High-Resolution Studies of Deuterium by Time-Domain Zero-Field NQR

Time-domain zero-field NQR methods are used to determine quadrupole coupling constants and asymmetry parameters for a variety of polycrystalhne solids. Results for aliphatic and aromatic groups are reported. Several cases are presented in which sites with small differences in quadrupole coupling constants are resolved, and very smah (CO. 1) asymmetry parameters are measured. Structure in the zero-field spectrum of diethylterephthalate due to dipolar couplings between inequivalent methylene deuterons is discussed; computer simulations of the experimental spectrum yield a reasonable assignment of the electric field gradient tensor orientations without the use of single crystals.