Spin decoupling in gyromagnetic resonance apparatus

Claim 1

A GYROMAGNETIC APPRATUS COMPRISING: A PROBE CONTAINING A SAMPLE OF A FIRST GROUP OF ATOM PORTIONS TO BE OBSERVED AND A SECOND GROUP OF ATOM PORTIONS; MEANS FOR APPLYING A POLARIZING MAGNETIC FIELD TO SAID SAMPLE; FIRST RADIO FREQUENCY FIELD MEANS FOR APPLYING TO SAID SAMPLE AN ALTERNATING MAGNETIC FIELD AT A FREQUENCY W1, SUBSTANTIALLY EQUAL TO THE LARMOR FREQUENCY OF SAID FIRST GROUP IN SAID POLARIZING FIELD FOR ALGINING THE FIRST GROUP IN AN ORBITAL PLANE SUBSTANTIALLY PERPENDICULAR TO THE POLARIZING FIELD; MEANS INCLUDIG A MODULATION OSCILLATOR FOR MODULATING THE POLARIZING FIELD; MEANS INCLUDING AMPLIFYING MEANS COUPLED TO THE PROBE FOR OBTAINING A RESONANCE SIGNAL FROM SAID PROBE; PHASE DETECTOR MEANS COUPLED TO SAID AMPLIFIER MEANS AND TO SAID FIRST RADIO FREQUENCY FIELD MEANS TO PROVIDE AN AUDIO FREQUENCY OUTPUT SIGNAL AS A MEASURE OF SAID RESONANCE SIGNAL; AN AUDIO FREQUENCY PHASE DETECTOR COUPLED TO SAID PHASE DETECTOR MEANS AND TO SAID MODULATION OSCILLATOR FOR PRODUCING A D.C. VOLTAGE; MEANS FOR RECORDING SAID D.C. VOLTAGE; SECOND RADIO FREQUENCY FIELD MEANS FOR APPLYING TO SAID SAMPLE AN ALTERNATING MAGNETIC FIELD AT A FREQUENCY W2 SUBSTANTIALLY EQUAL TO THE LARMOR FREQUENCY OF SAID SECOND GROUP IN SAID POLARIZING FIELD FOR SPIN DECOUPLING THE ATOM PORTIONS OF THE SECOND GROUP FROM THE ATOM PORTIONS OF THE FIRST GROUP; AND THIRD RADIO FREQUENCY MAGNETIC FIELD AT A FREQUENCY W3 FOR COMPENSATING FOR THE TILTING EFFECT OF THE SECOND RADIO FREQUENCY DECOUPLING MEANS ON THE FIRST GROUP, AND FOR PREVENTING RECOUPLING OF THE SPINS OF SAID TWO GROUPS, SAID FREQUENCIES W2 AND W3 BEING SELECTED SO THAT W1 IS BETWEEN W2 AND W3.