Dynamic polarization of 13C nuclei in solid 13C labeled pyruvic acid

Optimizing dissolution dynamic nuclear polarization

“…This time constraint becomes increasingly unreasonable for the hyperpolarization of lowgamma nuclei using trityl. For example, build-up time constants as long as s DNP ( 13 C) = 95 min were measured at 5 T and 930 m K using this polarizing agent [35]. On the other hand, DNP of highgamma nuclei ( 1 H, 19 F) at high magnetic fields can improve the maximal polarization while the polarization times remain reasonably short.…”

“…It is therefore debatable if increasing the magnetic field could provide any improvement in DNP efficiency. Still, several studies at 2.5, 4.5 and 5 T with trityl [34,35] and at 5 T with TEMPO [36] have clearly indicated that the nuclear spin polarization improves as the magnetic field increases, albeit at the price of longer build-up time constants. This time constraint becomes increasingly unreasonable for the hyperpolarization of lowgamma nuclei using trityl.…”

Cluster formation restricts dynamic nuclear polarization of xenon in solid mixtures

“…3,4 Unlike optical pumping techniques, 5,6 DNP is performed in the solid state, with 1000 times higher 129 Xe density and, potentially, higher production rates. 129 Xe DNP builds upon the earlier success of low-temperature DNP of 13 C-labelled biomolecules, where high 13 C polarization (15%−75%) 7 is retained at room temperature after a rapid dissolution. 8 However, in the previous DNP studies, 129 Xe polarization has varied widely and is still inferior to that of [1-13 C]pyruvate.…”

“…8 However, in the previous DNP studies, 129 Xe polarization has varied widely and is still inferior to that of [1-13 C]pyruvate. 7,9 One of the reasons may be a lack of experimental probes to access the microscopic DNP parameters described by recent theories. 10,11 Another reason is a poorly understood process of forming a solid sample from a gaseous ingredient.…”

The role of the glassy dynamics and thermal mixing in the dynamic nuclear polarization and relaxation mechanisms of pyruvic acid

“…In order both to optimize and to validate novel theoretical models of TM, several investigations of the nuclear and electron relaxation processes around 1.2 K have been performed. The effect of relevant parameters, including the radical concentration [14][15][16], the concentration of gadolinium complexes [14,17], the nuclear concentration [18,19], the amount of matrix deuteration [20], the effect of microwave saturation and the field strength [15,16,21] on the DNP performances of this molecule have been experimentally studied. Remarkably very recently, the relevance of these physical quantities on DNP kinetics has also been considered in the development of novel models describing TM throughout a rate equation approach [19,22,23].…”