Effects of higher rank multipoles on relaxation of an I = 3 spin system

Magnetic multipoles of rank higher than one become active in spin systems with I > 1/2 and their contribution to relaxation depends on dynamics. The appearance of multipole terms complicates the relaxation description and supports the multiexponential behavior of relaxation. In this paper the effects of high-rank multipoles on lineshape and longitudinal relaxation of I = 3 spin systems are presented. Results obtained from both numerical simulation and experimental data show that longitudinal and transverse relaxation are strongly influenced by these multipole terms, especially at lower temperature where, due to lower molecular mobility, the extreme narrowing condition is not fulfilled.