Franck-Condon transitions and thermodynamics of photoinduced processes of orientational relaxation in polar solutions

Polar luminescence probe+polar medium subsystems are considered. True minimization parameters of the free energy F are obtained. It is shown that Franck-Condon transitions between F-terms of different electronic states are generally not “vertical”. A complete thermodynamic classification of photoinduced processes of orientational relaxation in the excited S₁ and ground S₀ states is presented. Depending on the excitation conditions they can be either exo- or endothermic, spontaneous or induced (not spontaneous), and accompanied by an increase or decrease in entropy. Indifferent processes also take place. Regularities of shifts of fluorescence spectral bands and burned holes in time-resolved experiments are discussed. Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 753–765, November–December, 1997.     

New quasiparticles hystons and coherent photoinduced dynamics of molecules in polar disordered media

Using methods of statistical thermodynamics, it is shown that after pulse excitation the evolution of a “polar luminescent probe—polar disordered medium” system is described by an equation of damping vibrations. This allows the conclusion that in the solvate shell of the probe molecule synchronous rotational vibrations (librations) of the molecules of the medium occur, whose damping is caused by dielectric friction. Such a collective synchronous motion is considered as a motion of a quasiparticle called a hyston. The moment of inertia J_n and mass M_h of a hyston are defined as J_h=2m² ₁a^-3Ω₀ ^-2(ε-1)/(2ε+1), M_h=J_hM_s/J_s, where m₁ is the dipole moment of the probe molecule in the excited S₁-stute; a is the Onsager radius; Ω₀ is the cyclic frequency of harmonic vibrations of the hyston; ε is the dielectric constant; M_s and J_s are the mass and moment of inertia of a molecule of the medium, respectively. The correlation function of the motion of the molecules c(t) is a solution of the equation of hyston motion. The fluorescence response s(t) in measurements with time resolution coincides with the correlation function: s(t)=c(t). The concepts concerning hystons make it possible to describe macroscopic photoinduced coherent motion that is manifested against a background of thermal motion of the medium molecules. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnei Spektroskopii, Vol 65, No. 2, pp. 176–183, March–April, 1998.     

Change in the IR spectra of polar liquids in an electric field

The IR absorption spectra of thin nitrobenzene, ethylene glycol, and glycerin layers in an electric field are investigated. It was established that the spectrum change and electro-optical effects depend on the molecular structure of these liquids. Grodno State University, 22, Ozheshko St., Grodno, 230023, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 441–444, May–June, 1998.     

Infrared filters and analyzers of the composition of substances based on them

Results of investigations on designing band dispersion and dispersion-interference filters for the 4–30 μm IR range and cutoff filters for the 50–300 μm region are presented. Analyzers of the composition of a substance that are designed on the basis of band IR filters and analysis procedures are described. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 5, pp. 734–744, September–October, 1998.     

Angular distribution and polarization characteristics of radiation reflected by a fibrous superhigh-modulus composite material

The effect of a smooth surface binder film and the orientation of filler fibers of unidirectional superhigh-modulus organoplastic on space-polarization characteristics of He−Ne laser reflected radiation is investigated. B. I. Stepanov Institute of Physics of the National Academy of Sciences of Belarus, 68, F. Skorina Ave., Minsk, 220078, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 926–931, November–December, 1998.     

Temperature dependence of the width of spectral holes: Octaethylporphin in polymer matrices

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 145–150, March–April, 1995.     

Relationship between the diffusion rate constant and rate constant of triplet-triplet annihilation for porphyrins in liquid solutions

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70. F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 63, No. 4, pp. 613–621, July–August, 1996.     

Applicability of approximate methods of calculation of the frequency-contrast characteristics of aerosol layers within the wavelength range of 0.4–14 μm

The spectral dependences of the optical characteristics governing radiation transfer in scattering media are analyzed within the wavelength range of 0.4–14 μm for three types of aerosols. The wavelength ranges where approximate methods of calculation of frequency-contrast characteristics are applicable are established; the corresponding limitting masses of aerosol particles in a layer per unit of surface area are determined for which approximate methods provide acceptable accuracy. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 419–425 May–June, 1998.     

Calculation and analysis of the frequencies of normal vibrations of 2,3-Di-O-nitro-methyl-β-D-glucopyranoside

A calculation of the frequencies and forms of the normal vibrations of the 31-atom molecule 2,3-di-O-nitromethyl-β-D-glucopyranoside has been performed. Particular emphasis has been placed on the interpretation of the strongest bands in the spectrum of 2,3-di-O-nitro-methyl-β-D-glucopyranoside, which are due to vibrations of the nitrate groups. The present work has been reported at the IV International Congress of theoretically competent chemists, Jerusalem (Israel), July 7–12, 1996. B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 724–728, November–December, 1997.     

Influence of laser heating on the optical properties of a superhigh-modulus organoplastic material

The degree and azimuth of polarization and the indicatrix of the intensity of radiation (λ=0.63 μm) reflected by the surface of a monodirectional superhigh-modulus organoplastic material after structural transformations induced in it by CO₂-laser radiation are measured. It is shown that the space-polarization characteristics of the radiation reflected by the organoplastic material charred as a result of laser heating correspond to the parameters of radiation scattered by a nontransparent material with an isotropic surface in the approximation of geometrical optics. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 635–639, September–October, 1999.     

