THE NUCLEAR HEXADECAPOLE INTERACTION OF I-127 IN CADMIUM IODIDE MEASURED USING ZERO-FIELD 2-DIMENSIONAL NUCLEAR-MAGNETIC-RESONANCE

Two dimensional nuclear quadrupole correlation spectroscopy has been used to measure simultaneously the two nuclear Spin transition frequencies for the iodine resonance of cadmium iodide at zero;magnetic field. Because of the layer structure and resultant polymorphism in this substance, conventional zero-field NMR spectra are inhomogeneously broadened by several hundred kHz. However, the 2D spectra obtained by our method are subject only to homogeneous linewidth, which for this compound is of the order of 5 kHz. This greatly increased precision allows more accurate evaluation of the nuclear hexadecapole coupling in cadmium iodide; which we measure as 0.216+/-0.514 kHz (i.e., indistinguishable from zero). This gives a maximum value of the nuclear hexadecapole moment several times lower than that recently reported for the same nucleus in potassium iodide.