Ultrasonic Excitation of Nuclear Magnetic Energy Levels ofNa23in NaCl

Abstract

The nuclear magnetic levels of ${\mathrm{Na}}^{23}$ in a single crystal of NaCl placed in a strong magnetic field have been saturated by the pure quadrupole transition $\Delta m=2\mathrm{}$, caused by ultrasonic excitation. The observed transition rate has been compared with theoretical expressions to find that the electric field gradient generated at the nuclear site by the lattice distortion is very close to that expected from a simple classical model. Hence the large covalent and antishielding factor required to explain the spin-lattice relaxation time on the basis of the theory of Van Kranendonk is not found. Possible reasons for this discrepancy are discussed.