Detection of long-range dipole–dipole interactions between nuclear spins in distant solids

Prior work demonstrated that a given nuclear spin subset in a fluid can be monitored via the NMR signal from another, non-chemically bonded subset, even if within a separate container. Here we report an extension of these results to the case in which both ‘sample’ and ‘sensor’ spin systems are solids. For the present demonstration, we use the 71Ga signal from GaAs to detect the nuclear dipolar field induced by proton spins from an adjacent organic sample. Multipulse decoupling sequences are used to minimize homo- and heteronuclear couplings within the ‘sensor’ while preserving the long-range interaction with the proton field. Potential applications of this result are briefly discussed.