Xe + 2 are in good agreement with all electron CI calculations suggesting that the computed values for Xe* 2 excimers should be reliable. The lifetime for the O/sub u/ + state of the Xe 2 * is computed to be 5.6 nsec which is in the range of the experimentally determined values
Xie, Linfang; Ni, Jie; Tang, Bo; He, Guangyu; Chen, Haiqun
2018-03-01
A surface charge modified g-C3N4 was successfully prepared by protonation of nitric acid. Combination of the protonated g-C3N4 (pCN) and graphene oxide (GO) layers created a 2D/2D-type composite (pCN/GO) under the synergistic effect of sonication-exfoliation and self-assembly. The obtained 2D nanostructure of pCN/GO was explored by electron microscopy analysis. The photocatalytic degradation of rhodamine B (RhB) and ciprofloxacin (CIP) showed a distinctly high efficiency of pCN/GO-5% with excellent stability, which is superior not only to that of g-C3N4, pCN and g-C3N4/GO-5% nanocomposites we prepared, but also to what was reported previously. The optimized combination of GO and pCN afforded the pCN/GO composite intimate interfacial contact within the heterojunction, which promoted the separation of photogenerated electron-hole pairs as evidenced by zeta potential, photoluminescence and photocurrent measurements. A visible-light photocatalytic degradation mechanism associated with pCN/GO nanocomposites was also proposed.
Directory of Open Access Journals (Sweden)
Sen Zhou
2017-10-01
Full Text Available Analogs of the high-T_{c} cuprates have been long sought after in transition metal oxides. Because of the strong spin-orbit coupling, the 5d perovskite iridates Sr_{2}IrO_{4} exhibit a low-energy electronic structure remarkably similar to the cuprates. Whether a superconducting state exists as in the cuprates requires understanding the correlated spin-orbit entangled electronic states. Recent experiments discovered hidden order in the parent and electron-doped iridates, some with striking analogies to the cuprates, including Fermi surface pockets, Fermi arcs, and pseudogap. Here, we study the correlation and disorder effects in a five-orbital model derived from the band theory. We find that the experimental observations are consistent with a d-wave spin-orbit density wave order that breaks the symmetry of a joint twofold spin-orbital rotation followed by a lattice translation. There is a Berry phase and a plaquette spin flux due to spin procession as electrons hop between Ir atoms, akin to the intersite spin-orbit coupling in quantum spin Hall insulators. The associated staggered circulating J_{eff}=1/2 spin current can be probed by advanced techniques of spin-current detection in spintronics. This electronic order can emerge spontaneously from the intersite Coulomb interactions between the spatially extended iridium 5d orbitals, turning the metallic state into an electron-doped quasi-2D Dirac semimetal with important implications on the possible superconducting state suggested by recent experiments.
Single crystal growth and electronic states in RCu2Sb2
International Nuclear Information System (INIS)
Dung, Nguyen Duc; Takeda, Yuji; Ota, Yuuki; Ishikura, Tatsuro; Sugiyama, Kiyohiro; Settai, Rikio; Onuki, Yoshichika; Matsuda, Tatsuma D.; Haga, Yoshinori; Takeuchi, Tetsuya; Harima, Hisatomo; Goto, Saori; Mitsumoto, Keisuke; Akatsu, Mitsuhiro; Nemoto, Yuichi; Goto, Terutaka
2009-01-01
A series of ternary compounds RCu 2 Si 2 (R: rare earth) has been grown in single-crystalline form by the flux method. The magnetic and electronic properties of these compounds were investigated by measuring the electrical receptivity, specific heat, magnetization, thermal expansion, ultrasonic and dHvA measurements. The anisotropy in susceptibility and magnetization is relatively small in RCu 2 Si 2 , reflecting the small splitting energy of the 4f electronic state by the crystalline electric field. The quadrupolar interaction most likely plays an important role in the relatively high antiferromagnetic ordering temperature in PrCu 2 Si 2 . Characteristic features of the observed Fermi surfaces in YbCu 2 Si 2 and YbCu 2 Ge 2 are discussed on the basis of the band calculations. (author)
Electron acceleration in the Solar corona - 3D PiC code simulations of guide field reconnection
Alejandro Munoz Sepulveda, Patricio
2017-04-01
The efficient electron acceleration in the solar corona detected by means of hard X-ray emission is still not well understood. Magnetic reconnection through current sheets is one of the proposed production mechanisms of non-thermal electrons in solar flares. Previous works in this direction were based mostly on test particle calculations or 2D fully-kinetic PiC simulations. We have now studied the consequences of self-generated current-aligned instabilities on the electron acceleration mechanisms by 3D magnetic reconnection. For this sake, we carried out 3D Particle-in-Cell (PiC) code numerical simulations of force free reconnecting current sheets, appropriate for the description of the solar coronal plasmas. We find an efficient electron energization, evidenced by the formation of a non-thermal power-law tail with a hard spectral index smaller than -2 in the electron energy distribution function. We discuss and compare the influence of the parallel electric field versus the curvature and gradient drifts in the guiding-center approximation on the overall acceleration, and their dependence on different plasma parameters.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Chao-Zhi, E-mail: chzhzhang@sohu.com [Department of Chemistry, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Gu, Shu-Duo; Shen, Dan; Yuan, Yang [Department of Chemistry, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Zhang, Mingdao, E-mail: matchlessjimmy@163.com [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science & Technology, Nanjing 210044 (China)
2016-08-22
Electron-accepting molecules play an important role in developing organic solar cells. A new type of A-D-A molecule, 3,6-di([7-(5-bromothiophen-2-yl)-1,5,2,4,6,8-dithiotetrazocin-3-yl]thiophen -2-yl)-9-(2-ethylhexyl)carbazole, was synthesized. The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels are −3.55 and −5.85 eV, respectively. Therefore, the A-D-A type of compound could be used as electron acceptor for fabricating organic solar cell with a high open circuit voltage. Gibbs free energy (−49.2 kJ/mol) reveals that the process of A-D-A acceptor accepting an electron from poly(3-hexylthiophene) at excited state is spontaneous. The value of entropy (118 J/mol) in the process of an electron transferring from P3HT to the A-D-A acceptor at organic interface suggests that electrons generated from separation of electron-hole pairs at donor/acceptor interface would be delocalized efficiently. Therefore, the A-D-A molecule would be a potential acceptor for efficient organic BHJ solar cells.
RECENT DEVELOPMENTS ON THE 110 GHz ELECTRON CYCLOTRON INSTATLLATION ON THE DIII-D TOKAMAK
International Nuclear Information System (INIS)
PONCE, D.; CALLIS, R.W.; CARY, W.P.; FERRON, J.R.; GREEN, M.; GRUNLOH, H.J.; GORELOV, Y.; LOHR, J.; ELLIS, R.A.
2002-01-01
OAK A271 RECENT DEVELOPMENTS ON THE 110 GHZ ELECTRON CYCLOTRON INSTALLATION ON THE DIII-D TOKAMAK. Significant improvements are being implement4ed to the capability of the 110 GHz electron cyclotron system on the DIII-D tokamak. Chief among these is the addition of the fifth and sixth 1 MW class gyrotrons, increasing the power available for auxiliary heating and current drive by nearly 60%. These tubes use artificially grown diamond rf output windows to obtain high power with long pulse capability. The beams from these tubes are nearly Gaussian, facilitating coupling to the waveguide. A new fully articulating dual launcher capable of high speed spatial scanning has been designed and tested. The launcher has two axis independent steering for each waveguide. the mirrors can be rotated at up to 100 o /s. A new feedback system linking the DIII-D Plasma Control System (PCS) with the gyrotron beam voltage waveform generators permits real-time feedback control of some plasma properties such as electron temperature. The PCS can use a variety of plasma monitors to generate its control signal, including electron cyclotron emission and Mirnov probes. Electron cyclotron heating and electron cyclotron current drive (ECH and ECCD) were used during this year's DIII-D experimental campaign to control electron temperature, density, and q profiles, induce an ELM-free H-mode, and suppress the m=2/n=1 neoclassical tearing mode. The new capabilities have expanded the role of EC systems in tokamak plasma control
Fast electrons in small solar flares
International Nuclear Information System (INIS)
Lin, R.P.
1975-01-01
Because approximately 5-100 keV electrons are frequently accelerated and emitted by the Sun in small flares, it is possible to define a detailed characteristic physical picture of these events. The review summarizes both the direct spacecraft observations of non-relativistic solar electrons, and observations of the X-ray and radio emission generated by these particles at the Sun and in the interplanetary medium. These observations bear on the basic astrophysical process of particle acceleration in tenuous plasmas. It is found that in many small solar flares the approximately 5-100 keV electrons accelerated during flash phase constitute the bulk of the total flare energy. Thus the basic flare mechanism in these flares essentially converts the available flare energy into fast electrons. These electrons may produce the other flare electromagnetic emissions through their interactions with the solar atmosphere. In large proton flares these electrons may provide the energy to eject material from the Sun and to create a shock wave which could then accelerate nuclei and electrons to much higher energies. (Auth.)
Relativistic properties of spherical diodes with a radial electron flux
International Nuclear Information System (INIS)
Chetvertkov, V.I.
1987-01-01
Forward and backward electron diodes with concentric spherical electrodes (inner cathode, outer anode or vice versa) are considered under the assumption that the emission is limited by the space charge and the guiding magnetic field is predominantly radial within a region of solid angle α f < 4π bounding the electron flux. The Poisson equations for the relativistic factor γ are solved for generalized model dependences. Ultrarelativistic and new nonrelativistic solutions are found, and analytic approximations to the solution near the cathode are used to carry out numerical calculations. The characteristics of forward and backward diodes turn out to be related to the exact solutions for a planar diode. Accurate approximations are found for calculating the diode parameters in a wide range of voltages; they can also be used to check the validity of the 3/2 laws and the ultrarelativistic solutions
Electronic structures and photophysics of d8-d8 complexes
Czech Academy of Sciences Publication Activity Database
Gray, H. B.; Záliš, Stanislav; Vlček, Antonín
2017-01-01
Roč. 345, AUG 2017 (2017), s. 297-317 ISSN 0010-8545 R&D Projects: GA MŠk LH13015 Grant - others:COST(XE) CM1405 Institutional support: RVO:61388955 Keywords : excitation * electronic structures * photophysics Subject RIV: CG - Electrochemistry OBOR OECD: Physical chemistry Impact factor: 13.324, year: 2016
3D Printing of Plant Golgi Stacks from Their Electron Tomographic Models.
Mai, Keith Ka Ki; Kang, Madison J; Kang, Byung-Ho
2017-01-01
Three-dimensional (3D) printing is an effective tool for preparing tangible 3D models from computer visualizations to assist in scientific research and education. With the recent popularization of 3D printing processes, it is now possible for individual laboratories to convert their scientific data into a physical form suitable for presentation or teaching purposes. Electron tomography is an electron microscopy method by which 3D structures of subcellular organelles or macromolecular complexes are determined at nanometer-level resolutions. Electron tomography analyses have revealed the convoluted membrane architectures of Golgi stacks, chloroplasts, and mitochondria. But the intricacy of their 3D organizations is difficult to grasp from tomographic models illustrated on computer screens. Despite the rapid development of 3D printing technologies, production of organelle models based on experimental data with 3D printing has rarely been documented. In this chapter, we present a simple guide to creating 3D prints of electron tomographic models of plant Golgi stacks using the two most accessible 3D printing technologies.
International Nuclear Information System (INIS)
Grant, I.P.
1982-01-01
Possible relativistic effects in low energy electron scattering from atoms or positive ions has been investigated using the Dirac hamiltonian. Single channel formula and many channel expressions indicate that asymptotic estimation of radial wavefunctions can be carried out satisfactorily for most purposes using non-relativistic methods. (U.K.)
Hybrid 3D Printing of Soft Electronics.
Valentine, Alexander D; Busbee, Travis A; Boley, John William; Raney, Jordan R; Chortos, Alex; Kotikian, Arda; Berrigan, John Daniel; Durstock, Michael F; Lewis, Jennifer A
2017-10-01
Hybrid 3D printing is a new method for producing soft electronics that combines direct ink writing of conductive and dielectric elastomeric materials with automated pick-and-place of surface mount electronic components within an integrated additive manufacturing platform. Using this approach, insulating matrix and conductive electrode inks are directly printed in specific layouts. Passive and active electrical components are then integrated to produce the desired electronic circuitry by using an empty nozzle (in vacuum-on mode) to pick up individual components, place them onto the substrate, and then deposit them (in vacuum-off mode) in the desired location. The components are then interconnected via printed conductive traces to yield soft electronic devices that may find potential application in wearable electronics, soft robotics, and biomedical devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Isotopic exchange processes in cold plasmas of H2/D2 mixtures.
