Spectrometer for external detection of magnetic and related double resonance

In double resonance spectrometer apparatus including, a probe containing first abundant and second rare spin systems which are adapted to undergo gyromagnetic transitions due to dipolar coupling between abundant and rare spins at respective different gyromagnetic resonance frequencies, means for producing a unidirectional polarizing magnetic field through said probe in a predetermined direction, means for producing resonance transitions in both spin systems at different frequencies comprising first and second means respectively establishing first and second alternating magnetic fields substantially perpendicular to said predetermined direction of the polarizing magnetic field and substantially at the respective gyromagnetic frequency of said first and second spin systems, and means responsive to the resonance of said first spin system for detecting the resonance in said second spin system, the improvement comprising:

• first material containing said first spin system;
• and second but separate material containing said second spin system, wherein said first means establishing said first alternating magnetic field influences said first material and said second means establishing said second alternating magnetic field influences said second material and wherein said first and second means comprises coils respectively surrounding said first and second material.