International Research Fellowship Program: Hyperpolarized Solid State NMR Spectra of Materials and Catalysis Using Dynamic Nuclear Polarization

国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持Leah B.Casabianca博士与以色列魏茨曼研究所的Lucio Frydman博士合作的为期24个月的研究奖学金。核磁共振光谱无疑是确定化学系统和材料中结构和动力学的最通用和最有用的工具之一。没有其他技术可以与这种光谱学提供的丰富的原子细节相媲美。然而，核磁共振光谱学最大的缺点是灵敏度低。核磁共振非常适合于催化有机体系、功能化表面或无机纳米管的结构研究。应该只克服它的敏感性问题。这项工作的目标是发展新的核磁共振技术，利用低温动态核极化(DNP)来表征静态固体中的超极化核。DNP在固体金属核中的应用将通过脉冲序列的开发、专门用于极化转移到金属核的最佳超极化条件以及用于低温环境的硬件来验证、优化和理解。然后，这些方法将被用于检查催化剂和无机纳米管中的金属核。该项目的一个附带目标是研究使用单壁碳纳米管(SWNTs)和纳米钻石中的内源顺磁杂质作为DNP的极化剂的可行性，增强这些碳纳米材料中13C核的信号。催化剂在合成化学、工业化学以及日常生活中普遍存在，无机纳米管由于其无毒的性质而具有独特的潜在应用，碳纳米材料的应用范围从膜和传感器到电池和纳米电子学。虽然这些领域的结构表征传统上是由低分辨率技术主导的，但灵敏度增强型核磁共振有可能允许对这些和其他新兴先进材料进行原子水平的表征。这项工作将促进超极化固体核磁共振领域的发展，并将对催化和材料科学等其他领域产生积极影响。正在开发的技术将允许表征由于该方法固有的敏感性限制而传统上难以用核磁共振研究的体系，从而通过增加该技术的适用性来推动核磁共振领域的发展。此外，该项目将有助于从总体上理解超极化过程。这项工作将通过含金属催化剂、无机纳米管、单壁碳纳米管和其他碳基纳米材料的潜在应用而造福社会。这些材料的原子级结构表征将使这些系统在生物医学、电子、汽车和航空航天工业中的应用得以实现。

0965137CasabiancaThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Leah B. Casabianca to work with Dr. Lucio Frydman at the Weizman Institute in Israel.Nuclear Magnetic Resonance (NMR) spectroscopy is undoubtedly one of the most versatile and useful tools for the determination of structure and dynamics in chemical systems and materials. No other technique compares in the wealth of atomistic detail that can become available from this kind of spectroscopy. The greatest disadvantage of NMR spectroscopy, however, is its low sensitivity. NMR would be ideally suited for structural studies of catalytic organic systems, functionalized surfaces, or inorganic nanotubes ? should only its sensitivity problems be surmounted. This goal of this work is the development of new NMR techniques exploiting cryogenic dynamic nuclear polarization (DNP) to characterize hyperpolarized nuclei in static solids. The application of DNP to metal nuclei in solids will be validated, optimized and understood through the development of pulse sequences, optimal hyperpolarization conditions for polarization transfer specifically to metal nuclei, and hardware for use in cryogenic environments. These approaches will then be used to examine metal nuclei in catalysts and inorganic nanotubes. A concomitant goal of this project is to examine the feasibility of using endogenous paramagnetic impurities present in single-walled carbon nanotubes (SWNTs) and nanodiamonds as polarizing agents for DNP, enhancing the signal of 13C nuclei in these carbon nanomaterials. Catalysts are ubiquitous in synthetic and industrial chemistry as well as in everyday life, inorganic nanotubes have unique potential applications due to their non-toxic nature, and carbon nanomaterials have applications ranging from membranes and sensors to batteries and nanoelectronics. Whereas structural characterization in these fields has traditionally been dominated by low-resolution techniques, sensitivity-enhanced NMR has the potential to allow atomic-level characterization of these and other emerging advanced materials. The proposed work will lead to advances in the field of hyperpolarized solid-state NMR, and will also have a positive impact on other fields including catalysis and materials science. The techniques being developed will allow the characterization of systems that have traditionally been difficult to study by NMR due to the inherent sensitivity limitations of this method, thus advancing the field of NMR by increasing the applicability of this technique. In addition, this project will contribute to the understanding of hyperpolarization processes in general. This work will benefit society through the potential applications of metal-containing catalysts, inorganic nanotubes, SWNTs, and other carbon-based nanomaterials. Atomic-level structural characterization of these materials will allow applications of these systems in the biomedical, electronics, automotive, and aerospace industries to be realized.