Theory of Collisional Spectropolarimetric Effects

Abstract

A principal physical assumption underlying the mathematical formalism used to describe polarization effects is the concept of an ensemble of atomic particles (atoms, ions, molecules) in mixed states. These states are described by linear combinations of the wave functions, corresponding to the stationary states. A complete system could be represented mathematically in this case in terms of the density matrix, which is obtained by means of statistical averaging of the states of particular atoms. The density matrix formalism is widely used for the theoretical analysis of interference phenomena of atomic states^(33,36,102) In order to account in the most adequate way for the symmetry of a system, which could be specified within the framework of many typical problems related to the polarization of an atomic ensemble and the spectropolarimetric effects of its radiation, and to model many real physical situations, it is convenient to consider the density operator in the basis within which the irreducible representations of the rotational group are realized. The matrix elements in this representation are known as polarization moments.