Table of contents

The many-body perturbation theory (MBPT) is reviewed and applied to the atomic hyperfine interaction. Graphical methods are introduced by without mathematical details. The results are interpreted in terms of effective operators. For systems with a single valence electron-such as the alkali atoms-this operator has the same form as the ordinary hyperfine operator and is identical to the operator commonly used in the analysis of experimental hyperfine data. The origin of different contributions to this operator is discussed. Numerical results are given for the 2²S and 2²P states of the lithium atom, where accurate MBPT calculations have recently been performed. For systems with several valence electrons additional parameters are needed or, alternatively, the parameters of the one-body effective operator are allowed to be term-dependent. Recent experiments and corresponding theoretical investigations on alkaline-earth elements, with two valence electrons, are reviewed and, in particular, MBPT calculations on the calcium atom are discussed.

A review is given of the nucleation and growth processes occurring in thin film formation. Emphasis is given to quantitative nucleation theories and to the role of electron microscopy and surface techniques in providing data to test such theories. The relations between the thermodynamics of adsorption and the kinetics of crystal growth is stressed. Experimental examples are taken from the island growth, layer plus island (or Stranski-Krastanov) and layer growth modes. The shapes of growing crystallites are briefly discussed.