Effect of accumulation on the formation of multiply charged ions in solids under grazing incidence of multiple laser radiation

The effect of accumulation on the formation of multiply charged ions in optically opaque solids as a function of the number and the angle of incidence of laser pulses is investigated by mass spectrometry. It is revealed that the accumulation effect manifests itself at prethreshold power densities q = 10⁸–10⁹ W/cm² irrespective of the angle of incidence of laser radiation α = 18°–85° and at subthreshold power densities q > 10¹⁰ W/cm² in the case of grazing incidence of laser radiation at an angle α = 85°. The accumulation effect brings about an increase in the maximum charge multiplicity Z _max of tungsten ions and a decrease in the number of impurity ions and in their intensity. No accumulation effect is observed at subthreshold power densities when laser radiation is incident at an angle α = 18°.     

Influence of the prehistory of NaNbO3-Gd1/3NbO3 ceramics and single crystals on their dielectric properties

The dielectric properties of a ceramic and a single crystal of the same composition 0.9NaNbO₃-0.1Gd_1/3NbO₃ (NNG10) with different prehistories of the material are investigated in the low-and infralow-frequency ranges. It is revealed that the dielectric aging of the material based on the NaNbO₃ antiferroelectric with a smeared phase transition differs in character from similar phenomena observed in relaxor ferroelectrics.     

Influence of the defect structure on the electrical conductivity of Pb5Ge3O11 single crystals at high temperatures

The impedance spectra of Pb₅Ge₃O₁₁ single crystals are measured in the frequency range from 5 Hz to 13 MHz at temperatures of 600 to 800 K in dry air and in a dry or wet nitrogen gas. It is found that the temperature and the gas composition significantly affect the electrical properties of the compound. The data obtained are used to discuss the origin of crystal lattice defects and their influence on charge transfer. It is concluded that the conduction is mixed in character (p-type electronic and ionic due to oxygen ions). The proton conduction is shown experimentally to be feasible. The possible mechanisms of proton transport in Pb₅Ge₃O₁₁ are discussed.     

Structural phase transitions of the B1–B2 type in small-sized ionic crystals

The features of structural phase transitions that occur under high pressure are studied. The density functional theory is used to calculate the B1–B2 phase transition pressure as a function of the crystal size for small-sized alkali halide crystals. A size effect (an increase in the phase transition pressure as the crystal grain radius decreases) is revealed for the B1–B2 transitions in all halogen compounds except for lithium fluoride, for which the dependence is inverse.     

The role of intrachain dipole interactions in the formation of the supramolecular structure of crystallizing ferroelectric polymers

The role of intrachain dipole interactions in the formation of a lamellar morphology is investigated using a number of statistical vinylidene fluoride copolymers with nonpolar components as an example. It is shown that the large and interlamellar spacings regularly increase as the intrachain dipole interaction weakens.     

On the magneto-optics of orthoferrites with spin reorientation

The results of magneto-optical investigations into the Γ₂–Γ₄ spin reorientation in an Sm_0.6Tb_0.2Tm_0.2FeO₃ orthoferrite single crystal are reported. The magneto-optical parameters are determined taking into account the dichroism. The orientation of the antiferromagnetic vector in the canted phase is investigated as a function of the magnetic field and temperature. The magnetic anisotropy field strengths are determined by the processing of the results. The orientation contribution to the birefringence is estimated.     

Design of the cold atom PHARAO space clock and initial test results

In this paper we describe the cold atom clock PHARAO, designed for microgravity operation. All elements of the PHARAO engineering model have been manufactured and delivered to CNES, the French space agency. We present the clock design, its main characteristics, and initial science operation. PHARAO is one of the main components of the Atomic Clock Ensemble in Space payload that is scheduled to fly on board the International Space Station in 2010. PACS 07.87.+v; 06.30.Ft; 95.55.Sh; 32.80.Pj     

Nanophotonics and nanometrology with planar X-ray waveguide-resonator

The mechanism of X-ray waveguide-resonance propagation or the radiation superstream model, which can become the ground of X-ray nanophotonics, is discussed briefly. Some attention is devoted to features consideration of the simplest devices characterized by the waveguide-resonance transportation of X-ray beams. The experimental data showing the user possibilities of a simplest waveguide-resonators application for diffractometry are presented. We discuss the main reasons to improve the metrological characteristics for total reflection X-ray fluorescence (TXRF) analytical method in case when the target exciting beam is formed by a waveguide-resonator. Some problems appearing during the waveguide-resonator application are formulated.     

Magnetic properties of multiwalled carbon nanotubes as a function of acid treatment

We investigate the electronic properties of multiwalled carbon nanotubes both before and after acid treatment with concentrated sulphuric and nitric acids. Magnetic susceptibility measurements were performed using a SQUID magnetometer and show that there is a considerable enhancement in the density of states at the Fermi level. The data shows that the diamagnetic influence from the graphitic nanotubes dominates. We experimentally observe, after acid treatment, that the diamagnetic susceptibility remains unchanged at 5 K but notably decreases at 77 K. We propose the acid treatment has increased the Van Vleck paramagnetic contribution lowering the diamagnetic response from the π-electron orbital magnetisation. The Van Vleck paramagnetic contribution is finite-temperature dependent with a diminishing contribution at higher fields.     

Noether analysis of zilch conservation laws and their generalization for the electromagnetic field. II. Use of poincaré-invariant formulation of the principle of least action

Uzhgorod Branch, Institute of Nuclear Research, Ukrainian SSR Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 80, No. 3, pp. 340–352, September, 1989.