Applications of nuclear probe techniques to materials science

核磁共振（NMR）是物理、化学、生物和医学科学领域中最强大的分析工具之一。然而，NMR方法具有低灵敏度，这限制了其适用性。近年来，人们已经证明，氙气的高核自旋极化可以通过光泵浦方法实现。超极化氙可用于需要增强灵敏度和选择性的新型NMR实验。我们正在追求这样一个应用，即，增强固态核磁共振光谱的磁性在样品表面的研究。这样的实验研究是高度相关的新兴领域，如磁性纳米技术。我们还使用称为“μ子”的微小亚原子粒子研究材料内部的磁性。近年来，我们已经将这种方法应用于超导材料中磁通线（称为“涡旋”）的研究。这些研究的基本结果对于科学和技术应用具有重要意义，从电力传输到医学成像。在不久的将来，我们将应用这种方法来研究非常规系统中的竞争磁相和超导相。我们还将使用μ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知识基础，有一天将导致基于“分子”而不是传统的“原子”磁性构建块的新磁性设备。虽然元素周期表中的元素数量限制在一百左右，但有机化合物却有数百万种。因此，分子磁性在磁性材料的设计中提供了前所未有的灵活性，因此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.