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 u sed to measure simultaneously the two nuclear Spin transition frequenc ies for the iodine resonance of cadmium iodide at zero;magnetic field. Because of the layer structure and resultant polymorphism in this sub stance, conventional zero-field NMR spectra are inhomogeneously broade ned by several hundred kHz. However, the 2D spectra obtained by our me thod are subject only to homogeneous linewidth, which for this compoun d is of the order of 5 kHz. This greatly increased precision allows mo re accurate evaluation of the nuclear hexadecapole coupling in cadmium iodide; which we measure as 0.216+/-0.514 kHz (i.e., indistinguishabl e from zero). This gives a maximum value of the nuclear hexadecapole m oment several times lower than that recently reported for the same nuc leus in potassium iodide.