Hyperpolarization
One of the few disadvantages of the NMR method is its comparatively low sensitivity. However, we can improve NMR signals by several orders of magnitude using various hyperpolarization (HP) methods. With these methods, the low equilibrium polarization of nuclear spins at room temperature can be increased from 10-5 to the order of 1 in favorable cases.
Dynamic Nuclear Polarization (DNP)
In dynamic nuclear polarization (DNP), the higher polarization of electron spins is transferred to surrounding nuclear spins by the hyperfine interaction. We use as polarization agents matrices on which stabilized radicals are immobilized. The excitation of the electron spins and thus the transfer of polarization to nuclear spins takes place in special probe heads, which we are currently working on. This project is carried out within the SFB 1527 (High Performance Compact Magnetic Resonance - HyPERiON) in cooperation with the Karlsruhe Institute of Technology.
Parahydrogen-Induced Hyperpolarization (PHIP)
Para-hydrogen induced polarization (PHIP) is a chemically based hyperpolarization method based on reactions or interactions of molecules with para-hydrogen. Parahydrogen is the thermodynamically preferred spin isomer of molecular H2, which is almost exclusively present in molecular H2 at low temperatures (about 30 K). Upon transfer of the p-H2 to an unsaturated molecule in the context of a catalyzed hydrogenation reaction, a strong overpopulation of the two 1H nuclear spin states occurs, corresponding to the symmetry of the p-H2. A planned project in this context is the investigation of hydrogenation reactions in fixed-bed reactors with respect to conversion efficiency and mass transfer, which can be spatially resolved in the MRI system.
