Interplay of low-energy phonons and magnetic excitations in the Kondo insulator YbB12

Peculiarities in the lattice dynamics of the Kondo insulator Y bB(12) have been studied by inelastic neutron scattering. Selected phonon modes were traced above and below the temperature region (T ~ 50 K) where the gap opens in the electron density of states. The intensities of some low-energy modes exhibit an anomalous temperature dependence for q vectors close to the Brillouin zone boundary, suggesting a renormalization of the phonon eigenvectors. This effect is thought to arise from a coupling with magnetic excitations of the same symmetry, which exist at nearby energies. It is argued that this magnetovibrational coupling may in turn play a role in the steep temperature crossover existing in Y bB(12) between the low-temperature (Kondo insulator) and high-temperature (incoherent spin-fluctuation) regimes, which is rapidly suppressed by lighter Zr substitution.     

Dynamics of colloid silver nanoparticles in an evaporating water drop

The method of photon correlation spectroscopy is used to investigate the distribution of the diffusion coefficient of silver nanoparticles in an evaporating water drop given that the drop base area remains unchanged (the pinning condition). It is established that the capillary flow dominates over the diffusion nanoparticle motion in redistribution of concentration of the dissolved nanoparticles.     

Structure and properties of the surface alloy formed by irradiating a film/substrate system with a high-intensity electron beam

A film/substrate system has been treated with a submillisecond high-intensity electron beam. Examinations have shown that the electron-beam treatment of the film/substrate system resulted in alloying of the surface layer of the material throughout the melt which was accompanied by the formation of nanodimensional phases.     

Prebreakdown excitation of crystals at double multiphoton resonance: II. Analysis of the effects of transformation of electronic band spectrum

The probabilities of multiphoton transitions between the valence and conduction bands at two-photon resonance on the adjacent transition between two conduction bands are calculated within the three-band model of a crystal. It is shown that, due to the effects of transformation of electronic band spectrum in the field of a strong light wave, the dependence of the multiphoton generation rate of electron-hole pairs on the light intensity j contains ranges where a small change in j leads to an increase in the generation rate of electron-hole pairs by several orders of magnitude, which may increase the number of nonequilibrium carriers to the level sufficient for initiating destruction of the material.     

Thrust characteristics of an airbreathing pulse detonation engine in flight at mach numbers of 0.4 to 5.0

Multidimensional calculations are performed to demonstrate that, by its characteristics, the pulse detonation engine (PDE) is a unique type of ramjet propulsion system, which can be used in both subsonic and supersonic aircraft. By a number of examples, it is shown that, in various thrust characteristics, such as the specific impulse, specific fuel consumption, and specific thrust, the PDE substantially exceeds ramjet engines.