Shifts of resonances in the presence of time-separated fields

A shift of resonance in the presence of time-separated fields due to the curvature of the wavefront of the field pulses is revealed. A scheme for the observation of resonances that allows the shift related to the recoil effect to be completely eliminated is proposed.     

Symmetries and conservation laws of Kadomtsev-Pogutse equations

Kadomtsev-Pogutse equations are of great interest from the viewpoint of the theory of symmetries and conservation laws and, in particular, enable us to demonstrate their potentials in action. This paper presents, firstly, the results of computations of symmetries and conservation laws for these equations and the methods of obtaining these results. Apparently, all the local symmetries and conservation laws admitted by the considered equations are exhausted by those enumerated in this paper. Secondly, we point out some reductions of Kadomtsev-Pogutse equations to more simpler forms which have less independent variables and which, in some cases, allow us to construct exact solutions. Finally, the technique of solution deformation by symmetries and their physical interpretation are demonstrated.     

Investigation into the structural and electrical properties of silver-intercalated zirconium diselenide

Silver-intercalated zirconium diselenides of the general formula Ag_xZrSe₂ are synthesized for the first time. The phase diagram of the Ag_xZrSe₂ compound is determined in the temperature range 423–523 K and at room temperature. An analysis has revealed the coexistence of two compounds, namely, Ag_0.125ZrSe₂ and Ag_0.25ZrSe₂, of which only the latter compound is stable at room temperature. The structural and electrical properties of Ag_xZrSe₂ diselenides are investigated. The results obtained indicate a polaron nature of charge-carrier localization. A comparison with isostructural intercalation compounds shows that free charge carriers play a dominant role in screening of the impurity potential.     

Evolution of the continuous interface between gases of different density during the passage of a shock wave

The evolution of the interface between gases of different density following the passage of a shock wave has been experimentally investigated. It is shown that replacing the discontinuous change of density on the wavy contact discontinuity by a continuous change in a layer of finite thickness leads to a reduction in the amplitude growth rate in the initial stage of development of Richtmyer—Meshkov instability. The experimentally determined values of the amplitude growth rate reduction factor are satisfactorily described by a model to be found in the literature. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.2, pp. 18–26, March–April, 1994.     

Phase separation in high-T c superconductors, copper oxides, and related antiferromagnetic phases CuO and Y2BaCuO5

The acoustic properties and crystal structure of high-T _c superconducting cuprates and the related antiferromagnetic phases CuO and Y₂BaCuO₅ exhibit similar properties at a temperature of about 160 K and 240 K. These properties can be associated with the formation of inhomogeneous state of phase separation. Analysis of the magnetic properties of Y₂BaCuO₅ shows that these effects are of a nonmagnetic nature. The results of EXAFS data for the high-T _c superconducting compound Hg_0.8Tl_0.2Ba₂Ca₂Cu₃O_8.10 show that the phenomenon of phase separation is suppressed by superconductivity.     

Complex magnetic susceptibility of uniaxial superparamagnetic particles in a strong static magnetic field

The magnetic relaxation of a system of single-domain ferromagnetic particles in the presence of a strong static magnetic field directed at an arbitrary angle relative to the particle anisotropy axis is investigated. A system of linear difference-differential equations for the moments (averaged spherical harmonics) is derived without recourse to the Fokker-Planck equation by averaging Gilbert’s equations with a fluctuating field. An exact solution (in terms of matrix continuous fractions) is found for this system. The relaxation times and spectra of the complex magnetic susceptibility are calculated. Fiz. Tverd. Tela (St. Petersburg) 40, 1642–1649 (September 1998)     

N-substituted hexamethyldisilazanes as new substances for the synthesis of functional films in the system Si-Ge-C-N-H

N-Organylbis(trimethylsilyl)amines of the general formula RN(SiMe₃)₂ (R = Me₃Si, Et₃Ge) were synthesized by reaction of sodium bis(trimethylsilyl)amide with the corresponding trialkylsilyl(germyl) halide. Their IR, UV, and ¹H, ¹³C, and ²⁹Si NMR spectra were studied, and saturated vapor pressures and thermal stabilities were determined. The possibility of using the RN(SiMe₃)₂ compounds as precursors in chemical vapor deposition of films with specified composition was estimated by thermodynamic modeling.     

The effect of the iterative triple and quadruple cluster amplitudes on the adiabatic potential curve in the coupled cluster calculations of the ground electronic state of the Yb dimer

The dissociation energy, equilibrium internuclear distance, and spectroscopic constants for the ¹Σ ground state of the Yb₂ molecule are calculated. The relativistic effects are introduced through generalized relativistic effective core potentials with very high precision. The scalar relativistic coupled cluster method particularly well suited for closed‐shell van der Waals systems is used for the correlation treatment. Extensive generalized correlation basis sets were constructed and used. The relatively small corrections for high‐order cluster amplitudes and spin—orbit interactions are taken into account using smaller basis sets and the spin—orbit density functional theory. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

On the Brownian motion in a double-well potential in the overdamped limit

The Brownian motion of a particle in a double-well potential is considered and the position correlation function (excluding inertial effects) for the potential V(x)=ax²/2+bx⁴/4 is evaluated first by averaging the governing Langevin equation over its realizations. The exact solution is then obtained via matrix continued fractions by using a representation, which symmetrizes the recurrence relations for the observables generated by the averaging procedure leading to convergence of these recurrence relations unlike the previous approaches to the problem. A reliable approximate solution based on the exponential separation of the time scales of the fast intrawell and low overbarrier relaxation processes associated with the bistable potential is also given. It is shown that a knowledge of the three characteristic relaxation times (the integral, effective and the longest relaxation times) of the position correlation function allows one to accurately predict the relaxation behavior of the system in the overdamped limit for all time scales of interest.     

Interaction of a standing frequency-modulated wave with a gas in a flight region

A formula is obtained for the power of the nth harmonic absorbed upon interaction of a standing frequency-modulated wave with a gas for an arbitrary modulation frequency and amplitude of the frequency deviation. The flight effects, the quadratic Doppler effect, and the recoil effect are taken into account.