Abstract
In conclusion, I believe it fair to say that the marriage of ultrasonics and magnetic resonance holds promise of being a productive one. In the application of these disciplines to nuclear spins, little more has been done than to demonstrate the acoustic techniques and to apply them to a particular problem of quadrupolar coupling in the heavy alkali halides. Particularly promising is the extension of acoustic NMR techniques to bulk metals, to ferromagnetic crystals, and to the study of spin-lattice relaxation as a function of temperature. In the technique of phonon coupling to electron spins in paramagnetic materials, also, the reports to date have all been of a preliminary nature. Used in combination with the powerful new hypersonic technique of generating microwave acoustic waves, electron spin-phonon interaction measurements may help to resolve some of the present confusion regarding the mechanisms of spin-lattice relaxation in paramagnetic solids (29).