Transient magnetic resonance without RF pulses: Fast field switching

An unusual strategy for performing magnetic resonance experiments is demonstrated. Instead of employing conventional radiofrequency transmitter fields to perturb spin state populations away from equilibrium, as is the basis of most magnetic resonance spectrometers today, technological advances now make possible fast switching of the magnetic field orientation to achieve the same effect. This is demonstrated with an electron spin resonance experiment where the magnetic field is switched 90 degrees nonadiabatically with a dead time of a few tens of nanoseconds and an electron free induction decay observed. (C) 1999 Academic Press.