Jiménez-Redondo, Miguel; Carrasco, Esther; Herrero, Víctor J; Tanarro, Isabel
2011-05-28
Isotope exchange in low pressure cold plasmas of H(2)/D(2) mixtures has been investigated by means of mass spectrometric measurements of neutrals and ions, and kinetic model calculations. The measurements, which include also electron temperatures and densities, were performed in a stainless steel hollow cathode reactor for three discharge pressures: 1, 2 and 8 Pa, and for mixture compositions ranging from 100% H(2) to 100% D(2). The data are analyzed in the light of the model calculations, which are in good global agreement with the experiments. Isotope selective effects are found both in the surface recombination and in the gas-phase ionic chemistry. The dissociation of the fuel gas molecules is followed by wall recycling, which regenerates H(2) and D(2) and produces HD. Atomic recombination at the wall is found to proceed through an Eley-Rideal mechanism, with a preference for reaction of the adsorbed atoms with gas phase D atoms. The best fit probabilities for Eley-Rideal abstraction with H and D are: γ(ER H) = 1.5 × 10(-3), γ(ER D) = 2.0 × 10(-3). Concerning ions, at 1 Pa the diatomic species H(2)(+), D(2)(+) and HD(+), formed directly by electron impact, prevail in the distributions, and at 8 Pa, the triatomic ions H(3)(+), H(2)D(+), HD(2)(+) and D(3)(+), produced primarily in reactions of diatomic ions with molecules, dominate the plasma composition. In this higher pressure regime, the formation of the mixed ions H(2)D(+) and HD(2)(+) is favoured in comparison with that of H(3)(+) and D(3)(+), as expected on statistical grounds. The model results predict a very small preference, undetectable within the precision of the measurements, for the generation of triatomic ions with a higher degree of deuteration, which is probably a residual influence at room temperature of the marked zero point energy effects (ZPE), relevant for deuterium fractionation in interstellar space. In contrast, ZPE effects are found to be decisive for the observed distribution of
Yamagami, Kohei; Fujiwara, Hidenori; Imada, Shin; Kadono, Toshiharu; Yamanaka, Keisuke; Muro, Takayuki; Tanaka, Arata; Itai, Takuma; Yoshinari, Nobuto; Konno, Takumi; Sekiyama, Akira
2017-07-01
We have examined the local 3d electronic structures of Co-Au multinuclear complexes with the medicinal molecules d-penicillaminate (d-pen) [Co{Au(PPh3)(d-pen)}2]ClO4 and [Co3{Au3(tdme)(d-pen)3}2] by Co L2,3-edge soft X-ray absorption (XAS) spectroscopy, where PPh3 denotes triphenylphosphine and tdme stands for 1,1,1-tris[(diphenylphosphino)methyl]ethane. The Co L2,3-edge XAS spectra indicate the localized ionic 3d electronic states in both materials. The experimental spectra are well explained by spectral simulation for a localized Co ion under ligand fields with the full multiplet theory, which verifies that the ions are in the low-spin Co3+ state in the former compound and in the high-spin Co2+ state in the latter.
Ul Haq, Bakhtiar
2014-08-01
Stimulation of novel features in ZnO by impurity electrons has attracted a remarkable attention of researchers from the past decade. Consequently, ZnO has found several applications in the field of spintronics and optoelectronics. We report, the effect of 3d-(V, Ag) electrons on the properties of ZnO in stable wurtzite (WZ) and metastable zincblende (ZB) phase using the density functional theory. Introduction of V-3d electrons was found to induce a high magnetic moment value of 5.22 in WZ and 3.26 in the ZB phase, and moreover transform the semiconductor character of ZnO into a metallic nature. Ag-d electrons result in the p-type half-metallic nature of ZnO with a weak ferromagnetic background. Our calculations for ground-state magnetic ordering show that ZnO in the presence of impure 3d-(V, Ag) electrons favors ferromagnetic ordering, and obey the double exchange mechanism. However, impurity atoms have very marginal effect on the lattice parameters of ZnO, thereby exposing its potential to absorb the impurity atoms in high concentration. © 2014 Elsevier B.V. All rights reserved.
3D-vertical integration of sensors and electronics
International Nuclear Information System (INIS)
Lipton, R.
2007-01-01
Technologies are being developed which enable the vertical integration of sensors and electronics as well as multilayer electronic circuits. New thinning and wafer bonding techniques and the formation of small vias between resulting thin layers of electronics enable the design of dense integrated sensor/readout structures. We discuss candidate technologies based on SOI and bulk CMOS. A prototype 3D chip developed at Fermilab that incorporates three tiers of 0.18μm CMOS is described
Supersymmetric D2 anti-D2 Strings
Bak, Dongsu; Ohta, Nobuyoshi
2001-01-01
We consider the flat supersymmetric D2 and anti-D2 system, which follows from ordinary noncommutative D2 anti-D2 branes by turning on an appropriate worldvolume electric field describing dissolved fundamental strings. We study the strings stretched between D2 and anti-D2 branes and show explicitly that the would-be tachyonic states become massless. We compute the string spectrum and clarify the induced noncommutativity on the worldvolume. The results are compared with the matrix theory descri...
Mixing of t2 g-eg orbitals in 4 d and 5 d transition metal oxides
Stamokostas, Georgios L.; Fiete, Gregory A.
2018-02-01
Using exact diagonalization, we study the spin-orbit coupling and interaction-induced mixing between t2 g and egd -orbital states in a cubic crystalline environment, as commonly occurs in transition metal oxides. We make a direct comparison with the widely used t2 g-only or eg-only models, depending on electronic filling. We consider all electron fillings of the d shell and compute the total magnetic moment, the spin, the occupancy of each orbital, and the effective spin-orbit coupling strength (renormalized through interaction effects) in terms of the bare interaction parameters, spin-orbit coupling, and crystal-field splitting, focusing on the parameter ranges relevant to 4 d and 5 d transition metal oxides. In various limits, we provide perturbative results consistent with our numerical calculations. We find that the t2 g-eg mixing can be large, with up to 20% occupation of orbitals that are nominally "empty," which has experimental implications for the interpretation of the branching ratio in experiments, and can impact the effective local moment Hamiltonian used to study magnetic phases and magnetic excitations in transition metal oxides. Our results can aid the theoretical interpretation of experiments on these materials, which often fall in a regime of intermediate coupling with respect to electron-electron interactions.
International Nuclear Information System (INIS)
Elhandi, S.; Taj, S.; Attaourti, Y.; Manaut, B.; Oufni, L.
2010-01-01
The effect of the electron's anomalous magnetic moment on the relativistic electronic dressing for the process of electron-hydrogen atom elastic collisions is investigated. We consider a laser field with circular polarization and various electric field strengths. The Dirac-Volkov states taking into account this anomaly are used to describe the process in the first order of perturbation theory. The correlation between the terms coming from this anomaly and the electric field strength gives rise to the strong dependence of the spinor part of the differential cross section (DCS) with respect to these terms. A detailed study has been devoted to the nonrelativistic regime as well as the moderate relativistic regime. Some aspects of this dependence as well as the dynamical behavior of the DCS in the relativistic regime have been addressed.
Band Alignment of 2D Transition Metal Dichalcogenide Heterojunctions
Chiu, Ming-Hui
2016-09-20
It is critically important to characterize the band alignment in semiconductor heterojunctions (HJs) because it controls the electronic and optical properties. However, the well-known Anderson\\'s model usually fails to predict the band alignment in bulk HJ systems due to the presence of charge transfer at the interfacial bonding. Atomically thin 2D transition metal dichalcogenide materials have attracted much attention recently since the ultrathin HJs and devices can be easily built and they are promising for future electronics. The vertical HJs based on 2D materials can be constructed via van der Waals stacking regardless of the lattice mismatch between two materials. Despite the defect-free characteristics of the junction interface, experimental evidence is still lacking on whether the simple Anderson rule can predict the band alignment of HJs. Here, the validity of Anderson\\'s model is verified for the 2D heterojunction systems and the success of Anderson\\'s model is attributed to the absence of dangling bonds (i.e., interface dipoles) at the van der Waal interface. The results from the work set a foundation allowing the use of powerful Anderson\\'s rule to determine the band alignments of 2D HJs, which is beneficial to future electronic, photonic, and optoelectronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Electric field effect in multilayer Cr2Ge2Te6: a ferromagnetic 2D material
Xing, Wenyu; Chen, Yangyang; Odenthal, Patrick M.; Zhang, Xiao; Yuan, Wei; Su, Tang; Song, Qi; Wang, Tianyu; Zhong, Jiangnan; Jia, Shuang; Xie, X. C.; Li, Yan; Han, Wei
2017-06-01
The emergence of two-dimensional (2D) materials has attracted a great deal of attention due to their fascinating physical properties and potential applications for future nano-electronic devices. Since the first isolation of graphene, a Dirac material, a large family of new functional 2D materials have been discovered and characterized, including insulating 2D boron nitride, semiconducting 2D transition metal dichalcogenides and black phosphorus, and superconducting 2D bismuth strontium calcium copper oxide, molybdenum disulphide and niobium selenide, etc. Here, we report the identification of ferromagnetic thin flakes of Cr2Ge2Te6 (CGT) with thickness down to a few nanometers, which provides a very important piece to the van der Waals structures consisting of various 2D materials. We further demonstrate the giant modulation of the channel resistance of 2D CGT devices via electric field effect. Our results illustrate the gate voltage tunability of 2D CGT and the potential of CGT, a ferromagnetic 2D material, as a new functional quantum material for applications in future nanoelectronics and spintronics.
Small polarons in 2D perovskites
Cortecchia, Daniele; Yin, Jun; Birowosuto, Muhammad D.; Lo, Shu-Zee A.; Gurzadyan, Gagik G.; Bruno, Annalisa; Bredas, Jean-Luc; Soci, Cesare
2017-01-01
We demonstrate that white light luminescence in two-dimensional (2D) perovskites stems from photoinduced formation of small polarons confined at specific sites of the inorganic framework in the form of self-trapped electrons and holes. We discuss their application in white light emitting devices and X-ray scintillators.
Small polarons in 2D perovskites
Cortecchia, Daniele
2017-11-02
We demonstrate that white light luminescence in two-dimensional (2D) perovskites stems from photoinduced formation of small polarons confined at specific sites of the inorganic framework in the form of self-trapped electrons and holes. We discuss their application in white light emitting devices and X-ray scintillators.
Electron impact excitation of Fe-peak elements: forbidden transitions in the 3d5 manifold of Fe IV
International Nuclear Information System (INIS)
McLaughlin, B M; Hibbert, A; Scott, M P; Noble, C J; Burke, V M; Burke, P G
2005-01-01
Electron-impact excitation collision strengths of the Fe-peak element Fe IV are calculated in the close-coupling approximation using the R-matrix suite of codes PRMAT designed for parallel processors. One hundred and eight LS-coupled states arising from the 3d 5 , 3d 4 4s and 3d 4 4p configurations of Fe IV, are retained in the present calculations. Detailed multi-configuration interaction target wavefunctions are used with the aid of 3p 2 → 3d 2 electron promotions and a 4dbar correlation orbital in the present calculations. Effective collision strengths for optically forbidden transitions, which are extremely important in the analysis of lines in the Fe IV spectra, are obtained by averaging the electron collision strengths for a wide range of incident electron energies, over a Maxwellian distribution of velocities. Results are presented for electron temperatures (T e in Kelvin) in the range 3.3 ≤ Log T e ≤ 6.0 applicable to many laboratory and astrophysical plasmas for transitions within the 3d 5 manifold. The present results compared to previous investigations provide improved results for important lines in the Fe IV spectrum
Synthesis, properties and applications of 2D non-graphene materials
International Nuclear Information System (INIS)
Wang, Feng; Wang, Zhenxing; Wang, Qisheng; Wang, Fengmei; Yin, Lei; Xu, Kai; Huang, Yun; He, Jun
2015-01-01
As an emerging class of new materials, two-dimensional (2D) non-graphene materials, including layered and non-layered, and their heterostructures are currently attracting increasing interest due to their promising applications in electronics, optoelectronics and clean energy. In contrast to traditional semiconductors, such as Si, Ge and III–V group materials, 2D materials show significant merits of ultrathin thickness, very high surface-to-volume ratio, and high compatibility with flexible devices. Owing to these unique properties, while scaling down to ultrathin thickness, devices based on these materials as well as artificially synthetic heterostructures exhibit novel and surprising functions and performances. In this review, we aim to provide a summary on the state-of-the-art research activities on 2D non-graphene materials. The scope of the review will cover the preparation of layered and non-layered 2D materials, construction of 2D vertical van der Waals and lateral ultrathin heterostructures, and especially focus on the applications in electronics, optoelectronics and clean energy. Moreover, the review is concluded with some perspectives on the future developments in this field. (topical review)
Kharkwal, K. C.; Pramanik, A. K.
