Categorization of Relaxation Phenomena

Abstract

Spin relaxation, according to its very definition, is ubiquitous in magnetic resonance. The prerequisite of the detection of any magnetic-resonance signal is a nonequilibrium state of the spin systems which must be excited before. Principally, such athermal states are subject to relaxation processes. That is, all pulse sequences so far considered in the first part of this book can also be viewed as relaxation experiments although we have neglected any influence of this sort in the formal treatments up to now. Actually some of these pulse sequences were originally developed to the end of relaxation studies. Further experimental schemes suitable for the record of relaxation curves are given in Table 10.1 on 93 and in Chaps. 15 and 17. In view of the vast variety of relaxation-sensitive experiments it appears to be more favorable to classify spin relaxation via the relevant observable rather than via the experimental set-ups by which it is probed.