Yu.E. Geints, E.K. Panina, A.A. Zemlyanov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: фотонная наноструя, микросборка частиц, диэлектрические микрочастицы, photonic nanojet, microassembly of particles, dielectric microparticles
Subsection: OPTICS OF CLUSTERS, AEROSOLS, AND HYDROSOLES
The results of theoretical studies of spatially localized near-field light structures (photonic nanojets) that are formed when laser radiation is scattered on a meta-surface in the form of a single-layer ordered assembly of dielectric microparticles (spheres, cones) embedded in a transparent matrix (silicone film) are presented. By solving Maxwell's equations by the method of computational electrodynamics (FDTD), a detailed analysis of the main parameters of localized light structures (length, width, peak intensity) under the influence of the light fields of neighboring microparticles was carried out. It has been established that the main factors influencing the characteristics of the photon nanojet under study are the spatial orientation of the microcones, as well as the depth of their immersion into the silicone matrix. It is shown that a number of spatial configurations of conic microassemblies allow the creation of an ensemble of photon nanojet with specific characteristics unattainable for isolated microcones. Ordered clusters of spherical particles have an advantage in terms of a comprehensive assessment of the parameters of photonic nanojets.
The results of a theoretical investigation of the propagation of femtosecond pulses of a Ti:Sapphire laser in air during the self-focusing and filamentation are presented. The analysis of self-focusing of laser pulses was carried out on the basis of the method of diffraction beams and light tubes, which made it possible to establish that specific light structures are formed in the laser beam during self-focusing. One of such structures is the energy-replenishing diffraction-beam tube, which provides necessary energy for filamentation, and at the stage of post-filamentation pulse propagation exists in the form of a separate intense light channel. The dependences of the radius and power of the energy-replenishing tube on the initial beam radius and the peak power for a fixed pulse duration are established. It was revealed that the energy consumption of radiation per filamentation decreases with an increase in the beam radius and a decrease in its initial power. The peak power contained in the energy-replenishing light tube at the post-filamentation propagation stage of laser pulses does not exceed the critical self-focusing power for the Gaussian beam and weakly depends on the initial parameters of the pulse.
Single-phase and two-phase aerosol particles are considered. The influence of their structure and size distribution parameters on the optical characteristics of the stratospheric sulphate aerosol layer is simulated. The single-phase aerosol includes homogeneous particles, which are a liquid drop of 75% sulphuric acid, and the two-phase aerosol are drops of sulphuric acid with dissolved inorganic impurities. It is assumed that the latter can be two-layer, enlightened, and quasi-homogeneous. The dependence of instantaneous radiative forcing and radiative changes of surface temperature on the internal structure of stratospheric sulphate aerosol particles and the parameters of their size distribution is simulated. An aerosol layer with an optical thickness equal to 0.05 in the visible range is considered. Its particles can lead to the greenhouse and anti-greenhouse effects. Ensembles of two-layer particles with narrow size distributions, and ensembles with wider distributions and average radii not exceeding 0.25 ¸ 0.40 mm, create the anti-greenhouse effect on the order of 4 ¸ 8 W/m2, whereas for large average radii and wide distributions, occurring greenhouse effect (2 ¸ 6 W/m2) occurs.
A.N. Yermakov1, A.E. Aloyan2, V.O. Arutyunyan2 1V.L. Talroze Institute of Energy Problems of Chemical Physics of the Russian Academy of Sciences, 119334, Russia, Moscow, Leninsky prospect, bld. 38/2 2Marchuk Institute of Numerical Mathematics of the Russian Academy of Sciences, Gubkin str., 8, Moscow, 119333, Russia
Keywords: атмосфера, конденсация, коэффициент активности, органический аэрозоль, термодинамика, atmosphere, condensation, activity coefficient, organic aerosol, thermodynamics
Thermodynamic methods with the UNIFAC model have been used to study the distribution of hydrophobic and hydrophilic organic compounds in the atmosphere between the gas and aerosol phases. The results of calculations indicate that the formation of organic aerosol involving these multifunctional compounds is favored by their combined condensation with water vapor. Leading to the transfer of water molecules to the aerosol phase, the condensation is accompanied by an increased mass concentration of organic aerosol, which should be taken into account when comparing with field observation data.
