Signal amplification by reversible exchange (SABRE) boosts NMR signals of various nuclei enabling new applications spanning from magnetic resonance imaging to analytical chemistry and fundamental physics. SABRE is especially well positioned for continuous generation of enhanced magnetization on a large scale; however, several challenges need to be addressed for accomplishing this goal. Specifically, SABRE requires (i) a specialized catalyst capable of reversible H₂ activation and (ii) physical transfer of the sample from the point of magnetization generation to the point of detection (e.g., a high-field or a benchtop nuclear magnetic resonance [NMR] spectrometer). Moreover, (iii) continuous parahydrogen bubbling accelerates solvent (e.g., methanol) evaporation, thereby limiting the experimental window to tens of minutes per sample. In this work, we demonstrate a strategy to rapidly generate the best-to-date precatalyst (a compound that is chemically modified in the course of the reaction to yield the catalyst) for SABRE, [Ir(IMes)(COD)Cl] (IMes = 1,3-bis-[2,4,6-trimethylphenyl]-imidazol-2-ylidene; COD = cyclooctadiene) via a highly accessible synthesis. Second, we measure hyperpolarized samples using a home-built zero-field NMR spectrometer and study the field dependence of hyperpolarization directly in the detection apparatus, eliminating the need to physically move the sample during the experiment. Finally, we prolong the measurement time and reduce evaporation by presaturating parahydrogen with the solvent vapor before bubbling into the sample. These advancements extend opportunities for exploring SABRE hyperpolarization by researchers from various fields and pave the way to producing large quantities of hyperpolarized material for long-lasting detection of SABRE-derived nuclear magnetization.

中文翻译：

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通过原位检测实现大规模稳态增强核磁化

通过可逆交换 (SABRE) 进行的信号放大可增强各种核的 NMR 信号，从而实现从磁共振成像到分析化学和基础物理学的新应用。SABRE 特别适合大规模连续产生增强磁化；然而，要实现这一目标，需要解决若干挑战。具体来说，SABER 需要 (i) 一种能够产生可逆 H _{2的专用催化剂}活化和 (ii) 样品从磁化产生点到检测点的物理转移（例如，高场或台式核磁共振 [NMR] 光谱仪）。此外，(iii) 连续的仲氢鼓泡加速了溶剂（例如甲醇）的蒸发，从而将实验窗口限制为每个样品数十分钟。在这项工作中，我们展示了一种快速生成 SABRE [Ir(IMes)(COD)Cl] ( IMes = 1,3-bis-[2,4,6-trimethylphenyl]-imidazol-2-ylidene; COD = cyclooctadiene) 通过高度可及的合成。第二，我们使用自制的零场 NMR 光谱仪测量超极化样品，并直接在检测装置中研究超极化的场依赖性，无需在实验期间物理移动样品。最后，我们通过在向样品中鼓泡之前用溶剂蒸汽预饱和仲氢来延长测量时间并减少蒸发。这些进步扩展了来自各个领域的研究人员探索 SABRE 超极化的机会，并为生产大量超极化材料以长期检测 SABRE 衍生的核磁化铺平了道路。我们通过在将仲氢加入样品之前用溶剂蒸汽预饱和来延长测量时间并减少蒸发。这些进步扩展了来自各个领域的研究人员探索 SABRE 超极化的机会，并为生产大量超极化材料以长期检测 SABRE 衍生的核磁化铺平了道路。我们通过在将仲氢加入样品之前用溶剂蒸汽预饱和来延长测量时间并减少蒸发。这些进步扩展了来自各个领域的研究人员探索 SABRE 超极化的机会，并为生产大量超极化材料以长期检测 SABRE 衍生的核磁化铺平了道路。