Infrared cyclotron resonances in InSb at megagauss magnetic fields

Cyclotron resonance was studied in reflection in InSb at room temperature using pulsed magnetic fields of up to 1.4 MG and laser-obtained wavelengths of 10.6 and 5.56 μ. At 10.6μ, four resonances were found while one resonance was found at 5.56 μ.     

Optical band gap width in GaAs in megagauss magnetic fields

The band gap width in GaAs in magnetic fields of up to 10 MG is calculated using a five-band kp model. The selection rules for interband electron transitions in strong magnetic fields are found, and the dependences of the interband transition probabilities on a magnetic field are calculated. The electronic spectra calculated in the five-band model are compared with those calculated in the Kane model and in the tight-coupling approximation. The calculations are shown to agree with experimental data if the contribution from the density-of-states tails and excitonic effects to light absorption is taken into account.     

Faraday effect of europium organic glass in megagauss magnetic fields

The Faraday rotation of europium organic glass (based on polymethyl methacrylate) in megagauss fields is investigated experimentally and theoretically. The experiment was performed using an MK-1 magnetic explosion generator and laser radiation at the wavelength λ=0.85 μm at T=30 K. It is found that the dependence of the rotation angle of the polarization plane on the magnetic field is nonlinear. The theoretical results are compared with the experimental data. The contribution of the orbital angular momentum of europium ions to the Faraday effect is revealed. The conclusion is drawn that the previously found anomalies of the Faraday effect for the laser radiation at the wavelength λ=0.63 μm are brought about by the magnetooptical resonance, which is induced by the ultrastrong field. __________ Translated from Fizika Tverdogo Tela, Vol. 42, No. 4, 2000, pp. 708–711. Original Russian Text Copyright ? 2000 by Dolotenko, Zvezdin, Musaev, Platonov, Plis, A. Popov, V. Popov, Tatsenko, Filippov.     

Effective fields in laser-driven electron recollision and charge localization

We propose a model to describe correlated two-electron dynamics in strong laser fields during laser-induced recollision between an electron and its parent ion. We derive an effective interaction potential which describes the effect of the laser-driven electron collision with an ion while retaining the correlation between the colliding and the bound electron. Using dissociative ionization of molecular hydrogen as an example, we analyze the dynamics of correlation-driven electron localization in a dissociating hydrogen molecular ion.     

Measuring magnetic fields generated by DC currents in receive-only coils

DC decoupling currents applied to receive-only coils during radiofrequency transmission can create stray magnetic fields capable of changing the resonant frequency of nearby nuclei. It is difficult to measure these fields with conventional field-mapping techniques because the fields are not present when the signal is acquired. The stray fields can be measured empirically with cardiac tags.     

Photon echoes produced by switching electric fields

We demonstrate photon echoes in Eu3+:Y2SiO5 by controlling the inhomogeneous broadening of the Eu3+ 7F0<-->5D0 optical transition. This transition has a linear Stark shift, and we induce inhomogeneous broadening by applying an external electric field gradient. After optical excitation, reversing the polarity of the field rephases the ensemble, resulting in a photon echo. This is the first demonstration of such a photon echo, and its application as a quantum memory is discussed.     

Conformally planar gravitational fields produced by matter

A geometric property (spherical symmetry) which unambiguously distinguishes homogeneous cosmological models (Friedmann spaces) from other conformally planar gravitational fields is pointed out. Certain general properties of the distribution and motion of matter in conformally planar gravitational fields are established, and new solutions of the Einstein equations are derived.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 11, pp. 67–73, November, 1969.The author thanks D. D. Ivanenko and the participants in a seminar under his guidance for discussion of these results.     

Random fields in Ge-Si alloys produced by doping

A calculation is performed and estimates made of the binary correlation functions of the random field produced by the difference in the atomic pseudopotentials of solvent and dissolved materials. Also evaluated are elastic deformation fields in unordered Ge-Si solid replacement solutions with low Si content (up to 10 at. %).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 41–46, February, 1987.The author heartily thanks V. L. Bonch-Bruevich for his interest in the current study and many valuable discussions.     