Fluorescence-polarization detection of the scattering of molecular beams by a surface

We investigate analytically the effect of the forces that act both in the plane of a scattering surface and normally to it on the polarized fluorescence of reflected molecules in forward scattering. We show that as the velocity of the beam of incident molecules increases, the polarization degree of the fluorescence of reflected molecules becomes substantially different from that of free and/or desorbed molecules. Therefore, the detection of the scattering of molecular beams by a surface using the polarization degree of fluorescence can serve as a rather reliable means of diagnosing surfaces and determining the modes of scattering. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 205–212, March–April, 1999.     

Optoacoustic determination of low concentrations of gases by the use of commercial CO2-lasers

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Specktroskopii, Vol. 62, No. 6, pp. 81–86, November–December, 1995.     

Radiowave fluctuations in the polar ionosphere on the satellite-to-satellite paths under high solar activity

We analyze ionospheric fluctuations of decimeter radio waves on occultation polar paths between the navigational GPS satellites and the satellite CHAMP. Time dependences of the variance of the signal amplitude and amplitude fluctuation spectra under high solar activity in October–November 2003 are presented. The behavior of the signal amplitude fluctuations during occultation ionospheric sounding in the polar regions in different time of the day and in the equatorial regions in the daytime are considered. Radio-wave fluctuations are related to the solar-activity manifestations. It is shown that during strong solar-flare activity, intense small-scale plasma irregularities are excited in the polar ionosphere. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 185–193, March 2006.     

The nature of empirical constants in the equation relating the frequency of the stretching vibration of oh-groups to parameters of the [MO n ]-polyhedrons coordinating these groups

Institute of Physicoorganic Chemistry, Academy of Sciences of Belarus, 220603, Minsk, Ul. Surganova, 13, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 1, pp. 104–107, January–February, 1995.     

The effect of a plasma microfield on hydrogen radiation near the thresholds of spectral series

The authors consider the dependence of hydrogen plasma radiation on the nonideality parameter near the thresholds of spectral series. At low electron concentrations experimental data agree well with calculations based on the principle of spectroscopic stability. At higher electron concentrations the experimental data agree better with calculations that include a decrease in the thresholds of photorecombination in the statistical plasma microfield and a change in the statistical weight of the levels which is induced by their autoionization in the plasma microfield. A. V. Luikov Heat and Mass Transfer Institute of the National Academy of Sciences of Belarus, 15, P. Brovka St., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 22–26, January–February, 1998.     

X-ray photoelectronic spectroscopy of the processes of interaction between elements in contact layers on InP

Using the method of x-ray photoelectronic spectroscopy, we investigated of the interaction of gold-containing contact layers and indium phosphide in the process of thermal burning-in. We determined the dependence of the depth of the InP layer that had entered into interaction with the metal of the contact on the type of alloying admixture and the gold layer thickness. Institute of Electronics, National Academy of Sciences of Belarus, 22, Logoiskii Trakt, Minsk, 220090, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 144–147, January–February, 1999.     

Influence of isovalent substitutions on absorption spectra of orthoferrities

The role of impurity ions in formation of the optical properties of rare-earth orthoferrites is investigated. Optical spectra of the substituted against unsubstituted orthoferrites are presented. The influence of different isovalent substitutions on the optical absorption of orthoferrites that are promising for magnetooptics is studied. Institute of Solid-State and Semiconductor Physics of the Academy of Sciences of Belarus, 17, P. Brovka St., Minsk, 220072, Belarus. Translated from zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 642–645, September–October, 1997.     

New analytical possibilities of a steeloscope fitted with a multielement photodetector

It is shown that the use of a multielement photodetector (CCD strip) as an attachment to a steeloscope eliminates the subjectivity of visual analysis, makes it possible to obtain operative information on measurement results, extends the spectral range of the device, and improves the working conditions of analysts. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 284–286, March–April, 1998.     

Semiclassical approximation for the twodimensional Fisher–Kolmogorov–Petrovskii– Piskunov equation with nonlocal nonlinearity in polar coordinates

The two-dimensional Kolmogorov–Petrovskii–Piskunov–Fisher equation with nonlocal nonlinearity and axially symmetric coefficients in polar coordinates is considered. The method of separation of variables in polar coordinates and the nonlinear superposition principle proposed by the authors are used to construct the asymptotic solution of a Cauchy problem in a special class of smooth functions. The functions of this class arbitrarily depend on the angular variable and are semiclassically concentrated in the radial variable. The angular dependence of the function has been exactly taken into account in the solution. For the radial equation, the formalism of semiclassical asymptotics has been developed for the class of functions which singularly depend on an asymptotic small parameter, whose part is played by the diffusion coefficient. A dynamic system of Einstein–Ehrenfest equations (a system of equations in mean and central moments) has been derived. The evolution operator for the class of functions under consideration has been constructed in explicit form.     

Spectroscopic study of the interaction between porphyrin and chlorin molecules of opposite charge in solutions

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, Minsk, 220072, 70, F. Skorina Ave., Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 152–163, March–April, 1995.