Optically induced dynamics nuclear spin polarization in diamond

Optically_induced_dynamics_1Magnetic resonance imaging (MRI) detects the tiny magnetic moment generated by the nuclear spin of hydrogen atoms in your body. Its sensitivity depends strongly on nuclear spin polarisation, i.e. the magnetisation of the body. Motivated by this observation, dynamical nuclear spin polarisation (DNP), the transfer of electron spin polarization to nuclear spins, has recently been applied to enhance MRI signal. Typically, large signal enhancements (hyperpolarization) require cryogenic temperatures (< 2 K) and bulky, specialized equipment for achieving first a high electron polarization. The Nitrogen-Vacancy defect (NV centre) in diamonds and diamond nanocrystals (nanodiamonds) provides a unique alternative for DNP as the NV centre electron spin can be optically polarized to over 90% polarization at room temperature by short laser pulses.
In our paper we demonstrate an efficient scheme that realises laser induced 13C nuclear spin hyperpolarization in a bulk diamond at room temperature and low ambient magnetic field. Importantly, our protocol is robust against an unknown alignment of the diamond crystal, making this a viable protocol for optical polarization of solutions of nanodiamond. This result gives rise to the possibility of using nanodiamonds, suitably treated to attach themselves to targets that we would like to detect, as MRI markers for molecular imaging applications.