CHEMICAL-SHIFTS IN MAGNETIC-RESONANCE OF THE HE-3 NUCLEUS IN LIQUID SOLVENTS AND COMPARISON WITH OTHER NOBLE-GASES

Gas-to-solution solvent shifts of 3He dissolved in 17 pure liquids were measured. Two types of samples were used, under helium pressures of about 2 and 30 atm. No measurable pressure effect on the shift could be detected. The gas-to-solution shifts are dominated by the bulk susceptibility, for which correction was made. The resulting medium-shift range in our solvents is about 0.8 ppm. Hence 3He provides an excellent probe for the detection of minute local magnetic fields at the site of noble-gas atoms. For the first time shifts in liquid solvents for all four NMR-accessible noble-gas nuclei (3He, 21Ne, 83Kr, and 129Xe) can be compared. The medium shifts of 3He show a roughly linear correlation to medium shifts of 129Xe, 83Kr, and 21Ne in the same solvents. The corrected relative solvent shifts, that is, the solvent effects divided by σd, the diamagnetic shielding of the free atom, and by the number of nearest-neighbor solvent molecules, are approximately equal for all four noble gases. © 1993 by Academic Press, Inc.