Quadratic Echoes and the MRI of Solids

* 技术摘要 * 硬π脉冲与其δ函数近似之间的微小差异可用于产生新类别的自旋回波，这些自旋回波在NMR、磁共振成像（MRI）或固体显微镜以及相关光谱学中具有有前途的应用。例如，使用二次回波线窄脉冲序列，这是一种控制自旋相干性的新工具，该项目将寻求一种新的方法来进行高空间分辨率的固体MRI。 该项目重点关注从早期本科阶段到博士阶段的学生教育和培训，沿着K-12的推广工作。虽然该工作计划旨在做出基本的科学贡献，但也有潜在的社会效益。首先，推进新形式的自旋相干控制，适用于各种各样的自旋（或量子位）哈密顿量，将在光谱学的许多领域广泛有用。其次，从更少的（稀疏的）数据中提取更多的信息对用于生物学和化学（包括药物发现）结构确定的NMR有直接的好处，它也应该在其他领域发挥作用。第三，将一种全新的实验工具应用于颗粒物理学的问题，将推进这一对工业非常重要的领域的理论和实验。从历史上看，我们“看到”不透明固体内部的能力的提高产生了更广泛的影响。非技术摘要 * 从历史上看，“看到”不透明固体内部的新工具的开发一直是科学技术进步的重要推动力，具有深远的经济影响。 该项目将开发新的方法，以实现磁共振成像（MRI）领域的一个长期目标，即具有高空间分辨率的硬固体和软固体的多核MR图像。 传统的MRI只能检测液态水中氢的信号;固体的MRI要困难得多，很少有人尝试。该项目将使用二次回波线窄化的创新来开发固体的高分辨率MR成像，这是最近发现的，是NSF对好奇心驱动的基础研究投资的直接结果。 潜在的固体目标包括多孔岩石、复合材料、3D集成电路中的“硅通孔”、骨骼和软组织。尖端科学与广泛的潜在应用将使优秀的教育和培训的学生从早期的本科水平，通过博士，沿着K-12的推广工作。虽然该项目的工作计划旨在做出基本的科学贡献，但这项工作应该在其他科学和技术领域得到应用，而且也有潜在的社会效益。 例如，将一种全新的实验工具应用于颗粒物理学中的问题，如筒仓中谷物的性质，将推进对工业非常重要的领域的理论和实验。

****Technical Abstract****The small difference between hard pi-pulses and their delta-function approximation can be used to generate new classes of spin echoes which have promising applications in NMR, magnetic resonance imaging (MRI) or microscopy of solids, and related spectroscopies. For example, using the quadratic echo line-narrowing pulse sequence, a novel tool for the control of spin coherence, this project will pursue a new approach to carrying out MRI of solids with high spatial resolution. This project has a strong focus on the education and training of students from the early undergraduate level through the Ph.D., along with K-12 outreach efforts. While the plan of work is aimed at making fundamental scientific contributions, there are potential societal benefits as well. First, advancing new forms of spin coherence control, applicable to a wide variety of spin (or qubit) Hamiltonians, will be broadly useful in many areas of spectroscopy. Second, squeezing more information from less (sparse) data has immediate benefits to the kind of NMR that is used for structure determination in biology and chemistry (including drug discovery), and it should work in other areas as well. Third, applying an entirely new experimental tool to problems in granular physics will advance theory and experiment in a field that is very important to industry. Historically, improvements in our ability to 'see' inside opaque solids have had broader impacts.****Non-Technical Abstract****Historically, the development of new tools to 'see' inside opaque solids has been an important driver of progress in science and technology, with far-reaching economic impact. This project will develop new approaches to a long-standing goal in the field of magnetic resonance imaging (MRI), namely, multinuclear MR images of hard and soft solids with high spatial resolution. Conventional MRI detects only the signal from the Hydrogen in liquid water; MRI of solids is so much more difficult that it is rarely attempted. This project will develop high-resolution MR imaging of solids using the innovation of quadratic echo line-narrowing, which was recently discovered as a direct result of the NSF's investment in basic, curiosity-driven research. Potential solid targets include porous rocks, composite materials, "through-silicon vias" in 3D integrated circuits, bone and soft tissues. Cutting-edge science with a broad range of potential applications will enable excellent education and training of students from the early undergraduate level through the Ph.D., along with K-12 outreach efforts. While this project's plan of work is aimed at making fundamental scientific contributions, the work should find applications in other areas of science and technology, and there are potential societal benefits as well. For example, applying an entirely new experimental tool to problems in granular physics, such as the properties of grain in silos, will advance theory and experiment in a field that is very important to industry.