Table of contents

Alpha emitting is treated as a particular case of the nucleus decay. The classical Hamiltonian of the nuclear system is constructed, accounting for the Coulomb inner-nuclear interaction and strong interaction approximated by the "Yukava plus exponent" potential. The effective quantization in terms of the collective variable T (elongation) is performed. The effective mass, adjacent to T, depends on T and is of tensor character; its tensor character, is shown, can manifest itself in the collisional experiment as the "dependence of the potential barrier height" on the incident particle energy. The numerical calculations for ²¹⁰Po show that the mass tensor character is of principal value for the spectrum of the emitted alpha-particles. The possible consequences for the secondary processes in the atomic electron shell and for the electron-positron pair production are discussed.

Numerical calculations of the inner-shells atomic ionization probabilities and of the electron–positron pair production probabilities (in the bare nucleus) are carried out. The spectra of the ejected electrons as well as the spectra of the produced positrons have fine quasi-periodical structures (∼ 3000 eV) scaled by the inverse length of the De-Brogle wave of the α-particle. Another, large scale type, structurization is governed by the inverse length of the De-Brogle wave of the free electron or positron. The structure of the emitted light particles spectra is shown to be very sensitive to the model of the nucleus decay.

The Δ-nucleus optical potential from microscopic calculations in nuclear matter is used to study the effects of its energy dependence in charge-exchange (p, n) and (³He, T) reactions. The neutron or triton spectrum is calculated via response function of a finite nucleus accounting for pion renormalization effects and short-range correlations.

Only very small effects, 1-2%, were found for (³He, T) reaction where the changes in the high energy part of the triton spectrum are enhanced relative to the low-energy part by (³He, T) form factor. For the (p, n) reaction no visible effects were found.

The spectrum of neutral neon used as a carrier gas has been measured by the Fourier transform spectroscopy technique from 1800 to 9000 cm⁻¹. We report on transitions leading to improved energy levels for the 4f, 5f, 6f, 7f and the 5g configurations. In addition, we identify transitions leading to the previously unknown 6g and 7g configurations. Theoretically, we have generalized the polarization and pair coupling formulae to the extended quadrupole-polarization model. Explicitly accounting for the 6f'-7f (6g'-7g) quadrupole interaction, our two-parameter expression reproduces 18 observed levels (ng) with a mean deviation of 0.016 cm⁻¹. Inclusion of the 24 observed pairs of nf levels increases the mean deviation to 0.036 cm⁻¹.

Using a semiclassical approach, we have calculated electron-, proton- and ionized helium-impact line widths and shifts for 22 Al I multiplets. The resulting data have been compared with existing experimental and theoretical values.

The polarization degree of the X-line due to the M2 quadrupole transition in the Sc⁺¹⁹ was calculated with account for the hyperfine (HF) interaction. Two effects were considered, the incoherent emission of photons from HF structure levels and the admixing of E1 transition. The first one is shown to be the dominant one in the decrease of polarization due to the HF interaction. The calculated degree −7, 2% is in agreement with the experimental value −1 ± 10% within the experimental errors.

Spectra with spectral resolution λ/Δλ ≃ 3000-7000 in the vicinity of the He-like ion resonance lines Mg, Al, Si, P, S were obtained in CO₂ laser-produced plasma. The wavelengths of these satellites were measured and compared with numerical calculations. Identification of lines or a group of overlapping lines was performed. Twenty-two transitions of dielectronic satellites for Be-like ions, 41 transitions for B-like, 40 transitions for C-like, 22 transitions for N-like, 12 transitions for O-like ions and 2 transitions for F-like ions were identified. The average between theoretical and experimental wavelengths was ±(0.0005-0.001)Å, but in some cases it was ±(0.002-0.003)Å.

Transition data has been computed in the MCHF + Breit-Pauli approximation for a number of the low lying triplets in O III. Special attention was given to the 2p3p³P-2p3d³P transition which is a primary cascade for the Bowen fluorescence mechanism in O III. The relativistic, largely spin-orbit, effect on the intensity ratio of primary decays was found to be as large as 50%, whereas the effect on secondary cascades was less than 30%. Agreement with astrophysically observed intensity ratios is excellent. There also is good agreement between the present liftimes and the beam-foil mean lifetimes obtained by Pinnington et al., though for 2p3p³D and ³S the theoretical lifetimes are considerably shorter.

