NOISE EXCITATION OF HALF-INTEGER QUADRUPOLAR SPINS AT HIGH-FIELD

Quadrupolar parameters for half-integer nuclear spins are often derive d by an analysis of the second-order broadening superposed on the cent ral transition spectrum. Under typical conditions, where the exciting radiofrequency fields are weaker than first-order quadrupolar splittin gs, distortions in lineshape and intensity are difficult to avoid. We apply stochastic excitation to these systems and demonstrate that undi storted lineshapes can be observed independent of the magnitude of the quadrupolar interaction. This should provide a significant improvemen t in quantitative measures of nuclear spin densities.