Vol 26, No 1 (2018)

Temporal and spectral characteristics of laser-induced breakdown plasma in colloidal solutions of gold nanoparticles were experimentally studied. Near-infrared laser sources of nanosecond pulses were used. It was shown that under certain experimental conditions nanosized plasma around nanoparticles might change to laser-induced breakdown plasma in liquid. The dependencies of the plasma temporal and spectral characteristics on laser pulse duration as well as resulting nanoparticles properties were studied. Laser-induced breakdown plasma lifetime was shown to be comparable with laser pulse duration. The efficiency of gold nanoparticles fragmentation was shown to depend on laser pulse duration. Similar experiments were carried out under reduced external pressure. It turned out to affect the properties of both plasma plume and nanoparticles. Transmission electron microscopy and disc measuring centrifuge were used for nanoparticle morphology and size analysis. Extinction spectra of colloidal solutions and emission spectra of plasma were studied by means of optical spectroscopy.

Optical second harmonic generation, mechanical stresses, and structure are investigated in thin polycrystalline zinc sulfide films. The resulting data indicate that there is no correlation between the mechanical stresses and the quadratic optical nonlinearity. In view of the X-ray diffraction results, the nature of the nonlinearity is explained using the model of a nanotextured film consisting of crystallites with the sphalerite or wurtzite structure. It is shown that this model allows satisfactory agreement between calculations and experiment.

Spectra of coherent scattering at four-wave mixing of two diode laser radiation in liquid suspensions of dielectric nanoparticles are obtained for the first time. Dependence of the scattering resonance width on the concentration of nanoparticles in the suspension is studied. It is shown that the experimentally observed dependences of the width of the scattered radiation spectrum on the concentration of nanoparticles in the suspension result from the collective excitation of acoustic phonons.

A mesoscale droplet phase, which is spontaneously formed in aqueous solutions of some polar organic compounds, has been experimentally investigated by methods of dynamic light scattering and laser phase microscopy. It is shown that tetrahydrofuran and tert-butanol aqueous solutions demonstrate a strong peak of light scattering intensity in the range of molecular concentrations of about 0.02 to 0.08, which corresponds to inhomogeneities with a characteristic size of about 100 nm. These liquid droplets are enriched with molecules of dissolved substance. A similar light scattering peak for aqueous solutions of glycerol and ethylene glycol is less pronounced. A theoretical model of the phase separation of binary solutions with twinkling (i.e., existing for a finite time) intermolecular hydrogen bonds is developed. The model predicts the existence of an additional low-concentration light scattering peak near the spinodal of the solution free of hydrogen bonds. A characterization of solutions according to the numerical values of twinkling hydrogen bond parameters is outlined.

The spectral probability densities of the spontaneous emission and the generation of harmonics by a hydrogen atom in the field of intense laser pulse are calculated. A previously proposed approach is used, which is based on the Kramers−Henneberger transformation for the wave function of time-dependent Schrödinger equation and expansion in the unperturbed atomic eigenstates and the photon states. The spectral range up to the tenth harmonic is investigated with the laser pulse duration ranging from 6 to 12 optical cycles and the peak intensity varied from 1 to 10 TWcm⁻².

A method is developed for producing active laser elements (spectrum range 4 to 5 μm) based on polycrystalline solid solutions ZnS_xSe_x-1 doped with iron ions. Bilateral diffusion doping of the elements by Fe²⁺ ions is performed during hot isostatic pressing. Spectral and energy characteristics of the laser are investigated with the Fe²⁺:ZnS_0.1Se_0.9 active element kept at room temperature. It is found that the absorption band of the Fe²⁺:ZnS_0.1Se_0.9 crystal is blueshifted with respect to the Fe²⁺:ZnSe absorption band, while the lasing spectra of the Fe²⁺:ZnSe and Fe²⁺:ZnS_0.1Se_0.9 lasers and their energy parameters are almost identical. The lasing energy of 580 mJ is obtained at the slope efficiency with respect to the absorbed energy of 46%. Further increase in the lasing energy is limited by development of transversal parasitic oscillation at a large size of the pump beam spot.

A method for interferometric direction finding of a broadband sound source in an oceanic waveguide by a single vector-scalar receiver is presented. The method is based on the double Fourier transform of the interference pattern formed during motion. The efficiencies of the proposed direction finding method and the method based on measuring the delay times of signals arriving at spaced scalar receivers are compared based on the natural experiment results. The noise immunity of the interferometric direction finding method is considered.

A theoretical study is presented for two-dimensional (2D) and three-dimensional (3D) atom localization in a four-level atomic system involving a Rydberg state. The scheme is based on a mixture of two well-known V- and ladder-type systems illuminated by a weak probe field as well as control and switching laser beams of larger intensity, which could be standing waves. As a result of space-dependent atom− light interaction and due to the effect of Rydberg electromagnetically induced transparency or Rydberg electromagnetically induced absorption, various 2D and 3D localization structures appear. Specifically, the detecting probability and precision of 2D and 3D atom localization can be remarkably enhanced through suitable adjusting the controlling parameters of the system. The proposed scheme may provide a promising approach to achieve high precision and perfect resolution 2D and 3D atom localization.

We study the conditions for the anomalous transmission of electromagnetic waves through quantum overdense plasma. We show that this anomalous transmission is triggered due to the excitation of surface waves, as was observed in the classical overdense plasma. The conditions for the excitation of surface waves are obtained by studying the dispersion relation within the framework of quantum hydrodynamics. The corresponding consequences at the classical limits are consistent with the previous studies. In comparison with the classical regimes, the quantum dispersion curve exhibits an asymptotic behavior which indicates significant effects, in particular, at large wavelengths. Herein, to create the required evanescent waves, we consider the quantum plasma to be placed between two ordinary prisms and dielectrics. The effects of the main parameters, such as the permittivity of the prisms and dielectrics and the Fermi velocity, on the rate of the transmission and the magnetic field propagation are also evaluated.

The authors apologizes for this error in the paper “Time Dependence of the Luminescence from a Polymer Membrane Swollen in Water: Concentration and Isotopic Effects” by N.F. Bunkin, G.A. Lyakhov, V.A. Kozlov, 74 A.V. Shkirin, I.I. Molchanov, M.T.Vu, I.S. Bereza, N.G. Bolikov, V.L. Fouilhe, Igor S. Golyak, Ilya S. Golyak, I.L. Fufurin, V.S. Gorelik, E.V. Uspenskaya, H.S. Nguyen, and S.V. Gudkov.

Page 269, Section ACKNOWLEDGMENTS

This study was supported by the RFBR Projects 15-02-07586, 16-52-540001, and 17-02-00214, and the MEPhI Academic Excellence Project (Contract No. 02.a03.21.0005).

Should be read

This study was supported by the RFBR Projects 15-02-07586, 16-52-540001, and 17-02-00214, the MEPhI Academic Excellence Project (Contract No. 02.a03.21.0005), and the Bilateral Project on Science and Technology (Code No.VAST.HTQT.NGA.03/16-17).