Applications of nuclear probe techniques to materials science

核磁共振是物理、化学、生物和医学等领域最强大的分析工具之一。然而，核磁共振方法的灵敏度较低，限制了其适用性。近年来的研究表明，用光学泵浦的方法可以实现氙气的高核自旋极化。超极化氙气可用于需要提高灵敏度和选择性的新型核磁共振实验。我们正在寻求一种这样的应用，即用于研究样品表面磁性的增强型固态核磁共振光谱学。这类实验研究与磁性纳米技术等新兴领域高度相关。我们还使用被称为“µ子”的微小亚原子粒子来研究物质内部的磁性。近年来，我们已经将这种方法应用于研究超导材料中的磁通线，即所谓的涡旋。这些研究的基本结果对从电力传输到医学成像的科学和技术应用具有重要意义。在不久的将来，我们将把这种方法应用于非常规系统中竞争磁相和超导相的研究。我们还将使用介子来研究基于分子化学的新型磁体。我们工作的科学成果将有助于建立知识库，有朝一日将导致基于“分子”而不是传统的“原子”磁性构建块的新的磁性设备。虽然元素周期表中的元素数量被限制在100个左右，但有数百万种有机化合物。因此，分子磁学在磁性材料的设计中提供了前所未有的灵活性，因此也是一个吸引越来越多兴趣的研究领域。

Nuclear magnetic resonance (NMR) is one of the most powerful analytical tools in the fields of physics, chemistry, biology and medical sciences. Nevertheless, the NMR method suffers from a low sensitivity that limits its applicability. In recent years it has been demonstrated that high nuclear-spin polarization of xenon gas can be achieved by optical pumping methods. The hyperpolarized xenon may be used for novel NMR experiments that require enhanced sensitivity and selectivity. We are pursuing one such application, namely, enhanced solid-state NMR spectroscopy for the study of magnetism at sample surfaces. Such experimental investigations are highly relevant for emerging areas such as magnetic nanotechnology. We also study magnetism deep inside materials using tiny subatomic particles called 'muons'. In recent years we have applied this method to the study of magnetic flux lines, called 'vortices', in superconducting materials. The fundamental results from these studies are significant for scientific and technological applications, ranging from electrical power transmission to medical imaging. In the near future we will apply this method to the study of competing magnetic and superconducting phases in unconventional systems. We will also use muons to study new classes of magnets based on molecular chemistry. The scientific outcome of our work will contribute to the knowledge base that will one day lead to new magnetic devices based on 'molecular' rather than traditional 'atomic' magnetic building blocks. While the number of elements in the periodic table is limited to one hundred or so, there are several million organic compounds. Thus molecular magnetism offers an unprecedented flexibility in the design of magnetic materials, and accordingly is an area of research that is attracting increasing interest.