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Theoretical broadening coefficients of rotation vibration water vapor lines induced by hydrogen pressure are given. The averaged frequency method has been used to calculate line widths. Calculations have been performed for a wide interval of rotational quantum numbers in the spectral region from 500 to 10 000 cm^-1. Line widths have been computed by the averaged frequency method for rotation quantum number J from 0 to 20, data have been obtained by interpolation of J- dependence for J from 20 to 50. Temperature exponents for line widths have been defined.

Absorption spectrum of carbon oxide confined in nanopores of hybrid SiO₂/Al₂O₃ xerogel has been recorded for the first time. Half-width values of spectral lines was obtained, their dependence on quantum numbers was considered and compared with the data available in literature.

Article belongs to the series of works aimed at improving the performance of radiation codes that implement the statistical Monte Carlo method. A brief description of the main blocks of the two programs for calculating the intensity of solar radiation in a vertically inhomogeneous medium, basis, in FORTRAN, and its optimized version, in the C language, is presented. The results of tests aimed at assessing the performance of each of the code under different conditions of numerical experiment are presented. In the cases examined, the performance indicators of optimized C code were higher as compared with the basis one. It is shown that differences in execution time of the codes are reduced by increasing the optical density of the atmosphere, and using more efficient computers. Developed C program can serve as a basis for creating a high-performance radiation code.

The atmospheric transparency window of 8-12 mm is one of the main spectral intervals forming thermal balance of the atmosphere; at that, the contribution of continual absorption to the radiative balance is the most significant. The results of simulation of upward and downward fluxes for different meteorological situations (cloudy and cloudless) are presented; and role of H₂O continuum is estimated with use of different models of continual absorption.

The paper presents the results of quality assessment of images made using a copper bromide vapor laser monitor. Two different imaging techniques were used for the study: laser illumination and amplification using laser active medium (so called laser monitor). The images were numerically evaluated using the following informative parameters: standard error, Shannon entropy (H), and zero mean normalized cross-correlation (ZNCC). It is shown that use of an active medium introduces into images small distortions, which depend on the stability of amplification properties of the active medium. In the scheme of laser illumination, the influence of instability is less pronounced. The imaging in single-frame mode can decrease the distortions introduced by the active medium.

In laboratory conditions at low pressures of air, corresponding to heights of tens of kilometers above sea level, the apokamp was formed. Apokamp is a plasma jet extending from the spark discharge channel formed by two electrodes, one of which is high voltage and has a positive polarity, and the other is under floating potential. It is established that underpressure apokamp has spectral and morphological features associated with blue jets and starters that observed in the upper layers of the atmosphere.

The influence of gas pressure measurement errors in the chamber of a photoacoustic detector on accuracy of restoration of fast VT-relaxation time of molecules is investigated with the use of numerical simulation of a shape of photoacoustic signal. Using the relaxation of water vapor molecules from the lower excited vibrational state as an example, it is found that for values of the radius of the Gaussian laser beam ω₀ ~ 1 mm, typical in experiments with MK-301 microphone, the relaxation time τ⁰_VT ~ 10^-6 s x mbar can be restored from the dependencies of duration of photoacoustic compression pulse on gas pressure with a relative errors δτ⁰_VT ≤ 10%, if systematic measurement error of pressure does not exceed 0.03 mbar. An error of restoration is directly proportional to the propagation time of sound through the illuminated area.

The content of CO₂ and H₂O in vacuum-extracted tree-ring wood of stem and root discs of certain conifer species was measured. Annual distributions of these gas components were found to exhibit cyclic behavior. Moreover, distinct cyclicity was also revealed in interannual variations of the total pressure of the vacuum-extracted tree-ring gas samples. It may be safely suggested that diffusion of stem CO₂ into the atmosphere will show the same periodic variability. Two hypotheses about the origin of the cyclicity in the tree-ring CO₂ distributions are examined.

Asymptotic solutions of the problem of reconstructing the distribution of the structural characteristics of the refractive index fluctuations from the measurement data of the backscatter enhancement effect are derived. Solutions are expressed through fractional derivatives of the backscattering gain in the case of small aperture receiver, or through the ordinary derivatives in the case of receivers with a large aperture. The properties of the integral equation kernel are studied in detail, from which the asymptotic formulas follow. Attention is drawn to the fact that the kernel is oscillating in general. Kernel oscillations little impact the value of the backscattering enhancement, but their impact can be significant on the derivatives of this factor.

The spectrum formation of difference frequency generation between CO₂ and CO lasers radiation is theoretically and experimentally studied in an AgGaSe₂ crystal at I type phase matching. The study shows a promise of this crystal for developing selective laser sources tunable in the wavelength range 12-16.6 microns. Phase-matching angles for difference frequency generation between CO and CO₂ lasers radiation were measured and compared with those calculated by various dispersion equations. The combination of dispersion equations, which describes the difference frequency generation in the wavelength range 12-16.6 μm the most correctly, was chosen.