Grant for Exploratory Research: NMR of Reactive Intermedi- ates and Surfaces Using Spin Polarized Xe

Zilm教授获得了实验物理化学项目的探索性研究资助，用于开发核磁共振方法，该方法将利用新发现的光学偏振技术，在氙气中产生近乎完美的自旋极化Xe-129原子核。原则上，这种极化转移到原子核的分子在固体氙基质可以实现核磁共振信号的增强高达四个数量级。这些新颖的实验有望对氙基质分离中小浓度分子的检测产生重大影响。这意味着在化学反应中以非常小的稳定量产生的活性物质可以用核磁共振检测到，提供详细的结构信息。这也意味着即使在如此低的浓度下，也可以观察到低灵敏度的原子核，如天然丰富的碳-13和硅-29。这个探索性研究项目将利用刚刚发现的方法，利用氙将极化转移到其他原子核，使氙中的核自旋完全极化，从而使它们的核磁共振谱提高一万倍。初步实验将确定有效极化转移所需的条件。氙可以用作固体基质，用于检测极少量的活性分子和分子片段。氙也可以放置在表面上，只允许检测表面原子。

Professor Zilm is supported by a grant for exploratory research from the Experimental Physical Chemistry Program to develop the NMR methods which would take advantage of the newly discovered optical polarization techniques for producing nearly perfectly spin-polarized Xe-129 nuclei in xenon gas. In principle, the transfer of this polarization to nuclei in a molecule in a solid xenon matrix can be achieved for enhancement of the NMR signals by up to four orders of magnitude. These novel experiments are expected to have high impact on the detection of orders of magnitude smaller concentrations of molecules in xenon matrix isolation. This would mean that reactive species which are created in very small steady state quantities in a chemical reaction could be detected with NMR, providing detailed structural information. This would also mean that low sensitivity nuclei, such as naturally abundant carbon-13 and silicon-29 could be observed even at these low concentrations. %%% This exploratory research project will make use of the just discovered method of completely polarizing the nuclear spins in xenon by using the xenon to transfer polarization to other nuclei, thus enhancing their nuclear magnetic resonance spectra by ten thousand fold. The preliminary experiments will determine the conditions that are necessary for the efficient polarization transfer. The xenon could be used as a solid matrix for the detection of very small amounts of reactive molecules and molecule fragments. The xenon can also be laid down on a surface to allow the detection of only surface atoms.