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Spacechem magic8/14/2023 ![]() ![]() Simulations performed on model, static, samples have shown that the microwave power is non-uniformly distributed in the magic angle spinning (MAS) rotor when using conventional dynamic nuclear polarization (DNP) instrumentation. As a result, this new software is employed to investigate the MAS speed dependence of the enhancement factors in large spin systems where spin diffusion is of importance, as well as to investigate the impacts of solvent and polarizing agent deuteration on the performance of MAS DNP. As the propagator cannot be stored, a Monte Carlo optimization method is used to determine the steady-state enhancement factors. The Landau-Zener equation is used to treat all interactions concerning electron spins, and the low-order correlations in the Liouville space method is used to accurately treat the more » spin diffusion, as well as its MAS speed dependence. Here, we present the first approach to fully ab initio large-scale simulations of MAS DNP enhancements. The simulation of DNP processes which might, for example, aid in refining the experimental conditions or the design of better performing polarizing agents, is, however, plagued with significant challenges, often limiting the system size to only 3 spins. Magic-angle-spinning (MAS) dynamic nuclear polarization (DNP) has recently emerged as a powerful technology enabling otherwise unrealistic solid-state NMR experiments. Finally, we then apply it to predict the DNP enhancements in core–shell metal-organic-framework nanoparticles and reveal new insights into the composition of the particles’ shells. We show that this model can reproduce the MAS rate and concentration dependence of DNP enhancements and build-up time constants. We build on more » this work by using ab initio simulations to train a hybrid model that makes use of a rate matrix to treat nuclear spin diffusion. We recently developed an ab initio model capable of calculating DNP enhancements in systems of up to ~1000 nuclei however, this scale is insufficient to accurately simulate the dependence of DNP enhancements on radical concentration or magic angle spinning (MAS) frequency. This scale prevents us from gaining a complete understanding of the spin dynamics and applying simulations to design sample formulations. ![]() Fundamentally, DNP involves ensembles of thousands of spins, a scale that is difficult to match computationally. Solid-state nuclear magnetic resonance can be enhanced using unpaired electron spins with a method known as dynamic nuclear polarization (DNP).
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