Interatomic forces in the b.c.c. transition metals

Using information obtained from X-ray scattering data, a model for the charge density in the transition metals is constructed. In this model the charge density is given by the sum of the charges situated at the ionic and bond centre sites. Within this framework, expressions for the second order elastic constants and the phonon frequencies in the cubic transition metals are obtained. These quantities have been calculated with and without the bond charge contributions for iron. The comparison with the experimental results shows that the introduction of bond charges, and hence angularity in the force-fields, in iron leads to distinctly better agreement with experiment. From a study of the elastic constants of the other b.c.c. transition metals some observations as to the nature of the angular force fields are made.     

Contributions to crystal field parameters for Er3+: Au from ligand electrons and nuclei

A pseudo-point charge model has been found from a calculation of the 4f/ligand charge penetration effects, in Er³⁺: Au within a more general recently developed many-body theory for crystal fields in metals. In this particular system contributions to crystal field parameters (CFP) directly from neighbours may be described in terms of a Coulomb interaction using different effective total charges on the ligands for the fourth order and sixth order components of the crystal field. It has been found that the penetration effects considerably enhance the CFP with respect to their point charge model (PCM) values. The sixth order CFP is much more affected than the fourth CFP by such effects. The calculation of these effective charges is presented in the absence of any contributions from 5d virtual bound states.     

Some applications of field-ionization and field-evaporation techniques in the study of surfaces

After a résumé of field electron emission microscopy a brief survey of field-ionization and field-evaporation techniques is presented, with selected illustrations of applications to surface studies. The field-emission microscope is well established as a surface tool, notably in studies of chemisorption. Field-ion microscopy is used to examine the bulk microstructure of materials as well as their surface properties, and has recently been extended to include many of the common non-refractory metals. The atom-probe fieldion microscope provides the ability to chemically-analyse the atoms resolved in a fieldion image. New developments include the discovery of complex and unexpected structures in desorption images formed by field-evaporating ions and the use of desorption imaging to reveal the locations of different atomic species at a surface.     

Wave-Corpuscle Mechanics for Electric Charges

It is well known that the concept of a point charge interacting with the electromagnetic (EM) field has a problem. To address that problem we introduce the concept of wave-corpuscle to describe spinless elementary charges interacting with the classical EM field. Every charge interacts only with the EM field and is described by a complex valued wave function over the 4-dimensional space time continuum. A system of many charges interacting with the EM field is defined by a local, gauge and Lorentz invariant Lagrangian with a key ingredient—a nonlinear self-interaction term providing for a cohesive force assigned to every charge. An ideal wave-corpuscle is an exact solution to the Euler-Lagrange equations describing both free and accelerated motions. It carries explicitly features of a point charge and the de Broglie wave. Our analysis shows that a system of well separated charges moving with nonrelativistic velocities are represented accurately as wave-corpuscles governed by the Newton equations of motion for point charges interacting with the Lorentz forces. In this regime the nonlinearities are “stealthy” and don’t show explicitly anywhere, but they provide for the binding forces that keep localized every individual charge. The theory can also be applied to closely interacting charges as in hydrogen atom where it produces discrete energy spectrum.     

Intensifying process of polarization effect within pixellated CdZnTe detectors for X-ray imaging

The intensifying process of polarization effect at room temperature in a pixellated Cadmium zinc telluride (CdZnTe) monolithic detector is studied. The process is attributed to the increase in build up space charges in the CdZnTe crystal, which causes an expansion of the space charge region under the irradiated area. The simulations of electric potential distributions indicate that the distorted electric potential due to the high X-ray flux is significantly changed and even deteriorated due to increasing space charges within the irradiated volume. An agreement between the space charge distribution and electric potential is discussed.     