2017-12-01
The 3d-5d based double perovskites are of current interest as they provide model systems to study the interplay between electronic correlation (U) and spin-orbit coupling (SOC). Here, we report detailed structural, magnetic and transport properties of doped double perovskite material (Sr1-x Y x )2FeIrO6 with x ≤slant 0.2 . With substitution of Y, the system retains its original crystal structure but structural parameters change with x in nonmonotonic fashion. The magnetization data for Sr2FeIrO6 show antiferromagnetic type magnetic transition around 45 K however, a close inspection of the data indicates a weak magnetic phase transition around 120 K. No change of structural symmetry has been observed down to low temperature, although the lattice parameters show sudden changes around the magnetic transitions. Sr2FeIrO6 shows an insulating behavior over the whole temperature range, which nevertheless does not change with Y substitution. The nature of charge conduction is found to follow thermally activated Mott’s variable range hopping and power law behavior for parent and doped samples, respectively. Interestingly, evolution of structural, magnetic and transport behavior in (Sr1-x Y x )2FeIrO6 is observed to reverse with x > 0.1 , which is believed to arise due to a change in the transition metal ionic state.
International Nuclear Information System (INIS)
Botch, B.H.; Dunning, T.H. Jr.; Harrison, J.F.
1981-01-01
The major differential valence correlation effects of the lowest lying states arising from the s 2 d/sup n/, sd/sup n/+1, and d/sup n/+2 configurations of the first-row transition metal atoms have been characterized using MCSCF and CI procedures. The important correlation effects are found to be, first, angular correlation of the 4s 2 pair arising because of the near degeneracy of the 4s and 4p orbitals and, second, radial correlation of the 3d electron pairs. This large differential radial correlation of the 3d electrons can be interpreted as being due to nonequivalent d orbitals in the sd/sup n/+1 and d/sup n/+2 excited states. Both of these effects can be incorporated into a simple MCSCF wave function that reduces the error in the excited state atomic dissociation limits (approx.0.2 eV in Sc--Cr and approx.0.5 eV in Mn--Cu for the sd/sup n/+1--s 2 d/sup n/ excitation energy), yet still is of a form which lends itself easily to molecular calculations
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
Magnetic gating of a 2D topological insulator
Dang, Xiaoqian; Burton, J. D.; Tsymbal, Evgeny Y.
2016-09-01
Deterministic control of transport properties through manipulation of spin states is one of the paradigms of spintronics. Topological insulators offer a new playground for exploring interesting spin-dependent phenomena. Here, we consider a ferromagnetic ‘gate’ representing a magnetic adatom coupled to the topologically protected edge state of a two-dimensional (2D) topological insulator to modulate the electron transmission of the edge state. Due to the locked spin and wave vector of the transport electrons the transmission across the magnetic gate depends on the mutual orientation of the adatom magnetic moment and the current. If the Fermi energy matches an exchange-split bound state of the adatom, the electron transmission can be blocked due to the full back scattering of the incident wave. This antiresonance behavior is controlled by the adatom magnetic moment orientation so that the transmission of the edge state can be changed from 1 to 0. Expanding this consideration to a ferromagnetic gate representing a 1D chain of atoms shows a possibility to control the spin-dependent current of a strip of a 2D topological insulator by magnetization orientation of the ferromagnetic gate.
Heavy quark fragmentation functions for D-wave quarkonium and charmed beauty mesons
International Nuclear Information System (INIS)
Cheung, K.; Yuan, T.C.
1995-09-01
At the large transverse momentum region, the production of heavy-heavy bound-states such as charmonium, bottomonium, and anti bc mesons in high energy e + e - and hadronic collisions is dominated by parton fragmentation. The authors calculate the heavy quark fragmentation functions into the D-wave quarkonium and anti bc mesons to leading order in the strong coupling constant and in the non-relativistic expansion. In the anti bc meson case, one set of its D-wave states is expected to lie below the open flavor threshold. The total fragmentation probability for a anti b antiquark to split into the D-wave anti bc mesons is about 2 x 10 -5 , which implies that only 2% of the total pseudo-scalar ground state B c comes from the cascades of these orbitally excited states
Energy Technology Data Exchange (ETDEWEB)
Jeffries, J R; Moore, K T; Butch, N P; Maple, M B
2010-05-19
We examine the degree of 5f electron localization in URu{sub 2}Si{sub 2} using spin-orbit sum rule analysis of the U N{sub 4,5} (4d {yields} 5f) edge. When compared to {alpha}-U metal, US, USe, and UTe, which have increasing localization of the 5f states, we find that the 5f states of URu{sub 2}Si{sub 2} are more localized, although not entirely. Spin-orbit analysis shows that intermediate coupling is the correct angular momentum coupling mechanism for URu{sub 2}Si{sub 2} when the 5f electron count is between 2.6 and 2.8. These results have direct ramifications for theoretical assessment of the hidden order state of URu{sub 2}Si{sub 2}, where the degree of localization of the 5f electrons and their contribution to the Fermi surface are critical.
Zhang, Chendong
2017-01-07
By using direct growth, we create a rotationally aligned MoS2/WSe2 hetero-bilayer as a designer van der Waals heterostructure. With rotational alignment, the lattice mismatch leads to a periodic variation of atomic registry between individual van der Waals layers, exhibiting a Moiré pattern with a well-defined periodicity. By combining scanning tunneling microscopy/spectroscopy, transmission electron microscopy, and first-principles calculations, we investigate interlayer coupling as a function of atomic registry. We quantitatively determine the influence of interlayer coupling on the electronic structure of the hetero-bilayer at different critical points. We show that the direct gap semiconductor concept is retained in the bilayer although the valence and conduction band edges are located at different layers. We further show that the local bandgap is periodically modulated in the X-Y direction with an amplitude of ~0.15 eV, leading to the formation of a two-dimensional electronic superlattice.
Wearable energy sources based on 2D materials.
Yi, Fang; Ren, Huaying; Shan, Jingyuan; Sun, Xiao; Wei, Di; Liu, Zhongfan
2018-05-08
Wearable energy sources are in urgent demand due to the rapid development of wearable electronics. Besides flexibility and ultrathin thickness, emerging 2D materials present certain extraordinary properties that surpass the properties of conventional materials, which make them advantageous for high-performance wearable energy sources. Here, we provide a comprehensive review of recent advances in 2D material based wearable energy sources including wearable batteries, supercapacitors, and different types of energy harvesters. The crucial roles of 2D materials in the wearable energy sources are highlighted. Based on the current progress, the existing challenges and future prospects are outlined and discussed.
Electronic band structure of TiFese2 in ferromagnetic phase
International Nuclear Information System (INIS)
Jahangirli, Z.A.; Mimura, K.; Shim, Y.; Mamedov, N.T.; Wakita, K.; Orudzhev, G.S.; Jahangirli, Z.A.
2011-01-01
Electronic band structure of crystalline TiFeSe 2 has been calculated using full-potential method of Linear Augmented Plane Wave (LAPW) in density-functional approach with exchange-correlation potential taken in Generalized Gradient Approximation (GGA). The chemical bond in TiFeSe 2 is shown to be metallic because energies of 3d-electrons localized at iron atoms are close to Fermi energy level
Coupling of spin and orbital motion of electrons in carbon nanotubes
DEFF Research Database (Denmark)
Kuemmeth, Ferdinand; Ilani, S; Ralph, D C
2008-01-01
Electrons in atoms possess both spin and orbital degrees of freedom. In non-relativistic quantum mechanics, these are independent, resulting in large degeneracies in atomic spectra. However, relativistic effects couple the spin and orbital motion, leading to the well-known fine structure in their...... systems, entailing new design principles for the realization of quantum bits (qubits) in nanotubes and providing a mechanism for all-electrical control of spins in nanotubes....
Fabrication of single phase 2D homologous perovskite microplates by mechanical exfoliation
Li, Junze; Wang, Jun; Zhang, Yingjun; Wang, Haizhen; Lin, Gaoming; Xiong, Xuan; Zhou, Weihang; Luo, Hongmei; Li, Dehui
2018-04-01
The two-dimensional (2D) Ruddlesden-Popper type perovskites have attracted intensive interest for their great environmental stability and various potential optoelectronic applications. Fundamental understanding of the photophysical and electronic properties of the 2D perovskites with pure single phase is essential for improving the performance of the optoelectronic devices and designing devices with new architectures. Investigating the optical and electronic properties of these materials with pure single phase is required to obtain pure single phase 2D perovskites. Here, we report on an alternative approach to fabricate (C4H9NH3)2(CH3NH3) n-1Pb n I3n+1 microplates with pure single n-number perovskite phase for n > 2 by mechanical exfoliation. Micro-photoluminescence and absorption spectroscopy studies reveal that the as-synthesized 2D perovskite plates for n > 2 are comprised by dominant n-number phase and small inclusions of hybrid perovskite phases with different n values, which is supported by excitation power dependent photoluminescence. By mechanical exfoliation method, 2D perovskite microplates with the thickness of around 20 nm are obtained, which surprisingly have single n-number perovskite phase for n = 2-5. In addition, we have demonstrated that the exfoliated 2D perovskite microplates can be integrated with other 2D layered materials such as boron nitride, and are able to be transferred to prefabricated electrodes for photodetections. Our studies not only provide a strategy to prepare 2D perovskites with a single n-number perovskite phase allowing us to extract the basic optical and electronic parameters of pure phase perovskites, but also demonstrate the possibility to integrate the 2D perovskites with other 2D layered materials to extend the device’s functionalities.
Zając, Magdalena; Rudowicz, Czesław; Ohta, Hitoshi; Sakurai, Takahiro
2018-03-01
Utilizing the package MSH/VBA, based on the microscopic spin Hamiltonian (MSH) approach, spectroscopic and magnetic properties of Fe2+ (3d6; S = 2) ions at (nearly) orthorhombic sites in Fe(NH4)2(SO4)2·6H2O (FASH) are modeled. The zero-field splitting (ZFS) parameters and the Zeeman electronic (Ze) factors are predicted for wide ranges of values of the microscopic parameters, i.e. the spin-orbit (λ), spin-spin (ρ) coupling constants, and the crystal-field (ligand-field) energy levels (Δi) within the 5D multiplet. This enables to consider the dependence of the ZFS parameters bkq (in the Stevens notation), or the conventional ones (e.g., D and E), and the Zeeman factors gi on λ, ρ, and Δi. By matching the theoretical SH parameters and the experimental ones measured by electron magnetic resonance (EMR), the values of λ, ρ, and Δi best describing Fe2+ ions in FASH are determined. The novel aspect is prediction of the fourth-rank ZFS parameters and the ρ(spin-spin)-related contributions, not considered in previous studies. The higher-order contributions to the second- and fourth-rank ZFSPs are found significant. The MSH predictions provide guidance for high-magnetic field and high-frequency EMR (HMF-EMR) measurements and enable assessment of suitability of FASH for application as high-pressure probes for HMF-EMR studies. The method employed here and the present results may be also useful for other structurally related Fe2+ (S = 2) systems.
Orthotropic Piezoelectricity in 2D Nanocellulose.
