NMR Studies of Molecular Motion in Constrained Environments

在化学学部物理化学项目的这个项目中，威廉玛丽学院的Gina Hoatson教授将致力于开发脉冲核磁共振（NMR）光谱学的新技术，以扩大可访问的时间尺度范围，从而确定分子运动速率以及相关的动力学轨迹。这些方法包括选择性反演方法，双量子线形状的确定，阿达玛德激发光谱方法，这是随机核磁共振的一种变体，比传统的脉冲核磁共振具有相当大的优势，以及粉末的光谱密度测量。在这项工作的过程中要研究的系统包括分子晶体、包合化合物和液晶。核磁共振（NMR）波谱是一种强大的、普遍的方法，通过组成原子的核磁铁与电磁辐射的相互作用来研究固体和液体。核磁铁对这种辐射的吸收不仅是特定化学元素的特征，而且还受到化学环境的影响。原子核因此充当微观探针，并产生关于固体或液体物质的结构和动力学的特定位置信息。理论和实验技术的不断发展，极大地提高了核磁共振方法作为凝聚态物质性质基础研究工具的性能，并极大地扩展了它在物理、化学、材料科学、生物学和医学等领域的应用。在这个项目中，计划进一步发展使核磁共振方法能够处理困难或迄今为止无法解决的问题，从而扩大其适用于实际问题的范围。

In this project in the Physical Chemistry Program of the Chemistry Division, Prof. Gina Hoatson of the College of William and Mary will engage in developing new techniques of pulsed nuclear magnetic resonance (NMR) spectroscopy in order to expand the accessible range of time scales over which the rates of molecular motion as well as the associated dynamical trajectories can be determined. These include methods of selective inversion, the determination of double quantum line shapes, methods of Hadamard excitation spectroscopy, which is a variant of stochastic NMR possessing considerable advantages over conventional pulsed NMR, and spectral density measurements on powders. Systems to be investigated in the course of this work include molecular crystals, inclusion compounds, and liquid crystals. %%% Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful, ubiquitious method for the study of solids and liquids through the interaction of nuclear magnets of the constituent atoms with electromagnetic radiation. The absorption of this radiation by the nuclear magnets is not only characteristic of the specific chemical element but is also affected by the chemical environment. The atomic nuclei thus act as microscopic probes and yield site specific information about the structure and dynamics of the solid or liquid substance. Continual developments in theoretical and experimental techniques have resulted in vastly improved performance of the NMR method as a tool for basic studies of the properties of condensed matter and have greatly expanded its application to problems in physics, chemistry, materials science, biology, and medicine. In this project further developments are planned to enable the NMR method to deal with difficult or so far undoable problems and thereby extend the range of its applicability to practical problems.