Magnetic Resonance of Metal Hydrides and Transfer of Laser-Generated Polarization

金属氢化物的磁共振和激光产生的偏振的转移

• 批准号: 9987888
• 负责人: Mark Conradi
• 金额: $ 37.2万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-15 至 2003-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9987888&HistoricalAwards=false
• 关键词: Magnetic; Resonance; Metal; Hydrides; Transfer

The position and atomic motions of H and D atoms in the trihydrides (and trideuterides) YH3, LuH3, and LaH3 are important to understanding the electronically insulating nature of these 'switchable mirror' materials. Deuterium NMR will be used to identify the sites occupied and will be particularly important in LaDx, where the deuterium/metal ratio can be varied continuously from x=2 (metallic) to x=3 (insulating). NMR will also be used to look for cell-to-cell inequivalences in the lanthanum species and to study the phase transition at 240K in ZrBe2D1.5. High power diode laser-based optical pumping techniques will be used to produce 129Xe in liter quantities with nuclear spin polarization up to 40%. This polarization is up to 100,000 times that of Xe gas in thermal equilibrium at typical fields and temperatures. The goal is to devise methods for transferring the spin polarization from 129Xe to spins of analytical interest, such as hydrogen, 13C, 15N, etc. Such transfer methods could revolutionize the sensitivity of analytical NMR, allowing samples of 1 microgram or less to be examined.%%%Many metals absorb hydrogen readily, making them useful for applications such as hydrogen fuel storage devices and batteries. In this project the various aspects of the behavior of such metal hydrogen systems, 'metal hydrides,' will be investigated by means of the nuclear magnetic resonance (NMR) technique. An example is the 'switchable mirror' behavior of the metal trihydrides involving the metal yttrium, lutetium, or lanthanum. The fundamentals of this phenomenon need to be better understood in order to utilize this behavior in practical devices. Other properties of the metal hydrides will also be investigated. In recent years it has become possible to use laser light to orient the nuclear spins of certain isotopes of xenon and helium gases, which thereby have become 'nuclear spin polarized.' The resulting enhancement of NMR signal strength by factors up to 100,000 has already found applications in medical diagnostics. Further applications are envisioned by transferring the spin polarization to the nuclear spins of atoms in molecules of biological and/or chemical interest, such as carbon, hydrogen, or nitrogen. This research is directed to explore the possibilities of such polarization transfer. Graduate and undergraduate students will participate in this research. They will thereby acquire knowledge and skills that will prepare them for employment in forefront areas of condensed matter physics and materials science.***

三氢化合物YH3、LuH3和LaH3中H和D原子的位置和原子运动对于理解这些“可切换镜面”材料的电子绝缘性质是很重要的。氢核磁共振将被用来确定被占据的位置，这在LaDx中将特别重要，在LaDx中，氘/金属的比率可以从x=2(金属)到x=3(绝缘)连续变化。核磁共振也将被用来寻找La物种中的细胞到细胞的不等价性，并研究ZrBe2D1.5在240K的相变。基于高功率半导体激光的光学泵浦技术将被用于生产高达40%的核自旋极化的公升129Xe。在典型的磁场和温度下，这种极化是热平衡下Xe气体的10万倍。其目标是设计出将自旋极化从129Xe转移到有分析意义的自旋，如氢、13C、15N等的方法。这种转移方法可以彻底改变分析核磁共振的灵敏度，允许检测1微克或更小的样品。%许多金属很容易吸收氢，使它们对氢燃料存储设备和电池等应用有用。在这个项目中，将通过核磁共振技术来研究这种金属氢系统--金属氢化物--行为的各个方面。一个例子是涉及金属Y、Lu或La的金属三氢化物的“可切换镜面”行为。需要更好地了解这种现象的基本原理，以便在实际设备中使用这种行为。金属氢化物的其他性质也将被研究。近年来，使用激光来定位氙气和氦气的某些同位素的核自旋已成为可能，从而使其成为“核自旋极化”。由此产生的高达100,000倍的核磁共振信号强度增强已经在医疗诊断中得到应用。通过将自旋极化转移到生物和/或化学感兴趣的分子(如碳、氢或氮)中原子的核自旋，可以预见进一步的应用。这项研究旨在探索这种极化转移的可能性。研究生和本科生将参与这项研究。因此，他们将获得知识和技能，为他们在凝聚态物理和材料科学的前沿领域就业做好准备。