A generally covariant formulation of classical electrodynamics for charges of finite extension

A generally covariant formulation of classical electrodynamics for charges of finite extension has been developed. The charges are required to maintain a prescribed “rigid” shape throughout the course of their motion. An action principle is formulated for the coupled system consisting of the charges plus electromagnetic and gravitational fields. The action principle yields a complicated set of coupled integro-differential equations for the motion and fields. A perturbation expansion in powers of the size of the charge distribution is obtained. In the limit that the size of the charge tends to zero, only a few kinematical features survive in the equations of motion. The resulting equations of motion have the DeWitt-Brehme [Ann. Phys.9 (1969), 220] form, but with additional curvature-coupling terms which were omitted by them owing to an algebraic error.     

The unambiguous identification of vacancy migration stage in resistivity recovery of irradiated metals based on trapping of vacancies at probe impurity atoms

The method of resistivity recovery is a powerful tool for studying point defects in irradiated metals. However, the method is nonspecific with respect to a type (vacancy or interstitial) of investigated defects. To overcome this shortcoming, we made use of opposite signs of excess electric charges of the vacancies and self-interstitial atoms in a lattice. Resistivity loss takes place on trapping of vacancies at impurity atoms if excess charges of the impurity atom and defect are opposite in sign. A way of selecting the impurity atoms with the excess charge opposite in sign to that of vacancies is proposed. The specific evolution of resistivity recovery spectrum induced by vacancy trapping at the selected impurity atoms (probe traps) allows one to unambiguously identify the stage of free long-range vacancy migration.     

Model of Coulomb interaction,interaction coupling constants,and particle mass

A model is proposed for the elementary Coulomb interaction and a formula is given for the Coulomb interaction energy of elementary charges. It is postulated that the electron charge is elementary and that a free charge cannot be a fraction of the electron charge. An explanation is given for the mass of charged leptons and some hadrons.Institute of High-Current Electronics, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 21–26, July, 1995.     

Conversion of topological charge of optical vortices in a parametric frequency converter

It is shown that sum-frequency generation of light beams with vortices allows to construct vortices of different topological charges. An optical parametric amplifier enables to produce a vortex with opposite topological charge (to the reverse vortex). In this way, a frequency converter can be seen as a prototype of an optical processor which allows to produce simple arithmetical operations with topological charges of the interacting vortices.     

Theory of spin Hall effect: extension of the Drude model

An extension of the Drude model is proposed that accounts for the spin and spin-orbit interaction of charge carriers. Spin currents appear due to the combined action of the external electric field, crystal field, and scattering of charge carriers. The expression for the spin Hall conductivity is derived for metals and semiconductors that is independent of the scattering mechanism. In cubic metals, the spin Hall conductivity sigma s and charge conductivity sigma c are related through sigma s=[2pi variant /(3mc2)]sigma2c with m being the bare electron mass. The theoretically computed value is in agreement with experiment.     

Attenuation of the Electric Potential and Field in Disordered Systems

We study the electric potential and field produced by disordered distributions of charge to see why clumps of charge do not produce large potentials or fields. The question is answered by evaluating the probability distribution of the electric potential and field in a totally disordered system that is overall electroneutral. An infinite system of point charges is called totally disordered if the locations of the points and the values of the charges are random. It is called electroneutral if the mean charge is zero. In one dimension, we show that the electric field is always small, of the order of the field of a single charge, and the spatial variations in potential are what can be produced by a single charge. In two and three dimensions, the electric field in similarly disordered electroneutral systems is usually small, with small variations. Interestingly, in two and three dimensional systems, the electric potential is usually very large, even though the electric field is not: large amounts of energy are needed to put together a typical disordered configuration of charges in two and three dimensions, but not in one dimension. If the system is locally electroneutral—as well as globally electroneutral—the potential is usually small in all dimensions. The properties considered here arise from the superposition of electric fields of quasi-static distributions of charge, as in non-metallic solids or ionic solutions. These properties are found in distributions of charge far from equilibrium.     

Energy dependence on fractional charge for strongly interacting subsystems

The energies of a pair of strongly interacting subsystems with arbitrary noninteger charges are examined from closed- and open-system perspectives. An ensemble representation of the charge dependence is derived, valid at all interaction strengths. Transforming from resonance-state ionicity to ensemble charge dependence imposes physical constraints on the occupation numbers in the strong-interaction limit. For open systems, the chemical potential is evaluated using microscopic and thermodynamic models, leading to a novel correlation between ground-state charge and an electronic temperature.     