García, Y; Ruiz-Blanco, Yasser B; Marrero-Ponce, Yovani; Sotomayor-Torres, C M
2016-10-06
The control of electromechanical responses within bonding regions is essential to face frontier challenges in nanotechnologies, such as molecular electronics and biotechnology. Here, we present Iβ-nanocellulose as a potentially new orthotropic 2D piezoelectric crystal. The predicted in-layer piezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon this fact and by using a combination of ab-initio and ad-hoc models, we introduce a description of electrical profiles along chemical bonds. Such developments lead to obtain a rationale for modelling the extended piezoelectric effect originated within bond scales. The order of magnitude estimated for the 2D Iβ-nanocellulose piezoelectric response, ~pm V -1 , ranks this material at the level of currently used piezoelectric energy generators and new artificial 2D designs. Such finding would be crucial for developing alternative materials to drive emerging nanotechnologies.
Orthotropic Piezoelectricity in 2D Nanocellulose
García, Y.; Ruiz-Blanco, Yasser B.; Marrero-Ponce, Yovani; Sotomayor-Torres, C. M.
2016-10-01
The control of electromechanical responses within bonding regions is essential to face frontier challenges in nanotechnologies, such as molecular electronics and biotechnology. Here, we present Iβ-nanocellulose as a potentially new orthotropic 2D piezoelectric crystal. The predicted in-layer piezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon this fact and by using a combination of ab-initio and ad-hoc models, we introduce a description of electrical profiles along chemical bonds. Such developments lead to obtain a rationale for modelling the extended piezoelectric effect originated within bond scales. The order of magnitude estimated for the 2D Iβ-nanocellulose piezoelectric response, ~pm V-1, ranks this material at the level of currently used piezoelectric energy generators and new artificial 2D designs. Such finding would be crucial for developing alternative materials to drive emerging nanotechnologies.
ELECTRON CYCLOTRON CURRENT DRIVE IN DIII-D: EXPERIMENT AND THEORY
International Nuclear Information System (INIS)
PRATER, R; PETTY, CC; LUCE, TC; HARVEY, RW; CHOI, M; LAHAYE, RJ; LIN-LIU, Y-R; LOHR, J; MURAKAMI, M; WADE, MR; WONG, K-L
2003-01-01
A271 ELECTRON CYCLOTRON CURRENT DRIVE IN DIII-D: EXPERIMENT AND THEORY. Experiments on the DIII-D tokamak in which the measured off-axis electron cyclotron current drive has been compared systematically to theory over a broad range of parameters have shown that the Fokker-Planck code CQL3D provides an excellent model of the relevant current drive physics. This physics understanding has been critical in optimizing the application of ECCD to high performance discharges, supporting such applications as suppression of neoclassical tearing modes and control and sustainment of the current profile
Scott, Riccardo; Heckmann, Jan; Prudnikau, Anatol V.; Antanovich, Artsiom; Mikhailov, Aleksandr; Owschimikow, Nina; Artemyev, Mikhail; Climente, Juan I.; Woggon, Ulrike; Grosse, Nicolai B.; Achtstein, Alexander W.
2017-12-01
Intrinsically directional light emitters are potentially important for applications in photonics including lasing and energy-efficient display technology. Here, we propose a new route to overcome intrinsic efficiency limitations in light-emitting devices by studying a CdSe nanoplatelets monolayer that exhibits strongly anisotropic, directed photoluminescence. Analysis of the two-dimensional k-space distribution reveals the underlying internal transition dipole distribution. The observed directed emission is related to the anisotropy of the electronic Bloch states governing the exciton transition dipole moment and forming a bright plane. The strongly directed emission perpendicular to the platelet is further enhanced by the optical local density of states and local fields. In contrast to the emission directionality, the off-resonant absorption into the energetically higher 2D-continuum of states is isotropic. These contrasting optical properties make the oriented CdSe nanoplatelets, or superstructures of parallel-oriented platelets, an interesting and potentially useful class of semiconductor-based emitters.
Bučinský, Lukáš; Jayatilaka, Dylan; Grabowsky, Simon
2016-08-25
This study investigates the possibility of detecting relativistic effects and electron correlation in single-crystal X-ray diffraction experiments using the examples of diphenyl mercury (HgPh2) and triphenyl bismuth (BiPh3). In detail, the importance of electron correlation (ECORR), relativistic effects (REL) [distinguishing between total, scalar and spin-orbit (SO) coupling relativistic effects] and picture change error (PCE) on the theoretical electron density, its topology and its Laplacian using infinite order two component (IOTC) wave functions is discussed. This is to develop an understanding of the order of magnitude and shape of these different effects as they manifest in the electron density. Subsequently, the same effects are considered for the theoretical structure factors. It becomes clear that SO and PCE are negligible, but ECORR and scalar REL are important in low- and medium-order reflections on absolute and relative scales-not in the high-order region. As a further step, Hirshfeld atom refinement (HAR) and subsequent X-ray constrained wavefunction (XCW) fitting have been performed for the compound HgPh2 with various relativistic and nonrelativistic wave functions against the experimental structure factors. IOTC calculations of theoretical structure factors and relativistic HAR as well as relativistic XCW fitting are presented for the first time, accounting for both scalar and spin-orbit relativistic effects.
Electronic parameters of Sr2Nb2O7 and chemical bonding
DEFF Research Database (Denmark)
Atuchin, V.V.; Grivel, Jean-Claude; Korotkov, A.S.
2008-01-01
/2)) and Delta(O-Sr) = BE(O 1s)-BE(Sr 3d(5/2)), were used to characterize the valence electron transfer on the formation of the Nb-O and Sr-O bonds. The chemical bonding effects were considered on the basis of our XPS results for Sr2Nb2O7 and earlier published structural and XPS data for other Sr- or Nb...
Sausage instabilities in the electron current layer and its role in the concept of fast ignition
International Nuclear Information System (INIS)
Das, Amita; Jain, Neeraj; Kaw, Predhiman; Sengupta, Sudip
2004-01-01
The fast ignition concept of laser fusion utilizes hot electrons produced at the surface of the target by an incident intense laser pulse for the creation of the hot spot for ignition. As the hot electrons move inwards to the core of the precompressed target, the electrons from the background plasma provide a return shielding current. Three dimensional PIC simulations have shown that intense Weibel, tearing and coalescence instabilities take place which organize the current distribution into a few current filaments. In each of these filaments the central core region constitutes a current due to the fast electrons propagating inwards towards the pellet core, while the outer cylindrical shell region carries the return shielding current. The presence of instabilities and their subsequent nonlinear development can hinder the propagation of fast electrons towards the core influencing the location of the hot spot for ignition. Earlier studies showing the existence of sausage-like modes were carried out in the nonrelativistic limit and under the assumption of equal electron densities of the fast and the cold electrons. The fast electron density, in general, differs considerably from the background plasma density as it is dependent on the incident laser intensity. This paper incorporates relativistic effects and also studies the dependence of the growth rate on the fast electron density. Finally, nonlinear saturation of the instability and its impact on the stopping of the fast electron motion towards the core have also been investigated using numerical simulations. The simulations have, however, currently been carried out for non-relativistic dynamics. The results show that the sheared velocity profile of the channel gets flattened, causing an effective drop in the inward moving current. (author)
Electronic structures and Eu3+ photoluminescence behaviors in Y2Si2O7 and La2Si2O7
International Nuclear Information System (INIS)
Zhang Zhiya; Wang Yuhua; Zhang Feng; Cao Haining
2011-01-01
Research highlights: → Host excitation near the band gap of Y 2 Si 2 O 7 and La 2 Si 2 O 7 is analyzed. → The calculated result well explains Eu 3+ PL behaviors in Y 2 Si 2 O 7 and La 2 Si 2 O 7 . → The electronic structure and Eu 3+ VUV PL in La 2 Si 2 O 7 are first estimated. - Abstract: The electronic structures and linear optical properties of Y 2 Si 2 O 7 (YSO) and La 2 Si 2 O 7 (LSO) are calculated by LDA method based on the theory of DFT. Both YSO and LSO are direct-gap materials with the direct band gap of 5.89 and 6.06 eV, respectively. The calculated total and partial density of states indicate that in both YSO and LSO the valence band (VB) is mainly constructed from O 2p and the conduction band (CB) is mostly formed from Y 4d or La 5d. Both the calculated VB and CB of YSO exhibit relatively wider dispersion than that of LSO. In addition, the CB of YSO presents more electronic states. Meanwhile, the VB of LSO shows narrower energy distribution with higher electronic states density. The theoretical absorption of YSO shows larger bandwidth and higher intensity than that of LSO. The results are compared with the experimental host excitations and impurity photoluminescence in Eu 3+ -doped YSO and LSO.
Transport coefficients for carbon, hydrogen, and the organic mixture C2H3
International Nuclear Information System (INIS)
Rinker, G.
1986-02-01
Electrical and thermal transport coefficients are calculated for amorphous elemental carbon and hydrogen, using the best available systematic theoretical methods. The density range considered is 10 -3 g/cm 3 less than or equal to rho less than or equal to 10 6 g/cm 3 for carbon, and 10 -4 g/cm 3 less than or equal to rho less than or equal to 10 5 g/cm 3 for hydrogen. The temperature range considered is 10 -2 eV less than or equal to kT less than or equal to 10 4 eV. Calculational methods include relativistic partial-wave analysis of the extended Ziman theory, and nonrelativistic plane-wave analysis (Born approximation) of the original Ziman theory. Physical models include relativistic Dirac-Fock-Slater and nonrelativistic Thomas-Fermi-Dirac electron-ion potentials, and one-component-plasma ion-ion structure factors. A mixing algorithm is used to obtain approximate transport coefficients for the atomic ratio C 2 H 3 . 10 refs., 31 figs
Energy Technology Data Exchange (ETDEWEB)
Begović, Nebojša N. [Faculty of Physical Chemistry, University of Belgrade (Serbia); Institute of General and Physical Chemistry, Belgrade (Serbia); Blagojević, Vladimir A. [Faculty of Physical Chemistry, University of Belgrade (Serbia); Ostojić, Sanja B.; Radulović, Aleksandra M. [Institute of General and Physical Chemistry, Belgrade (Serbia); Poleti, Dejan [Faculty of Technology and Metallurgy, University of Belgrade (Serbia); Minić, Dragica M., E-mail: dminic@ffh.bg.ac.rs [Faculty of Physical Chemistry, University of Belgrade (Serbia); Department of Biomedical Sciences, State University of Novi Pazar (Serbia)
2015-01-15
Thermally activated 3D to 2D structural transformation of the binuclear [Ni{sub 2}(en){sub 2}(H{sub 2}O){sub 6}(pyr)]·4H{sub 2}O complex was investigated using a combination of theoretical and experimental methods. Step-wise thermal degradation (dehydration followed by release of ethylene diamine) results in two layered flexible coordination polymer structures. Dehydration process around 365 K results in a conjugated 2D structure with weak interlayer connectivity. It was shown to be a reversible 3D to 2D framework transformation by a guest molecule, and rehydration of the dehydration product occurs at room temperature in saturated water vapor. Rehydrated complex exhibits lower dehydration temperature, due to decreased average crystalline size, with higher surface area resulting in easier release and diffusion of water during dehydration. Thermal degradation of dehydration around 570 K, results in loss of ethylene diamine, producing a related 2D layered polymer structure, without interconnectivity between individual polymer layers. - Highlights: • Reversible 3D to 2D framework topochemical transformation on dehydration around 365 K. • Resulting polymer exhibits 2D layered structure with weak interlayer connectivity. • Dehydration is fully reversible in saturated water vapor at room temperature. • Further degradation around 570 K yields 2D polymer without interlayer connectivity. • 2D polymer exhibits conjugated electronic system.
Probing collective oscillation of d -orbital electrons at the nanoscale
Energy Technology Data Exchange (ETDEWEB)
Dhall, Rohan [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA; Vigil-Fowler, Derek [National Renewable Energy Laboratory, Golden, Colorado 80401, USA; Houston Dycus, J. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA; Kirste, Ronny [Adroit Materials, Inc., Cary, North Carolina 27518, USA; Mita, Seiji [Adroit Materials, Inc., Cary, North Carolina 27518, USA; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA; Collazo, Ramon [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA; LeBeau, James M. [Adroit Materials, Inc., Cary, North Carolina 27518, USA
2018-02-05
Here, we demonstrate that high energy electrons can be used to explore the collective oscillation of s, p, and d orbital electrons at the nanometer length scale. Using epitaxial AlGaN/AlN quantum wells as a test system, we observe the emergence of additional features in the loss spectrum with the increasing Ga content. A comparison of the observed spectra with ab-initio theory reveals that the origin of these spectral features lies in excitations of 3d-electrons contributed by Ga. We find that these modes differ in energy from the valence electron plasmons in Al1-xGaxN due to the different polarizabilities of the d electrons. Finally, we study the dependence of observed spectral features on the Ga content, lending insights into the origin of these spectral features, and their coupling with electron-hole excitations.
