Table of contents

We observed the spectrum of neutral krypton (Kr I) in its naturally occurring isotopic mixture as emitted by a microwave-excited electrodeless discharge lamp with the National Institute of Standards and Technology (NIST) 2 m Fourier transform spectrometer (FTS). The spectra cover the region from 6699 to 12 200 Å with a resolution of 0.01 cm⁻¹ and the region from 9000 to 47 782 Å with a resolution of 0.007 cm⁻¹. We present a line list that includes more than 630 classified lines, about 290 newly observed, and provides an accurate and comprehensive description of the infrared spectrum. The response of the FTS was characterized by using a radiometrically calibrated tungsten strip lamp to obtain relative intensities accurate to 10% or better over the entire spectral range for lines with good signal-to-noise ratio (SNR). All eight levels of the 4s² 4p⁵ (²P_3/2)6g configuration have been located as well as one previously unknown level of the 4s² 4p⁵ (²P_3/2)6f configuration. Our new data have been combined with previous precise measurements to determine improved values for 64 even and 77 odd parity levels of Kr I.

The magnetocaloric effect (MCE) in samples GdAl_1.7(Fe_1-xCo_x)_0.3 with x= 0, 0.1, 0.2, 0.3 and 0.4 were investigated by x-ray diffraction (XRD) and magnetization measurements. It was found that five samples crystallize well in the MgCu₂-type structure. The lattice parameter and the values of Curie temperature decrease with increasing Co content, whereas the magnetic-entropy change and cooling capacity increase. In the magnetic-field change of 2.0 T the maximum of the magnetic-entropy change and refrigerant capacity in sample GdAl_1.7Fe_0.7Co_0.3 reach 4.8 J kg⁻¹ K⁻¹ and 88.3 J kg⁻¹, respectively. The maximum of the magnetic-entropy change is comparable to that of Gd metal (3.8 J kg⁻¹ K⁻¹ in Δ B=1.5 T).

In this paper, by using the notion of negativity, we study the degree of entanglement of a two-level atom interacting with a quantized radiation field, described by the Jaynes–Cummings model (JCM). We suppose that initially the field is in a pure state and the atom is in a general mixed state. In this case the negativity fully captures the entanglement of the JCM. We investigate the case that the initial state of the field is a coherent state. The influences of the detuning on the degree of entanglement are also examined.

Global measurements of the hydroxyl mesospheric airglow over an extended period of time have been made possible by the NASA SABER infrared sensor aboard the TIMED satellite which has been functioning since December of 2001. The orbital mission has continued over a significant portion of a solar cycle. Experimental data from SABER for several years have exhibited equatorial enhancements of the nighttime mesospheric OH (Δv=2) airglow layer consistent with the high average diurnal solar flux. The brightening of the OH airglow typically means more H+O₃ is being reacted. At both the spring and autumn seasonal equinoxes when the equatorial solar UV irradiance mean is greatest, the peak volume emission rate (VER) of the nighttime Meinel infrared airglow typically appears to be both significantly brighter plus lower in altitude by several kilometres at low latitudes compared with midlatitude findings.

A non-integrable, variable coefficient nonlinear Schrödinger equation which governs the nonlinear pulse propagation in an inhomogeneous medium is considered. The same equation is also applicable to optical pulse propagation in averaged, dispersion-managed optical fibre systems, or fibre systems with phase modulation and pulse compression. Multi-scale asymptotic techniques are employed to establish the leading order approximation of a solitary wave. A direct numerical simulation shows excellent agreement with the asymptotic solution. The interactions of two pulses are also studied.

Based on the experimental hyperfine structure data given in our previous study, the multi-configuration method has been used to calculate the fine structure of the odd parity configurations 3d4s4p, 4s² 4p and 3d² 4p of neutral Scandium taking into account configuration interaction effects. Magnetic dipole hyperfine structure constants are analysed in the effective-operator formalism for the isotope ⁴⁵Sc. Relativistic one-electron parameters of the magnetic dipole hyperfine structure a_nl^k_sk_l(k_sk_l= 01, 10, 12) were fitted to the experimental data by a least-squares fit procedure. Theoretical predictions for the magnetic dipole hyperfine structure constants A for all levels of the three configurations are given.

An alternative representational method is proposed for the investigation of relativistic elastic collision. Although using four vectors is a common way to represent relativistic quantities, complex quaternionic representation has some advantages with a simpler and more expressive nature. This study shows that the complex quaternionic approach provides a very convenient and useful tool for the formulation of these types of collisions.

This study addresses the adaptive synchronization of the modified van der Pol–Duffing (MVDPD) oscillator with offset terms. From our investigations of the system dynamics, we obtain that the system presents a chaotic behaviour at weak values of the offset parameters. Routh–Hurwitz criteria are used to study the asymptotic stability of the steady states. An adaptive observer design method is applied to achieve synchronization of two identical MVDPD oscillators with offset. Numerical simulations are given to validate the proposed synchronization approach. Moreover, as an application, the proposed scheme is applied to secure communication. Also, simulation results verify the proposed scheme's success in the communication application.

