Volume 123, Nº 3 (2017)

On the basis of data on spin-exchange complex cross sections in the Rb–Rb and Cs–Rb systems, the magnetic-resonance-frequency shifts of rubidium atoms upon collisions in a mixture of Cs–Rb alkalimetal atoms are calculated. The results obtained are compared with the experimental data and the previous theoretical data.

Halfwidths and shifts of CH₃D lines are calculated for the case of nitrogen broadening. The calculations are performed for room temperature (296 K) for vibrational–rotational lines in the ν₃ parallel band, with the rotational quantum numbers varying in the ranges of 0 ≤ J ≤ 70 and 0 ≤ K ≤ 20. For each line, the temperature-dependence characteristics are calculated in the range of 200–400 K recommended for the HITRAN database. The calculations are carried out using a semiempirical method with a correction factor the parameters of which are adjusted on a number of experimental values.

The processes of formation and dissociation of aggregates and formation of solvates of 2,2-difluoro- 4-methylnaphto-[2,1-е]-1,3,2-dioxaborine (1) with the chloroform molecule have been investigated by the methods of stationary and time-resolved spectroscopy. It has been revealed that, in the case of solutions in chloroform, a slow (within 1 h) dissociation of aggregates under the effect of solvent molecules takes place. It has been demonstrated that using chloroform as a solvent allows varying the content of luminophor aggregates in the polymeric composite and, thus, controlling the material spectral-luminescence properties.

Changes in the absorption and luminescence spectra of fluorophosphate glasses doped with PbSe caused by low-temperature Ag⁺–Na⁺ ion exchange are considered. It is found that the silver distribution gradient in a near-surface layer about 16 μm thick leads to two different processes of interaction between metal and semiconductor nanoparticles. PbSe molecular clusters and quantum dots more efficiently grow in deep layers with a low silver concentration. The near-surface glass layers with a high silver concentration exhibit formation of Ag metal nanoparticles, on the surface of which interaction with PbSe molecular clusters leads to the formation of Ag–Se–Pb bonds, which transform into Ag₂Se layers in the process of heat treatment. The appearance of the new phase is confirmed by X-ray diffraction.

Light-transforming polymeric materials based on two luminophor dopants (europium(III) nitrate with 1,10-phenanthroline and quinaldic acid characterized by intense luminescence in the spectral range of 400–650 nm) have been fabricated. It has been established that the photoresistance of polymeric materials based on the fabricated composites is higher than that of the polymeric material activated with europium(III) nitrate with 1,10-phenanthroline. It has been also established that luminescence and photochemical characteristics of polymeric composites are determined by the dopant molar ratio: the maximum luminescence intensity and photoresistance characterize the polymeric material containing europium(III) nitrate with 1,10-phenathroline and quinaldic acid at a molar ratio of 1: 2.

Submicron-powder luminophores CaMoO₄ and CaWO₄ obtained via solid-phase reactions have been studied using diffuse-reflection (DR) spectroscopy and photoluminescence (PL) spectroscopy. It is found that the diffuse-reflection spectrum in the range of a fundamental absorption edge of <300 nm is distorted by PL overlapping, so that subsequent calculations of optical band gap E_g of luminophores CaMoO₄ and CaWO₄ result in an overestimation of this value. An algorithm for the correct processing of diffuse-reflection spectra is described. It is based on a subtraction of the photoluminescence spectrum in the range of fundamental absorption. The correct E_g values and energy values for the defect levels in the bandgap of CaWO₄ and CaMoO₄ are determined to amount to 4.78, 4.83, and 4.86 ± 0.01 eV and 3.97, 4.07, 4.16 ± 0.01 eV, respectively.

The possibility of cluster-state generation on the basis of mixing radiation from two independent lasers in an asymmetric Mach–Zehnder interferometer is shown in this paper. The formulation of the problem is close to that considered before by Menicucci (Phys. Rev. A 83, 62314 (2011)) and Yokouama et al. (Nature Photonics 7, 982 (2013)). The specificity of the current consideration is that our sources of squeezed light (phase-locked sub-Poissonian lasers) radiate bright light in a mixed state, in contrast to an optical parametric oscillator in the subthreshold mode. We also take into account the multimode structure of the radiation, not restricting ourselves to only a constant component of the field-noise characteristics. To set the cluster state, the van Loock–Furusawa separability criterion is used.

Specificities of propagation of three-dimensional extremely short optical pulses in germanene are determined taking into account a constant external electric field. This field has had a significant impact on the evolution of an extremely short pulse in this structure.

In the Rayleigh–Gans–Debye approximation, we solve the problem of second-harmonic generation by an elliptically polarized electromagnetic wave incident on the surface of a spherical particle that is coated by an optically nonlinear layer and is placed in a dielectric. The formulas obtained characterize the spatial distribution of the electric field of the second harmonic in the far-field zone. The most general form of the second-order dielectric susceptibility tensor is considered, which contains four independent components, with three of them being nonchiral and one, chiral. Consistency and inconsistencies between the obtained solution and formulas from works of other authors are found. We analyze the directivity patterns that characterize the spatial distribution of the generated radiation for the nonchiral layer and their dependences on the anisotropy and ellipticity coefficients of the incident wave. It is found that, with increasing radius of the nonlinear layer, the generated radiation becomes more directional. Combinations of parameters for which no radiation is generated are revealed. Based on this, we propose methods for experimental determination of the anisotropy coefficients.

The results of calculations of the dynamics of a field in a cavity that consists of a stationary mirror and a periodically displacing mirror are presented. The initial distribution of the field corresponds to the equilibrium thermal (Planck) distribution. It is shown that, if conditions of a resonant excitation are implemented, pulses can be formed the degree of unipolarity of which increases from the initial zero degree to an almost maximum (unit) degree.

The layout of an X-ray source for diagnostics of the compressed state of laser plasma is proposed, and its optimal parameters are calculated under the conditions required for nuclear fusion. Such a source operating in a pulsed regime is intended to be used for determining the spatial distribution of laser-plasma density with high temporal resolution by means of multiframe (pulses follow with a specified time interval) backlight imaging of the main target by X-ray pulses obtained by irradiation of a secondary target by picosecond laser pulses.

The luminescence polarization properties of new recording media obtained by directed synthesis—disulfochlorides of luminescent dyes (homologues of 1,7-diamino-3,9-dihydrodibenzo-[1,2,3de:4,5,6- d'e']diquinoline-2.8-dione (1,5-diaminoanthradipyridone) series), with the general structure (ClSO₂)₂-1,5-di-AAP-di-R—are investigated. Polarized photoluminescence spectra are recorded, and spectral dependences of the degree of anisotropy of phosphor on its chemical structure at different acidities of the medium are plotted.

The influence of the numerical aperture of a light beam probing an object on the value measured with a confocal interference microscope when determining the thickness of layered object has been theoretically and experimentally investigated. The dependence of the measured value on the numerical aperture in the form of an analytical formula is obtained. It is established that the measured value is determined by the average longitudinal spatial frequency of the field probing the object. The results of experimental verification of the dependence obtained allow us to conclude that it is possible to increase the measurement accuracy of geometrical thickness and refractive index of layered micro-objects by the methods of confocal microscopy.

The efficiency of polarized and nonpolarized radiation for determining microphysical parameters of native erythrocyte populations has been studied. On the basis of using regression relations between determined and measured parameters of native erythrocyte populations, possibilities of the simultaneous rapid determination of their average volume and average surface area, which can be used as a new diagnostic erythrocytometric parameter, are demonstrated.