Collinear three-body disintegrations of tungsten nuclei by 1-GeV protons

The (2E, 2V) measurement method is applied to analyze the kinematics of the separation of two complementary collinear fragments of the disintegration of tungsten nuclei by 1-GeV protons. In addition to the main process of binary fission, three branches of collinear three-body disintegration, which are associated with various mechanisms of the excitation of a deformed fissioning nucleus, are observed.     

Search for an effect of superconductivity on the phonons in Ba(Fe1−xCox)2As2

Inelastic neutron scattering was used to search for an influence of superconductivity on the phonons in optimally doped and in slightly overdoped Ba(Fe_1?xCo_x)₂As₂, x = 0.06 and x = 0.10. The study focused on phonons with energies close to the superconducting gap energy 2Δ because it is well known that such phonons will respond most strongly to the opening of the gap. We were able to obtain high quality data but nevertheless, we could not detect any influence of superconductivity on the phonons, neither on the linewidths nor on the frequencies. Our results imply that any coupling of low energy phonons to the electrons has to be very small, much smaller than observed in conventional superconductors with a high T_c. Our results are in line with the low coupling strength predicted by density functional theory for the investigated phonon branches.     

A Probe of Valence and Conduction Band Electronic Structure of Lead Oxide Films for Photodetectors

We investigate how the electronic structure of amorphous lead oxide (a-PbO) films deposited on ITO substrate is changed after annealing at various temperatures. Both experimental soft X-ray spectroscopic and density functional theory (DFT) based computational techniques are used to explore the electronic structure of this material. X-ray emission, resonant X-ray inelastic scattering, and X-ray absorption spectroscopic techniques are employed to directly probe the valence and conduction bands. We discover that the films are very stable and remain amorphous when exposed to temperatures below 300 °C. An amorphous-to-polycrystalline (α-PbO phase) transformation occurs during annealing at 400 °C. At 500 °C, an alpha to beta phase change is observed. These structural modifications are accompanied by the band gap value changing from 1.4±0.2 eV to 2.0±0.2 eV upon annealing at 400 °C and to 2.6±0.2 eV upon annealing at 500 °C. A difference between surface and bulk structural properties is found for all samples annealed at 500 °C and above; these samples also exhibit an unexpected suppression of O : 2p density of states (DOS) near the bottom of the conduction band, whereas additional electronic states appear well within the valence band. This study provides a significant step forward to understanding the electronic properties of two polymorphic forms of PbO needed for optimization of this material for use in X-ray sensors.     

Dislocation generation in heat-treated nitrogen-doped silicon wafers when applying external loads

The features of generation and motion of dislocations in nitrogen-doped dislocation-free silicon wafers after their multistage thermal treatments are investigated. It is established that doping with nitrogen leads to a substantial increase in stresses of the onset of plastic deformation from the external and internal heterogeneous sources in heat-treated wafers. The motion velocity of dislocations in nitrogen-doped silicon wafers is lower than in undoped wafers. The strengthening effect of nitrogen is apparently caused by its activating effect on the decomposition process of a supersaturated solid solution of oxygen during heat treatment.     

Electrodynamic theory for near-field microwave microscopy of plane-layered structures and its application to metrology of thin dielectric films

A theory for near-field microwave microscopy of plane-layered structures has been developed. The probe of a near-field microscope is considered as electrically small antenna, which emits quasi-static fields and waves in a medium with an arbitrary 1D permittivity profile. The accuracy of the theory has been demonstrated by microscopy of thin dielectric films deposited on a conductive substrate. The possibility of determining film permittivity with an error of 5–7% is shown.     

q-Dependence of the giant bond-stretching phonon anomaly in the stripe compound La1.48Nd0.4Sr0.12CuO4 measured by IXS

Inelastic X-ray scattering (IXS) was used to study the Cu-O bond-stretching vibrations in the static stripe phase compound La_1.48Nd_0.4Sr_0.12CuO₄. It was found that the intrinsic width in Q-space of the previously reported huge anomalous phonon softening and broadening is approximately 0.08 r.l.u. HWHM. A detailed comparison was also made to inelastic neutron scattering (INS) studies, which indicate a two-peak lineshape (with superimposed broad and narrow peaks) in the vicinity of the anomaly. The high resolution IXS data show that the narrow peak is mostly an artifact of the poor transverse Q-resolution of INS. Otherwise, the agreement between the INS and IXS was excellent.     

Anodic oxide-film of the Co—Sn—O composition

Properties and electrocatalytic activity of thin-film (∼2 μm) oxide coatings on aTi support are considered by the example of the anodic chlorine evolution reaction. The coatings are obtained by thermally decomposing Co and Sn chloride solutions of different compositions on a Ti plate. The Co and Sn oxides are present in all studied compositions as individual phases and form no compounds or solid solutions. The oxide coating containing 70 at. % Co and 30 at. % Sn reveals a maximum electrocatalytic activity. The existence of the optimum composition is attributed to a favorable effect tin dioxide has on the formation of a transition layer between the Ti support and oxide coating. Tin dioxide hampers the Ti diffusion in the main coating and its subsequent oxidation, thus diminishing the negative impact titanium oxides have on the coating     

Influence of solvents on the molecular and crystal structure of the complex of 1,3-diallyl-5-[3-(diphenylphosphino)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione with palladium(II) dichloride

X-ray diffraction study demonstrated that the molecular and crystal structures of the complexes of 1,3-diallyl-5-[3-(diphenylphosphino)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (1) with PdCl₂ are determined to a large degree by intra- and intermolecular short contacts between different-polarity groups of the complex molecules. The strength and the existence of the complexes may be affected by the solvents from which the crystals are grown. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1199–1204, July, 2000.     

Hybrid structures based on quantum dots and graphene nanobelts

Optics and Spectroscopy - Luminescence and photoelectric properties of hybrid structures based on CdSe/ZnS quantum dots (QDs) and multilayer graphene have been investigated. A correlation between...