Low-cost, pseudo-Halbach dipole magnets for NMR

We present designs for compact, inexpensive and strong dipole permanent magnets aimed primarily at magnetic resonance applications where prepolarization and detection occur at different locations. Low-homogeneity magnets with a 7.5 mm bore size and field up to nearly 2 T are constructed using low-cost starting materials, standard workshop tools and only few hours of labor – an achievable project for a student or postdoc with spare time. As an application example we show how our magnet was used to polarize the nuclear spins in approximately 1 mL of pure [$^{13}$C]-methanol prior to detection of its high-resolution NMR spectrum at zero field (measurement field below 10$^{-10}$ T), where signals appear at multiples of the carbon-hydrogen spin-spin coupling frequency $^{1}$J$_{CH}$=140.7(1) Hz.This work has received support from the European Research Council (author DS, grant agreement FP7-205119 R-EvolutioN-MR) and from the European Commission’s Seventh Framework Program (author MCDT under the Marie Curie International Outgoing Fellowship Programme, grant agreement FP7-625054 ODMR-CHEM; author DS, 2007–2013)

Real-Time Polarimetry of Hyperpolarized 13C Nuclear Spins Using an Atomic Magnetometer

We introduce a method for nondestructive quantification of nuclear spin polarization, of relevance to hyperpolarized spin tracers widely used in magnetic resonance from spectroscopy to in vivo imaging. In a bias field of around 30 nT we use a high-sensitivity miniaturized 87Rb-vapor magnetometer to measure the field generated by the sample, as it is driven by a windowed dynamical decoupling pulse sequence that both maximizes the nuclear spin lifetime and modulates the polarization for easy detection. We demonstrate the procedure applied to a 0.08 M hyperpolarized [1-13C]-pyruvate solution produced by dissolution dynamic nuclear polarization, measuring polarization repeatedly during natural decay at Earth's field. Application to real-time and continuous quality monitoring of hyperpolarized substances is discussed