Determination of the dipolar interaction of 23Na in solution by triple-quantum relaxation time measurements

The measurement of the dipolar interaction of Na-23 with hydrogen nuclei in glycerol solution is reported. The method, applied previously to Li-7 (U. Eliav and G. Navon, J. Magn. Reson. A 123, 32 (1996)), is based on the measurement of the triple-quantum relaxation time of Na-23. Several models of motion are discussed. The analysis of the results yielded 1.9 MHz and 12.5 kHz for the quadrupolar and the Na-23-H-1 dipolar interaction, respectively. It is shown that under the conditions of long correlation times the triple-quantum relaxation time can be sensitive to dipolar interactions smaller than the quadrupolar interaction by as much as a factor of 5000. This indicates the possibility of measuring interatomic distances for nuclei with sizable quadrupolar moments. (C) 1998 Academic Press.