Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

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

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

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...

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...

¹H NMR: Long-Range Coupling

¹H NMR: Long-Range Coupling

The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.

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.
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 involved orbitals. The...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Integrating machine learning and clinicopathological data to stratify survival risk in young women with localized breast cancer.

Frontiers in medicine·2026

Same author

The first complete genome sequence of Ammi majus latent virus from the new natural host culantro.

Archives of virology·2026

Same author

VirPhyKit: An Integrated Toolkit for Viral Phylogeographic Analysis.

Ecology and evolution·2025

Same author

Molecular characterization of a proposed novel macluravirus identified in sand ginger (Kaempferia galanga).

Archives of virology·2025

Same author

A Novel Multi-Gene Combined RT-PCR Assay for Rapid and Sensitive Detection of Maize Dwarf Mosaic Virus.

Viruses·2025

Same author

Spatial Regulation of Rice Leaf Morphology by miRNA-Target Complexes During Viral Infection.

Plant, cell & environment·2025

Search research articles

Related Experiment Video

Updated: Jun 4, 2026

Silicon Nanowires and Optical Stimulation for Investigations of Intra- and Intercellular Electrical Coupling

Silicon Nanowires and Optical Stimulation for Investigations of Intra- and Intercellular Electrical Coupling

Published on: January 28, 2021

Coupling characteristics between two conical micro/nano fibers: simulation and experiment.

Zehua Hong¹, Xinwan Li, Linjie Zhou

¹State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai, China.

|March 4, 2011

Summary

Conical micro/nano fibers (CMNFs) exhibit coupling efficiency dependent on both overlapping length and taper angle. Numerical simulations and experiments confirm that CMNFs achieve over 90% coupling efficiency with a stable, flat-top spectral response.

More Related Videos

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

Published on: January 8, 2014

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

Published on: July 29, 2013

Related Experiment Videos

Last Updated: Jun 4, 2026

Silicon Nanowires and Optical Stimulation for Investigations of Intra- and Intercellular Electrical Coupling

Silicon Nanowires and Optical Stimulation for Investigations of Intra- and Intercellular Electrical Coupling

Published on: January 28, 2021

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

Published on: January 8, 2014

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

Published on: July 29, 2013

Area of Science:

Photonics
Optical Engineering
Materials Science

Background:

Micro/nano fiber couplers are crucial optical components.
Uniform micro/nano fibers (UMNFs) have well-defined coupling characteristics.
Investigating novel fiber geometries like conical micro/nano fibers (CMNFs) is essential for advancing optical coupler performance.

Purpose of the Study:

To investigate the coupling characteristics of conical micro/nano fibers (CMNFs).
To compare the coupling behavior of CMNFs with uniform micro/nano fibers (UMNFs).
To determine the influence of overlapping length and taper angle on CMNF coupling efficiency and spectral response.

Main Methods:

Numerical simulations were employed to model the coupling behavior of CMNFs.
Experimental investigations were conducted to validate simulation findings.
Coupling efficiency and spectral response (3-dB bandwidth) were measured.

Main Results:

Coupling efficiency in CMNFs depends on both overlapping length and taper angle, unlike UMNFs.
Increasing overlapping length leads to a stable coupling efficiency, with convergence speed dictated by the taper angle.
Convergent coupling efficiency exceeding 90% was experimentally achieved.
The spectral response exhibited a "box-shape" profile with a 2 nm 3-dB bandwidth, similar to a flat-top bandpass filter.

Conclusions:

CMNF coupling characteristics are significantly influenced by their geometry (taper angle) and the degree of overlap.
The findings validate the simulation results and highlight the potential of CMNFs for high-efficiency optical coupling.
CMNF couplers demonstrate promising performance for applications requiring flat-top spectral filtering.