Effect of electronic coupling of Watson-Crick hopping in DNA poly(dA)-poly(dT)
Risqi, A. M.; Yudiarsah, E.
2017-07-01
Charge transport properties of poly(dA)-poly(dT) DNA has been studied by using thigh binding Hamiltonian approach. Molecule DNA that we use consist of 32 base pair of adenine (A) and thymine (T) and backbone is consist of phosphate and sugar. The molecule DNA is contacted electrode at both ends. Charge transport in molecule DNA depend on the environment, we studied the effect of electronic coupling of Watson-Crick hopping in poly(dA)-poly(dT) DNA to transmission probability and characteristic I-V. The electronic coupling constant influence charge transport between adenine-thymine base pairs at the same site. Transmission probability is studied by using transfer matrix and scattering matrix method, and the result of transmission probability is used to calculate the characteristic I-V by using formula Landauer Buttiker. The result shows that when the electronic coupling increase then transmission probability and characteristic I-V increase slightly.
Electron mobility in few-layer MoxW1-xS2
International Nuclear Information System (INIS)
Chandrasekar, Hareesh; Nath, Digbijoy N
2015-01-01
Heterostructures of two-dimensional (2D) layered materials are increasingly being explored for electronics in order to potentially extend conventional transistor scaling and to exploit new device designs and architectures. Alloys form a key underpinning of any heterostructure device technology and therefore an understanding of their electronic properties is essential. In this paper, we study the intrinsic electron mobility in few-layer Mo x W 1−x S 2 as limited by various scattering mechanisms. The room temperature, energy-dependent scattering times corresponding to polar longitudinal optical (LO) phonon, alloy and background impurity scattering mechanisms are estimated based on the Born approximation to Fermi’s golden rule. The contribution of individual scattering rates is analyzed as a function of 2D electron density as well as of alloy composition in Mo x W 1−x S 2 . While impurity scattering limits the mobility for low carrier densities (<2–4×10 12 cm −2 ), LO polar phonon scattering is the dominant mechanism for high electron densities. Alloy scattering is found to play a non-negligible role for 0.5 < x < 0.7 in Mo x W 1−x S 2 . The LO phonon-limited and impurity-limited mobilities show opposing trends with respect to alloy mole fractions. The understanding of electron mobility in Mo x W 1−x S 2 presented here is expected to enable the design and realization of heterostructures and devices based on alloys of MoS 2 and WS 2 . (paper)
Bhartia, Bhavesh; Bacher, Nadav; Jayaraman, Sundaramurthy; Khatib, Salam; Song, Jing; Guo, Shifeng; Troadec, Cedric; Puniredd, Sreenivasa Reddy; Srinivasan, Madapusi Palavedu; Haick, Hossam
2015-07-15
Formation of dense monolayers with proven atmospheric stability using simple fabrication conditions remains a major challenge for potential applications such as (bio)sensors, solar cells, surfaces for growth of biological cells, and molecular, organic, and plastic electronics. Here, we demonstrate a single-step modification of organophosphonic acids (OPA) on 1D and 2D structures using supercritical carbon dioxide (SCCO2) as a processing medium, with high stability and significantly shorter processing times than those obtained by the conventional physisorption-chemisorption method (2.5 h vs 48-60 h).The advantages of this approach in terms of stability and atmospheric resistivity are demonstrated on various 2D materials, such as indium-tin-oxide (ITO) and 2D Si surfaces. The advantage of the reported approach on electronic and sensing devices is demonstrated by Si nanowire field effect transistors (SiNW FETs), which have shown a few orders of magnitude higher electrical and sensing performances, compared with devices obtained by conventional approaches. The compatibility of the reported approach with various materials and its simple implementation with a single reactor makes it easily scalable for various applications.
Energy Technology Data Exchange (ETDEWEB)
Combe, Rene
1956-06-27
In the first part of this research thesis, the author reports the development of a linear electron accelerator with a presentation of charged waveguides which are their main components. He also proposes a recall of the charged waveguide theory, an overview of some experimental guides, a description of the calculation method, and reports the actual realisation of the accelerator waveguide. The apparatus is precisely described, and results obtained during tests are presented. The second part of the thesis addresses the study of millimetre wavelength waves. It reports the study of the electron movement in a sinusoidal inverter, and in a helical inverter (a solenoid in which the electron has a helical trajectory). Then, the author proposes a detailed presentation of electron radiation theory: fundamental wavelength, total radiated power, angular and spectral distribution of radiation. The author finally reports a comparison between radiations obtained with different devices [French] La premiere partie de ce memoire traite precisement de l'etude et de la construction de notre accelerateur lineaire d'electrons, le chapitre I etant consacre aux fluides d'ondes charges, qui en constituent l'element essentiel. Apres un rappel de la theorie de ces guides, on expose quelques contributions theoriques, on etudie un certain nombre de guides experimentaux, et on decrit la methode de calcul et la realisation du guide de l'accelerateur. Le chapitre II renferme la description de l'appareil et l'expose des resultats obtenus lors de ses essais. La deuxieme partie: recherches sur les ondes millimetriques, commence (chapitre III) par l'etude du mouvement de l'electron dans un ondulateur sinusoidal, ou dans un ondulateur helicoidal, solenoide, dans lequel l'electron decrit une trajectoire en helice: nous etudions concurremment les deux dispositifs. Le chapitre IV contient la theorie detaillee du rayonnement de l'electron: longueur d'onde fondamentale, puissance totale rayonnee
Structural and electronic properties of in-plane phase engineered WSe2: A DFT study
Bhart, Ankush; Kapoor, Pooja; Sharma, Munish; Sharma, Raman; Ahluwalia, P. K.
2018-04-01
We present first principal investigations on structural and electronic properties of in-plane phase engineered WSe2 with armchair type interface. The 2H and 1T phases of WSe2, joined along x-direction is a natural metal-semiconductor heterostructure and therefore shows potential for applications in 2D electronics and opto-electronics. The electronic properties transit towards metallic 1T region. No inflections across interface shows negligible mismatch strain which is unlike what has been reported for MoS2. Charge density analysis shows charge accumulation on 1T domain. This can lead to reduction of Schottky barrier heights at the metal-semiconductor junction. STM analysis confirms transition of 1T phase towards distorted 1T' structure. The present results provide essential insights for nano-devices using 2D hybrid materials.
Theory of Magnetoelectric Properties of 2D Systems
Chen, S. C.; Wu, J. Y.; Lin, C. Y.; Lin, M. F.
2017-12-01
This book addresses important advances in diverse quantization phenomena. 'Theory of Magnetoelectric Properties of 2D Systems' develops the generalized tight-binding model in order to comprehend the rich quantization phenomena in 2D materials. The unusual effects, taken into consideration simultaneously, mainly come from the multi-orbital hybridization, the spin-orbital coupling, the intralayer and interlayer atomic interactions, the layer number, the stacking configuration, the site-energy difference, the magnetic field, and the electric field. The origins of the phenomena are discussed in depth, particularly focusing on graphene, tinene, phosphorene and MoS2, with a broader model also drawn. This model could be further used to investigate electronic properties of 1D and 3D condensed-matter systems, and this book will prove to be a valuable resource to researchers and graduate students working in 2D materials science.
Medium energy electron cooling R and D at Fermilab -- Context and status
International Nuclear Information System (INIS)
MacLachlan, J.A.
1996-05-01
Electron cooling at the proposed Recycler 8 GeV storage ring has been identified as a key element in exploiting the capacity of the Fermilab Main Injector for an additional factor of ten in Tevatron luminosity above the goal for the next collider run, ultimately to > 10 33 cm -2 s -1 . The most basic requirement for increased luminosity is a large stack of antiprotons cooled to emittance comparable to that of the proton beam. Although electron cooling is inferior to the stochastic technique for cooling large emittance beams, its rate is practically independent of the antiproton intensity. For cooling intense beams of low or moderate emittance, electron cooling excels. The realization of electron cooling for 8 GeV antiprotons requires major extension of existing practice in electron energy and length of the cooling interaction region. It will require 4.3 MeV dc electron beam maintaining high quality and precise collinearity with the antiprotons over a 66 m straight section. The initial goal of the R and D project is 200 mA electron current in about three years; the plan is to reach 2 A over the following three years
International Nuclear Information System (INIS)
Biddlecombe, C.S.; Edwards, C.B.; Shaw, M.J.
1981-10-01
The computer code PE2D has been used to optimise the design of a compact, 500kV, low inductance vacuum diode interface assembly for SPRITE, a sophisticated electron beam pumped exciplex laser system under construction at RAL. Electrostatic modelling of various dielectric interfaces has been achieved in cylindrical symmetry under conditions not amenable to more traditional methods of electrostatic field plotting. (author)
International Nuclear Information System (INIS)
Ernst, V.
1978-01-01
The idea of the systematic Weisskopf-Wigner approximation as used sporadically in atomic physics and quantum optics, is extended here to the interaction of a field of non-relativistic fermions with a field of relativistic bosons. It is shown that the usual (non-existing) interaction Hamiltonian of this system can be written as a sum of a countable number of self-adjoint and bounded partial Hamiltonians. The system of these Hamiltonians defines the order hierarchy of the present approximation scheme. To demonstrate its physical utility it is shown that in a certain order it provides satisfactory quantum theory of the 'self-energy' of the fermions under discussion. This is defined as the binding energy of bosons bound to the fermions and building up the latter's 'individual Coulomb or Yukawa fields' in the sense of expectation values of the corresponding field operator. In states of more than one fermion the bound photons act as a mediating agent between the fermions; this mechanism closely resembles the Coulomb or Yukawa 'forces' used in conventional non-relativistic quantum mechanics. (author)
Phase separation and d-wave superconductivity induced by extended electron-exciton interaction
Energy Technology Data Exchange (ETDEWEB)
Cheng Ming [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)], E-mail: cheng896@hotmail.com; Su Wupei [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)
2008-12-15
Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling.
Phase separation and d-wave superconductivity induced by extended electron-exciton interaction
International Nuclear Information System (INIS)
Cheng Ming; Su Wupei
2008-01-01
Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling
Dass, Devi
2018-03-01
Graphene nanoribbon (GNR), a new 2D carbon nanomaterial, has some unique features and special properties that offer a great potential for interconnect, nanoelectronic devices, optoelectronics, and nanophotonics. This paper reports the structural analysis, electronic properties, and band gaps of a GNR considering different chirality combinations obtained using the pz orbital tight binding model. In structural analysis, the analytical expressions for GNRs have been developed and verified using the simulation for the first time. It has been found that the total number of unit cells and carbon atoms within an overall unit cell and molecular structure of a GNR have been changed with the change in their chirality values which are similar to the values calculated using the developed analytical expressions thus validating both the simulation as well as analytical results. Further, the electronic band structures at different chirality values have been shown for the identification of metallic and semiconductor properties of a GNR. It has been concluded that all zigzag edge GNRs are metallic with very small band gaps range whereas all armchair GNRs show both the metallic and semiconductor nature with very small and high band gaps range. Again, the total number of subbands in each electronic band structure is equal to the total number of carbon atoms present in overall unit cell of the corresponding GNR. The semiconductors GNRs can be used as a channel material in field effect transistor suitable for advanced CMOS technology whereas the metallic GNRs could be used for interconnect.
Yang, Shengxue; Jiang, Chengbao; Wei, Su-huai
2017-06-01
Two-dimensional (2D) layered inorganic nanomaterials have attracted huge attention due to their unique electronic structures, as well as extraordinary physical and chemical properties for use in electronics, optoelectronics, spintronics, catalysts, energy generation and storage, and chemical sensors. Graphene and related layered inorganic analogues have shown great potential for gas-sensing applications because of their large specific surface areas and strong surface activities. This review aims to discuss the latest advancements in the 2D layered inorganic materials for gas sensors. We first elaborate the gas-sensing mechanisms and introduce various types of gas-sensing devices. Then, we describe the basic parameters and influence factors of the gas sensors to further enhance their performance. Moreover, we systematically present the current gas-sensing applications based on graphene, graphene oxide (GO), reduced graphene oxide (rGO), functionalized GO or rGO, transition metal dichalcogenides, layered III-VI semiconductors, layered metal oxides, phosphorene, hexagonal boron nitride, etc. Finally, we conclude the future prospects of these layered inorganic materials in gas-sensing applications.
