2. Gradient field NMR

2.1 Principle of NMR

NMR is concerned with the dynamics of nuclear spins (kinetic moments). The spin of a particle such as an atomic nucleus is quantum in nature, with no classical equivalent. In the general case, a rigorous quantum mechanical treatment is required, there are however many cases where a "classical" approach is sufficient, especially for a ½ spin when the effects of mutual interactions between neighboring spins can be neglected. This is the case for the majority of the techniques discussed in this article.

In this chapter, we present a classical approach to the phenomenon of resonance, treating the spin variable as a classical angular momentum, represented by a vector. This approach allows us to grasp the principle of NMR intuitively and...