Development and Application of Depth-Resolved beta-Detected Nuclear Magnetic Resonance to electronic, ionic and molecular phenomena in the Solid State

深度分辨 β 检测核磁共振技术在固态电子、离子和分子现象中的开发和应用

• 批准号: RGPIN-2014-04806
• 负责人: MacFarlane, William
• 金额: $ 2.48万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=658267
• 关键词: Development; Application; Depth; Resolved; beta

Radioactivity is easy to detect since the nuclear decay emits high energy particles. In fact, it was first discovered by the accidental exposure of photographic film by such particles. Modern electronic detectors are extremely sensitive and can detect radioactivity from even a few radioactive atoms, enabling *radiotracer* techniques, where a chemical species, tagged with a radioactive atom, is followed through chemical, physical and biological processes. This is the basis for medical imaging techniques, such as Positron Emission Tomography (PET). Here, radioactive decay merely reports the location of the radiolabelled species. Certain kinds of radioactivity, however, can give a much more detailed picture of the local environment of the radioactive probe atom, a property that is the basis of beta-detected nuclear magnetic resonance (ß-NMR), the technique on which this proposal is based.**Detection by radioactive beta decay makes ß-NMR an exceptionally sensitive means to study the local atomic properties of materials. However, it is complicated to carry out such measurements. The radioactive ions used necessarily have very short halflives on the order of seconds or less, so they must be made immediately before being used. The ISAC facility at TRIUMF, Canada's national lab for nuclear and particle physics, located at UBC in Vancouver, provides beams of such short-lived radioactive ions. Our main probe is a heavy isotope of Li, 8Li (halflife 848 milliseconds). Only a few other labs in the world can make such beams but more are being constructed. Our efforts at TRIUMF lead the world in the development of ß-NMR, and based on our success, other labs are now looking to follow.**The difficulty and complexity of such measurements means that we restrict the use of ß-NMR to problems that it is uniquely capable of addressing. A key capability of ß-NMR is the ability to implant the radioactive probe at different depths in a material. While there are many powerful probes of the *surface*, the top atomic layer, of a material, there are very few that can study materials as a function of depth below a surface. Our main motivation then is to use ß-NMR to study surface and interface effects that give rise to poorly understood depth-dependent phenomena in solids on depth scales of a few nanometers (1 billionth of a meter) to a few hundred nm, an important range for modern electronic technology.**Interfaces between dissimilar materials like metal/semiconductor, metal/polymer or electrode/electrolyte are crucial to all sorts of devices. As devices are further miniaturized towards the limit of *nanotechnology*, every atom in the device is near an interface. However, interface effects are not well understood. This proposal aims to study interface problems using the depth-resolved power of ß-NMR.**Specifically, we will study new materials that may be the basis for next generation technologies, e.g. topological insulators and correlated electronic conductors that have unique electromagnetic properties for new types of devices that may sidestep fundamental limitations of conventional semiconductor devices. We will study nanostructured catalytic metals and interface effects in Li ion conductors, with the aim of a better fundamental understanding and enable new generations of battery technology, crucial for the increasing energy demands of portable devices. We will also explore new applications of ß-NMR to polymers and certain problems in biochemistry that cannot be addressed in other ways.**Canada will benefit by leading the world in advanced materials research with outcomes that lead to a better fundamental understanding that will afford optimization of current technologies as well as development of radically new ones.

放射性很容易检测，因为核衰减会发出高能量颗粒。实际上，它首先是通过这种粒子对摄影膜的意外暴露发现的。现代电子探测器非常敏感，甚至可以从几个放射性原子中检测到放射性，从而使 * radiotracer *技术通过化学，物理和生物学过程遵循了一个用放射性原子标记的化学物种。这是医学成像技术的基础，例如正电子发射断层扫描（PET）。在这里，放射性衰减仅报告了放射性标记物种的位置。然而，某些类型的放射性可以使放射性探针原子的局部环境更详细，该特性是β被发现的核磁共振（ß-NMR）的基础，该提议基于的技术是基于的。但是，进行此类测量很复杂。使用的放射性离子一定要在几秒钟或更短的时间内具有非常短的半镜头，因此必须在使用之前立即制作它们。位于温哥华UBC的加拿大国家核和粒子物理实验室Triumf的ISAC设施提供了如此短的放射性离子的光束。我们的主要探测是Li，8Li（半幸福848毫秒）的沉重同位素。世界上只有其他几个实验室可以制造出这样的光束，但正在建造更多的梁。我们在Triumf的努力领导世界发展β-NMR的发展，基于我们的成功，其他实验室现在正在寻求遵循。**此类测量的难度和复杂性意味着我们将β-NMR的使用限制为β-NMR的关键能力是在不同材料中植入放射性探针的能力。虽然 *表面 *有许多强大的问题，即一种材料的顶部原子层，但很少有能够研究材料作为深度以下深度的函数。当时，我们的主要动机是使用β-NMR研究表面和界面效应，从而使深度依赖性现象在固体中的深度依赖性现象不足，而在几百纳米的深度尺度上，对几百nm的深度尺度（10亿米）来说，这是现代电子技术的重要范围。随着设备朝着 *纳米技术 *的极限进行小型化，因此设备中的每个原子都靠近接口。但是，界面效应尚不清楚。该建议旨在使用ß-NMR的深度分辨能力研究界面问题。拓扑绝缘子和相关的电子导体具有针对新型设备的独特电子性能，这些设备可能会避开常规半导体设备的基本局限性。我们将研究局部导体中的纳米结构催化金属和界面效应，以更好的基本理解并使新一代电池技术能够提高，这对于便携式设备的能源需求不断提高至关重要。我们还将探索β-NMR在聚合物中的新应用以及无法以其他方式解决的生物化学问题的某些问题。