Electron diffraction study of the structure of the molecule of para-chloronitrobenzene p-C6H4ClNO2 in the gaseous phase

Journal of Structural Chemistry -     

Gas-Phase Electron Diffraction and Quantum-Chemical Studies of the Molecular Structure of N,N-dimethyldiaziridine

Molecular structure of N,N-dimethyldiaziridine was studied by gas-phase electron diffraction and quantum-chemical methods. It is confirmed that the molecule has a trans conformation, but the structural parameters r(endo-C–N) 1.448(2) Å, r(exo-C–N) 1.468(2) Å, and r(N–N) 1.514(6) Å differ substantially from the results of our previous electron diffraction study.     

Formation and magnetic properties of the silicon-cobalt interface

Formation of the Si/Co interface and its magnetic properties have been studied by high-resolution photoelectron spectroscopy with synchrotron radiation. The experiments have been performed in situ in superhigh vacuum (5 × 10^?10 Torr) with coating thicknesses up to 2 nm. It has been found that, in the initial stage of silicon deposition on the surface of polycrystalline cobalt maintained at room temperature, ultrathin layers of the Co₃Si, Co₂Si, CoSi, and CoSi₂ silicides are formed. The three last phases are nonmagnetic, and their formation gives rise to fast decay of magnetic linear dichroism in photoemission of Co 3p electrons. At deposition doses in excess of ～0.4 nm Si, a film of amorphous silicon grows on the sample surface. It has been established that the Si/Co interphase boundary is stable at temperatures up to ～250°C and that further heating of the sample brings about escape of amorphous silicon from the sample surface and initiates processes involving silicide formation.     

Tunneling of magnetoacoustic waves through a gap in ferromagnetic crystals with a relative longitudinal displacement

The tunneling of a plane monochromatic acoustic wave through a gap between two ferromagnets under conditions of their relative longitudinal displacement has been considered. It has been shown that, when the gap thickness h is comparable to the wavelength, the complete transmission of the acoustic wave at the Damon-Eshbach frequency becomes possible. When the gap thickness is smaller than the wavelength, the complete transmission of the acoustic wave occurs but already at two resonant frequencies. The inclusion of the longitudinal displacement of one of the crystals, in all cases, leads to the violation of resonance conditions and, consequently, to a noticeable decrease in the coefficient of transmission of the acoustic wave through the gap between two ferromagnets; this effect is more pronounced, the higher is the velocity of motion of the crystal. It has been demonstrated that there is a possibility of the wave front reversal occurring with the amplification of the reflected magnetoacoustic wave.     

Dynamic deep temperature recovery by acoustic thermography using neural networks

In an experiment, the deep temperature, which changed with time, was recovered for a model object, bovine liver. The liver was heated for 6 min by laser radiation (810 nm), transmitted via a light guide to a depth of 1 cm. During heating and subsequent cooling, the deep temperature was measured by acoustic thermography. For independent control, we used three electronic telemeters, the indications of which were also subsequently recovered. Deep temperature was recovered using a neural network with a time delay. During the last 2 min of heating, the mean square error of recovery for an averaging time of 50 s did not exceed 0.5°C. Such a result makes it possible to use this method for solving a number of medical problems.     

Stretching,Amplification, and Compression of Microwave Pulses Using Helically Corrugated Waveguides

Radiophysics and Quantum Electronics - We demonstrate the possible implementation of the chirped pulse amplification (CPA) method, which is widely used in optics, for the microwave frequency band....     

Dynamics of Spatially Inhomogeneous Spin Polarization of Nonequilibrium Conduction Electrons in Magnetic Transitions

Physics of the Solid State - The equation of the dynamics of the magnetic moment motion that has been averaged over the ensemble of nonequilibrium spin-injected electrons in a ferromagnetic...     

Generation of a Periodic Sequence of High-Power Ultrashort Pulses in a Chain of Coupled Backward-Wave and Traveling-Wave Tubes Operating in the Regimes of Amplification and Nonlinear Kompfner Suppression

We have studied the dynamics of an electronic microwave generator with backward-wave and traveling-wave tubes connected in the feedback circuit and operating in the regimes of amplification and nonlinear Kompfner absorption, respectively. It is shown that radiation generated in such a system can have the form of a periodic sequence of ultrashort pulses. The studied mechanism of pulse generation is analogous to the method of passive mode locking, which is widely used in laser physics.