Ultrasonic spin echoes

Generation and detection of ultrasonic spin echoes (phonon echoes) and of ultrasonically induced rf magnetic field spin echoes are reported. With the latter, signal-to-noise improvements of 2 orders of magnitude were found over direct ultrasonic absorption spectroscopy. The effects of momentum conservation selection rules are discussed, as are properties and applications of the various echoes. © 1972 The American Physical Society.