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Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance

机译:通过零场至超低场核磁共振测量未截断的核自旋相互作用

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摘要

Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) provides a new regime for the measurement of nuclear spin-spin interactions free from the effects of large magnetic fields, such as truncation of terms that do not commute with the Zeeman Hamiltonian. One such interaction, the magnetic dipole-dipole coupling, is a valuable source of spatial information in NMR, though many terms are unobservable in high-field NMR, and the coupling averages to zero under isotropic molecular tumbling. Under partial alignment, this information is retained in the form of so-called residual dipolar couplings. We report zero- to ultralow-field NMR measurements of residual dipolar couplings in acetonitrile-2- ~(13)C aligned in stretched polyvinyl acetate gels. This permits the investigation of dipolar couplings as a perturbation on the indirect spin-spin J coupling in the absence of an applied magnetic field. As a consequence of working at zero magnetic field, we observe terms of the dipole-dipole coupling Hamiltonian that are invisible in conventional high-field NMR. This technique expands the capabilities of zero- to ultralow-field NMR and has potential applications in precision measurement of subtle physical interactions, chemical analysis, and characterization of local mesoscale structure in materials.
机译:零场至超低场核磁共振(ZULF NMR)为测量核自旋-自旋相互作用提供了一种不受大磁场影响的新机制,例如,与塞曼·汉密尔顿方程不相干的术语被截断。一种这样的相互作用,即磁偶极-偶极偶合,是NMR中空间信息的宝贵来源,尽管在高场NMR中看不到许多术语,并且在各向同性分子翻滚下偶合平均为零。在部分对准下,该信息以所谓的残留偶极耦合形式保留。我们报告了在拉伸的聚乙酸乙烯酯凝胶中对齐的乙腈-2-〜(13)C中残留的偶极偶合的零场至超低场NMR测量。这允许在不施加磁场的情况下研究偶极耦合作为对间接自旋-自旋J耦合的扰动。作为在零磁场下工作的结果,我们观察到偶极-偶极耦合哈密顿量的项在常规高场NMR中不可见。该技术扩展了零场至超低场NMR的功能,并在微妙的物理相互作用的精确测量,化学分析以及材料中局部尺度结构的表征方面具有潜在的应用。

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  • 来源
    《Physical review》 |2015年第22期|220202.1-220202.6|共6页
  • 作者单位

    Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA,Department of Chemistry, University of California at Berkeley, California 94720, USA,Helmholtz-Institut Mainz, Johannes Gutenberg-Universitdt, 55099 Mainz, Germany;

    Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA,Department of Chemistry, University of California at Berkeley, California 94720, USA;

    Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA,Department of Chemistry, University of California at Berkeley, California 94720, USA;

    Department of Physics, University of California at Berkeley, California 94720-7300, USA;

    Department of Chemistry, University of California at Berkeley, California 94720, USA;

    Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA,Department of Chemistry, University of California at Berkeley, California 94720, USA;

    Helmholtz-Institut Mainz, Johannes Gutenberg-Universitdt, 55099 Mainz, Germany,Department of Physics, University of California at Berkeley, California 94720-7300, USA,Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA;

    Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA,Department of Chemistry, University of California at Berkeley, California 94720, USA;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    effects of internal magnetic fields; high resolution NMR;

    机译:内部磁场的影响;高分辨率核磁共振;

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