Effects of higher-rank multipoles on spectral lineshapes of I = 3 2 quadrupolar nuclei near the null point in inversion-recovery experiments

The effects of higher-rank multipoles on the spectral lineshape of I = 3 2 quadrupolar nuclei have been examined near the null point in inversion-recovery measurements. ⁷Li NMR inversion-recovery experiments were performed on LiCl dissolved in isopropanol-d₈/D₂O solution at 225 K. The state multipole formalism approach was applied to interpret relaxation processes and analyze lineshapes. The experimental spectra could be simulated using a correlation time of 1.1 ns for the fluctuation of the direction of the electric field gradient at the ⁷/Li nucleus and a quadrupolar coupling constant of 42.7 kHz. The excellent agreements between observed and simulated spectra demonstrate that analysis of spectral lineshapes derived from inversion-recovery experiments provides a convenient way of determining the quadrupolar coupling constant and the fluctuation correlation time of the electric field gradient at the nucleus and of observing the dynamic frequency shift.