Ultrasonically Induced Spin Transitions in Sodium Iodide

We have examined the influence of ultrasonic vibrations on the nuclear magnetization of sodium and iodine nuclei in a single crystal of sodium iodide. Our results support Sternheimer's calculations of quadrupole polarizability of ionic cores. In addition measurements made on the line width of the ultrasonic excitation effective in bringing about nuclear spin transitions show that the line width for iodine nuclei is narrower than the line width for the sodium nuclei. These results appear somewhat anomalous in the light of previous explanations of Pound, Watkins, and Reif.