Quasi-static field of an elementary electric dipole in a moving,isotropic, warm plasma

We have investigated the field of an elementary electric dipole in a medium moving at nonrelativistic velocities. We used a quasi-static approximation and a hydrodynamic model of the plasma, taking into account the thermal motion of the electrons. The plasma is assumed to be isotropic, uniform, and infinite. We demonstrate that the intrinsic spatial dispersion of the medium (in the associated reference frame) produces a change in the plasma wave part of the source field.Kirovskii State Teachers Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedeni Radiofizika, No. 10, pp. 1227–1236, October, 1994.     

Resonant excitation of evanescent spatial harmonics in medium formed by parallel metallic nanorods

The results of analytical modeling of the resonant excitation of evanescent harmonics in a medium formed by parallel metallic nanorods taking into account the spatial dispersion are presented. Analytical expressions are derived for the reflection and transmission coefficients, as well as for the amplitudes of electromagnetic waves inside the medium. These expressions are compared to similar expressions that were previously obtained using a local model of an ultimately anisotropic material without taking into account the spatial dispersion. The obtained expressions are simplified for various partial cases, including the superresolution imaging of a source that is located at a considerable distance from the metamaterial layer. A layer of a medium composed from finitesized wires is numerically simulated and it is demonstrated that, due to the effect of resonant excitation of evanescent spatial harmonics in the layer, subwavelength details of an object that is considerably distant from the layer can be distinguished inside of the layer.     

Plasmon-polariton surface waves at the interface of a dielectric and a nanocomposite with metal inclusions

The features of the propagation of the surface waves a plasmon-polariton-type at the interface of a dielectric and a nanocomposite material with spherical metal inclusions have been considered. The analysis has been performed taking into account damping of propagating waves, which results in the complexity of dispersion relations, and taking into account the nanoparticle size. The frequency dependences of the group velocity and the depth of surface wave penetration into each medium have been constructed, and the distributions of energy fluxes in the structure have been obtained.     

Control of excitons in a bent bunch of molecular aggregates by dipole–dipole interaction with quantum dots

The nonlocal dipole–dipole interaction is studied between excitations in chromophores forming a bunch or a tube of J-aggregates and closely spaced quantum dots (QDs). Equations describing the evolution of exciton pulses in a quasi-one-dimensional medium are derived taking into account the interaction with the transition resonant to nanoparticles. It is shown that the efficient controllable resonance energy transfer can occur in the system between QDs and an exciton pulse. The efficiency of this process significantly increases if the bunch of aggregates is deformed to bend nanoparticles round. It is shown that the interaction of permanent dipole moments of QDs and chromophores leads to the formation of a potential barrier or a well. It is found that the combined influence of these factors can be used to efficiently control the dynamics of pulses in aggregates.     

The electric moment of a spherical particle,with the conductivity of the particle and medium taken into account

The behavior of a solid particle in an inhomogeneous electric field depends on the size and sign of the electric dipole moment of the particle. The dipole moment of a spherical particle is calculated, taking into account the conductivity of the particle and the surrounding medium.     

Heating of Low-Density Matter by Soft X-Ray Radiation and Radiation Waves

We investigate the nonlinear radiative thermal conductivity model, which is theoretically well substantiated and based on a small number of assumptions. We consider the spatial and temporal evolutions for a low-density polymer foam heated by radiation waves taking into account the dependence of the absorption coefficients on the quantum energy. The form of the radiation wavefront (its slope and speed of propagation) differs from the classical form by a low-temperature “tongue” penetrating deep into the plasma. The plasma in this segment of the wavefront is heated up to a temperature of 1–2 eV by photons in the hard part of the spectrum, with energies for which hν/kT?>?4. We simulate numerically the experiments at the PHELIX facility to heat a low-density cellulose triacetate (TAC, C₁₂H₁₆O₈) taking into account the radiation transfer. The energy and the spectral flux of radiation that passed through the TAC layer are satisfactorily consistent with the experimental results.     