We describe diffusion processes when aerosol particles are moving in the atmosphere. The impact of particles' inertia and diffusion coefficient on multistream formation was determined via the numerical solution of the Fokker-Planck equation. The simulation has been performed within the certain range of parameters, considering turbulent diffusion effects in real atmospheric conditions. The results of the study may be useful in interpreting aerosol optical sensing data.
The ingress of carbon into the snow cover with ions of organic carboxylic acids (formic (formate), acetic (acetate), and oxalic (oxalate)) in the permafrost landscapes of Eastern Siberia is studied. The content of ions of organic carboxylic acids is estimated in areas with the latitude-zonal and mountain-belt type of permafrost landscapes. The maximal content is observed in middle-taiga landscapes. The density of ingress of ions of organic carboxylic acids in snow of permafrost landscapes is subject to altitudinal zonation and follows a decrease in the total mass of plants, which are the main source of organic carboxylic acids in the atmosphere. In the middle-taiga landscapes, organic carboxylic acids can have a significant effect on the ingress of carbon with precipitation. In all mountain-belt types of permafrost landscapes, the bulk of carbon comes from carbonates (bicarbonates), and the role of organic carboxylic acids in the ingress of carbon into snow is insignificant and sharply decreases with an increase in altitude.
S.M. Bobrovnikov1,2, E.V. Gorlov1,2, V.I. Zharkov1 1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia 2National Research Tomsk State University, 36, Lenin Avenue, Tomsk, 634050,Russia
Keywords: лидар, комбинационное рассеяние света, дистанционное обнаружение, высокоэнергетические материалы, lidar, Raman scattering, remote detection, high energetic materials
Experimental results on the remote detection of surface traces of some high energetic materials using a Raman lidar constructed on the basis of an excimer KrF laser with the narrow generation line and a multi-channel spectrum analyzer based on the diffraction spectrograph and a time gated ICCD camera are presented. The sensitivity of the lidar system for a detection range of 10 m was evaluated. The influence of a substrate material on the sensitivity of the detection method is analyzed.
a:2:{s:4:"TYPE";s:4:"HTML";s:4:"TEXT";s:104:"A.V. Nevzorov1, S.I. Dolgii1, A.P. Makeev1,2, A.V. El’nikov3";} 1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia 2National Research Tomsk State University, 36, Lenin Avenue, Tomsk, 634050, Russia 3Surgut State University, 1, Lenin Avenue, Surgut, 628403, Russia
Keywords: лидар, лазерное зондирование атмосферы, вертикальное распределение стратосферного аэрозоля, lidar, laser sounding of atmosphere, stratospheric ozone vertical distribution
In the work, we present the observations of anomalous aerosol layers in the stratosphere over Tomsk (56.5°N, 85.0°E), performed at the Siberian Lidar Station, Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences at two wavelengths (355 and 532 nm) in the summer-fall period of 2017, as well as the trajectory analysis of their motion. The trajectory analysis shows that these aerosol layers in the stratosphere over Tomsk were due to forest fires in the region of the Lake Athabasca (Canada) occurred in mid-August. The analysis of observations on the basis of Ångström parameter allowed us to conjecture that, within assumptions described in the paper, the Ångström parameter of the background ensemble of scattering particles in the stratosphere is X » 2.8. It is noteworthy that the values of Ångström parameter ( X = 1 ¸ 2.5), obtained at altitudes where aerosol layers were located, were characteristic for soot aerosol.
V.G. Sokovikov, A.G. Filonov, D.V. Shiyanov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: лазер на парах европия, ионный Eu-лазер, атомный Eu-лазер, буферный газ, деградация активной среды, europium vapor laser, ion Eu-laser, atom Eu-laser, buffer gas, degradation of the active medium
Subsection: OPTICAL SOURCES AND RECEIVERS FOR ENVIRONMENTAL STUDIES
The lasing characteristics of atomic He + Eu and Ne + Eu vapor lasers at the y8P9/2 → 87Deq \o\al(11/2,0) transition with a wavelength of 1.76 mm were compared. It is shown that the output power and pulsed energy of the He + Eu laser, depending on the pump power and pulse repetition frequency, are slightly worse than those of the Ne + Eu laser. An empirical model is proposed to explain the behavior of the He + Eu laser output power as a function of the input power. It was established that the lifetime of the He + Eu laser does not exceed two hours, while the Ne + Eu laser by the end of the experiment operated about 200 hours. It has been suggested that the relaxation of metastable levels of the ion and atom of europium and degradation of active media consisting of a mixture of europium and helium vapors is responsible for the same process involving helium.
