Piezoelectric signal suppression by a composite-pulse sequence in NMR

Numerous NMR techniques are available for the study of nuclei with spin I > =1. These nuclei interact with their surrounding electric field gradient, which depends on the symmetry of the crystallographic site. Spurious (or piezoelectric) signals, due to the piezoelectric and ferroelectric properties of a LiNbO3 crystal and generated by the vibration of the macroscopic electric dipole of the crystal, have been observed with the one-pulse sequence and cancelled using a composite-pulse sequence. The suppression of these piezoelectric signals by this sequence is illustrated by lithium-7 (I=3/2) nuclei. Java applets available in our web site www.pascal-man.com for the determination of quadrupole parameters from one-dimensional nutation method are also presented.