The Theory of Coupling Constants
As we have implied already, when we observe the spin of a particle it is invariably in an electromagnetic environment. In particular it is surrounded by other particles, at various distances, which may or may not have spins, and it is the interactions between the particle’s spin and other spins which we shall examine in this chapter. To a good approximation these interactions, which are responsible for hyperfine splitting of the resonance spectrum, are independent of the applied field, so we do not have to introduce the field into the discussion. Also since the electronic orbital angular momentum is effectively quenched in the molecules and radicals which we shall consider, we shall not be including the interactions between spins and the orbital motion of the electrons. Furthermore most of our examples will be about radicals or molecules in solution, when the anisotropic dipole-dipole interaction between the spins averages to zero, so in these cases we shall consider only the Fermi contact term in trying to rationalize the empirical data.
KeywordsSpin Density Atomic Orbital Hyperfine Splitting Canonical Structure Coupling Tensor
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