Excitation phenomena and line intensities in high-resolution NMR powder spectra of half-integer quadrupolar nuclei

Abstract

A theoretical analysis of the general excitation phenomena of half-integer $I>\frac{1}{2}$ nuclear spins in a strong radio-frequency field shows that coherence between the affected spin states leads to complicated time behavior of the total nuclear magnetization. Very short excitation pulses lead to quantitatively useful high-resolution NMR spectra of quadrupolar nuclei in powder samples spun at the magic angle, while selective spin-state time development during longer rf pulses permits the use of two-dimensional Fourier-transform NMR techniques with simultaneous measurement of the isotropic chemical shifts and the corresponding quadrupole interaction parameters.