Multiple quantum NMR transitions of8Li (T 1/2=0.84 s) in single crystals and powders of LiTaO3, and the quadrupole moment of8Li

Multiple quantum nuclear magnetic resonance (NMR) transitions were observed on polarized⁸Li nuclei, which were produced by capture of polarized neutrons in a single crystal of LiTaO₃. The asymmetric⁸Liβ-radiation distribution was used for the detection of NMR. A quadrupole moment ratio ¦Q(⁸Li)/Q(⁷Li)¦=0.78(1) was determined. Saturation of multiple quantum transitions in nuclear radiation detected NMR may lead to a reduction in measuring time of up to two orders of magnitude, as compared to single quantum detection methods. The measured spectra agree well with an exact lineshape calculation. The same measurements were also performed on a LiTaO₃ powder sample. This was done to test a method to obtain quadrupole coupling constants from high field NMR multiple quantum powder patterns, which are easily detectable, also for higher nuclear spins. This latter method may be applicable also to conventional NMR detection techniques.