Quadrupole Coupling Tensor for 11B in Datolite

Abstract

The electric quadrupole splitting of the 11B nuclear magnetic resonance signal have been studied in a single crystal of datolite (H Ca B SiO5) placed in a magnetic field of 6350 Gauss and the methods developed by Volkoff and coworkers have been used to analyse the data. The space group of datolite, P 2 1/C, permits two different orientations of the otherwise identical quadrupole coupling tensors existing at the four boron sites in the unit cell. The observed five line 11B (I = 3/2) spectrum is consistent with the crystal symmetry. The quadrupole coupling constant, eqQ/h, and asymmetry parameter, η, at the unique boron site have been determined as well as the orientation of the principal axes of the electric field gradient tensor. The value of 172±1 Kc/sec found for eqQ/h in datolite is consistent with the overall range of values observed for BO4 tetrahedra in other crystals.