Exotic behavior of hydrogen atoms in solid H2 at temperatures below 1 K

We present the first magnetic resonance study of atomic hydrogen embedded in solid H2 films for temperatures 150-900 mK. We found that at T approximately 150 mK average concentrations of H atoms of order 10(18 cm(-3) are very stable against recombination during two weeks of observations. The distribution of the population of the two lowest hyperfine states is found to be non-Boltzmann, with a very large occupation of the ground state. We consider the possibility of formation in solid H2 of regions with high local concentrations of H atoms, where collective quantum phenomena might occur.     

Field-induced magnetic order and simultaneous lattice deformation in TlCuCl(3)

We report the results of Cu and Cl nuclear magnetic resonance experiments and thermal expansion measurements in magnetic fields in the coupled dimer spin system TlCuCl3. We found that the field-induced antiferromagnetic transition as confirmed by the splitting of NMR lines is slightly discontinuous. The abrupt change of the electric field gradient at the Cl sites, as well as the sizable change of the lattice constants, across the phase boundary indicate that the magnetic order is accompanied by simultaneous lattice deformation.     

Sequential Identification of Linear Dynamic Systems with Memory

This paper presents a sequential estimator for some unknown parameters in stochastic linear systems with memory. As examples stochastic differential equations with time delayed drift are considered. Based on the maximum likelihood method, we construct an estimation procedure with given accuracy in the sense of the L _p -norm (p 2). It is shown, that this procedure works also in certain cases, when the normalized information matrix of the observed process is asymptotically degenerated. The almost surely consistency of the proposed estimators and the asymptotic behavior of the length of observations are derived.     

Crystal Structure Investigation of Ternary Potassium–Manganese–Zirconium Molybdate with a Nasicon Type Structure

The crystal structure and composition of the ternary (K, Mn, Zr) molybdate were refined using X-ray diffraction data (KM-4 KUMA-Diffraction automatic diffractometer, MoK radiation, graphite monochromator, scan mode, 548 F(hkl), R=0.0427). The unit cell dimensions are a=b=9.474(1), c=24.371(4) , V=1894.4 ³, Z=6, _calc = 3.337 g/cm³, space group R c. The crystal structure is a 3D framework of oxygen vertex-sharing (Mn, Zr)O₆ octahedra and MoO₄ tetrahedra, with potassium atoms located in the large channels; it belongs to the Nasicon structural type.     

Pair correlations in lower-dimensional systems

We consider a system consisting of separate fibers weakly coupled to each other. Each fiber is characterized by a scalar order parameter. We study the correlation of order parameter fluctuations depending on the number of fibers in the system. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 147, No. 1, pp. 129–136, April, 2006.     

EPR studies of aluminium oxide phase compositions

EPR method of radiation probes is suggested for use to identify Al oxide-hydroxide phase composition in catalysts. A possibility to determine mixture components is exemplified by a heterogeneous mixture -Al₂O₃+Al(OH)₃ (bayerite). Parameters for the hole centers formed in Al₂O₃ and Al(OH)₃ are given.

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- . Al₂O₃ (-) Al(OH)₃ () . Al₂O₃ Al(OH)₃.

     

Polarization parameters in the reactions π− p ↑→ηn and π− p ↑→η′n at 40 GeV/c

The polarization parameter in the reactions π^? p→ηn and π^? p→η′n at 40 GeV/c with ?t ranging from 0 to 2.6 (GeV/c)² and 1.0 (GeV/c)², respectively, was measured in experiments using a propanediol polarized target. Only gamma particles from the neutral meson decay were detected. The polarization parameter of the first reaction turns out to be negative in a widet interval (0.05t<1.6 (GeV/c)²) and probably changes its sign at larger values oft. The average value of the polarization parameter of the second reaction is equal to ?17±8)% in the region 0.05t<0.5 (GeV/c)².     

Three-cascaded 1407-nm Raman laser based on phosphorus-doped silica fiber

We report a laser-diode-pumped 1407-nm Raman fiber laser with an output power of 1 W. In this three-cascaded cw Raman laser, based on a single active phosphorus-doped silica fiber, for the first time to the authors' knowledge successive generation of Stokes components of essentially different frequency shifts (1330 and 490cm(-1)) has been realized. These Stokes components are associated with both constituents (P(2)O(5) and SiO(2)) of the fiber core glass.     

Intrinsic magnetic inhomogeneity of Eu substituted La0.7Pb0.3Mno3 single crystals

The study of magnetic and magnetotransport properties of the crystals of (La_1−yEu_y)_0.7Pb_0.3MnO₃ system has been carried out. Eu ions enter the crystals being in trivalent nonmagnetic state. Europium ions possessing of smaller ionic radius in comparison with La ions, induce local distortions of Mn–O–Mn bonds in the system that cause random distribution of magnetic exchange interactions in magnitude and, probably, in sign. The competition of magnetic interactions leads to the appearance of the inhomogeneous magnetic state in the crystals. The enhancement of concentration of Eu ions results in decrease of the Curie temperature and broadening of the inhomogeneous magnetic state area. At y=0–0.4 the coexistence of the paramagnetic phase with conductivity of the polaronic type and the ferromagnetic metallic phase is observed in a bounded temperature interval both above and below T_C. Below T_C the increasing of y up to 0.6 induces the magnetic state representing the coexistence of two different FM phases. These phases are spatially separated due to frustration of FM and AFM exchange interactions on phase boundaries. Above T_C, up to 1.6T_C ferromagnetic clusters exist in a paramagnetic matrix similar to the case of samples with y=0–0.4. Concerning electric properties, the samples with y=0–0.4 reveal the metal–insulator transition at temperature that practically coincides with T_C. The sample with y=0.6 has conductivity of insulator character up to the lowest temperatures. For all investigated compositions y=0–0.6 the CMR effect is observed in the area where the inhomogeneous magnetic state exists. The effect is determined by different conductivity of the coexisting phases, as well as by sensitivity of the inhomogeneous state to external magnetic field.     

Self-similar solutions of the Laplacian growth problem in the half-plane

We investigate a version of the Laplacian growth problem with zero surface tension in the upper half-plane. Using the method of time-dependent conformal maps, we find families of self-similar exact solutions that are expressible in terms of the hypergeometric function.