Table of contents

After a brief introduction in which the concepts of the magnetic and electric dipole moments of particles are introduced and questions are discussed associated with the discrete P and T transformations, the main part of the paper follows which consists of two sections. In the first of these the validity of quantum electrodynamics is analyzed on the basis of measurements of the anomalous magnetic moments of electrons and muons. Special emphasis is placed on experimental methods of measurement and on their historical development. The most detailed description is provided of three recent experiments: 1) measurement of (g – 2) for muons at CERN; 2) the spin resonance experiment on single electrons at the University of Washington; 3) the precise comparison of electron and positron magnetic moments carried out using the VEPP-2M storage ring at Novosibirsk. In the next section a review is given of the tests of CPT, CP, and T invariance from muon decay correlations and lifetime measurements. Finally the present status of experimental searches for an electric dipole moment (the existence of which would violate both P and T invariance) of electrons and muons is discussed.

The development of selective photoionization of atoms is reviewed. This is a very general method for laser isotope separation, and it has extremely interesting spectroscopic applications. Processes tending to restrict the applicability of the method are discussed. Examples cited include the use of selective photoionization to study the superior structure in atomic spectra, the resonance transfer of excitation energy, and the spectroscopy of atomic Rydberg states. Questions involved in laser isotope separation by selective photoionization are discussed.

A systematic review is given of the phenomenon of spin polarization in electronic and atomic collisions, which has recently been the subject of experimental investigation. These experiments are topical and important because polarization phenomena are associated with interference and thus constitute a very precise and sensitive means of investigating the structure and properties of matter and of analyzing physicochemical processes. A unified theory of polarization phenomena in electronic and atomic collisions, which includes an account of the most recent known experiments, is presented. The unified description is achieved with the aid of the scattering amplitude matrix and the spin density matrix formalism. Particular attention is devoted to processes in two-particle systems consisting of particles with spins 1/2 and 1. Processes involving a change in the spin of the target, which occurs as a result of exchange interactions, are characteristic for electron-atomic collisions. Exchange excitation of atoms and Penning ionization processes are examples of such collisions. The theory of polarization produced in such processes is reviewed and whenever possible, the results are compared with experimental data. Possible future applications of polarized electrons in the physics of electronic and atomic collisions are indicated.

The physical effects which result in the polarization of the electrons produced in the ionization of unpolarized atoms by an electromagnetic field in the optical frequency range are discussed. Attention is focused on the Fano effect and resonance many-photon ionization. Basic equations for the angular and polarization properties of the photoelectrons are derived. A corresponding experiment is described, and the results are compared with the theoretical predictions. The outlook for the use of these processes to develop sources of polarized electrons is discussed.

We review the literature on spectroscopic methods of studying processes of vibrational relaxation of molecules in condensed media; special attention is paid to liquids. We discuss the features and advantages of the following methods: spontaneous Raman scattering, picosecond spectroscopy, and active Raman spectroscopy. Comparison of the results obtained by the different methods yields detailed information on the course of relaxation processes.