Energy Technology Data Exchange (ETDEWEB)
Gontier, Y; Trahin, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1967-07-01
The general expression for the amplitude of the probability of ionisation by a multiphoton absorption process is derived. Its non-relativistic limit is taken and the bipolar approximation is used for calculating the ionisation cross-section of hydrogen-like atoms. This latter involves the summation over intermediate virtual states by means of: a) a recursion relationship concerning angular functions, b) a particular technique which when applied to radial functions makes it possible to solve a system of inhomogeneous first-order differential equations. (authors) [French] On etablit l'expression generale de l'amplitude de probabilite d'ionisation par un processus d'absorption multiphotonique. On en prend la limite non-relativiste et l'on utilise l'approximation dipolaire avant de calculer la section efficace d'ionisation d'atomes hydrogenoides. Cette derniere fait intervenir des sommations sur des etats virtuels intermediaires effectuees a l'aide: a) d'une relation de recurrence qui concerne les fonctions angulaires, b) d'une technique particuliere qui, appliquee aux fonctions radiales, conduit a resoudre un systeme d'equations differentielles inhomogenes du premier ordre. (auteur)
Recent developments on the 110 GHz electron cyclotron installation on the DIII-D tokamak
International Nuclear Information System (INIS)
Ponce, D.; Callis, R.W.; Cary, W.P.; Ferron, J.R.; Green, M.; Grunloh, H.J.; Gorelov, Y.; Lohr, J.; Ellis, R.A.
2003-01-01
Significant improvements are being implemented to the capability of the 110 GHz electron cyclotron system on the DIII-D tokamak. Chief among these is the addition of the fifth and sixth 1 MW class gyrotrons, increasing the power available for auxiliary heating and current drive by nearly 60%. These tubes use artificially grown diamond r.f. output windows to obtain high power with long pulse capability. The beams from these tubes are nearly Gaussian, facilitating coupling to the waveguide. A new fully articulating dual launcher capable of high speed spatial scanning has been designed and tested. The launcher has two axis independent steering for each waveguide. The mirrors can be rotated at up to 100 deg./s. A new feedback system linking the DIII-D Plasma Control System (PCS) with the gyrotron beam voltage waveform generators permits real-time feedback control of some plasma properties such as electron temperature. The PCS can use a variety of plasma monitors to generate its control signal, including electron cyclotron emission and Mirnov probes. Electron cyclotron heating and electron cyclotron current drive were used during this year's DIII-D experimental campaign to control electron temperature, density, and q profiles, induce an ELM-free H-mode, and suppress the m=2/n=1 neoclassical tearing mode. The new capabilities have expanded the role of EC systems in tokamak plasma control
Gersch-Rodriguez-Smith computation of deep inelastic electron scattering on 4He
International Nuclear Information System (INIS)
Viviani, M.; Kievsky, A.; Rinat, A.S.
2003-01-01
We compute cross sections for inclusive scattering of high-energy electrons on 4 He, based on the two lowest orders of the Gersch-Rodriguez-Smith series. The required one- and two-particle density matrices are obtained from nonrelativistic 4 He wave functions using realistic models for the nucleon-nucleon and three-nucleon interaction. The computed results for E=3.6 GeV agree well with the NE3 SLAC-Virginia data
Vattikuti, S. V. Prabhakar; Shim, Jaesool; Byon, Chan
2018-02-01
The development of high-activity, long-life, precious-metal-free photocatalysts for redox reactions in photoelectrochemical cells and fuel cells remains challenging. The synthesis of high-activity heterostructured photocatalysts is crucial for efficient energy conversion strategies. Herein, a novel photocatalyst based on 1D Bi2S3 nanorods self-assembled on 2D exfoliated tungsten disulfide (e-WS2) nanosheets has been developed for the degradation of methyl orange (MO) dye in aqueous solution. We demonstrate a novel and facile hydrothermal method for the synthesis of a Bi2S3 nanorod/e-WS2 nanosheet heterostructure. The photocatalytic properties of the heterostructure under visible light were investigated. Enhanced photocatalytic activity was attributed to the presence of strong surface active sites, as well as the specific morphology of the composite. We also observed the fast transfer of electron-hole pairs at the material interface. This work demonstrates a non-noble semiconductor photocatalyst for the degradation of pollutants and evolution of H2.
International Nuclear Information System (INIS)
Amaro, J. E.; Barbaro, M. B.; Caballero, J. A.; Donnelly, T. W.; Udias, J. M.
2007-01-01
The semi-relativistic approach to electron and neutrino quasielastic scattering from nuclei is extended to include final-state interactions. Starting with the usual nonrelativistic continuum shell model, the problem is relativized by using the semi-relativistic expansion of the current in powers of the initial nucleon momentum and relativistic kinematics. Two different approaches are considered for the final-state interactions: the Smith-Wambach 2p-2h damping model and the Dirac-equation-based potential extracted from a relativistic mean-field plus the Darwin factor. Using the latter, the scaling properties of (e,e ' ) and (ν μ ,μ - ) cross sections for intermediate momentum transfers are investigated
Energy Technology Data Exchange (ETDEWEB)
Bernard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1967-04-01
The theoretical characteristics of the electron linear accelerator are: 30 MeV for the energy W{sub S} and 250 mA for the peak current I{sub c}. The main utilization is the intense production of fast neutrons by the reactions ({gamma},n) and ({gamma},f) induced in a target of natural uranium by the accelerated electrons. In the first part of the thesis, relative to the study and the realization of the accelerator, a new equation of dispersion is established analytically when the guide is loaded with round-edged irises. The relation is compared with the equation established by CHU and Hansen, WALKINSHAW, KVASIL in the case of a guide loaded with flat-edged irises. The experimental and theoretical curves of dispersion are compared. The accuracy of every relation of dispersion is estimated. The second part of the thesis is relative to the theoretical study of the electrons dynamics in the guide; it allows the derivation of the parameters of the beam: dispersion of phase, energy, dispersion of energy and the relation W{sub S} = f (I{sub c}). The results relative to the first experiments are given and compared with the theoretical expectations. (author) [French] Les caracteristiques nominales theoriques de l'accelerateur lineaire d'electrons sont: 30 MeV pour l'energie W{sub S} et 250 mA pour le courant de crete I{sub c}. L'utilisation principale envisagee est la production de neutrons rapides par les reactions ({gamma},n) et ({gamma},f) induites dans une cible d'uranium naturel par les electrons acceleres. Dans la premiere partie de la these relative a l'elude et a la realisation de l'accelerateur, une nouvelle equation de dispersion (ou equation aux frequences) est etablie analytiquement pour un guide charge par des iris a bord rond. Cette relation est comparee a celles etablies par CHU et HANSEN, WALKINSHAW, KVASIL dans le cas du guide charge par des iris a bord plat. On compare les courbes de dispersion theoriques et experimentales et on evalue la precision de
International Nuclear Information System (INIS)
Gunawardana, Binuka; Liu, Han-Chun; Samaraweera, Rasanga L.; Mani, R.G.; Reichl, C.; Wegscheider, W
2017-01-01
Microwave radiation-induced magneto-resistance oscillations are examined under bichromatic excitation for various frequency combinations in order to obtain a better understanding of the lineshape observed in the dual excitation experiment of the high mobility GaAs/AlGaAs 2D electron system. Here, we examine superposition- or lack thereof- in the lineshape observed in the bichromatic experiment, and report a trend observed between the monochromatic and bichromatic responses of the oscillatory diagonal resistance. (paper)
Electron Beam Propagation in a Plasma
Directory of Open Access Journals (Sweden)
Kyoung W. Min
1988-06-01
Full Text Available Electron beam propagation in a fully ionized plasma has been studied using a one-dimensional particle simulation model. We compare the results of electrostatic simulations to those of electromagnetic simulations. The electrostatic results show the essential features of beam-plasma instability which accelerates ambient plasmas. The results also show the heating of ambient plasmas and the trapping of plasmas due to the locally generated electric field. The level of the radiation generated by the same non-relativistic beam is slightly higher than the noise level. We discuss the results in context of the heating of coronal plasma during solar flares.
Dietrich, Scott
Heterostructures made of semiconductor materials may be one of most versatile environments for the study of the physics of electron transport in two dimensions. These systems are highly customizable and demonstrate a wide range of interesting physical phenomena. In response to both microwave radiation and DC excitations, strongly nonlinear transport that gives rise to non-equilibrium electron states has been reported and investigated. We have studied GaAs quantum wells with a high density of high mobility two-dimensional electrons placed in a quantizing magnetic field. This study presents the observation of several nonlinear transport mechanisms produced by the quantum nature of these materials. The quantum scattering rate, 1tau/q, is an important parameter in these systems, defining the width of the quantized energy levels. Traditional methods of extracting 1tau/q involve studying the amplitude of Shubnikov-de Haas oscillations. We analyze the quantum positive magnetoresistance due to the cyclotron motion of electrons in a magnetic field. This method gives 1tau/q and has the additional benefit of providing access to the strength of electron-electron interactions, which is not possible by conventional techniques. The temperature dependence of the quantum scattering rate is found to be proportional to the square of the temperature and is in very good agreement with theory that considers electron-electron interactions in 2D systems. In quantum wells with a small scattering rate - which corresponds to well-defined Landau levels - quantum oscillations of nonlinear resistance that are independent of magnetic field strength have been observed. These oscillations are periodic in applied bias current and are connected to quantum oscillations of resistance at zero bias: either Shubnikov-de Haas oscillations for single subband systems or magnetointersubband oscillations for two subband systems. The bias-induced oscillations can be explained by a spatial variation of electron
Single-layer MoS2 electronics.
Lembke, Dominik; Bertolazzi, Simone; Kis, Andras
2015-01-20
CONSPECTUS: Atomic crystals of two-dimensional materials consisting of single sheets extracted from layered materials are gaining increasing attention. The most well-known material from this group is graphene, a single layer of graphite that can be extracted from the bulk material or grown on a suitable substrate. Its discovery has given rise to intense research effort culminating in the 2010 Nobel Prize in physics awarded to Andre Geim and Konstantin Novoselov. Graphene however represents only the proverbial tip of the iceberg, and increasing attention of researchers is now turning towards the veritable zoo of so-called "other 2D materials". They have properties complementary to graphene, which in its pristine form lacks a bandgap: MoS2, for example, is a semiconductor, while NbSe2 is a superconductor. They could hold the key to important practical applications and new scientific discoveries in the two-dimensional limit. This family of materials has been studied since the 1960s, but most of the research focused on their tribological applications: MoS2 is best known today as a high-performance dry lubricant for ultrahigh-vacuum applications and in car engines. The realization that single layers of MoS2 and related materials could also be used in functional electronic devices where they could offer advantages compared with silicon or graphene created a renewed interest in these materials. MoS2 is currently gaining the most attention because the material is easily available in the form of a mineral, molybdenite, but other 2D transition metal dichalcogenide (TMD) semiconductors are expected to have qualitatively similar properties. In this Account, we describe recent progress in the area of single-layer MoS2-based devices for electronic circuits. We will start with MoS2 transistors, which showed for the first time that devices based on MoS2 and related TMDs could have electrical properties on the same level as other, more established semiconducting materials. This
Consideration of Relativistic Dynamics in High-Energy Electron Coolers
Bruhwiler, David L
2005-01-01
A proposed electron cooler for RHIC would use ~55 MeV electrons to cool fully-ionized 100 GeV/nucleon gold ions.* At two locations in the collider ring, the electrons and ions will co-propagate for ~13 m, with velocities close to c and gamma>100. To lowest-order, one can Lorentz transform all physical quantities into the beam frame and calculate the dynamical friction forces assuming a nonrelativisitc, electrostatic plasma. However, we show that nonlinear space charge forces of the bunched electron beam on the ions must be calculated relativistically, because an electrostatic beam-frame calculation is not valid for such short interaction times. The validity of nonrelativistic friction force calculations must also be considered. Further, the transverse thermal velocities of the high-charge (~20 nC) electron bunch are large enough that some electrons have marginally relativistic velocities, even in the beam frame. Hence, we consider relativistic binary collisions treating the model problem of ...
