Interference of Atomic States

In this monograph we describe an important and relatively new class of phenomena in the field of high-resolution atomic spectroscopy: the interference effects manifest in the angular distribution and polarization of spontaneous radiation and absorption by atoms. Although the quantum-theoretical descrip tion of these interference effects is quite subtle, it turns out - as so often in quantum mechanics - that a simple classical or semi-classical description offers much insight and can even explain quantitative features. In this presentation, however, we attempt to give the full story. Beginning with the simple semi classical description, we then present the quantum-mechanical analysis based on the density-matrix formalism and the statistical tensor. The remaining two chapters discuss experimental observations and data analysis. A great variety of effects have now been observed and can be used to obtain highly accu rate information about hyperfine structure, atomic constants, interaction con stants, etc. The authors have assumed only a basic knowledge of quantum mechanics and electromagnetism, thus making the book accessible to those beginning a graduate studies program. It is also aimed at practising spectroscopists and all researchers for whom atomic spectroscopy is an important tool - for these readers it will hopefully offer some new solutions and ideas for furthering their research. February 1993 E. B. Alexandrov M. P. Chaika G. I. Khvostenko Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2. Classical Description of Interference Phenomena in Radiation 2. 1 The Classical Oscillator Model of Atomic Emission . .