Conformally flat gravitational fields produced by an ideal fluid

The problem of finding conformally flat gravitational fields produced by a perfect fluid is solved completely.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No.12, pp.22–25, December, 1980.     

Magnetic susceptibility of the V<Subscript>15</Subscript> nanocluster in megagauss magnetic fields

The low-temperature behavior of the magnetic susceptibility of the V₁₅ low-spin cluster in ultrastrong magnetic fields of up to 550 T was studied. Ultrastrong magnetic fields were generated by an MK-1 magnetic explosion generator. Anomalies in the susceptibility were found to exist in fields B₁=200 T and B₂=350 T. It is concluded that these anomalies indicate the initial phase of a field-induced transformation of the cluster magnetic structure from quasi-ferrimagnetic to ferromagnetic. This transformation occurs by discrete quantum jumps at low temperatures. The experimental data are compared with theory.     

Transverse and longitudinal periodicities in fields produced by polarization gratings

The spatial periodicities in Fresnel diffraction patterns produced by polarization gratings [Opt. Lett. 24 (1999) 584] and their generalizations are investigated, with particular attention to the state of polarization of the diffracted field. It is shown, e.g., that in certain planes the polarization vector can rotate periodically, while being constant in certain other parallel planes.     

Experimental investigation of stochastic pulsation and formation of light bullets with megagauss magnetic fields by an intense laser pulse propagating in a preionized plasma

The generation of extremely stable light bullets in a preformed plasma near critical density has been observed experimentally during the interaction of intense picosecond laser beam with a metallic target in air. Optical probing measurements indicate the formation of pulsating channels, typically of about 5 microm in diameter, directed towards a heating laser beam, as well as of disconnected massive plasma blocks moving also towards the laser beam. The velocities of the dense plasma blocks reach the values of 4.5x10(8) cm/s. The blocks are stable during their acceleration and propagation in air. Self-generated magnetic fields up to 4-7 MG were observed by means of the Faraday rotation of a probe laser beam.     

Coherent information storage with photon echoes produced by switching electric fields

We demonstrate modified photon echoes in Eu³⁺:Y₂SiO₅ by controlling the inhomogeneous broadening of the optical transition in Eu³⁺. These modified photon echoes are shown to be capable of storing phase and amplitude modulation.     

Pulsed CO2 laser-driven production of ultrafine silicon,silicon carbide,silicon nitride and silicon oxynitride powders

Summary Ultrafine Si, Si₃N₄, SiC and silicon oxynitride powders have been produced by irradiating gas-phase reactants by means of a CO₂ laser. The mechanism of SiH₄ CO₂ laser-induced absorption and dissociation is discussed on the basis of the results of the spectral and time-resolved measurement of fragment chemiluminescence. The role played by the SiH₂ radical in the powder formation is investigated. The quality of Si, Si₃N₄, SiC and silicon oxynitride powders is checked by means of several off-line diagnostics (IR spectroscopy, X-ray diffraction at wide and small angle, BET analysis). The possibility of controlling powder stoichiometry and doping from the gas-phase reactant concentration is discussed.     

Movement of gas-filled cavities in alkalihalide crystals produced by external force fields

The migration of gas-filled cavities in KBr, NaCl, LiF single-crystals is investigated experimentally in an electric field and a temperature gradient.It is shown, that migration in an electric field is strongly dependent on the surface purity, due to its influence on matter transport along cavity surface. It is found that the velocity of cavity (v), having a ‘dirty’ surface follows a V～1/R dependence. (R—cavity size). In case of a ‘pure’ cavity surface. V is independent of R. Different types of V-vs-R dependence result in intermediate regions.Migration in a temperature gradient is also sensitive to surface purity. When the state of surface purity is determined, an appropriate critical size (R^*) exists such that if R is smaller than R^*, V～R and if R is larger than R^*, V is independent of R.Some constants of investigated process are determined from obtained experimental data.