Relaxation in Multispin Systems

For multispin systems in which mixing of nuclear spin states occurs owing to dipolar couplings among deuterons, the relaxation is influenced by crosscorrelation terms between individual quadrupolar interaction tensors in addition to the auto-correlation terms [5.17, 5.30]. It is reasonable to expect that these cross-correlation terms may provide additional information on the motional processes. The static Hamiltonian Hq for two deuterons is 

FIGURE 5.2. Typical deuterium NMR spectrum obtained at 15.3 MHz of 5CB-di5 (upper trace) and MBBA-dis (lower trace). The peak assignments are carbon numbers referred in Fig. 5.3. 

the cross-products between Hamiltonian matrix elements of different rriL values are ignored in Eq. (5.50) when there is cylindrical symmetry 

FIGURE 5.3. A schematic diagram of a 5CB-di5 (upper) and a MBBA-dia (lower) molecule, showing the carbon labeling. 0 refers to the deuterated ring in 5CB. 

---

L. G. Werbelow and D. M. Grant, "Intramolecular dipolar relaxation in multispin systems" in Advances in Magnetic Resonance, vol. 9, edited by J. S. Waugh (Academic Press, New York, 1977), pp. 83-144. 

---