Simultaneous Detection of H and D NMR Signals in a Micro-Tesla Field

We present NMR spectra of remote-magnetized deuterated water, detected in an unshielded environment by means of a differential atomic magnetometer. The measurements are performed in a μT field, while pulsed techniques are applied - following the sample displacement - in a 100 μT field, to tip both D and H nuclei by controllable amounts. The broad-band nature of the detection system enables simultaneous detection of the two signals and accurate evaluation of their decay times. The outcomes of the experiment demonstrate the potential of ultra-low-field NMR spectroscopy in important applications where the correlation between proton and deuteron spin-spin relaxation rates as a function of external parameters contains significant information.