Local-field effects in reflectance anisotropy spectra of the (001) surface of gallium arsenide

Characteristic reflectance anisotropy spectra of the naturally oxidized (001) surfaces of GaAs undoped crystals and Ga_0.7Al_0.3As epitaxial films are measured in the energy range 1.5–5.7 eV. The spectra are interpreted in the framework of the microscopic model proposed for a GaAs(001)/oxide interface and the reflectance anisotropy (difference) theory developed for a multilayer medium with a monolayer of atomic dipoles located near one of the interfaces. The anisotropy of dipole polarizability and the anisotropy of the plane lattice formed by dipoles are taken into account within the unified Green function approach of classical electrodynamics. A good agreement between the measured and calculated reflectance anisotropy spectra of the oxidized GaAs(001) surfaces shows that the local field effects at the semiconductor-oxide interface make the main contribution to these spectra.     

Calculation of dipole moment functions with density functional theory: application to vibrational band intensities

We have calculated fundamental and overtone XH stretching vibrational band intensities for H₂O, benzene, cyclohexane, 1,3-butadiene, and HCN. The band intensities were calculated with a simple harmonically coupled anharmonic oscillator local mode model and a series expanded dipole moment function. The dipole moment functions were obtained from local, non-local and hybrid density functional theory calculations with basis sets ranging from 6–31G(d) to 6–311++G(3df,3pd). The calculated band intensities have been compared with intensities calculated with conventional ab initio methods and with experimental results. Compared with conventional correlated ab initio methods, a carefully chosen density functional method and basis set seems to give better fundamental and overtone intensities with far less resources used. We have found that the density functional methods appear to be less sensitive to the choice of basis set, with little difference between the results obtained with a non-local or hybrid density functional method.     

Excitons in molecular J-aggregates of cyanine dyes: Simulation of trapping and energy transfer

A theoretical model is provided to simulate the energy transfer and trapping of excitons in cyanine J-aggregates for various geometrical configurations. Intermolecular interactions are calculated using the extended dipole method. Frenkel exciton states are obtained by a numerical diagonalization of the aggregate Hamiltonian taking into account the static disorder. A model of exciton–phonon coupling is used to describe the trapping and the energy transfer processes among the exciton states. Scattering rates are calculated and used in a Master Equation to obtain the time evolution of the excitonic populations after initial excitation. Configurationally averaged absorption lineshapes and time-resolved fluorescence decays are obtained. Our simulation model is applied to describe the excitation energy transfer between two closely spaced linear chains of pseudoisocyanine (PIC) molecules and to a two-dimensional monolayer composed of a mixing of oxacyanine and thiacyanine molecules.     

Radiative frequency shift without ultraviolet divergency in a two-level hydrogenic atom

Summary By taking into account the retardation effects a finite result for the frequency shift of the Lyman α-radiation from a two-level hydrogenic atom is obtained. This result shows a nonnegligible correction as compared to previous results obtained in the dipole approximation with a cut-off frequency.     

The effect of spatial dispersion on the interaction of short-wavelength oscillations with small-scale plasma irregularities

Using the statistical random-phase approximation, we derive the equations describing the interaction of short-wavelength oscillations with irregularities of a magnetized plasma taking into account thermal effects of the spatial dispersion. It is shown that an additional energy exchange between the wave and the plasma electrons, which is not related to resonance particles or collisions, occurs in a medium with random irregularities due to the effect of spatial dispersion. This energy exchange can be significant if the scales of the irregularities along the magnetic field are not very large, so that the dispersion effects in the interaction of a wave with irregularities are greater than the dissipative ones. We consider in detail the case, typical for the ionosphere, where the irregularities are field-aligned and the plasma oscillations are polarized almost perpendicular to the magnetic field. An equation describing the differential redistribution of plasma-oscillation energy in the wavenumber space due to multiple scattering by the irregularities was obtained taking into account the influence of spatial dispersion on the scattering process. We discuss application of the results obtained to the interpretation of some ionospheric experiments. Institute for Solar-Terrestrial Magnetism, lonosphere, and Radio Wave Propagation of the Russain Academy of Sciences, Troitsk, Moscow region, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 43, No. 4, pp. 310–324, April, 2000.     

