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相关概念视频

Spin–Spin Coupling Constant: Overview01:08

Spin–Spin Coupling Constant: Overview

892
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
892
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

977
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
977
NMR Spectroscopy: Spin–Spin Coupling01:08

NMR Spectroscopy: Spin–Spin Coupling

1.3K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
1.3K
Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)01:22

Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)

1.0K
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
1.0K
¹H NMR: Interpreting Distorted and Overlapping Signals01:02

¹H NMR: Interpreting Distorted and Overlapping Signals

1.0K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.0K
Atomic Nuclei: Nuclear Spin01:08

Atomic Nuclei: Nuclear Spin

1.7K
All atomic particles possess an intrinsic angular momentum, or 'spin'. Electrons, protons, and neutrons each have a spin value of ½, although protons and neutrons in nuclei may have higher half-integer spins owing to energetic factors.
Atomic nuclei have a net nuclear spin, , which can have an integer or half-integer value. In atomic nuclei, the spins of protons are paired against each other but not with neutrons, and vice versa. Consequently, an even number of protons does not...
1.7K

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相关实验视频

Updated: Jun 10, 2025

Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection
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合作式自旋放大器用于增强量子传感.

Minxiang Xu1, Min Jiang1, Yuanhong Wang1

  • 1CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, Hefei 230026, China; Anhui Province Key Laboratory of Scientific Instrument Development and Application, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, Hefei 230026, China; CAS Center for Excellence in Quantum Information and Quantum Physics, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, Hefei 230026, China; and Hefei National Laboratory, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, Hefei 230088, China.

Physical review letters
|October 11, 2024
PubMed
概括

研究人员使用合作的贵重气体Xe旋转提高了量子传感器相干时间的18倍. 这一突破放大了磁信号,为基础物理研究提供了高度敏感的磁场传感.

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相关实验视频

Last Updated: Jun 10, 2025

Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection
12:57

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Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
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科学领域:

  • 量子计量学和传感技术
  • 原子,分子和光学物理学
  • 凝聚物质物理学 凝聚物质物理学

背景情况:

  • 量子传感器的灵敏度通常受到量子系统的连贯时间的限制.
  • 提高连贯时间对于在量子传感中推进精度测量至关重要.

研究的目的:

  • 展示一种用于增强量子传感器连贯时间的新方法.
  • 研究合作旋转在磁场传感中的信号放大潜力.

主要方法:

  • 使用可调节的反电路,诱导贵重气体Xe旋转之间的合作.
  • 使用合作的Xe旋转作为磁信号的旋转放大器.
  • 使用合作自旋放大器实现磁场传感,并与Rb自旋气磁力计进行比较.

主要成果:

  • 通过合作,Xe旋转的连贯时间提高了18倍.
  • 使用合作旋转,证明了磁信号的显著放大至少3个数量级.
  • 实现了磁场灵敏度为 4 fT/Hz^{1/2},超过了 ^{87}Rb磁力计的旋转投射噪声.

结论:

  • 合作旋转提供了一种强大的机制来增强连贯时间和放大量子传感器中的信号.
  • 开发的合作自旋放大器在磁场测量中实现了前所未有的灵敏度.
  • 这项工作引入了一类新的"合作量子传感器",在基础物理中具有广泛的应用.