Direct measurement of transverse relaxation time of intermolecular multiple quantum coherences in NMR

A one-dimensional NMR method is presented for measuring the transverse rela xation time, T-2,(n), of intermolecular multiple quantum coherences (IMQCs) of coherence order n, in highly polarized spin systems. The pulse sequence proposed in this paper effectively suppresses the effects of radiation dam ping, molecular diffusion, inhomogeneity of magnetic field, and variations of dipolar correlation distance, all of which may affect quantitation of T2 ,n This pulse sequence can be used to measure not only IMQC transverse rela xation time T2,(n)(n > 1) quickly and directly, but also the conventional t ransverse relaxation time. Experimental results demonstrate that the quanti tative relationship between T-2,(n)(n > 1) and T-2 is T-2,(n) approximate t o T-2/n. These results will be helpful for understanding the fundamental pr operties and mechanisms of IMQCs.