CAREER:Developing Novel Nuclear Magnetic Resonance Contrast and Sensitivity Enhancement Mechanisms for Materials and Reactions Studies

加州大学圣巴巴拉分校的Song-I han在实验物理化学计划的支持下开发了新的核磁共振对比机制，通过对选定的流体分子进行有针对性的信号增强来突出材料和工艺的分子特定功能。将寻求和开发两种不同的实现非平衡核自旋极化的方法，提出获得不同类型对比的机制。一种方法是利用固体基质中插入的或自然未配对的电子进行核磁共振信号调制，这在以前还没有被证明。在这项研究工作中，(1)广泛使用的Overhauser效应将扩展到更广泛的核和分子范围，(2)将更好地了解材料中核与未配对电子之间的相互作用，(3)分子在多孔材料中的流动弥散、吸收和反应性--难以研究的性质--将被原位获取，以及(4)将揭示多相催化剂中活性中心的下落。该项目将通过理论努力、利用新兴的高功率微波技术的仪器开发以及跨学科知识的整合来实现研究目标。该项目开发的新颖的对比度和更高的灵敏度将使目前难以获得的分子-材料相互作用的开发成为可能。在化学反应、生物功能、药物输送和石油研究等广泛领域，直接追踪小分子在多孔介质中的传输和吸收的发展能力是非常重要的。教育项目计划包括为本科生和高中生组织基于磁共振的研讨会和实地研究，使他们有机会实践学习磁场以及如何利用核磁共振来了解环境中的常见材料。

Song-I Han of the University of California-Santa Barbara is supported by the Experimental Physical Chemistry Program to develop novel contrast mechanisms for nuclear magnetic resonance (NMR) that highlight molecule-specific functions of materials and processes by targeted signal enhancement of selected fluid molecules. Two different approaches for achieving non-equilibrium nuclear spin polarization will be pursued and developed, presenting mechanisms to obtain different types of contrast. One approach, utilizing inserted or natural unpaired electrons in solid matrices for NMR signal modulation, has not been demonstrated previously. In the research effort, (1) the widely used Overhauser effect will be extended to a broader range of nuclei and molecules, (2) a better understanding of the interactions between nuclei and unpaired electrons in materials will be achieved, (3) flow dispersion, absorption and reactivity of molecules in porous materials -- difficult properties to study-- will be accessed in situ, and (4) light will be shed on the whereabouts of active sites in heterogeneous catalysts. Theoretical efforts, instrumentation development utilizing emerging, high-power, microwave technology and the integration of interdisciplinary knowledge will be employed to meet the research aims.Novel contrast and higher sensitivity NMR as developed in this project will allow the exploitation of molecule-material interactions that are currently difficult to access. The developing capability to trace directly the transport and absorption of small molecules into porous media in situ is highly significant in a broad range of areas such as chemical reaction, biological function, drug delivery, and petroleum research. The educational project plan includes the organization of magnetic resonance based workshops and field studies for undergraduate and high school students that will give them the opportunity for hands-on learning about magnetic fields and how NMR can be used to learn about common materials in the environment.