Elementary theory of electron spin-lattice relaxation (theory and methods of T1 measurements)

Abstract

Here the review article comes to an end; it dealt with some new ideas which may be interesting for physicists who are familiar with the magnetic resonance effects but not specialized in the field of relaxation. The theory was therefore built up elementarily. The experimental methods are described in sufficient detail. The author will be happy if he succeeded in arousing the readers' interest, who may then have recourse to more special papers as compiled in the reference list. We are sure that, although some thirty years have passed since Waller published his excellent paper [30], the investigations into the process of spin-lattice relaxation are still actual. The discovery of the masers and lasers focused the interest particularly to this field of research. A glance at the reference list shows us how many important papers are available published in the past years. The “bottle-neck phonons,” relaxation in ruby and rare earths, the discovery of new processes-all these problems are objects of active investigations carried out by a great number of scientists, among which we find outstanding specialists. None the less, there is, fortunately for the researchers, still much to do. The complexity of the problems' theory is considerable and many problems are so far unsolved. On the other hand, the measurement of relaxation times is a rather subtle procedure which often is not feasible. So there are all possibilities open for new technical ideas. The work in this field is known to be connected with difficulties but has also p promising future.