Shimming for High-Resolution NMR Spectroscopy
Shimming for High-Resolution NMR Spectroscopy
复制标题
高分辨率核磁共振波谱匀场
DOI：
10.1002/9780470034590.emrstm1228
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
T. Speck
中科院分区：
文献类型：
--
作者：
M. Weiger;T. Speck
匀场是一个磁场的过程，是高质量NMR测量的必要准备。本文主要研究高分辨液态核磁共振波谱仪的匀场技术，其中静态场是由超导磁体产生的。然而，所描述的许多原理和技术可以被转移到其他情况。通常使用的匀场系统，它提供了作为球谐函数的校正场，是从电磁学的一般考虑推导出来的。阐明了场不均匀性与光谱质量之间的关系，这是匀场的基础。在这方面，匀场标准的关键参数匀场详细讨论，并描述了合适的优化算法。这些一般原则适用于常规匀场和梯度匀场。此外，提供一个足够的基本均匀性的手段进行了讨论，包括磁铁和探针的设计，以及NMR样品本身。
保留字：
场均匀化;
麦克斯韦方程组
球谐函数;
梯度匀场;
野外测绘;
匀场判据;
线形优化;
正交性;
试样旋压;
磁体设计;
探头设计;
磁性材料
Shimming is the procedure of homogenizing a magnetic field, and is essential as a preparation for NMR measurements of high quality. This article is focused on shimming for high-resolution liquid-state NMR spectroscopy, in which the static field is created by means of superconducting magnets. Nevertheless, many of the principles and techniques described can be transferred to other situations. The commonly used type of shim system, which provides the correction fields as spherical harmonics, is derived from general considerations on electromagnetism. Being fundamental in shimming, the relationship between field inhomogeneity and spectral quality is elucidated. In this context, the shim criterion—the key parameter for shimming—is discussed in detail, and suitable optimization algorithms are described. These general principles are applied both to conventional and gradient shimming. In addition, means of providing a sufficient basic homogeneity are discussed, including magnet and probe design as well as the NMR sample itself.
Keywords:
field homogenization;
Maxwell equations;
spherical harmonics;
gradient shimming;
field mapping;
shim criterion;
line shape optimization;
orthogonality;
sample spinning;
magnet design;
probe design;
magnetic materials