Table of contents

A new formulation is proposed for the investigation of the non-adiabatic non-Abelian connection and phase factor by making use of the invariant theory and invariant-related unitary transformation method. In order to illustrate the formulation, we calculate the non-adiabatic non-Abelian connection and phase factor associated with the motion of a charged particle in a time-dependent magnetic field (the time-dependent Landau level problem).

It is pointed out that Haldane's 'statistical interaction' is implicit in the generalised, interpolative quantum statistics developed in a different context and this relationship has been further clarified by the recent work of Wu and Rajagopal. The interpolative quantum statistics, therefore, also applies to the thermodynamics of the elementary excitations in pure Laughlin liquids.

Some OGY based methods for synchronization of chaotic trajectories using small parameter perturbations rely heavily on the dynamical equations of systems. We present an alternative method for the synchronization of chaos via parameter perturbation using only time series data. Employing a very simple local model constructed from time series data, parameter perturbations necessary to achieve synchronization are easily obtained. Synchronization can be achieved even though the local model is very crude when using very short time series data.

We present a unified description of elastic, high energy electron – molecule scattering in terms of a scaled differential cross section regarded as a universal function of a scaled momentum transfer. The predictions of the function are in agreement with the experimental cross sections for CH₄, C₂H₄, C₂H₆, CO, N₂, O₂, H₂O and CO₂.

The radiative lifetimes of excited Hg I nd ³D₂ (n = 7–11) states have been determined using two-photon excitation and time resolved fluorescence spectroscopy. The dependence of these data versus principal quantum number is discussed.

Absolute energies of the autoionizing states 1s2s²2pⁿ [LSJ] with n = 3–6, 1s2s2pⁿ [LSJ] with n = 4–6 and 1s²pⁿ [LSJ] with n = 5–6, and non-autoionizing states 1s²2s2pⁿ [LSJ] with n = 2–6, 1s²2s2pⁿ [LSJ] with n = 3–6, and 1s²2pⁿ [LSJ] with n = 4–6 were calculated for ions with a nuclear charge Z = 6–54 by using the 1/Z perturbation theory method. These states were considered as the states with one or few holes in the Ne-like core state 1s²2s²2p⁶. Relativistic corrections were taken into account in the frame of the Breit operators. The autoionization rates for the above-mentioned autoionizing states and ions were computed as well and are shown in grafic forms as Z-dependences. These new atomic data represent an important material, which can be used in different areas of atomic and plasma physics involving the study of multiply-charged ions.

Reduced matrix elements and transition rates are calculated for all magnetic dipole (M1) transitions within 2l2l' configurations and for some 2l3l' - 2l2l' transitions in Be-like ions with nuclear charges ranging from Z = 4 to 100. Many-body perturbation theory (MBPT), including the Breit interaction, is used to evaluate retarded M1 matrix elements. The calculations start with a (1s)² Dirac-Fock potential and include all possible n = 2 configurations, leading to 4 odd-parity and 6 even-parity states, and some n = 3 configurations. First-order perturbation theory is used to obtain intermediate coupling coefficients. Second-order MBPT is used to determine the matrix elements, which are evaluated for all 11 M1 transitions within 2l2l' configurations and for 35 M1 transitions between 2l3l' and 2l2l' states. The transition energies used in the calculation of oscillator strengths and transition rates are obtained from second-order MBPT. The importance of negative-energy contributions to M1 transition amplitudes is discussed.

The coupled conductive-radiative transfer in a participating, inhomogeneous plane-parallel medium with anisotropic scattering and reflecting boundaries is considered. The radiative transfer equation is solved in its integral form for linear anisotropic scattering using the variational method. The coupling of the radiative to the conductive transfer is solved using an iterative method. The temperature and the conductive, radiative and total net fluxes through the medium are calculated for homogeneous and inhomogeneous media and for isotropic and anisotropic scattering. The results for homogeneous media are compared with the published calculations.