Optical properties in photoelectron diffraction theory

Photoelectron diffraction effects may be strongly influenced by optical properties of the solid. Due to refraction and absorption of light at a surface, the state of polarization of light may be changed and, therefore, the corresponding photoelectron diffraction intensity. In order to include optical properties of solids in photoelectron diffraction theory, a general polarization vector of light is defined taking into account both refraction and absorption of light at the vacuum–solid boundary. In a first step, the radiation field of light inside the solid is approximated macroscopically according to classical electrodynamics. Analytical expressions are derived within a real-angle representation of Fresnel equations to reveal the influence of refraction and absorption of light on the state of polarization of light. A general refractive index in dependence on the incident angle of light is introduced which determines the refractive angle inside the solid (refraction law with real angles) and the order of influence of absorption of light. The general polarization vector is applied in the calculation of dipole transition matrix elements in a multiple-scattering cluster model of photoelectron diffraction, where the process of photoabsorption (dipole transition matrix element) and multiple scattering processes of photoelectrons (scattering path operator) are considered separately. Different analytical and numerical results of photoelectron diffraction effects are presented for light of general polarization incident at general angles taking into account the optical properties of the solid. Examples are shown and discussed in detail for Cu(001) and GaAs(110) surfaces.     

Ab initio study of the structure and dynamical properties of crystalline ice

We investigated the structural and dynamical properties of a tetrahedrally coordinated crystalline ice from first principles based on density functional theory within the generalized gradient approximation with the projected augmented wave method. First, we report the structural behaviour of ice at finite temperatures based on the analysis of radial distribution functions obtained by molecular dynamics simulations. The results show how the ordering of the hydrogen bonding breaks down in the tetrahedral network of ice with entropy increase, in agreement with the neutron diffraction data. We also calculated the phonon spectra of ice in a 3× 1× 1 supercell using the direct method. So far, due to the direct method used in this calculation, the phonon spectra are obtained without taking into account the effect of polarization arising from dipole–dipole interactions of water molecules, which is expected to yield the splitting of longitudinal and transverse optic modes at the Γ point. The calculated longitudinal acoustic velocities from the initial slopes of the acoustic mode are in reasonable agreement with the neutron scattering data. Analysis of the vibrational density of states shows the existence of a boson peak at low energy of the translational region, a characteristic common to amorphous systems.     

The influence of higher spatial harmonics of atomic polarization on the saturated absorption resonance upon excitation of open dipole transitions by a field of counterpropagating waves

The effect of a double structure of saturated absorption resonance in the field of counterpropagating light waves interacting with an atomic gas is studied. The experimental observation of this effect was first reported in 2011 in a work by our colleagues at the P.N. Lebedev Physical Institute of the Russian Academy of Sciences (Laboratory of Frequency Standards). The essence of the effect lies in the fact that, on exciting an open dipole transition, another, narrower, resonance of an opposite sign can be observed at the center of the ordinary saturated absorption resonance. A theoretical analysis of this effect has also been performed in this work in terms of a simple spectroscopic model of an atom with two nondegenerate energy levels without taking into account higher spatial harmonics of atomic polarization and polarizations of light waves (scalar model). The present work is devoted to the development of a theory of the formation of a central narrow resonance for the example of a real F _g = 1 → F _e = 1 atomic transition and to the study of its main characteristics (amplitude, width, contrast, and amplitude-to-width ratio). In addition, the theoretical results obtained without taking into account the influence of higher spatial harmonics and with inclusion of the influence of first higher harmonics are compared. This comparison shows that their influence on the parameters of the new nonlinear resonance is strong even in moderately intense light fields (R ~ γ, where R is the Rabi frequency). The results of this study can be of interest for quantum metrology, as well as for many experiments in which the laser-radiation frequency is stabilized by the saturated absorption resonance on open dipole transitions in atoms and molecules.     

Interaction Energies in a System of Three Organic Molecules Versus Their Structure and Mutual Induction

A method for the analysis of the interaction energies in a three-molecule nanocluster containing hydrocarbon molecules with double carbon–carbon bonds is presented. It is assumed that one of the molecules (pentene) has a dipole moment; the other two (aromatic molecules) have no dipole moments. The molecules in the considered three-molecule nanocluster are bounded by the long-range dispersion and induction interactions with the Coulomb repulsive forces at short intermolecular distances taken into account. Analytical expressions are obtained in terms of the presented method to calculate the dispersion and induction energies. In these expressions, the Coulomb repulsion at short distances is taken into account for each pair of molecules, which is possible owing to the specific charge properties of the double bonds in the considered molecules, which lead to the residual positive charges at the carbon atoms in these bonds. It was shown that the total interaction energy reached its minimum at smaller intermolecular distances between each pair of molecules compared with those in the corresponding isolated two-molecular nanocluster consisting of the same molecules.     

