Table of contents

The reactions ²²Ne(α,nγ)²⁵Mg and ²⁴Mg(d,pγ)²⁵Mg have been studied at E_α = 10 MeV and E_d = 4.7 MeV using particle-gamma and gamma-gamma coincidence technique. Energies and gamma radiation branching ratios of levels in ²⁵Mg up to 6 MeV have been obtained.

Thom's theory for elementary catastrophes is outlined. Some physical instabilities are discussed and it is suggested that the back-bending of the moment of inertia of elements in the rare earth region can be described within this model.

A comparison is made between experimental and theoretical level assignments and static electromagnetic moments of nuclei in the region ₇₂Hf-₇₇Ir. The theoretical calculations are based on the modified oscillator model. Equilibrium deformation values, and ₄, are determined for doubly-even and odd-mass nuclei from the minima in the potential energy surfaces. The influence of the different parameters entering the expressions for the magnetic dipole moment is analysed. The electric quadrupole and hexadecapole moments are calculated on the assumption that the nucleus is a homogeneously charged body with a sharp surface and a shape corresponding to that of an equipotential surface. In some selected cases, the electric multipole moments are evaluated by use of the single-particle wave functions.

The beam-foil method has been used for spectral studies of aluminum in the wavelength region 1 800-7 000 Å. Most of the lines were from Al III and Al IV, and several hydrogenic transitions were identified in Al IV-Al VI. Mean lives of 10 excited states in Al III are presented. Correction for analyzed main cascades has been applied when possible. In general, good agreement was found with earlier experimental results and theoretical estimates. The cascade correction method was also tested with simulated decay curves and proved to give a better estimate of the lifetime than the multiexponential fit.

The spectra of Y VII, VIII, Zr VIII, IX, Nb X and Mo X, XI are studied for the first time and our 1971 analysis of Nb IX is improved. By analyses of the transitions 4s²4p^k-4s²4p^k-15s all the levels of the configurations 4p³, 4p²5s, 4p² and 4p5s are established in the spectra concerned.

The effect of the spatial resolution function of the spectrometer on beamfoil lifetime measurements is studied. Intensity curves obtained by convolution of the measured spatial resolution function and a sum of exponentials are compared with measured decay curves. Optimum spatial resolution functions are discussed and results of the analysis of decay curves obtained using different beam lengths viewed by the spectrometer are given, for two transitions presenting strong cascading: 3s3d³D-3s4f³F⁰ in SV (568 Å) and 3d²D-4f²F⁰ in S VI (465 Å).

HeI induced valence electron spectra of benzene and the hexafluorides of sulphur, molybdenum, tungsten and uranium are presented together with a HeII spectrum of sulphur hexafluoride. Vibrational band structure has been resolved in the spectra of all molecules and the energies of these bands are reported. A description is also given of the multichannel detector system which has facilitated the recordings of these spectra.

The boundary value problem of an anisotropic plasma half-space excitation by the given space-time distribution of sources is solved. The energy relations are determined for the spontaneous emission from a semi-bounded non-equilibrium plasma. The generalization of the well-known results of classical radiation theory is established (in particular, Kirchhoff's law) for the case of non-equilibrium emission from a half-space of anisotropic plasma.

The quasistatic surface excitation spectra are investigated in a one-component plasma with a low-density electron beam and in a non-isothermal electron-ion plasma with electron drift relative to the ions. The possible instability of such excitations and the anomal effective temperature growth for the quasistationary part of the spontaneous field are shown. The threshold values of the electron beam velocities for various branches of the surface excitations are calculated.

Neutron scattering measurements on dilute solutions, aqueous and nonaqueous, of polyethylene oxide are reported. No interaction of a hydrophobic or hydrophilic nature is detected in water. The spectra from polyethylene oxide molecules over almost the whole momentum transfer region can be explained in terms of Langevin diffusion models both for the translational and the rotational motion. At small momentum transfers (x < 0.5 A^-1) another molecular motion involving large amplitudes and small characteristic times should be included. This unknown motion may involve conformational changes of the molecule but also spontaneous fluctuations of its long axis.