Mixtures of water and glycerol provide popular matrices for low‐temperature spectroscopy of vitrified samples. However, they involve counterintuitive physicochemical properties, such as spontaneous nanoscopic phase separations (NPS) in solutions that appear macroscopically homogeneous. We demonstrate that such phenomena can substantially influence the efficiency of dynamic nuclear polarization (DNP) by factors up to 20 % by causing fluctuations in local concentrations of polarization agents (radicals). Thus, a spontaneous NPS of water/glycerol mixtures that takes place on time scales on the order of 30–60 min results in a confinement of polarization agents in nanoscopic water‐rich vesicles, which in return affects the DNP. Such effects were found for three common polarization agents, TEMPOL, AMUPol and Trityl.

中文翻译：

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样品通过纳米相分离而成熟会影响动态核极化的性能

水和甘油的混合物为玻璃化样品的低温光谱学提供了流行的基质。但是，它们涉及违反直觉的理化性质，例如在宏观上看起来均匀的溶液中的自发纳米相分离（NPS）。我们证明，这种现象可以通过引起极化剂（自由基）的局部浓度波动，而对高达30％的因子产生实质性影响，对动态核极化（DNP）的效率产生实质性影响。因此，水/甘油混合物的自发NPS发生在30-60分钟左右的时间范围内，导致极化剂被限制在纳米级富水囊泡中，这反过来又影响了DNP。对于三种常见的极化剂，TEMPOL，AMUPol和Trityl，发现了这种效果。