Influence of relaxation on the two-dimensional nutational nuclear-quadrupole-resonance spectra

The influence of relaxation and frequency detuning on the nutational frequency and the damping factor of a nutational interference pattern is analyzed. It is established that relaxation leads to decrease in nutational frequency, while detuning increases the nutation frequency. A relation is obtained between the relaxation times and the frequency detuning at which the influence of both factors cancels out. Conditions such that singularities of the nutational nuclear-quadrupole-resonance (NQR) spectrum (I = 3/2) may be resolved are determined, and a formula for the asymmetry parameter η is obtained, taking account of relaxation. Having determined the region of existence of nutation and established the conditions under which the singularities of the NQR spectrum of the powder (I = 3/2) may be resolved, the asymmetry parameter may be reliably determined from the experimental nutational spectrum of the powder. Experimental nutational 35Cl NQR spectra are given for TiCl4 and 2,4,6-trichloro-1, 3, 5-triazine. © 1999 Kluwer Academic/Plenum Publishers.