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Atomic Nuclei: Nuclear Magnetic Moment00:59

Atomic Nuclei: Nuclear Magnetic Moment

All atomic nuclei are positively charged. When they have a nonzero spin, they behave like rotating charges. As a consequence of their charge and spin, these nuclei generate a magnetic field (B). This, in turn, gives rise to a magnetic moment (μ), which is randomly oriented in the absence of an external magnetic field. When an external magnetic field (B0) is applied, the magnetic moment vectors can align with the field or against it in 2 + 1 orientations. A hydrogen nucleus, which is just a...
Atomic Nuclei: Nuclear Spin State Overview01:03

Atomic Nuclei: Nuclear Spin State Overview

NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
Atomic Nuclei: Nuclear Spin State Population Distribution01:14

Atomic Nuclei: Nuclear Spin State Population Distribution

Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
Atomic Nuclei: Magnetic Resonance01:05

Atomic Nuclei: Magnetic Resonance

The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
Atomic Nuclei: Nuclear Relaxation Processes01:23

Atomic Nuclei: Nuclear Relaxation Processes

In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis,  the precessing magnetic moments are randomly oriented around the z-axis. This...
Atomic Nuclei: Types of Nuclear Relaxation01:28

Atomic Nuclei: Types of Nuclear Relaxation

Nuclear relaxation restores the equilibrium population imbalance and can occur via spin–lattice or spin–spin mechanisms, which are first-order exponential decay processes.
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...

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関連する実験動画

Updated: Jul 21, 2026

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
10:54

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR

Published on: February 23, 2016

高磁場での溶液状態のダイナミックな核極化.

Nikolaus M Loening1, Melanie Rosay, Volker Weis

  • 1Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

Journal of the American Chemical Society
|July 26, 2002
PubMed
まとめ

ダイナミック・ニュクレア・ポラライゼーション (DNP) は,核磁共鳴 (NMR) 信号を強化する. スキャラ・リラクゼーションにより,DNPは高磁場での溶液で利用され,従来の方法の限界を克服します.

科学分野:

  • 核磁共振 (NMR) スペクトロスコピー
  • スピン物理学 スピン物理学
  • 化学生物物理学 化学生物物理学

背景:

  • ダイナミック・ニュクレア・ポラライゼーション (DNP) は,電子・スピン・ポラライゼーションを原子核に転送することによって,NMR信号を放大する.
  • 従来のDNPメカニズム (固体効果,熱混合) は溶液状態のNMRでは限られている.
  • オーバーハウザー効果 (OE) は,典型的には二極のリラックスに依存し,高磁場 (>1 T) で無効と考えられています.

研究 の 目的:

  • 高磁場での溶液状態NMRにおけるDNPのスケーラリラクゼーションの可能性を調査する.
  • 高い磁場強度で溶液中のDNPの限界に関する従来の理解に挑戦する.
  • スキャラ・リラクゼーション媒介OEによって達成されたNMR信号の強化を定量化するために.

主な方法:

  • 溶液中のスケーラリラクゼーションによるダイナミックな核極化 (DNP) を利用した.
  • 室温と5Tの磁場での実験 (1Hは211MHz,電子は140GHz) を実施した.
  • 31P,13C,15N,および19F核の測定された核磁共振 (NMR) 信号強化.

主要な成果:

  • スケーラリラクゼーションによって媒介されるオーバーハウザー効果 (OE) の有意な強化が観察されました.

さらに関連する動画

Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy and Imaging
11:43

Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy and Imaging

Published on: December 30, 2016

Preparation of Fungal and Plant Materials for Structural Elucidation Using Dynamic Nuclear Polarization Solid-State NMR
09:37

Preparation of Fungal and Plant Materials for Structural Elucidation Using Dynamic Nuclear Polarization Solid-State NMR

Published on: February 12, 2019

関連する実験動画

Last Updated: Jul 21, 2026

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
10:54

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR

Published on: February 23, 2016

Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy and Imaging
11:43

Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy and Imaging

Published on: December 30, 2016

Preparation of Fungal and Plant Materials for Structural Elucidation Using Dynamic Nuclear Polarization Solid-State NMR
09:37

Preparation of Fungal and Plant Materials for Structural Elucidation Using Dynamic Nuclear Polarization Solid-State NMR

Published on: February 12, 2019

  • 180 (31P),42 (13C),-36 (15N),および8 (19F) のNMR信号強化を達成しました.
  • 5Tの溶液中のDNPのスケーラリラクゼーションの有効性を実証しました.

    • 結論:

    • スキャラ・リラクゼーションは,高磁場での溶液状態NMRにおけるDNPのための実用的なメカニズムを提供します.
    • この発見は,DNPの適用範囲を,二極リラクゼーションの限界を超えて拡大します.
    • 観察された改善は,溶液NMR実験における感度向上のための新しい道を示唆しています.