Coherent polarization spectroscopy of two-photon absorption
Coherent polarization spectroscopy of two-photon absorption
L.S. Aslanyan, V.F. Kamalov, N.I. Koroteev (USSR), and N.G. Khadzhiiski(Bulgaria)
A polarization scheme for four-photon spectrscopy of two - quantum transitions in isotropic media and cubic crystals is presented; a new way of measuring the scattering cross section in two-photon absorption is demonstrated. Irreducible tensor groups are used in averaging the components of the tensor for the molecular resonant hyperpolarizability, and arelationship is established for the invariants of the molecular tensor for two-photon polarizability and the nonzero components of the tensor for the third-order macroscopic susceptibility. Theoretical estimates and experimental results are presented for the polarization dispersion of the signal in various organic liquids. Similar estimates have been made for GaF and ZnSe crystals.
Show AbstractOptimization of some methods of measurement of low temperature
Optimization of some methods of measurement of low temperature
S.P. Vyatchanin, A.V. Loginov and A.A. Ovodov
Expressions for the minimal error of measurement of low (≤ 1K) temperature are found; the value of the error is found for the optimal amount of the outer effect. The optimal amount of the outer effect is determined with allowance for two competitive factors: on the one hand, it is desirable to reduce the noise effect (of the sample or the measuring device) on the precision of measurements; on the other, it is also desirable to considerably reduce heating of the sample during measurement. Prom this point of view, several types of low-temperature thermometers were tested: molecular and nuclear paramagnets, NMR-thermometers and thermoresistive thermometers.
Show AbstractTheory of induced synchrotron radiation for the ultrarelativistic case
Theory of induced synchrotron radiation for the ultrarelativistic case
F.A. Korolev and A.V. Tulupov
Formulas derived in fundamental studies by A.A. Sokolov and I.M. Ternov on synchrotron radiation are used for the probabilities of induced transition, wave functions, and the electron energy spectrum in a magnetic field. The expression for the electron energy is used in derivinga formula for the radiation frequency, which is considerably higher than the nonrelativistic cyclotron frequency in the ultrarelativistic case. Products of matrix elements in the Dirac matrices are derived, and a formula is derived for the probabilities of induced emission and absorption on the assumption that the incident electromagnetic wave is linearly polarized. The values are substituted into the formula for the power in the stimulated transitions to derive an expression for the power in the induced emission for a relativistic rotatin gelectron. The formula implies that relativistic electrons can be used to generate high-power electromagnetic radiation in the submillimeter and infrared wavelength ranges.
Show AbstractEffects of temperature" on radioluminescence and the color-center concentration in a ruby crystal
Effects of temperature" on radioluminescence and the color-center concentration in a ruby crystal
T.S. Bessonova and A.I. Sobko
Standard equations for the kinetics of the concentrations of free and trapped charges have been used to obtain explicit expressions for the radioluminescence intensity and the concentration of induced absorption centers in ruby with a low chromium concentration. It is assumed that such a ruby corresponds to a band model containing one hole level and two electron levels. The calculations are performed for the approximation of arbitrary trap filling. It is shown that: 1) the increase in the recombination cross section at the radioluminescence centers on reducing the temperature reduces the intensity of the induced absorption and 2) the more rapid rise in the performance of the recombination chann e l at the blue-emission centers reduces the proportion of recombinations that lead to emission of the R lines.
Show AbstractFirst-order perturbations in the rotation of a satellite in a circular orbit
First-order perturbations in the rotation of a satellite in a circular orbit
Yu.V. Barkin (USSR) and S.M. El-Shaburi (Egypt)
A study is made of the perturbed motion of a solid satellite about its center of mass; it is assumed that the satellite moves in a circular orbit in the central field of a planet.
Show AbstractThe correlation contributions to the thermodynamic parameters of a crystal
The correlation contributions to the thermodynamic parameters of a crystal
P.N. Nikolaev and P.N. Vabishchevich
Bogolyubov's method has been used in numerical estimation of the correlation contributions to the free energy and specific heat of a crystal. The correlations improve the agreement between the ory and experiment for the specific heat. The correction terms in the free energy increase as the atomic weights decrease for crystals of the inert gases.
Show AbstractKinematic mode synchronization in a YAG:Nd^(3+) pulsed laser
Kinematic mode synchronization in a YAG:Nd^(3+) pulsed laser
N.V. Kravtsov, V.A. Sidorov, and A.M. Susov
Results are reported for a pulsed laser employing yttrium-aluminum garnet in a nonstationary cavity. Kinetic synchronization of the axial modes occurs in such a laser when the rate of change of cavity length exceeds 2 cm/sec; the establishment of kinematic synchronization is examined. It is found that the ultrashort pulses arising in such a laser have parameters closely reproducible from burst to burst. The length of the ultrashort pulses and the shift in the center of the lasing spectrum are examined in relation to the rate of change of cavity length.
Show AbstractHamilton ian formulation of the equations of motion for the hydrodynamics of a compressible fluid in a uniformly rotating frame of reference
Hamilton ian formulation of the equations of motion for the hydrodynamics of a compressible fluid in a uniformly rotating frame of reference
V.I. Pavlov and P.M. Treblev
A Hamiltonian formulation is given for the equations of hydrodynamics for a compressible liquid in a uniformly rotating frame of reference; it is shown that the liquid is stratified, while the motion in general is of vortex type. A Clebsch representation is used for the momentum density. It is shown that this formalism can be applied to solve wave problems in media of hydrodynamic type.
Show AbstractEffects of spatial dispersion in the nonlinearity on the nonstationary self-focussing of a laser beam in a liquid crystal
Effects of spatial dispersion in the nonlinearity on the nonstationary self-focussing of a laser beam in a liquid crystal
V.A. Vysloukh and V.A. Makarov
The finite-element method has been used in a program for numerical solution of the equations describing laser self-focussing in the isotropic phase for nematic liquid crystals. It is shown that the spatial dispersion in the nonlinear susceptibility arising from the thermal and orientation mechanisms stabilizes the time envelope of the laser pulse, while sharpening the leading edge and reducing the characteristic selff ocussing length.
Show AbstractThe limiting resolution in collinear acoustooptic light filtration
The limiting resolution in collinear acoustooptic light filtration
V.B. Voloshinov and V.N. Parygin
Collinear acoustooptic filtration in a long crystal is considered, where the acoustic power density varies on account of damping and divergence. An estimate is made of the limiting passband for such a filter in the visiblerange. It is shown for a quartz crystal that a length of about 20 cm may be taken as optimal, while the realistically attainable passband is 0.1 nm.
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