The First Experiments (ca. 1945)

Felix Bloch (1905-1983)		Edward Purcell (1912-1997)

"I have not yet lost a feeling of wonder, and of delight, that this delicate motion should reside in all the ordinary things around us... I remember... looking on snow with new eyes. There the snow lay around my doorstep - great heaps of protons quietly precessing in the earth's magnetic field. To see the world for a moment as something rich and strange is the private reward of many a discovery.

But I am afraid it has little bearing on the sober question we must, as physicists, ask ourselves: What can we learn from all this about the structure of matter? "

Edward Purcell

Nobel Lecture, 1952

The Bloch 'cross-coil' design and nuclear induction

- No signal in the receiver unless the sample participates.

- That only occurs at a specific transmitter radiofrequency.

On resonance	Not on resonance