Electron Energy Loss Spectroscopy of YBa2Cu3O7–x

Electronic excitations of Y–Ba–Cu–O polycrystalline material in superconducting form have been investigated by electron energy loss spectroscopy in reflection. The data obtained confirm recent band structure models for this material. Low electron energy losses correspond to energy levels close to the Fermi energy with an upper and lower Hubbard subband and an anionic O 2p band in the middle. Loss peaks due to interband transitions, plasmon excitations, and core electron excitations have been observed, the origin of which is interpreted by a schematic energy level diagram.     

Ferromagnetic Resonance of FeNi/Cu/FeNi Thin Film on Coplanar Waveguide with Operating Frequency of 1 to 20 GHz

Russian Physics Journal - The paper presents the calculation results of the coplanar waveguide geometry using the method of conformal mapping and computerized simulation with COMSOL Multiphysics...     

Polarization optics for X-rays

An experimental arrangement for X-rays is described which is analogous to the optical bench for polarization investigations. Using this arrangement elliptically polarized X-rays should be generated and proved. Although the dynamical theory of X-ray diffraction is needed for X-ray optics the polarization phenomena can be phenomenologically interpreted in analogy to visible light optics. The experimental results showed that with a wedge-shaped crystal used as the phase shifter any polarization state of X-rays can be generated.     

The Crystal and Molecular Structure of the Smectogenic Compound 5-Hexyl-2-(4-bromophenyl)-1,3-dioxane

The title compound with the formula C₆H₁₃ C₄O₂H₆ C₆H ₄Br (HBPD) crystallizes in the monoclinic space group C 2/c with lattice parameters a = 28.48 Å, b = 5.71 Å, c = 20.19 Å, β = 97.4° and molecules per unit cell. The structure has been solved by the heavy atom method and refined to a final R value of 0.094. – The HBPD molecules adopt a fully stretched form, both the alkyl and phenyl substituent are in equatorial position with respect to the chair-shaped dioxane ring. The orientation of the phenyl group is an intermediate between the perpendicular and parallel conformation. The molecules show a nearly perfect parallel arrangement in the crystal lattice.     

Synthesis and stabilizing properties of amphipolar polyelectrolytes

The European Physical Journal E - A series of well-defined amphipolar block, graft and statistical copolymers based on the same polar and non-polar monomers were synthesized and investigated for...     

On the change of dislocation structure during the postdeformation of cold worked molybdenum single crystals at elevated temperature

Molybdenum single crystals predeformed at low temperature (T₁ ≦ 293 K) exhibit during tensile reloading at T₂ = 493 K pronounced work softening accompanied by stress serrations and localized slip. It is shown that the initial state for the development of coarse slip bands is the formation of narrow obstacle-free slip channels. The change from the homogeneous dislocation structure to the cell structure proceeds in a heterogeneous and discontinuous manner.     

New class of level statistics in correlated disordered chains

We study the properties of the level statistics of 1D disordered systems with long-range spatial correlations. We find a threshold value in the degree of correlations below which in the limit of large system size the level statistics follows a Poisson distribution (as expected for 1D uncorrelated-disordered systems), and above which the level statistics is described by a new class of distribution functions. At the threshold, we find that with increasing system size, the standard deviation of the function describing the level statistics converges to the standard deviation of the Poissonian distribution as a power law. Above the threshold we find that the level statistics is characterized by different functional forms for different degrees of correlations.     

On the motion control of microparticles by means of an electromagnetic field increasing with time for spectroscopic applications

The possibility of controlling the motion of microparticles by means of external electromagnetic fields (nonresonance laser radiation, in particular) that induce potential wells for such particles, which are characterized by fixed spatial distribution but deepen over time to a certain level, are analyzed. It is assumed that the particles are located in high vacuum and are affected by nondissipative external forces. Slowing down of relatively fast particles when they pass through the discussed potential wells is shown. Such slowing down of particles is demonstrated using a nonresonance laser beam with intensity increasing over time as an example. Specific features of particle dynamics in the electromagnetic fields under consideration in the case of a one-dimensional rectangular potential well are studied in detail based on simple analytical relations derived from the fundamental equations of classical mechanics. The methods of particle cooling and localization demonstrated in the present work can substantially increase spectroscopy resolution of various microparticles, including, under certain conditions, atoms and molecules.     

Emission of neutrino pairs by an electron in an ultrastrong magnetic field

The transitions of relativistic electrons in a magnetic field with the emission of an antineutrino-neutrino pair are considered. Probabilities are obtained for electron transitions to the ground state and weakly excited states. It is shown that in the case of an ultrastrong magnetic field (HH_o=m²c³/e=4.41·10¹³ G) such transitions made a considerable contribution to the total probability of the process.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 110–114, March, 1978.In conclusion, the authors express their profound gratitude to A. A. Sokolov for his attention to our work.