Development of Next-Generation Hyperpolarization Methods for Chemical Analysis

在化学系化学测量和成像项目的支持下，以及物理系原子、分子和光学实验物理项目的共同资助下，杜克大学的Warren Warren教授和他的团队正在努力扩大“超极化”核磁共振（NMR）光谱学的实用性和可及性。核磁共振是化学家的强大工具；它对确定分子结构和监测化学反应的进展是有用的。核磁共振的临床表亲，磁共振成像（MRI）是产生人体软组织图像的重要工具。然而，这两种方法通常都存在灵敏度低的问题——这意味着它们不能检测到少量或低浓度的样品。“超极化”方法可以将核磁共振信号增加1000倍或更多，但通常在技术上具有挑战性且极其昂贵。Warren小组正在探索新策略背后的基础化学和物理，以期提供常规超极化作为任何核磁共振光谱仪的简单且经济有效的附加组件。该团队还为代表性不足的群体成员提供这些关键技术的研究和培训机会，并提供大量的K-12科学外展。Warren小组研究了核磁共振和核磁共振中超极化、长寿命核自旋态的产生、量子统计力学和表征。他们试图在不发生化学反应的情况下，大幅提高溶液中对氢气体（p-H2）中15N、13C和19F等原子核的普遍性、分数极化和绝对极化水平，从而实现从定量测量溶液中旋转态对反应性的影响到暗物质探测的应用。制造和储存大量p-H2的能力应该能够创造出巨大的（公斤大小）连续超极化目标，这些目标可以作为超灵敏的磁力计（例如用于暗物质探测），或者可以大大减少临床MRI所需磁铁的尺寸。通过使用简单，廉价的实验室设备以L-atm/小时的水平制造p-H2的能力，也可以扩大适用性。虽然超低场核磁共振并不新鲜，但这项工作旨在使其成为主流，同时也能实现更好的高场实验。其目的是减少或消除实现超极化的成本和复杂性障碍。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, and co-funding from the Atomic, Molecular, and Optical Experimental Physics Program in the Division of Physics, Professor Warren Warren and his group at Duke University are working to expand the utility and accessibility of “hyperpolarized” nuclear magnetic resonance (NMR) spectroscopy. NMR is a powerful tool for chemists; it is useful for determining molecular structure and for monitoring the progress of chemical reactions. NMR's clinical cousin, magnetic resonance imaging (MRI) is an important tool for producing images of soft tissues in the body. However, both methods usually suffer from low sensitivity - meaning that they cannot detect small amounts of sample or low concentrations. "Hyperpolarization" methods can increase NMR signals by a factor of 1000 or more, but are usually technically challenging and extremely expensive. The Warren group is exploring the fundamental chemistry and physics behind new strategies with prospects of providing routine hyperpolarization as a simple and cost-effective add-on to any NMR spectrometer. The team is also providing research and training opportunities in these critical technologies for members of underrepresented groups, and providing substantial K-12 science outreach.The Warren group studies the production, quantum statistical mechanics, and characterization of hyperpolarized, long-lived nuclear spin states in NMR and MRI. They seek to drastically improve the generality, fractional polarization, and absolute polarization levels of nuclei such as 15N, 13C and 19F from parahydrogen gas (p-H2) in solution, without chemical reaction, thereby enabling applications ranging from quantifying rotational-state effects on reactivity in solution to dark matter detection. The ability to make and store large quantities of p-H2 should enable creation of massively large (kg size) continuously hyperpolarized targets which can serve as ultrasensitive magnetometers (e.g. for dark matter detection) or can drastically reduce the size of the magnets needed for clinical MRI. Applicability can also be expanded by the ability to make p-H2 at the L-atm/hour level using a simple, inexpensive laboratory apparatus. While ultra-low-field NMR is not new, this work aims to bring it into the mainstream, while also enabling better high-field experiments. The aim is to reduce or eliminate the cost and complexity barriers to implementation of hyperpolarization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.