The unique structure of [(C4H9)4N]3[Pb(NO3)5]—one step forward in understanding transport properties in tetra-n-butylammonium-based solid electrolytes

Structural Chemistry - The crystal and molecular structure of tris(tetrabutylammonium) pentanitratoplumbate(II) was determined and characterized by single-crystal and powder X-ray diffraction and...     

Radiation of a Resonant Medium Excited by a Periodically Phase-Modulated Laser in the Regime of Strong Coupling between the Field and the Matter

Optics and Spectroscopy - The radiation of a two-level resonant medium that is placed into a cavity and is excited by a periodically phase modulated laser pulse is studied theoretically. The...     

Measurement of the Intensity Distribution of a Hard X-Ray Radiation Source

Physics of Atomic Nuclei - The procedure of measurement of the brightness distribution of the hard X-ray source of the MIB-7.5 betatron with a penumbral aperture is detailed (i.e., a measurement...     

Collisions of Single-Cycle and Subcycle Attosecond Light Pulses in a Nonlinear Resonant Medium

By numerically solving the system of Maxwell–Bloch equations, we have examined theoretically collisions of extremely short single-cycle and unipolar subcycle pulses in a nonlinear resonant medium under conditions that the light interacts coherently with the medium. The dynamics of the electric field of structures of light-induced polarization and inversion difference has been considered in the situation in which pulses are overlapped in the medium. We show that the states of the medium (to the right and to the left of the overlap region of the pulses) may differ. In particular, we show that polarization waves with different characteristics can exist in the regions of the medium that are located on opposite sides of the overlap region of the pulses. These waves travel in different directions and have different spatial frequencies.     

Generation of Extremely Short Pulses upon Excitation of a Resonant Medium by a Superluminal Light Spot

The possibility of generation of quasi-unipolar extremely short pulses (with a duration of several periods of field oscillations) is theoretically analyzed for the excitation of a circular, nonlinear, and resonant medium with a light spot. The light spot rotates along a circle with a velocity that exceeds the speed of light in vacuum, while particles of the medium are distributed uniformly along the circle. It is shown that, by introducing a delay in the form of a phase plate into the system, one can control the shape, the duration, and the amplitude of generated pulses.     

Dynamics of nonlinear three-dimensionalwaves on the interface between two fluids in a channel with low-sloping bottom and top

A combined approach is proposed to describe the transformation of three-dimensional disturbances of the interface between two incompressible immiscible fluids of different densities contained in a channel with fixed rigid top and bottom. It is assumed that the wavelengths are moderately large, the amplitudes are small but finite, the top and the bottom can be gently sloping, and capillary effects are small. The system of equations derived is applicable for modeling disturbances simultaneously scattering in arbitrary horizontal directions. Some typical wave problems are numerically solved and the effect of governing parameters is shown.     

Synthesis of tris(β,β,γ-oximinoalkyl)amines from aliphatic nitro compounds and methyl vinyl ketone

A general strategy for the assembly of previously unknown tris(β,β,γ-oximinoalkyl)amines from aliphatic nitro compounds and methyl vinyl ketone is described. The strategy involves N,N-bis(siloxy)enamines as key intermediates. The latter are accessible by double silylation of alkylnitro compounds. Nickel(II) and copper(II) complexes of tris(β,β,γ-oximinoalkyl)amines are prepared and structurally characterized.     

Dynamic and molecular association in premicellar aqueous solutions of dicarboxylate amino acid-based surfactant as studied by 1H NMR

We examined a series of amino acid-based surfactants with two carboxylic groups separated by a spacer of one, two, or three carbon atoms with sodium and calcium counterions in the premicellar concentration region near the CMC. ¹H nuclear magnetic resonance (NMR) spectroscopy and NMR diffusometry techniques were used to study the local environment, association, and translational dynamics of the surfactant's molecules. We measured the self-diffusion coefficients of the micelles, calculated the effective hydrodynamic radii, and determined the temperature region in which the premicelles exist. With an increase in temperature from 295 to 335 K, the premicellar state of the surfactant is replaced by the monomeric state.     

Generation of unipolar pulses in nonlinear media

Methods recently proposed for generating unipolar pulses in nonlinear media in terahertz and optical electromagnetic ranges are reviewed. Such pulses have nonzero “electric area” (time integral of the field strength over the entire duration of a pulse) and, correspondingly, a significant component of the field with zero frequency, thus exhibiting quasistatic properties. Effective generation of unipolar pulses would allow, e.g., transferring mechanical momentum to charged particles and, thereby, controlling the motion of wave packets of matter, which can be useful for compact accelerators of charged particles and for other applications.