International Nuclear Information System (INIS)
Rebled, J.M.; Yedra, Ll.; Estrade, S.; Portillo, J.; Peiro, F.
2011-01-01
The successful combination of electron beam precession and bright field electron tomography for 3D reconstruction is reported. Beam precession is demonstrated to be a powerful technique to reduce the contrast artifacts due to diffraction and curvature in thin foils. Taking advantage of these benefits, Precession assisted electron tomography has been applied to reconstruct the morphology of Sn precipitates embedded in an Al matrix, from a tilt series acquired in a range from +49 o to -61 o at intervals of 2 o and with a precession angle of 0.6 o in bright field mode. The combination of electron tomography and beam precession in conventional TEM mode is proposed as an alternative procedure to obtain 3D reconstructions of nano-objects without a scanning system or a high angle annular dark field detector. -- Highlights: → Electron beam precession reduces spurious diffraction contrast in bright field mode. → Bend contour related contrast depends on precession angle. → Electron beam precession is combined with bright field electron tomography. → Precession assisted BF tomography allowed 3D reconstruction of a Sn precipitate.
Measurement of the Deuteron Spin Structure Function g_1^d(x) for 1 (GeV/c)^2 < Q^2 < 40 (GeV/c)^2
E155 Collaboration
1999-01-01
New measurements are reported on the deuteron spin structure function g_1^d. These results were obtained from deep inelastic scattering of 48.3 GeV electrons on polarized deuterons in the kinematic range 0.01 < x < 0.9 and 1 < Q^2 < 40 (GeV/c)^2. These are the first high dose electron scattering data obtained using lithium deuteride (6Li2H) as the target material. Extrapolations of the data were performed to obtain moments of g_1^d, including Gamma_1^d, and the net quark polarization Delta Si...
Anthony , P.L.; Arnold , R.G.; Averett , T.; Band , H.R.; Berisso , M.C.; Borel , H.; Bosted , P.E.; Bultmann , S.L.; Buenerd , M.; Chupp , T.; Churchwell , S.; Court , G.R.; Crabb , D.; Day , D.; Decowski , P.
1999-01-01
New measurements are reported on the deuteron spin structure function g_1^d. These results were obtained from deep inelastic scattering of 48.3 GeV electrons on polarized deuterons in the kinematic range 0.01 < x < 0.9 and 1 < Q^2 < 40 (GeV/c)^2. These are the first high dose electron scattering data obtained using lithium deuteride (6Li2H) as the target material. Extrapolations of the data were performed to obtain moments of g_1^d, including Gamma_1^d, and the net quark polarization Delta Si...
Relativistic and nonrelativistic classical field theory on fivedimensional space-time
International Nuclear Information System (INIS)
Kunzle, H.P.; Duval, C.
1985-07-01
This paper is a sequel to earlier ones in which, on the one hand, classical field theories were described on a curved Newtonian space-time, and on the other hand, the Newtonian gravitation theory was formulated on a fivedimensional space-time with a metric of signature and a covariantly constant vector field. Here we show that Lagrangians for matter fields are easily formulated on this extended space-time from simple invariance arguments and that stress-energy tensors can be derived from them in the usual manner so that four-dimensional space-time expressions are obtained that are consistent in the relativistic as well as in the Newtonian case. In the former the theory is equivalent to General Relativity. When the magnitude of the distinguished vector field vanishes equations for the (covariant) Newtonian limit follow. We demonstrate this here explicity in the case of the Klein-Gordon/Schroedinger and the Dirac field and its covariant nonrelativistic analogue, the Levy-Leblond field. Especially in the latter example the covariant Newtonian theory simplifies dramatically in this fivedimensional form
Manganese catalyzed cis-dihydroxylation of electron deficient alkenes with H(2)O(2).
Saisaha, Pattama; Pijper, Dirk; van Summeren, Ruben P; Hoen, Rob; Smit, Christian; de Boer, Johannes W; Hage, Ronald; Alsters, Paul L; Feringa, Ben L; Browne, Wesley R
2010-10-07
A practical method for the multigram scale selective cis-dihydroxylation of electron deficient alkenes such as diethyl fumarate and N-alkyl and N-aryl-maleimides using H(2)O(2) is described. High turnovers (>1000) can be achieved with this efficient manganese based catalyst system, prepared in situ from a manganese salt, pyridine-2-carboxylic acid, a ketone and a base, under ambient conditions. Under optimized conditions, for diethyl fumarate at least 1000 turnovers could be achieved with only 1.5 equiv. of H(2)O(2) with d/l-diethyl tartrate (cis-diol product) as the sole product. For electron rich alkenes, such as cis-cyclooctene, this catalyst provides for efficient epoxidation.
Excitonic and Polaronic Properties of 2D Hybrid Organic–Inorganic Perovskites
Yin, Jun
2017-01-20
We theoretically characterize the unusual white-light emission properties of two-dimensional (2D) hybrid organic inorganic perovskites with an APbX(4) structure (where A is a bidentate organic cation and X = Cl, Br). In addition to band structure calculations including corrections due to spin orbit couplings and electron hole interactions, a computationally intensive molecular cluster approach is exploited to describe the excitonic and polaronic properties of these 2D perovskites at the atomistic level. Upon adding or removing an electron from the neutral systems, we find that strongly localized small polarons form in the 2D clusters. The polaron charge density is distributed over just lattice sites, which is consistent with the calculated large polaron binding energies, on the order of similar to 0.4-1.2 eV.
International Nuclear Information System (INIS)
March, N.H.
2003-09-01
The Feynman propagator, and its parallel in statistical mechanics, namely the canonical density matrix, are first used to treat both homogeneous and confined electron assemblies in the presence of a static electric field of arbitrary strength. The models are relevant to plasmas having variable electron density and degeneracy. The second topic concerns atomic ions in intense magnetic fields. Semiclassical theory is here applied, non-relativistic and relativistic approximations being invoked. Both treatments are shown to be embraced by a generalization of Emden's equation. (author)
Random path formulation of nonrelativistic quantum mechanics
International Nuclear Information System (INIS)
Roncadelli, M.
1993-01-01
Quantum amplitudes satisfy (almost) the same calculus that probabilities obey in the theory of classical stochastic diffusion processes. As a consequence of this structural analogy, a new formulation of (nonrelativistic) quantum mechanics naturally arises as the quantum counterpart of the Langevin description of (classical) stochastic diffusion processes. Quantum fluctuations are simulated here by a Fresnel white noise (FWN), which is a (real) white noise with imaginary diffusion constant, whose functional (pseudo) measure yields the amplitude distribution for its configurations. Central to this approach is the idea that classical dynamical trajectories in configuration space are perturbed by the FWN. Hence, a single (arbitrary) classical dynamical path gets replaced by a family of quantum random paths (QRPs) - one for each FWN sample - all originating from the same space-time point (x', t'). The QRPs are the basic objects of the present formulation and are given by a Langevin equation with the FWN, whose drift is controlled by a (arbitrary) solution to the classical Hamilton-Jacobi equation. So, our approach is manifestly based on classical dynamics. Now, a transition amplitude is associated with each QRP: it gives the amplitude that a particle starting from (x', t') will reach (x'', t'') by travelling just along the considered QRP. The quantum mechanical propagator (x'', t'' modul x', t') then emerges as the FWN average of the transition amplitude along a QRP. Thus, quantum mechanics looks like classical mechanics as perturbed by the FWN. The general structure of this formulation is discussed in detail, along with some practical and conceptual implications. (author). 14 refs
The ionic versus metallic nature of 2D electrides: a density-functional description.
Dale, Stephen G; Johnson, Erin R
2017-10-18
The two-dimensional (2D) electrides are a highly unusual class of materials, possessing interstitial electron layers sandwiched between cationic atomic layers of the solid. In this work, density-functional theory, with the exchange-hole dipole moment dispersion correction, is used to investigate exfoliation and interlayer sliding of the only two experimentally known 2D electrides: [Ca 2 N] + e - and [Y 2 C] 2+ (2e - ). Examination of the valence states during exfoliation identifies intercalated electrons in the bulk and weakly-bound surface-states in the fully-expanded case. The calculated exfoliation energies for the 2D electrides are found to be much higher than for typical 2D materials, which is attributed to the ionic nature of the electrides and the strong Coulomb forces governing the interlayer interactions. Conversely, the calculated sliding barriers are found to be quite low, comparable to those for typical 2D materials, and are effectively unchanged by exclusion of dispersion. We conjecture that the metallic nature of the interstitial electrons allows the atomic layers to move relative to each other without significantly altering the interlayer binding. Finally, comparison with previous works reveals the importance of a system-dependent dispersion correction in the density-functional treatment.
Electron transport in NH3/NO2 sensed buckled antimonene
Srivastava, Anurag; Khan, Md. Shahzad; Ahuja, Rajeev
2018-04-01
The structural and electronic properties of buckled antimonene have been analysed using density functional theory based ab-initio approach. Geometrical parameters in terms of bond length and bond angle are found close to the single ruffle mono-layer of rhombohedral antimony. Inter-frontier orbital analyses suggest localization of lone pair electrons at each atomic centre. Phonon dispersion along with high symmetry point of Brillouin zone does not signify any soft mode. With an electronic band gap of 1.8eV, the quasi-2D nano-surface has been further explored for NH3/NO2 molecules sensing and qualities of interaction between NH3/NO2 gas and antimonene scrutinized in terms of electronic charges transfer. A current-voltage characteristic has also been analysed, using Non Equilibrium Green's function (NEGF), for antimonene, in presence of incoming NH3/NO2 molecules.
International Nuclear Information System (INIS)
Chamberlain, M.B.; Baun, W.L.
1975-01-01
Soft x-ray appearance potential spectra of the 3d and 4d levels of polycrystalline cerium metal are reported in this paper. Resonant x-ray emissions are observed when the electron-excitation energy sweeps through the ionization energies of the 3d and 4d levels. The resonant x rays excited at the 3d-level onsets are considerably more intense, and are excited at a lower electron-excitation energy than the 3d-series characteristic x rays. In the neighborhood of the 4d-electron thresholds, four line-like structures extend to approx.8 eV below the 4d-electron binding energies, while two broad and more intense structures occur above the 4d onsets, with the largest one reaching a peak intensity at 12 eV above the 4d thresholds. The resonant emissions apparently arise from the decay of threshold-excited states which are bound to the inner vacancy and have core configurations nd 9 4f 3 , (n=3,4). The exchange interaction between the three 4f electrons and the respective d-orbital vacancy spreads the 4d-threshold structures over a 20 eV range of excitation energies and the 3d-threshold structures over a much smaller range
Energy Technology Data Exchange (ETDEWEB)
Wang, Yuxian [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Xie, Yongbing, E-mail: ybxie@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Sun, Hongqi [Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Xiao, Jiadong; Cao, Hongbin [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Shaobin, E-mail: shaobin.wang@curtin.edu.au [Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)
2016-01-15
Highlights: • 2D γ-MnO{sub 2}/2D rGO hybrids (MnO{sub 2}/rGO) via a facile hydrothermal route were prepared. • MnO{sub 2}/rGO exhibits high activity in catalytic ozonation of 4-nitrophenol. • ·O{sub 2}{sup ̄} and {sup 1}O{sub 2} are the major radicals for 4-nitrophenol degradation and mineralization. • A synergistic effect of ozonation and peroxymonosulfate oxidation was evaluated. - Abstract: Two-dimensional reduced graphene oxide (2D rGO) was employed as both a shape-directing medium and support to fabricate 2D γ-MnO{sub 2}/2D rGO nano-hybrids (MnO{sub 2}/rGO) via a facile hydrothermal route. For the first time, the 2D/2D hybrid materials were used for catalytic ozonation of 4-nitrophenol. The catalytic efficiency of MnO{sub 2}/rGO was much higher than either MnO{sub 2} or rGO only, and rGO was suggested to play the role for promoting electron transfers. Quenching tests using tert-butanol, p-benzoquinone, and sodium azide suggested that the major radicals responsible for 4-nitrophenol degradation and mineralization are O{sub 2}{sup ̄} and {sup 1}O{sub 2}, but not ·OH. Reusability tests demonstrated a high stability of the materials in catalytic ozonation with minor Mn leaching below 0.5 ppm. Degradation mechanism, reaction kinetics, reusability and a synergistic effect between catalytic ozonation and coupling peroxymonosulfate (PMS) activation were also discussed.
