The role of electron polarization on nuclear spin diffusion

Abstract

Dynamic nuclear polarization (DNP) is capable of boosting signals in nuclear magnetic resonance by orders of magnitude by creating out-of-equilibrium nuclear spin polarization. The diffusion of nuclear spin polarization in the vicinity of paramagnetic dopants is a crucial step for DNP and remains yet not well understood. In this Letter, we show that the polarization of the electron spin controls the rate of proton spin diffusion in a DNP sample at 1.2 K and 7 T; at increasingly high electron polarization, spin diffusion vanishes. We rationalize our results using a 2 nucleus -1 electron model and Lindblad's Master equation, which generalizes preexisting models in the literature and qualitatively accounts for the experimental observed spin diffusion dynamics.

Quantitative analysis of cross-talk in partly deuterated samples of nuclear spins hyperpolarized by dynamic nuclear polarization (DNP) in the thermal mixing regime

“…As mentioned above, these are strongly coupled to the electrons and can be lumped together so that they contribute to the energy of the non-Zeeman electron reservoir, which then also acquires a larger heat capacity c NZ , and therefore a longer relaxation time. 31,48,53 Therefore, it is possible to fit a parameter f, such that Dc = fc H , where Dc is the heat capacity that is transferred from c H to c NZ . Accordingly, one must redefine c…”