Blank Aharon, Twig Ygal, Ishay Yakir
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 32000, Israel.
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 32000, Israel.
J Magn Reson. 2017 Jul;280:20-29. doi: 10.1016/j.jmr.2017.02.019. Epub 2017 Feb 28.
Magnetic resonance is a very powerful methodology that has been employed successfully in many applications for about 70years now, resulting in a wealth of scientific, technological, and diagnostic data. Despite its many advantages, one major drawback of magnetic resonance is its relatively poor sensitivity and, as a consequence, its bad spatial resolution when examining heterogeneous samples. Contemporary science and technology often make use of very small amounts of material and examine heterogeneity on a very small length scale, both of which are well beyond the current capabilities of conventional magnetic resonance. It is therefore very important to significantly improve both the sensitivity and the spatial resolution of magnetic resonance techniques. The quest for higher sensitivity led in recent years to the development of many alternative detection techniques that seem to rival and challenge the conventional "old-fashioned" induction-detection approach. The aim of this manuscript is to briefly review recent advances in the field, and to provide a quantitative as well as qualitative comparison between various detection methods with an eye to future potential advances and developments. We first offer a common definition of sensitivity in magnetic resonance to enable proper quantitative comparisons between various detection methods. Following that, up-to-date information about the sensitivity capabilities of the leading recently-developed detection approaches in magnetic resonance is provided, accompanied by a critical comparison between them and induction detection. Our conclusion from this comparison is that induction detection is still indispensable, and as such, it is very important to look for ways to significantly improve it. To do so, we provide expressions for the sensitivity of induction-detection, derived from both classical and quantum mechanics, that identify its main limiting factors. Examples from current literature, as well as a description of new ideas, show how these limiting factors can be mitigated to significantly improve the sensitivity of induction detection. Finally, we outline some directions for the possible applications of high-sensitivity induction detection in the field of electron spin resonance.
磁共振是一种非常强大的方法，至今已在许多应用中成功应用了约70年，产生了大量的科学、技术和诊断数据。尽管磁共振有许多优点，但其一个主要缺点是灵敏度相对较低，因此在检查异质样品时空间分辨率较差。当代科学技术经常使用极少量的材料，并在非常小的长度尺度上研究异质性，这两者都远远超出了传统磁共振的当前能力。因此，显著提高磁共振技术的灵敏度和空间分辨率非常重要。近年来，对更高灵敏度的追求导致了许多替代检测技术的发展，这些技术似乎与传统的“老式”感应检测方法相竞争并对其提出挑战。本文的目的是简要回顾该领域的最新进展，并对各种检测方法进行定量和定性比较，以关注未来的潜在进展和发展。我们首先给出磁共振中灵敏度的通用定义，以便能够对各种检测方法进行适当的定量比较。在此之后，提供了有关磁共振中最近开发的主要检测方法的灵敏度能力的最新信息，并对它们与感应检测进行了批判性比较。我们从这种比较中得出的结论是，感应检测仍然不可或缺，因此，寻找显著改进它的方法非常重要。为此，我们提供了从经典力学和量子力学推导出来的感应检测灵敏度表达式，以确定其主要限制因素。来自当前文献的例子以及新想法的描述，展示了如何减轻这些限制因素以显著提高感应检测的灵敏度。最后，我们概述了高灵敏度感应检测在电子自旋共振领域可能的应用方向。