Electronic structure of LaFe{sub 2}X{sub 2} (X = Si,Ge)
Energy Technology Data Exchange (ETDEWEB)
Hase, I., E-mail: i.hase@aist.go.jp [Electronics and Photonics Research Institute, AIST, Tsukuba, Ibaraki 305-8568 (Japan); Yanagisawa, T. [Electronics and Photonics Research Institute, AIST, Tsukuba, Ibaraki 305-8568 (Japan)
2011-11-15
We have calculated the electronic structure of LaFe{sub 2}Si{sub 2} and LaFe{sub 2}Ge{sub 2} from first-principles. The obtained Fermi surfaces of LaFe{sub 2}Si{sub 2} and LaFe{sub 2}Ge{sub 2} resemble those of LaRu{sub 2}Ge{sub 2}, which well explains the result of the dHvA experiments of CeRu{sub 2}Ge{sub 2}. Their density of states curves show the common feature with CaFe{sub 2}As{sub 2}. D(E{sub F}) strongly depends on the distortion of the FeX{sub 4} tetrahedra and/or the height of the X atom, as also found in iron-pnictide system. Recently found iron-pnictide superconductor (Ba,K)Fe{sub 2}As{sub 2} and the heavy-fermion superconductor CeCu{sub 2}Si{sub 2} both have the same crystal structure. In this paper we have calculated the electronic structure of LaFe{sub 2}Si{sub 2} and LaFe{sub 2}Ge{sub 2} from first-principles. These compounds also have the same crystal structure and closely related to both of (Ba,K)Fe{sub 2}As{sub 2} and CeRu{sub 2}Ge{sub 2}. The obtained Fermi surfaces of LaFe{sub 2}Si{sub 2} and LaFe{sub 2}Ge{sub 2} resemble those of LaRu{sub 2}Ge{sub 2}, which are already found that they well explain the results of the dHvA experiments of CeRu{sub 2}Ge{sub 2}. Their density of states curves show the common feature with CaFe{sub 2}As{sub 2}. The density of states at the Fermi level strongly depends on the distortion of the FeX{sub 4} tetrahedra and/or the height of the X atom from the two-dimensional Fe plane, as also found in iron-pnictide system. The electronic specific heat coefficient is 11.8 mJ/mol K{sup 2} for LaFe{sub 2}Si{sub 2} and 12.5 mJ/mol K{sup 2} for LaFe{sub 2}Ge{sub 2}, which is about 1/3 and 1/2 of experimental results, respectively.
International Nuclear Information System (INIS)
McLaughlin, B.M.; Scott, M.P.; Sunderland, A.G.; Noble, C.J.; Burke, V.M.; Ramsbottom, C.A.; Reid, R.H.G.; Hibbert, A.; Bell, K.L.; Burke, P.G.
2007-01-01
Effective collision strengths are presented for the Fe-peak element Fe III at electron temperatures (T e in degrees Kelvin) in the range 2 x 10 3 to 1 x 10 6 . Forbidden transitions results are given between the 3d 6 , 3d 5 4s, and the 3d 5 4p manifolds applicable to the modeling of laboratory and astrophysical plasmas
Mapping Thermal Expansion Coefficients in Freestanding 2D Materials at the Nanometer Scale
Hu, Xuan; Yasaei, Poya; Jokisaari, Jacob; Öǧüt, Serdar; Salehi-Khojin, Amin; Klie, Robert F.
2018-02-01
Two-dimensional materials, including graphene, transition metal dichalcogenides and their heterostructures, exhibit great potential for a variety of applications, such as transistors, spintronics, and photovoltaics. While the miniaturization offers remarkable improvements in electrical performance, heat dissipation and thermal mismatch can be a problem in designing electronic devices based on two-dimensional materials. Quantifying the thermal expansion coefficient of 2D materials requires temperature measurements at nanometer scale. Here, we introduce a novel nanometer-scale thermometry approach to measure temperature and quantify the thermal expansion coefficients in 2D materials based on scanning transmission electron microscopy combined with electron energy-loss spectroscopy to determine the energy shift of the plasmon resonance peak of 2D materials as a function of sample temperature. By combining these measurements with first-principles modeling, the thermal expansion coefficients (TECs) of single-layer and freestanding graphene and bulk, as well as monolayer MoS2 , MoSe2 , WS2 , or WSe2 , are directly determined and mapped.
Spinor-electron wave guided modes in coupled quantum wells structures by solving the Dirac equation
International Nuclear Information System (INIS)
Linares, Jesus; Nistal, Maria C.
2009-01-01
A quantum analysis based on the Dirac equation of the propagation of spinor-electron waves in coupled quantum wells, or equivalently coupled electron waveguides, is presented. The complete optical wave equations for Spin-Up (SU) and Spin-Down (SD) spinor-electron waves in these electron guides couplers are derived from the Dirac equation. The relativistic amplitudes and dispersion equations of the spinor-electron wave-guided modes in a planar quantum coupler formed by two coupled quantum wells, or equivalently by two coupled slab electron waveguides, are exactly derived. The main outcomes related to the spinor modal structure, such as the breaking of the non-relativistic degenerate spin states, the appearance of phase shifts associated with the spin polarization and so on, are shown.
Electron Fermi acceleration in collapsing magnetic traps: Computational and analytical models
International Nuclear Information System (INIS)
Gisler, G.; Lemons, D.
1990-01-01
The authors consider the heating and acceleration of electrons trapped on magnetic field lines between approaching magnetic mirrors. Such a collapsing magnetic trap and consequent electron energization can occur whenever a curved (or straight) flux tube drifts into a relatively straight (or curved) perpendicular shock. The relativistic, three-dimensional, collisionless test particle simulations show that an initial thermal electron distribution is bulk heated while a few individual electrons are accelerated to many times their original energy before they escape the trap. Upstream field-aligned beams and downstream pancake distributions perpendicular to the field are predicted. In the appropriate limit the simulation results agree well with a nonrelativistic analytic model of the distribution of escaping electrons which is based on the first adiabatic invariant and energy conservation between collisions with the mirrors. Space science and astrophysical applications are discussed
CT of calcaneal fractures: 3-D-reformations with electronic disarticulation
International Nuclear Information System (INIS)
Freund, M.; Hohendorff, B.; Zenker, W.; Hutzelmann, A.; Heller, M.
1996-01-01
25 patients with intra-articular calcaneal fractures underwent diagnostic CT-examinations. Axial slices, sagittal and 3-D-reformations with and without electronic disarticulation were performed. The sagittal and both types of 3-D-reformations were compared to the axial slices with regard to the diagnostic criteria: Involvement of articular facets, number of fragments, and traumatic changes of the hindfoot. The best proof of involvement of articular facets is found in axial slices and 3-D-reconstructions after disarticulation followed by sagittal reconstructions. Usually on 3-D-reconstructions without disarticulation articular facets cannot be identified because of overlapping bones. The number of fragments is clearly demonstrated by axial slices and sagittal reconstructions followed by 3-D-reconstructions after disarticulation. Traumatic changes of the hindfoot can be diagnosed in all four forms of visualisation. The decisive diagnosis for treatment planning is made based on the axial slices supported by sagittal reformations. In unclarified cases 3-D-reformations after electronic disarticulation may provide further information. 3-D-reformations without disarticulation are useless. (orig./MG) [de
International Nuclear Information System (INIS)
Yan-Ling, Li; Guo-Hua, Zhong; Zhi, Zeng
2009-01-01
This paper investigates the structural and electronic properties of rhenium diboride by first-principles calculation based on density functional theory. The obtained results show that the calculated equilibrium structural parameters of ReB 2 are in excellent agreement with experimental values. The calculated bulk modulus is 361 GPa in comparison with that of the experiment. The compressibility of ReB 2 is lower than that of well-known OsB 2 . The anisotropy of the bulk modulus is confirmed by c/a ratio as a function of pressure curve and the bulk modulus along different axes along with the electron density distribution. The high bulk modulus is attributed to the strong covalent bond between Re-d and B-p orbitals and the wider pseudogap near the Fermi level, which could be deduced from both electron charge density distribution and density of states. The band structure and density of states of ReB 2 exhibit that this material presents metallic behavior. The good metallicity and ultra-incompressibility of ReB 2 might suggest its potential application as pressure-proof conductors. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Saïl, K.; Bassou, G.; Gafour, M. H.; Miloua, F.
2015-12-01
Conjugated organic systems such as thiophene are interesting topics in the field of organic solar cells. We theoretically investigate π-conjugated polymers constituted by n units ( n = 1-11) based on the thiophene (Tn) molecule. The computations of the geometries and electronic structures of these compounds are performed using the density functional theory (DFT) at the 6-31 G( d, p) level of theory and the Perdew-Burke-Eenzerhof (PBE) formulation of the generalized gradient approximation with periodic boundary conditions (PBCs) in one (1D) and two (2D) dimensions. Moreover, the electronic properties (HOCO, LUCO, E gap, V oc, and V bi) are determined from 1D and 2D PBC to understand the effect of the number of rings in polythiophene. The absorption properties—excitation energies ( E ex), the maximal absorption wavelength (λmax), oscillator strengths, and light harvesting—efficiency are studied using the time-dependent DFT method. Our studies show that changing the number of thiophene units can effectively modulate the electronic and optical properties. On the other hand, our work demonstrates the efficiency of theoretical calculation in the PBCs.
A study of a sector spectrophotometer and auroral O+(2P-2D) emissions
Swenson, G. R.
1976-01-01
The metastable O+(2P-2D) auroral emission was investigated. The neighboring OH contaminants and low intensity levels of the emission itself necessitated the evolution of an instrument capable of separating the emission from the contaminants and having a high sensitivity in the wavelength region of interest. A new type of scanning photometer was developed and its properties are discussed. The theoretical aspects of auroral electron interaction with atomic oxygen and the resultant O+(2P-2D) emissions were examined in conjunction with N2(+)1NEG emissions. Ground based measurements of O+(2P-2D) auroral emission intensities were made using the spatial scanning photometer (sector spectrophotometer). Simultaneous measurements of N2(+)1NEG sub 1,0 emission intensity were made in the same field of view using a tilting photometer. Time histories of the ratio of these two emissions made in the magnetic zenith during auroral breakup periods are given. Theories of I sub 7319/I sub 4278 of previous investigators were presented. A rocket measurement of N2(+)1NEG sub 0,0 and O+(2P-2D) emission in aurora was examined in detail and was found to agree with the ground based measurements. Theoretical examination resulted in the deduction of the electron impact efficiency generating O+(2P) and also suggests a large source of O+(2P) at low altitude. A possible source is charge exchange of N+(1S) with OI(3P).
International Nuclear Information System (INIS)
Chen, Mau Hsiung.
1987-01-01
The experimental observations of the 3p 6 3d 9 2 D - 3p 5 3d 10 2 p transitions of the Co-like ions and 3p 6 3d 8 3 F 4 - 3p 5 3d 9 3 F 3 of the Fe-like ions have recently been extended to highly charged ions of heavy elements up to uranium (Z = 92). A comparison between the observed energies and calculated values from the Dirac-Fock model indicated persistent discrepancies of 3 to 4 eV for all ions. Systematic multiconfiguration Dirac-Fock calculations for these transitions have been carried out with emphases on the effects of electron correlation. The previously found discrepancies theory and experiment have mostly removed after the inclusion of the electron-electron correlation effects in the theoretical calculations. 13 refs
Electrical spin injection into high mobility 2D systems.
Oltscher, M; Ciorga, M; Utz, M; Schuh, D; Bougeard, D; Weiss, D
2014-12-05
We report on spin injection into a high mobility 2D electron system confined at an (Al,Ga)As/GaAs interface, using (Ga,Mn)As Esaki diode contacts as spin aligners. We measured a clear nonlocal spin valve signal, which varies nonmonotonically with the applied bias voltage. The magnitude of the signal cannot be described by the standard spin drift-diffusion model, because at maximum this would require the spin polarization of the injected current to be much larger than 100%, which is unphysical. A strong correlation of the spin signal with contact width and electron mean free path suggests that ballistic transport in the 2D region below ferromagnetic contacts should be taken into account to fully describe the results.