The enhancement of the second harmonic generation (SHG) of light due to edge plasmon excitation on a metal grating is studied. Optimal conditions for edge plasmon excitation by laser radiation are evaluated. The role of surface and edge plasmons on the enhancement of SHG is considered.

Based on an assumption of the existence of an inner and gauge symmetry between two superfluid components, a phenomenological derivation of equations of relativistic superfluidity theory for systems with two types of condensates is given in a non-dissipative approximation. The effect of mutual dragging of superfluid components is considered as a consequence of interaction of condensates treated as quantum scalar fields. Thermodynamics identities for the pressure, energy and expression for the energy-momentum tensor are found. The limit of low velocities is considered.

A kinetic theory for low-frequency electrostatic waves in weakly-coupled dusty plasmas is developed, taking into account dust correlations. For this purpose the first two equations of the Born-Bogoliubov-Green-Kirkwood-Yvon hierarchy are solved using a perturbation scheme based on the large difference in the plasma and dust dynamic time-scales. A dispersion relation is derived which includes the effects of the dust pair correlation function. The validity of our investigation for understanding the salient features of damped dust-acoustic waves in a low-temperature laboratory dusty plasma is discussed.

Investigation of a monochromatic point x-ray source of photon energy ~5 keV has been carried out. The source was set up using a laser produced aluminium plasma as a cathode and a point-tip titanium anode. Optimum parameters of the diode were determined from experimental measurements of x-ray intensity dependence on laser pulse energy, applied accelerating voltage, and distance between target (cathode) and anode, using Nd:glass laser pulses (FWHM 30 ns) of 2 mJ to 4 J energy. Electron temperature characterization of the target plasma was also performed from the XUV emission spectrum (5 to 80 Å). Parameters of x-ray radiation in Ti K-shells are 1) spectral brightness of ~10²⁰ photons/cm²-sec-sr-keV, 2) spatial size ~300 microns, and 3) x-ray pulse duration less than 20 ns.

It was found that metastable atoms diffusing in a parent gas and bombarding a metal electrode, will cause an electric charge to build up on the electrode. Laser resonant pumping of a transition with a metastable lower level will cause depletion of the metastable atom density that, consequently, alters the electrode potential. It has been shown that in the case of neon, 1s₅ metastable atoms are predominantly responsible for appearance of the optovoltaic (OV) signal that is defined as a potential difference between two electrodes equidistant from the discharge. By the laser induced fluorescence method a stationary distribution of metastables, produced by a discharge and diffusing into a neutral gas, has been measured. The results are supported by a model. Dependence of the OV signal on the position of the laser beam between the discharge and one of the electrodes has also been measured and a physical model developed.

In this paper we study the process of electron capture and ionization due to collisions between the bare ions D⁺ or He²⁺ and excited ions C⁵⁺ (n = 8). At typical impact energies of some keV/amu, this process can be of importance in the computation of the equilibrium ion population in fusion plasmas.

Optical transmission spectra are very sensitive to inhomogeneities of thin films. In particular, non-uniform film thickness leads to shrinking of the transmission spectrum at normal incidence. This non-uniformity has to be taken into account, because its ignorance may lead to serious errors in the calculated values of the refractive index and the film thickness. This paper presents a method, which transforms the optical transmission spectrum of a wedge-shaped thin film into a spectrum of a uniform film whose thickness is equal to the average thickness of the non-uniform film. This allows to calculating the refractive index, the average thickness, as well as a parameter indicating the degree of film thickness uniformity. The method is successfully applied to wedge-shaped obliquely-deposited chalcogenide glass thin films of chemical composition GeS₂. The dispersion of the refractive index in the subgap region is discussed in terms of the Wemple-DiDomenico single-oscillator model. The optical -absorption edge is described using the 'non-direct transition' model suggested by Tauc, and the optical gap is calculated by Tauc's extrapolation. Far-infrared spectroscopy has been used to clearly complement the results derived from the present optical measurements.