We solve the two-component Dirac equation in the presence of a spatially one-dimensional symmetric attractive cusp potential. The components of the spinor solution are expressed in terms of Whittaker functions. We compute the bound states solutions and show that, as the potential amplitude increases, the lowest energy state sinks into the Dirac sea becoming a resonance. We characterize and compute the lifetime of the resonant state with the help of the phase shift and the Breit–Wigner relation. We discuss the limit when the cusp potential reduces to a delta point interaction.

By means of the nuclear parton distribution studied only with lepton deep-inelastic scattering experimental data, the effect of spatially inhomogeneous shadowing is studied in the p-A Drell–Yan dimuon production process. Using multiple soft rescattering theory, the initial state energy loss effect is also considered within the Glauber framework. The calculated results are compared to the E772 and E866 data. It is shown that the theoretical results while considering the energy loss effect are in good agreement with the experimental data. In this paper, we also compare the calculated results of inhomogeneous shadowing with those of homogeneous and find that the inhomogeneous shadowing results exhibit a stronger energy loss effect than the homogeneous results at the same parameter.

La_0.67Sr_0.33Mn_0.95Zn_0.05O₃ film has been deposited on LaAlO₃ (100) substrate by the magnetron sputtering method. The results concerning the photoinduced character of the film are reported. In the ferromagnetic metallic state, the increasing photoinduced resistance is caused by photoinduced demagnetization of the spin correlation system in manganites. The photoinduced relaxation character of the film indicates that the time constant increases with increasing temperature, which is attributed to the thermal fluctuation.

Pb_1−xSm_xSe (x=0.03, 0.06 and 0.09) compounds are synthesized by solid-state reaction. The x-ray diffraction technique, scanning electron microscope, electrical and thermoelectric power measurements were used to characterize the prepared samples. The samples are sintered at 488 K and the effect of the sintering time on the transport properties was investigated. The metal–insulator transition occurrence depends on both the Sm content and the sintering time. The energy band gap E_g was calculated for the sintered samples of 0.06 Sm composition in the intrinsic region. The Seebeck coefficient measurements show that all the samples under investigation are n-type semiconductor materials with electron carrier predomination at low temperature and hole conduction contribution at high temperature. The power factor S²σ was calculated and gave a good indication of the wide application of the investigated compositions as thermoelectric materials.

The specific heat of a spin-one Heisenberg antiferromagnetic chain with transverse and longitudinal single-ion anisotropies in the presence of an applied magnetic field is explored on the basis of the Schwinger boson mean-field theory. The specific heat as functions of temperature, the anisotropy as well as the applied field are discussed, respectively. The results indicate that new features of the specific heat as a function of temperature at the transverse single-ion anisotropy are very different from those obtained at longitudinal single-ion anisotropy in an applied transverse field.

The ions of the boron isoelectronic sequence (7⩽Z⩽45) are investigated using the configuration interaction method on the basis of transformed radial orbitals with a variable parameter. The energy spectra and the radiative lifetimes of the levels of configurations 2s² 2p, 2s2p², 2p³ and 2s² 3l are obtained. The aim of the present work is the investigation of the influence of the two-electron transitions on the radiative lifetimes of levels of configuration 2s²3p. It has been shown that the two-electron transitions are crucial for radiative lifetimes of these levels. The dependence of the influence on Z is discussed. The E2 transitions from 2s²3p are also calculated for ions Z⩾25.

This paper studies the dependence of a fluctuation pattern of produced pions on the target excitation for ¹⁶O–AgBr interactions at 2.1 and 60 AGeV. For studying target excitation dependence, the data for produced pions are distributed into three sets depending on the number of grey tracks (n_g). The different sets correspond to the different degrees of target excitation. We have investigated the fluctuation pattern of emitted pions corresponding to different sets in both η (pseudo-rapidity) and ϕ (azimuthal angle) space. The effective fluctuation strength is calculated for each set for both η and ϕ space. The study reveals that the fluctuation pattern of pions depends on target excitation and the dependence is more pronounced at the lower projectile energy.

We have investigated the stability of the lower hybrid wave in a collisional plasma containing hydrogen and positively and negatively charged oxygen ions. The collisions of all the species in the plasma have been considered. The electrons, streaming parallel to the magnetic field, can excite the instability if their drift velocity exceeds the parallel phase velocity of the wave. This is true for both the weakly as well as the strongly collisional cases. If the ion collisions are neglected, the growth/damping rate depends on the electron collision frequency and is modified by a factor dependent directly on the number densities and square of the charges on the oxygen ions and inversely on the masses of these ions. Ion collisions, however only damp the wave; this damping being dependent also on the ion collision frequencies, in addition to the above dependencies. We find that the dispersion relation in the low collisional limit can account for lower hybrid waves in the observed frequency range.

An alternative treatment is proposed for the calculations carried out within the frame of the Nikiforov–Uvarov method, which removes a drawback in the original theory and bypasses some difficulties in solving the Schrödinger equation. The present procedure is illustrated with the example of orthogonal polynomials. The relativistic extension of the formalism is discussed.

