Effects of reverse transfer from traps on luminescence quantum yields
Effects of reverse transfer from traps on luminescence quantum yields
P.V. Elyutin, M.L. Isakova
Energy migration is examined in a disordered system of donor and acceptor molecules with allowance for the probability of reverse transfer from the acceptor to the donor. It is shown that this transfer may lead to a nonmonotone dependence of the quantum yield on the donor concentration.
Show AbstractA method of simulating nonlinear flow incorporating velocity shear and compressibility
A method of simulating nonlinear flow incorporating velocity shear and compressibility
V.N. Kozhevnikov, L.E. Rontu (Finland)
A new method is given for transforming the initial nonlinear equations for the two-dimensional stationary case of altitude stratification in the atmosphere, where a slight simplification in the equation of continuity enables one to derive interesting particular cases where the flow treatment amounts exactly to solving a linear equation for the streamline function. A study is made to see how well one can incorporate the altitude profiles for the stability and velocity. The approach is compared with previous ones.
Show AbstractChoice of molecular center in calculating the thermodynamic parameters of liquids and gases
Choice of molecular center in calculating the thermodynamic parameters of liquids and gases
A.D. Okhotsimskii, V.G. Gryaznov
The center of an unsymmetrical rigid molecule may be taken as the point in it at which the molecular interaction potential is closest to being of central type. A simple method has been devised for calculating the coordinates of this center. This method has been used in calculating liquid critical volumes.
Show AbstractStochastic oscillations in a two-temperature electron-hole plasma in a semiconductor
Stochastic oscillations in a two-temperature electron-hole plasma in a semiconductor
V.L. Bonch-Bruevich, Le Vu Ki (Vietnam)
A study is made of nonstationary states in an electron-hole plasma produced by optical absorption in a semiconductor with direct transitions. Allowance is made for recombination mechanisms involving phonon and/or radiative transitions as well as collisional ones (interband ones); the adiabatic approximation (slow recombination) is not used. Explicit conditions are derived for self-excited oscillations in the carrier concentration and in the electron and hole temperatures.
Show AbstractShock-wave propagation in a gas mixture
Shock-wave propagation in a gas mixture
F.V. Shugaev, A.E. Kondrashov, E.N. Fomenko
A study is made on the spatial interaction of an initially planar shock wave with acoustic and entropy perturbations in a perfect gas thermodynamically in equilibrium. Experiments nave been performed on shock-wave transmission by a gas mixture having a concentration gradient in a shock tube. It is observed that a vortex is formed behind the reflected wave.
Show AbstractRight-left asymmetry in the elastic scattering of polarized electrons at nuclei with allowance for the second Born approximation
Right-left asymmetry in the elastic scattering of polarized electrons at nuclei with allowance for the second Born approximation
B.K. Kerimov, V.N. Alizade, M.Ya. Safin
A study has been made on the second Born approximation for the cross section and the right-left asymmetry $A_{RL}$ for elastic scattering of longitudinally polarized electrons by zero-spin nuclei. An analytic expression is obtained for this correction in the case of the $lp$-shell nuclei, whose form factors are described by the harmonic-oscillator model. A simple expression has also been found for $A_{RL}$ on the basis of the second Born approximation in the case of point nuclei. The angle dependence of $A_{RL}$ has been studied by reference to $^{12}C$.
Show AbstractPolarized luminescence in polydisperse system analysis
Polarized luminescence in polydisperse system analysis
R.Z. Syunyaev, L.V. Levshin, B.D. Ryzhikov
The Levshin-Perrin formula has been modified for the case of a polydisperse system in which the particles of the dispersed phase can luminesce. The size distribution is considered as a Volmer one, which contains an unknown parameter n. A formula is derived, from which calculations are made on the accessory quantity S for various n. Comparison with the S derived from experiment enables one to determine n in the distribution.
Show AbstractThe electronic absorption spectra of polyatomic molecules in liquid solvents
The electronic absorption spectra of polyatomic molecules in liquid solvents
V.M. Boitsov, V.I. Yuzhakov
A description is given of the vibronic absorption spectra of liquid solutions of polyatomic compounds, which enables one to determine the dependence of the half-width for the homogeneous (relaxation) Lorentz component $\Gamma (\nu_s)$ on the transition frequency and the same for the square of the electronic matrix element for the transition dipole moment $|\mu (\nu_s)|^2$. It is shown that these functions are solutions to the proposed equation system; they have been determined for the absorption spectra of acetone in various solvents at T = 297 K.
Show AbstractIon-sound response in pulsed plasma probing
Ion-sound response in pulsed plasma probing
Yu.V. Korpusova, A.A. Kuzovnikov, K.G. Pukalov, V.S. Sviridkina, A.K. Sukhov, V.V. Tarasova
Experiments have been performed on ion-sound instability produced by voltage pulses and the effects on the propagation from plasma density inhomogeneity. It is found that the amplitude of the perturbations increases away from the source, while the perturbations acquire an oscillatory structure. If the plasma density is reduced to the level at which the ionic Langmuir frequency becomes comparable with the ion-sound frequency, it is found that the ion sound is not transmitted.
Show AbstractDetermining free-field bounds and acoustic type for a sound source
Determining free-field bounds and acoustic type for a sound source
A.N. Ivannikov, D.I. Kravchenko
A description is given of an apparatus and of certification results on a sound chamber in relation to the sound-field phase structure. Results are also given on the phase structure of the near fields from sound sources
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