The R-matrix method is used to calculate electron impact collision strengths for various transitions among the 1s² 2s²2p⁶, (1s²2s²2p⁵) 3s, 3p and 3d configurations of Cl VIII based on extensive configuration interaction wavefunctions. The standard and no-exchange R-matrix codes have been used to calculate the contribution of partial waves with L ⩽ 9 and L > 9 respectively. Collision strengths are tabulated at selected energies in the range 25-80 Ryd for all 105 transitions among the lowest 15 target states. Effective collision strengths are also tabulated for electron temperatures in the range log T_e = 4.00 to log T_e = 6.40K.

The energies of the atomic systems 1s2s²2pⁿ and 1s²2s²2pⁿ with n = 0-6 for Z = 18, 26 have been calculated using two methods: SUPERSTRUCTURE (including only the configurations of the complexes: 1s2s²2pⁿ + 1s2pⁿ⁺² and 1s²2s²2pⁿ + 1s²2pⁿ⁺²) and perturbation theory (MZ). Nonrelativistic and relativistic parts of energy have been considered separately. Relativistic effects have been taken into account by the Breit-Pauli operators. Relativistic shift and splitting have been discussed.

Branching ratios of multiply charged Ne, Ar, Kr and Xe ions produced following soft X-ray absorption by the rare gases have been measured using a time-of-flight mass spectrometer and monochromatized synchrotron radiation. Ratios of double, triple and quadruple valence photoionization to single valence photoionization, of multiple Auger transitions to the normal Auger transition from a core hole or core-valence two-hole state, and of the multiple photoionization with a core hole to single core photoionization have been determined using the measured branching ratios of the multiply charged ions.

New direct observation data on the 2s-2p atomic state coherent mixing upon hydrogen atoms passage through a metal-wall slit are presented. The experimental results are interpreted in terms of atomic state interference, the state mixing amplitude being derived directly from the experimental data obtained.

We have determined effective collision strengths for fine-structure transitions among the 2s²2p² and 2s2p³ configurations of seven ions in the C I isoelectronic sequence, by interpolating or extrapolating from data calculated by the R-matrix method for the C-like species Si IX, Ca XV and Fe XXI. We present the results as coefficients to polynomial fits which may be used to estimate the effective collision strengths to an accuracy of ±20%.

The three-dimensional evolution of a short laser pulse is considered. The linear stability analysis that takes account of the scattered light convection and predicts a development of pulse modulation at the electron plasma frequency, is carried out. It is demonstrated that a laser pulse with a power above or close to the critical, which is required to provide a pulse relativistic self-focusing, undergoes compression and self-modulation in the course of self-consistent pulse evolution and, as a result, resonant excitation of an extremely strong plasma wave occurs. It is shown that for a properly taken initial pulse and plasma parameters it is possible to obtain a wake field of an extremely high intensity for a fairly long time to provide a new promising outlook for the laser accelerator concept. The influence of plasma inhomogeneity and pulse initial focusing on the considered self-resonant plasma wave excitation is studied.

We present dynamical theory of soliton excitations in nonlinear coupled incommensurate chains which consists of two deformable chains of different atomic species, each with its own chemical potential, on the same substrate. In the continuum approximation, the motion equations are a set of coupled Sine-Gordon equations. The soliton solutions of these coupled equations are studied in detail. It has been shown that the frequency of the internal oscillations depends on the coupling parameter. The interaction energy between the two weakly coupled Sine-Gordon systems has been found. Results of the dynamical theory have been related to the transport properties in organic conductors such as TTF-TCNQ, KCP and others. Indeed, we have calculated some meaningful physical parameters of these compounds within the soliton limit, and discussed different types of behaviors shown at the transition with respect to variations of the physical parameters.

Results of detailed studies of spectra of Pc1 wave packets observed simultaneously on Geos-1 and at Husafell on July 13, 1977 and on September 2, 1977 are presented. The transmission coefficients for three components of the signals have been computed and compared with theoretical results. Four groups of modulated maxima-satellites were first discovered in signal spectra not only on the Earth, but also on Geos-1. Their frequencies coincide with the frequencies of pulsations of Pc3 and Pc4. The cross-correlation functions of Pc1 signals on Geos-1 and on the Earth have been computed. They are small and do not exceed 0.2-0.4. The central frequencies of signal spectra on Geos-1 and on the Earth do not coincide but differ with ∼ 0.04 Hz.