Electrostatic potential of a point charge lattice having lamina geometry

The Coulomb potential energy of a lattice of point charges having infinite extension in two dimensions only is evaluated using an Ewald-like transformation. An exponential rather than a Gaüssian charge spreading function is used. The derived expansion is rapidly convergent.     

Electromagnetic energy-momentum tensor and elementary classical point charges

An energy-momentum tensor of electromagnetic fields associated with elementary classical point charges is constructed. This tensor represents finite amounts of energy-momentum and of corresponding fluxes. The differences between this tensor and the ordinary one, which is associated with continuously distributed charged matter, stem from the elementary nature of point charges. The new tensor is free of the 4/3 problem of the momentum of a point charge. Implications of the third-order Lorentz-Dirac equation are discussed.     

Ein ionenoptisches System zur Dämpfung transversaler Schwingungen in Strahlen schwerer Ionen

An ion-optical system of new type capable to reduce the divergency of heavy ion beams is proposed. The action of this system is based on the difference of mean charge of heavy ions in gas and in condensed matter. The beam is split into two parts of different mean charge and merged by unification of the mean charge alternately by local application of the different charge exchange media. Considering the beam to be bound to an axis by a series of identical coaxial lenses the ions will oscillate around the axis. Since one part of the beam remains unaffected by charge exchange processes on the average the particles of the other part are forced to increase their charges at positions near to the center line and to reduce their charges at positions of maximum elongation. This process will absorb oscillation energy from the beam. Also, the coordinates of the particles of the second part of the beam move differently in phase space while the particles are in higher charge states: the coordinates are shifted into the phase space domain occupied by the coordinates of the particles of the first part of the beam thus yielding an overall reduction of beam divergency.     

Electro-migration in a two-band metal and in Hall field; Application to an electron-hole drop

The Das-Peierls semi-classical model for a theory of electro-migration in metals is extended to a two-band system of electron and hole carriers. It is shown how the “effective charge” on the electro-migrating ion can be obtained from electro-migration experiments in Hall field. An experiment of this type is proposed to determine the charge on an electron-hole drop recently observed in some semi-conductors.     

Elastic anomalies in superlattices: An explanation

An explanation for the elastic anomalies that have been previously reported in metallic superlattices is presented. The explanation, valid for superlattices with sharp interfaces, makes use of the charge transfer which occurs when two metals with different work functions are in contact. However, contrary to the case of bulk materials where the transferred charge remains localized at the surface, in thin layers the transferred charge is distributed throughout the layer. This change in charge distribution explains the observed anomalies in the lattice constants and in the elastic properties.     

Full counting statistics of multiple Andreev reflection

We derive the full counting statistics of charge transfer through a voltage biased superconducting junction. We find that, for measurement times much longer than the inverse Josephson frequency, the counting statistics describes a correlated transfer of quanta of multiple electron charges, each quantum associated with the transfer of a single quasiparticle. An expression for the counting statistics in terms of the quasiparticle scattering amplitudes is derived.     

Model of inversion of DNA charge by a positive polymer: fractionalization of the polymer charge

We model one strand of DNA by a one-dimensional lattice (ODL) of negative charges and consider the problem of inversion of its charge by a positive polyelectrolyte (PE). In the neutral state of the ODL-PE complex, each of the ODL charges is locally compensated by a PE charge. When an additional PE molecule is adsorbed by ODL, its charge gets fractionalized into monomer charges of defects (tails and arches) on the background of the perfectly neutralized ODL. Defects spread all over the ODL, eliminating the self-energy of PE. For DNA this fractionalization mechanism leads to a substantial inversion of charge, a phenomenon which is widely used for gene delivery.     

与象电荷有关的能量和互作用力问题

指出与象电荷有关的系统的互能、互作用力和真实电荷系统的互能、互作用力分别相等,自能、有一般分别不等。