Pleiades Publishing Ltd

An electron-spectroscopic analysis is made of layered nanostructures and clusters at the surface and in the bulk of a solid. A new method of forming metal/insulator/semiconductor (superconductor) nanostructures is proposed based on ion-stimulated metal segregation effects at the surface of low-temperature gallium arsenide and a 123 high-temperature superconductor. The geometric parameters and electronic structure of these nano-objects are studied. It is shown that their electronic properties can be controllably varied in situ by acting on the surface. The dimensional transformation of the electronic properties of metal clusters is studied for clusters in the insulator SiO2, in the superconductor LTMBE-GaAs, and on silicon and graphite surfaces. The nature of this transformation is clarified. A diagnostics for cluster ensembles is developed by which one can determine the parameters needed to describe singleelectron transport: the average number of atoms per cluster, the average distance between clusters and isolated atoms, and the chemical state of the atoms. Ensembles of silver clusters with specified parameters are obtained on a silicon surface. It is shown that these ensembles are potentially useful for developing single-electron devices.

The dynamic and statistical characteristics of diffusion trajectories are studied by introducing the notion “fractional drift.” An equation for the random walk probability density for cases of subdiffusion and superdiffusion is derived. A solution to this equation is constructed on the basis of the Mittag-Leffler function properties.

Solutions to the diffraction problems are used to calculate the effective permittivity of a composite material consisting of alternating planar arrays of square resistive patches shifted relative to each other in a dielectric layer. The relaxation character of the dispersion is demonstrated. The dispersion characteristic can be varied in wide ranges using variations in the parameters of the structure. Relative shifts of the arrays substantially affect the dispersion of permittivity of the structure. A ratio of the wavelength to the period of the structure that provides adequacy of a homogenization procedure is estimated.

Generalized equations are derived that describe the linear stage of the resistive firehose instability of a relativistic electron beam whose radius and current change along the pulse. Such factors as reverse current, the perturbations of the plasma channel, and the evolution of the plasma conductivity due to impact ionization, avalanche ionization, and recombination are taken into account.

The reflection and refraction of longitudinal and transverse acoustic waves by the plane interface between an insulator and an easy-plane antiferromagnet undergoing a magnetic-field-induced orientational phase transition are analyzed. The angles of refraction, as well as all four coefficients of wave conversion, can be effectively controlled by varying the field. Conditions for the appearance of the critical angles of internal reflection and the effect of the magnetic field on these angles are considered. A glancing wave radiated into the material is shown to be a possibility near the phase transition.

Pulse characteristics of single barrier discharges as well as parameters of charges accumulated on the surface of a dielectric under the atmospheric pressure in the “needle-(0.1–2.0)-mm air gap-polymer barrier-plane” system are investigated. It is found experimentally that for the positive polarity of the needle, the voltage for the discharge initiation is higher than in the case of the negative polarity by ∼25–35%. The reversal of the needle polarity from negative to positive increases the amplitude of the discharge current and the accumulated surface charge by ∼1.5–3 times. For the positive polarity of the needle, the discharge is governed by a streamer mechanism, while for the negative polarity, the discharge is initiated by the formation of a single Trichel pulse. The single pulse regime is observed for the discharge current up to a certain electrode gap d CR. For the positive needle and for air gap width d air > d CR ≈ 1.5 mm, a multipulse burst corona is formed, while for the negative needle and d air > d CR ≈ 0.9 mm, a damped sequence of Trichel pulses evolves in the system.

We report on the results of calculation of the probabilities of rescattering of ultrashort (attosecond) electromagnetic field pulses at one- and two-center negative ions in the s state in the zero-range potentials approximation; the dependence of the rescattering spectra on the number of field oscillations per pulse is investigated.

The application of the multipulse sequences in nuclear quadrupole resonance (NQR) detection of explosive and narcotic substances has been studied. Various approaches to increase the signal to noise ratio (SNR) of signal detection are considered. We discussed two modifications of the phase-alternated multiple-pulse sequence (PAMS): the 180° pulse sequence with a preparatory pulse and the 90° pulse sequence. The advantages of optimal filtering to detect NQR in the case of the coherent steady-state precession have been analyzed. It has been shown that this technique is effective in filtering high-frequency and low-frequency noise and increasing the reliability of NQR detection. Our analysis also shows the PAMS with 180° pulses is more effective than PSL sequence from point of view of the application of optimal filtering procedure to the steady-state NQR signal.