ABSTRACT
In Chapter 8, a theory of quadrupolar lineshapes valid for an
arbitrary time-scale of molecular motion has been presented.
The theory uses the stochastic Liouville formalism. It has been
stressed that when the condition ωQτc < 1 (ωQ is the amplitude
of the quadrupole coupling, while τc denotes the correlation time
characterizing stochastic fluctuations of the quadrupole interaction)
is not fulfilled, one cannot explicitly define quadrupole relaxation
rates, although one can fully describe NMR spectra, linking their
shapes to the correlation time, τc. In this chapter we shall inquire
into how relaxation processes in systems consisting of spins I = 1/2 and P ≥ 1 coupled by dipole-dipole interactions are influenced by quadrupolar interactions of the P spin.
