Thermal Near Field and the Possibilities of Its Use for In-Depth Temperature Diagnostics of Media

We discover experimentally the effect of an electromagnetic thermal near field of a lossy medium. The effective depth d_eff of the layer in which the received signal is formed is found to be less than the skin-layer depth d_sk and is a function of the size D of the receiving antenna and its height h above the medium surface. The dependence d_eff(D,h) is obtained from measurements of the emission from a temperature-stratified water medium at a wavelength of 31 cm using a specially developed, electrically small antenna. The results of experimental studies of radiophysical parameters of the antenna are presented. We propose to use measurements of the dependence of the received emission on D and h as a new source of information on the in-depth temperature distribution. Methods for solving the corresponding inverse problems are developed, and the first results of retrieval of the subsurface temperature profile of a water medium are obtained.     

Synthesis and properties of pyrimidinylalkylsulfonamides 4. Reaction of the Na salt of p-toluenesulfonamide with mono-N-(ω-haloalkyl)uracils

Conclusions The direction of reaction and the composition and yields of products obtained by reaction of the Na salt of p-toluenesulfonamide with N-(-bromoalkyl)uracils depend primarily on the length of the alkyl chain in the latter: When the Na salt of p-toluenesulfonamide reacts with N-(-bromopropyl)-6-methyluracil, the latter undergoes intramolecular cyclization, whereas the Na salt of p-toluenesulfonamide undergoes intermolecular alkylation at the sulfonamide group on reaction with N-(-bromopentyl)-6-methyluracil. In analogous reactions, N-(-bromobutyl)uracils undergo both intramolecular cyclization, followed by opening of the oxazepine ring by nucleophilic reagents, and intermolecular alkylation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2079–2084, September, 1978.     

Specific features in the generation and motion of dislocations in silicon single crystals doped with nitrogen

The specific features in the generation and motion of dislocations are investigated in Si: N single crystals grown by the Czochralski method. The motion of dislocation loops is analyzed by the four-point bending technique in the temperature range 500–800°C. The dislocation loops are preliminarily introduced into the samples with the use of a Knoopp indenter at room temperature. It is found that doping with nitrogen leads to a considerable increase in the critical stress of the onset of dislocation motion from surface sources (indentations) and in the stress of the generation of dislocations from internal sources. The velocity of dislocation motion in Si: N crystals is less than that in undoped crystals (under comparable loads). The hardening effect of nitrogen is explained by the fact that nitrogen promotes the decomposition of a solid solution of oxygen in silicon during postcrystallization cooling.     

Synthesis and oxidation of sulfides containing an isocyanurate fragment

The reaction of 1-(ω-haloalkyl)-3,5-dimethylisocyanurates with sodium salt of methyl thioglycolate afforded the corresponding 1-[ω-(methoxycarbonylmethylthio)alkyl]-3,5-dimethylisocyanurates, the oxidation of which with the system 34% aqueous H₂O₂-0.2 M NaHCO₃-Mn^II leads to the corresponding sulfones. The oxidation of these compounds with 34% aq. H₂O₂ in Ac₂O gives alternative products, viz., sulfones, sulfoxides, or α-acyloxy sulfides, depending on the temperature and number of methylene groups between the isocyanurate fragment and the sulfur atom.     

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.