低能质子在半导体材料Si 和GaAs中的非电离能损研究

非电离能损(NIEL)引起的位移损伤是导致空间辐射环境中新型光电器件失效的主要因素.由于低能时库仑相互作用占主导地位,一般采用Mott-Rutherford微分散射截面,但它没考虑核外电子库仑屏蔽的影响.为此,本文采用解析法和基于Monte-Carlo方法的SRIM程序计算了考虑库仑屏蔽效应后低能质子在半导体材料Si,GaAs中的NIEL,SRIM程序在计算过程中采用薄靶近似法, 并与其他作者的计算数据和实验数据进行了比较.结果表明：用SRIM程序计算NIEL时采用薄靶近似法处理是比较合理的,同时考虑库仑 关键词： 低能质子 非电离能损 硅 砷化镓     

低能质子在半导体材料Si 和GaAs中的非电离能损研究

非电离能损(NIEL)引起的位移损伤是导致空间辐射环境中新型光电器件失效的主要因素.由于低能时库仑相互作用占主导地位，一般采用Mott-Rutherford微分散射截面，但它没考虑核外电子库仑屏蔽的影响.为此，本文采用解析法和基于Monte-Carlo方法的SRIM程序计算了考虑库仑屏蔽效应后低能质子在半导体材料Si,GaAs中的NIEL，SRIM程序在计算过程中采用薄靶近似法, 并与其他作者的计算数据和实验数据进行了比较.结果表明：用SRIM程序计算NIEL时采用薄靶近似法处理是比较合理的，同时考虑库仑     

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Using the fully relativistic configuration interaction (RCI) method and the multi-configuration Dirac-Fock (MCDF) method and taking quantum electrodynamical (QED) effect and Breit correction into account, wavelengths, transition probabilities and oscillator strengths were calculated for electric dipole (E1) transitions and magnetic dipole (M1) transitions in Au⁵⁰⁺ ion. The obtained energy levels of some excited states and wavelengths of transitions in Au⁵⁰⁺ ion from the method were compared with other theoretical and experimental results, and a good agreement with other results was shown. The calculated transition probabilities and oscillator strengths in E1 transitions using the velocity and length gauges respectively confirmed the accuracy of our calculations. The calculation results indicated that for high-Z highly ionized atom, some forbidden transitions could be very important.     

K - \bar K mixing in a low energy effective QCD

We consider the contribution from the siamese penguin diagram to $K - \bar K$ mixing. Combining some previous results, this contribution could be numerically significant, which is the motivation for the present calculation. For the siamese penguin, the effective lagrangian obtained from the perturbative region above ≈1 GeV is highly non-local. We account for such non-local effects by using an effective low-energy QCD, advocated by many authors, where the quarks are coupled to the pseudoscalar mesons π,K, η. Taking into account the momentum variation of the effective penguin interaction, it is found that the matrix element of the siamese penguin is finite in the limit $\Lambda _\chi \to \infty $ , theCP-conserving part being about 50% of the well known box contribution. However, taking into account the finiteness of the cut-off, a numerical integration shows that the siamese penguin contribution is drastically reduced, and is only 0.2–0.3% of the box result.     

Renormalization of optical excitations in molecules near a metal surface

The lowest electronic excitations of benzene and a set of donor-acceptor molecular complexes are calculated for the gas phase and on the Al(111) surface using the many-body Bethe-Salpeter equation. The energy of the charge-transfer excitations obtained for the gas phase complexes are found to be around 10% lower than the experimental values. When the molecules are placed outside the surface, the enhanced screening from the metal reduces the exciton binding energies by several eVs and the transition energies by up to 1 eV depending on the size of the transition-generated dipole. As a striking consequence we find that close to the metal surface the optical gap of benzene can exceed its quasiparticle gap. A classical image charge model for the screened Coulomb interaction can account for all these effects which, on the other hand, are completely missed by standard time-dependent density functional theory.