The coexistence of γ(γ′) and θ alumina observed by STM and LEED on top of oxide layer grown on CoAl(1 0 0)

We report the coexistence of γ(γ′) and θ alumina grown on the CoAl(1 0 0) surface. Both phases were observed after annealing of alumina at 1150 K by means of scanning tunnelling microscopy (STM). The crystal structures of γ(γ′) and θ alumina were indexed based on low energy electron diffraction (LEED) and STM experimental data.     

A method for estimating the local lattice distortions near a magnetic ion from ligand hyperfine parameters: Yb3+trigonal centers in SrF2 and BaF2

An empirical relationship describing the radial dependence of the nondipole part of the anisotropic constant for the ligand hyperfine interaction in alkaline-earth fluorides is proposed. This relationship is used for calculating the distances between the magnetic ion and the fluorine ions involved in its nearest environment. The results of the calculations are in good agreement with the values obtained by other methods for both cubic and tetragonal fluorine centers in these crystals. The distances from the magnetic ion to different groups of nonequivalent fluorine ions of the nearest environment in Yb³⁺ trigonal centers of SrF₂ and BaF₂ are determined. It is found that the Yb³⁺ ion is slightly displaced along the trigonal axis away from the compensating fluorine ion.     

Optical bistability of planar metal/dielectric nonlinear nanostructures

We study theoretically a nonlinear response of the planar metal/dielectric nanostructures constituted from periodical array of ultra thin silver layers and the layers of Kerr-like nonlinear dielectric. We predict hysteresis-type dependences of the components of the tensor of effective dielectric permittivity on the field intensity allowing the change in material transmission properties from transparent to opaque and back at extremely low intensities of the light. It makes possible to control the light by light in all-optical nanoscale devices and circuits.     

Surface morphology of electrolytic deposits of vanadium, cobalt, and manganese oxides

The surface morphology of V₂O₅, Co₂O₃, and MnO₂ electroplated under different electrolysis conditions was studied. The nature of the electrocrystallization of these materials was suggested on the basis of the analysis results.     

Linear theory of wave generation by a moving bottom

The computation of long wave propagation through the ocean obviously depends on the initial condition. When the waves are generated by a moving bottom, a traditional approach consists in translating the ‘frozen’ sea bed deformation to the free surface and propagating it. The present study shows the differences between the classical approach (passive generation) and the active generation where the bottom motion is included. The analytical solutions presented here exhibit some of the drawbacks of passive generation. The linearized solutions seem to be sufficient to consider the generation of water waves by a moving bottom. To cite this article: D. Dutykh et al., C. R. Acad. Sci. Paris, Ser. I 343 (2006).     

Direct mass measurements of neutron-deficient 152Sm projectile fragments at the FRS-ESR facility

The FRS-ESR facility at GSI provides one of the most efficient methods for direct mass measurements. In the present experiment, exotic nuclei were produced via fragmentation of ¹⁵²Sm projectiles in a thick beryllium target at 500-600 MeV/u, separated in-flight with the fragment separator FRS, and injected into the storage-cooler ring ESR. Time-resolved Schottky Mass Spectrometry was applied for mass measurements of stored and electron-cooled bare and few-electron ions. 373 different nuclides were identified by means of the spectra of their revolution frequencies. Masses for 18 nuclides (⁸⁴Zr, ⁹²Ru, ⁹⁴Rh, ^107,108,110Sb, ^111,112,114I, ¹¹⁸Ba, ^122,123La, ¹²⁴Ce, ¹²⁷Pr, ¹²⁹Nd, ¹³²Pm, ¹³⁴Sm, ¹³⁷Eu) have been determined for the first time. Masses for ^111,112I and ¹¹³Xe have been obtained via known α-decay energies. The experiment and first results will be presented.     

The global controllability of some mechanical systems with absolutely elastic impacts

Sufficient conditions are presented for the stabilizability and global controllability of certain natural Lagrangian systems with a non-negative potential energy when there are ideal unilateral constraints. In the general case, the number of controls is less than the number of degrees of freedom and the controls are bounded by preassigned quantities. Examples of globally controlled systems with two degrees of freedom are considered in which the action of the unilateral constraints is modelled within the framework of classical collision theory.     

Investigation of cold fusion in heavy water

An investigation of cold fusion of deuterium was performed by electrolyzing heavy water in a cell containing a palladium cathode while monitoring levels of tritium and neutron-capture gamma rays. No activity was detected that would indicate a sustained fusion reaction had taken place. Activities that were observed can be attributed to electrolytic enrichment and a normal cosmic-ray induced background.     

Solid solubility of the oxisulfides of Y, La, and Gd

The solid solubility in the systems Y₂O₂S---La₂O₂S, Y₂O₂S---Gd₂O₂S, and Gd₂O₂S---La₂O₂S has been investigated. Solid solutions of all compounds, throughout the whole composition range, were readily obtained, using coprecipitated oxalates and a polysulfide flux.