Rotational Resonance in milli-tesla fields detected by Field Cycling NMR

Rotational Resonance (R(2)) between different spin Zeeman levels in samples of adamantane C(10)H(16) (homonuclear R(2)) and a mixture of C(10)H(16) and C(10)D(16) (both homonuclear and heteronuclear R(2)) has been studied. A Field Cycling NMR instrument was used to match the external field frequency ν(0) to a fixed frequency of sample rotation ν(r) at ν(r) = 40, 50 or 60 kHz. Rotational Resonance is observed at rational frequency ratios of ν(0)/ν(r), such as 12, 23, 32 and 1. The method may prove to become a useful tool for the determination of spin-spin distances in condensed matter.