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Spin–Spin Coupling Constant: Overview

Spin–Spin Coupling Constant: Overview

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 have a...

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

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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.
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Double Resonance Techniques: Overview

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Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
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Spin–Spin Coupling: One-Bond Coupling

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Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...

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

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

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.
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Mesh Analysis for AC Circuits

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In the domain of radio communication, the significance of impedance matching must be considered. It is crucial to ensure the efficient transmission of signals between radio transmitters and receivers. Achieving this balance involves using impedance-matching circuits, with one fundamental configuration comprising a resistor, capacitor, and inductor.
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Related Experiment Video

Updated: Jun 13, 2026

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VO_x

Published on: May 13, 2020

Variable Coupling Scheme for High Frequency Electron Spin Resonance Resonators Using Asymmetric Meshes.

D S Tipikin¹, K A Earle, J H Freed

¹Cornell University, Department of Chemistry and Chemical Biology, Ithaca, NY, 14853.

Applied Magnetic Resonance

|May 12, 2010

Summary

This summary is machine-generated.

A new asymmetric mesh structure enhances electron spin resonance (ESR) spectrometer sensitivity by enabling continuously variable coupling. This innovation significantly improves signal-to-noise ratios for various sample types, including challenging lossy biological systems.

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Fabrication and Characterization of Superconducting Resonators

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Published on: May 21, 2016

Area of Science:

Spectroscopy
Materials Science
Biophysics

Background:

Spectrometer sensitivity is critical for electron spin resonance (ESR) and depends heavily on millimeter wave coupling to the sample and detection.
Previous research indicated that continuously variable coupling is essential for reliable and reproducible high sensitivity in ESR.

Purpose of the Study:

To introduce and evaluate a novel asymmetric mesh structure for continuously variable coupling in high frequency ESR.
To demonstrate the device's performance with diverse sample systems, including lossy and low-loss materials.

Main Methods:

Development of an asymmetric mesh structure allowing continuous coupling variation via rotation.
Quantification of spectrometer performance using nitroxide spin-label spectra in aqueous (lossy) and solid-state (low-loss) systems.
Assessment of signal-to-noise ratio improvements at 170 GHz and 95 GHz.

Main Results:

The novel asymmetric mesh structure provides continuously variable coupling by rotating the mesh.
Significant signal-to-noise ratio improvements were observed: approximately 7-fold at 170 GHz and 5-fold at 95 GHz for lossy samples.
The technique proved effective for both lossy and low-loss systems, demonstrating broad applicability.

Conclusions:

The asymmetric mesh structure offers a reliable method for optimizing millimeter wave coupling in high frequency ESR.
This advancement is particularly valuable for studying sensitive biological systems under physiological conditions.
The demonstrated sensitivity enhancements pave the way for broader applications of high frequency ESR.