RUI: Nuclear Magnetic Resonance Study of Hydrogen in New Materials

这一个人研究人员奖支持一个项目，该项目将使用核磁共振技术来研究氢在三种不同材料中的行为：La和Y氢化物、富勒烯和准晶。La和Y氢化物薄膜在低氢浓度时从反射态转变为高浓度时的透明态。这种“可切换的镜子”行为是由于金属到非金属的转变，但对这种转变仍缺乏详细的了解。核磁共振将被用来表征光学转变背后的关键结构和电子现象。碳基材料是一种很有吸引力的新型储氢材料，最近的注意力集中在碳纳米管的使用上。纳米管样品制备和分析的困难阻碍了测量关键性质的进展，包括氢传输速率。作为了解更复杂的纳米管材料的第一步，我们将使用核磁共振技术来研究固体富勒烯中的氢传输速率。准晶是一种具有非周期性但高度有序的结构和显著的电子性质的固体。显示电子态密度的精细结构的计算可以解释这些性质；然而，实验证据仍然存在争议。核磁共振弛豫测量与钛基准晶体的氢含量控制相结合，将被用来测试精细结构的存在。所有这些工作都将在一所文科大学使用本科生研究助理进行，他们将在准备和追求物理及相关领域的职业生涯时获得宝贵的经验。%的氢被一系列令人惊讶的固体吸收，通常会产生具有重大技术重要性的材料。这一个人研究人员奖将支持一个以本科生为主的机构的一个项目，该项目利用核磁共振(核磁共振)研究氢在三种不同材料中的行为：固体C60、稀土“可开关反射镜”和钛基准晶体。对C60中氢运动的核磁共振测量将作为了解更复杂的C60衍生物中氢运动的第一步，例如碳纳米管。碳纳米管是下一代储氢介质的有吸引力的候选者，对于开发清洁燃烧的氢作为一种可行的燃料至关重要。“可切换反射镜”是一种根据氢含量从反射变为透明的薄膜。对它们的结构和电子性质的核磁共振测量将使我们更好地从根本上理解开关现象。这种理解将有助于开发有用的设备，如光纤网络的开关。准晶是具有不寻常原子结构的固体，具有许多新的电子性质。对电子性质的核磁共振测量，结合对准晶含氢量的仔细控制，将被用来检验一些对这种不寻常性质的更具争议性的理论解释。所有这些工作都将在一所文理学院使用本科生研究助理进行，他们将在准备和追求物理及相关领域的职业生涯时获得宝贵的经验。

This individual investigator award supports a project that will use Nuclear Magnetic Resonance (NMR) techniques to investigate the behavior of hydrogen in three different materials: lanthanum and yttrium hydrides, fullerenes, and quasicrystals. Thin films of lanthanum and yttrium hydrides switch from a reflecting state at low hydrogen concentrations to a transparent state at high concentrations. This "switchable mirror" behavior is due to a metal-to-non-metal transition, but a detailed understanding of this transition is still lacking. NMR will be used to characterize the crucial structural and electronic phenomena underlying the optical transition. Carbon-based materials are attractive candidates for new hydrogen storage media, and recent attention has focused on the use of carbon nanotubes. Difficulties in nanotube sample preparation and analysis have hampered progress in measuring crucial properties, including the hydrogen transport rate. The rate of hydrogen transport in solid fullerene, as a first step towards understanding the more complicated nanotube materials, will be studied using NMR techniques. Quasicrystals are solids with aperiodic yet highly ordered structures and remarkable electronic properties. Calculations showing fine structure in the electronic density of states may explain these properties; however, the experimental evidence remains controversial. NMR relaxation measurements combined with control of the hydrogen content of a titanium-based quasicrystal will be used to test for the existence of the fine structure. All of this work will be carried out at a liberal arts college using undergraduate research assistants, who will gain valuable experience as they prepare for and pursue careers in physics and related fields.%%%Hydrogen is absorbed by a surprising array of solids, often yielding materials with significant technological importance. This individual investigator award will support a project at a predominately undergraduate institution that utilizes Nuclear Magnetic Resonance (NMR) to study the behavior of hydrogen in three different materials: solid C60, rare earth "switchable mirrors, " and titanium-based quasicrystals. NMR measurements of the motion of hydrogen in C60 will serve as the first step in understanding hydrogen motion in more complicated derivatives of C60, such as carbon nanotubes. Carbon nanotubes are attractive candidates for next generation hydrogen storage media, crucial for the development of clean-burning hydrogen as a viable fuel. "Switchable mirrors" are thin films that change from reflecting to transparent depending on the hydrogen content. NMR measurements of their structure and electronic properties will yield a better fundamental understanding of the switching phenomenon. This understanding will aid the development of useful devices, such as switches for optical fiber networks. Quasicrystals are solids with unusual atomic structures that have a number of novel electronic properties. NMR measurements of the electronic properties combined with careful control of the hydrogen content of a quasicrystal will be used to test some of the more controversial theoretical explanations of the unusual properties. All of this work will be carried out at a liberal arts college using undergraduate research assistants, who will gain valuable experience as they prepare for and pursue careers in physics and related fields.***