Development and Application of beta-detected NMR to Quantum Materials and Beyond

放射性衰变中释放出的高能粒子很容易被检测到，这一特性使得能够跟踪放射性标记物种通过化学、物理或生物过程的*放射性示踪剂*技术成为强大的医学成像技术的基础，如正电子发射断层扫描(PET扫描)。然而，某些类型的放射性可以报告的不仅仅是放射性标签的位置：它们可以感知其当地原子环境的电磁特征。最重要的例子是放射性贝塔衰变，用于贝塔探测的核磁共振(核磁共振)，这是这一提议的基础。 核磁共振放射性同位素的半衰期必须非常短，在几秒钟或更短的数量级上，所以它们是在使用前立即制成的。位于温哥华UBC的加拿大粒子加速器中心TRIUMF的ISAC设施提供短寿命的放射性同位素作为离子束。我们主要使用同位素8Li(半衰期0.848秒)。只有少数其他实验室可以制造这样的梁，但更多的实验室正在建造中。我们的努力在核磁共振的发展方面处于世界领先地位。随着其新的Ariel项目的实施，新的8Li源将于2021年推出，从而极大地增加了这些实验的可用时间。 离子注入核磁共振的一个关键优点是能够调整探头在材料中的深度。虽然有许多强大的表面敏感方法来研究最顶层的原子层，但很少有方法能够揭示表面下深度的特性。我们的主要目的是在几纳米(十亿分之一米)到几百纳米的深度尺度上研究表面和界面效应，这些效应导致了固体中鲜为人知的深度依赖现象，这是现代电子学的一个重要范围。金属/半导体、金属/聚合物或电极/电解液等材料界面对许多器件都是至关重要的。随着设备朝着“纳米技术”微型化，每个原子都在界面附近。然而，界面效应还没有被很好地理解。这项提议旨在利用核磁共振的深度分辨能力来研究界面问题。我们将研究将成为新技术基础的新材料，如锂电池用固态电解液、相关电子导体和具有独特电磁性能的拓扑材料，这些材料可以绕过传统材料的限制。我们将研究纳米结构的玻璃聚合物，以了解结构对分子动力学的影响，并将核磁共振的应用扩展到生物化学等新领域。 加拿大将受益于在先进材料研究领域处于世界领先地位，其成果将使人们更好地从根本上了解材料界面，从而能够优化现有技术和设计全新的技术。

The high energy particles emitted in radioactive decay are very easy to detect, a property that enables *radiotracer* techniques that follow a radiolabeled species through chemical, physical or biological processes, forming the basis for powerful medical imaging techniques like Positron Emission Tomography (PET scans). Certain types of radioactivity can, however, report much more than just the radiolabel's location: they sense the electromagnetic characteristics of its local atomic environment. The most important example is radioactive beta decay, used in beta-detected nuclear magnetic resonance (NMR) that is the basis of this proposal. NMR radioisotopes must have very short half-lives on the order of seconds or less, so they are made immediately before use. The ISAC facility at TRIUMF, Canada's particle accelerator centre, located at UBC in Vancouver, provides short-lived radioisotopes as ion beams. Mainly we use the isotope 8Li (halflife 0.848 seconds). Only a few other labs can make such beams, but more are being constructed. Our efforts lead the world in the development of NMR. With its new ARIEL project, a new source of 8Li will be available in 2021, dramatically increasing the amount of time available for these experiments. A key strength of ion-implanted NMR is the ability to adjust the depth of the probe in a material. While there are many powerful surface-sensitive methods to study the topmost atomic layer, there are very few that reveal properties as a function of depth below a surface. Our main motive is 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 electronics. Material interfaces, like metal/semiconductor, metal/polymer or electrode/electrolyte are crucial to many devices. As devices are miniaturized towards *nanotechnology*, every atom is near an interface. However, interface effects are not well understood. This proposal aims to study interface problems using the depth-resolved power of NMR. We will study new materials that will be the basis for new technologies, e.g. solid state electrolytes for Li+ batteries, correlated electronic conductors and topological materials with unique electromagnetic properties that may be used to sidestep limitations of conventional materials. We will study nanostructured glassy polymers to understand the effect of structure on molecular dynamics, and we will extend the application of NMR to new areas such as biochemistry. Canada will benefit by leading the world in advanced materials research with outcomes that result in a better fundamental understanding of material interfaces, enabling optimization of current technologies and engineering radically new ones.