ANALYSIS OF SIGNAL-TO-NOISE RATIOS FOR NOISE EXCITATION OF QUADRUPOLAR NUCLEAR SPINS IN ZERO-FIELD

Noise excitation has been applied to the problem of a spin-3/2 quadrup olar nuclear spins in zero magnetic field. We demonstrate that high-se nsitivity spectra can be observed with very weak rf pulses and that th e growth in signal intensities follows a universal curve which is simp ly related to the applied pulse angle, the spacing between those pulse s, and the T-1 of the nuclear spin system. These signal intensites are closely related to those observed in NMR experiments exploiting simil ar excitation sequences. Such sequences have numerous practical advant ages and in particular may be applied to large volume samples, or to n uclear spins which interact only weakly with magnetic fields, without sacrifice in either spectral bandwidth or signal intensity.