The qualitative behaviour of the response of a ship rolling in longitudinal waves whose amplitude or frequency (parameters) are slowly varied is presented. An analytical and numerical technique is used to predict the qualitative change taking place in the stable solutions of a ship model as one of the parameters is slowly changed. The analysis took into consideration linear, cubic and quantic terms in the polynomial expansion of the relative roll angle. The damping moment consists of the linear term associated with radiation and viscous damping and a cubic term due to frictional resistance and eddies behind bilge keels and hard bilge corners. Two methods (the averaging and the multiple time scales) are used to investigate a first-order approximate analytical solution. The modulation equations of the amplitudes and phases are obtained. These equations are used to determine steady state solutions. Numerical calculations are presented which illustrate the behaviour of the steady state response amplitude as a function of the detuning parameter. The stability of the proposed solution is determined applying Liapunov's first method. The effects of different parameters on the system behaviour are investigated numerically. The results obtained by the two methods are in excellent agreement.

Using 10.7 m and 3 m normal-incidence vacuum ultraviolet spectrographs, we investigated the spectrum of singly ionized potassium in the regions 495–612 Å and 1247–2150 Å. More than 120 new K II lines were identified. The previous study on this spectrum was revised and extended. All levels of the 3p⁵ 4f and 5f configurations as well as the levels of 3p⁵ 6f based on the 3p^5 2P_3/2 core state have now been located. Several new levels of 3p⁵ 3d were also located. The ionization limit was determined from the 3p⁵nf 1.5[4.5]₅ (n=4–6) series as 255072.8±1.5 cm⁻¹ (31.6250±0.0002 eV).

We study the problem of the formation of a collisionless plasma sheath at a plasma–wall transition with grazing incidence of the magnetic field. We show that for a large ratio of the ion gyroradius to the Debye length, and below a critical angle , the electrons moving parallel to the magnetic field B can no longer follow the ions gyrating perpendicular to B. The electrons then determine the characteristic times for information propagation, with low frequency oscillations appearing in the system. The electrons can accumulate in front of the wall, resulting in a negative space charge and a reduced electric field in front of the wall. The relevant physics for this case will be studied. For angles larger than the critical angle we recover the standard sheath which is determined by the Bohm condition. We use in the presented simulations deuterium with a ratio of ion temperature to electron temperature T_i/T_e = 2, and a ratio of ion gyroradius over Debye length equal to 20.

The density fluctuation in a nonextensive reaction–diffusion system is investigated, where the nonequilibrium stationary-state distribution is described by the generalized Maxwell–Boltzmann distribution in the framework of Tsallis statistics (or nonextensive statistics). By using the density operator technique, the nonextensive pressure effect is introduced into the master equation and thus the generalized master equation is derived for the system. As an example, we take the³He reaction–diffusion model inside stars to analyse the nonextensive effect on the density fluctuation and we find that the nonextensive parameter q different from one plays a very important role in determining the characteristics of the fluctuation waves.

We investigate the influence of the electron's anomalous magnetic moment on the process of relativistic Mott scattering in a powerful electromagnetic plane wave for which the ponderomotive energy is of the order of the magnitude of the electron's rest mass. For this purpose, we use the Coulomb–Dirac–Volkov and the Dirac–Volkov functions with the electron's anomaly to describe the initial and final states respectively. First-order Born differential cross-sections of induced and inverse bremsstrahlung are obtained for linearly polarized laser light. Numerical calculations are carried out for various parameters values (i.e. scattering angle, the nucleus charge, photon energy, electrical field) and are compared with results obtained by Li et al 2004 (J. Phys. B: At. Mol. Opt. Phys.37 653). It is found that for parameters used in the present work, incorporating the anomaly of the electron in the initial and final states yields cross-sections which are strongly modified whatever the scattering geometry as compared to the outcome of the previous treatment.

Possibilities of manipulating the Rabi frequency and luminescence rate from degenerate-level systems as well as the velocity of self-induced transparency of multi-level media are studied using a unitary transformation. The Rabi frequency and luminescence rate of an electronic system whose ground level is degenerate and coupled to a resonant mode are found to depend on the level of the degeneracy. The velocity of multi-mode optical solitons in a multi-level medium is found to be influenced by the number of propagating resonant pulses. Physical realizations of relevant systems are proposed.

Based on a prior effective Lagrangian model on single pion photoproduction from the nucleon, successfully tested in total and differential cross-sections, we study theoretically the helicity dependence from the interaction of circularly polarized photons and a longitudinally polarized nucleon target in the energy range from π-threshold through the Δ(1232)-resonance region. The doubly polarized total and differential cross-section differences for parallel and antiparallel helicity states are predicted and compared with the experiment. We show that the results are sensitive to interferences among different contributions to the process and, thus, represent a complementary test of the theoretical model. A quite satisfactory agreement with recent experimental data from the GDH-collaboration is obtained.

We propose a scheme for teleporting a multipartite quantum state via driven QED cavity technologies. The combined state of Bell states is employed as a quantum channel. By adopting QED cavity technologies, our scheme does not involve the Bell-state measurements and can be perfectly realized by communicators' single particle measurements, possible C-not transformation and classical communication. The probability of successful teleportation can reach 1.0. The theoretical scheme is experimentally feasible via current technologies.