Method and System for Dynamic Nuclear Polarization of Frozen Gases

Nicholas N. Kuzma¹, Mehrdad Pourfathi¹, Hoora Shaghaghi¹, Rajat Kumar Ghosh¹, Stephen J. Kadlecek¹, Rahim Rizi¹

We describe a new general approach for producing highly spin-polarized frozen gases, such as ¹²⁹Xe, ¹³CO₂, and ¹⁵N₂O, for magnetic resonance imaging. Each gas is liquefied and mechanically mixed with a free radical (trityl) dissolved in a liquid glassing agent (1-propanol) at a specific temperature and pressure. Molecular diffusion both in the liquid and in the solid state can cause self-segregation of these mixtures into pure frozen-gas clusters surrounded by the well-mixed matrix. We report the effects of the annealing temperature during the sample preparation on the subsequent T₁ relaxation times and on the efficiency of the DNP process in the ¹⁵N₂O system and contrast these new findings with our earlier ¹²⁹Xe results.