![Measuring the Spin-Lattice Relaxation Magnetic Field Dependence of Hyperpolarized [1-13C]pyruvate](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59399.jpg&w=3840&q=50)
对于在磁场循环实验中具有磁性等价核的系统来说,降诱导的偏振固有损失
S V Babenko1, O G Salnikov1, R Z Sagdeev1
1International Tomography Center SB RAS, Novosibirsk, Russian Federation.
The Journal of chemical physics
|March 11, 2025
概括
在对诱导极化 (PHIP) 实验中净磁化损失对于具有等价质子的系统得到了澄清. 这影响了超极化MRI对比剂和催化化中的机理学研究.
科学领域:
- 核磁共振 (NMR) 光谱学 核磁共振 (NMR) 光谱学
- 超极化技术 超极化技术
- 磁共振成像 (MRI) 是一种磁共振成像技术.
背景情况:
- 超诱导极化 (PHIP) 增强了NMR信号.
- 磁场循环 (MFC) 用于转移旋转顺序.
- 旋转系统中的磁性等价质子可以影响极化.
研究的目的:
- 为了阐明与MFC在PHIP实验中固有的净磁化损失 (Iz).
- 为了分析气和乙烯以太作为潜在的MRI对比剂的这些效应.
- 为了澄清在解离引发净对齐 (ALTADENA) 和异质核极化转移后对亚亚巴特纵向传输的影响.
主要方法:
- 研究了含有磁性等价质子的自旋系统.
- 作为代表性的例子,利用了气和乙醇.
- 适用于ALTADENA和MFC协议的相关原则.
主要成果:
- 量化了ALTADENA中乙烯 (干Iiz钱 ≈0.56) 和 (干Iiz钱 ≈0.45) 的净磁化固有损失.
- 在AmMnX型自旋系统的净异质核磁化中表现出类似的损失.
- 突出了这种损失的意义,与T1放松和adiabaticity相比,经常被忽视.
结论:
- 对于准确的信号增强和选择性评估,必须考虑PHIP系统中具有等价质子的净磁化固有的损失.
- 这些发现对于催化化和优化超极化MRI对比剂的机械学研究至关重要.
- 结果适用于液体或气体相中的各种多旋转系统.
相关概念视频
01:23Atomic Nuclei: Nuclear Relaxation Processes
598
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.
598
01:30Paramagnetism
2.5K
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
2.5K
01:31Ferromagnetism
2.4K
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
2.4K
01:27π Electron Effects on Chemical Shift: Overview
1.0K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.0K
00:59Atomic Nuclei: Nuclear Magnetic Moment
1.0K
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...
1.0K
01:05Atomic Nuclei: Magnetic Resonance
602
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...
602