Dynamic Nuclear Polarization (DNP) is a powerful suite of techniques that deliver multifold signal enhancements in nuclear magnetic resonance (NMR) and MRI. The generated athermal spin states can also be exploited for quantum sensing and as probes for many-body physics. Typical DNP methods require the use of cryogens, large magnetic fields, and high power microwave excitation, which are expensive and unwieldy. Nanodiamond particles, rich in Nitrogen-Vacancy (NV) centers, have attracted attention as alternative DNP agents because they can potentially be optically hyperpolarized at room temperature. Here, unraveling new physics underlying an optical DNP mechanism first introduced by Ajoy et al. [Sci. Adv. 4, eaar5492 (2018)], we report the realization of a miniature "optical nanodiamond hyperpolarizer," where 13C nuclei within the diamond particles are hyperpolarized via the NV centers. The device occupies a compact footprint and operates at room temperature. Instrumental requirements are very modest: low polarizing fields, low optical and microwave irradiation powers, and convenient frequency ranges that enable miniaturization. We obtain the best reported optical 13C hyperpolarization in diamond particles exceeding 720 times of the thermal 7 T value (0.86% bulk polarization), corresponding to a ten-million-fold gain in averaging time to detect them by NMR. In addition, the hyperpolarization signal can be background-suppressed by over two-orders of magnitude, retained for multiple-minute long periods at low fields, and deployed efficiently even to 13C enriched particles. Besides applications in quantum sensing and bright-contrast MRI imaging, this work opens possibilities for low-cost room-temperature DNP platforms that relay the 13C polarization to liquids in contact with the high surface-area particles.

中文翻译：

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室温“光学纳米金刚石超偏振器”：物理、设计和操作

动态核极化 (DNP) 是一套强大的技术，可在核磁共振 (NMR) 和 MRI 中提供多重信号增强。产生的无热自旋态也可用于量子传感和多体物理学的探针。典型的 DNP 方法需要使用致冷剂、大磁场和高功率微波激发，这些方法既昂贵又笨拙。富含氮空位 (NV) 中心的纳米金刚石颗粒作为替代 DNP 剂引起了人们的注意，因为它们可能在室温下发生光学超极化。在这里，解开 Ajoy 等人首次引入的光学 DNP 机制背后的新物理学。[科学。高级 4, eaar5492 (2018)]，我们报告了微型“光学纳米金刚石超偏振器”的实现，其中金刚石颗粒内的 13C 核通过 NV 中心被超极化。该设备占地面积小，可在室温下运行。仪器要求非常适中：低偏振场、低光学和微波辐射功率以及便于小型化的频率范围。我们在金刚石颗粒中获得了最佳报道的光学 13C 超极化，超过了热 7 T 值的 720 倍（0.86% 体极化），对应于通过 NMR 检测它们的平均时间增加了 1000 万倍。此外，超极化信号可以被背景抑制超过两个数量级，在低场下保留多分钟长时间，甚至可以有效地部署到 13C 富集粒子。除了在量子传感和明亮对比度 MRI 成像中的应用，