# What is the unit hyperfine coupling constant?

## What is the unit hyperfine coupling constant?

The values of the hyperfine coupling constant range from -93.9 to -94.6 G and those of the zero-field splitting range from -79.5 to -80.5 G. A critical evaluation of the advantages and drawbacks of the 11 methods is included: the best value for A’ is -94.30 G and that for D’ is -79.95 G.

## What is hyperfine splitting constant?

The hyperfine splitting (hfs) is a special feature of ESR caused by the interaction of electron spins with the magnetic nuclei in the sample. The magnetic field separation between two neighboring peaks in the splitting due to the same nucleus is called the hfs-constant of that magnetic nucleus.

What is the alpha constant?

In physics, the fine-structure constant, also known as Sommerfeld’s constant, commonly denoted by α (the Greek letter alpha), is a fundamental physical constant which quantifies the strength of the electromagnetic interaction between elementary charged particles.

How many lines are expected in ESR spectrum of methyl radical?

four lines
1. Spectrum of methyl radical at 77 “K (low surface coverage). The four lines are designated 1, 3, 3a, and la on increasing H.

### What are hyperfine lines?

Share Give Feedback External Websites. Hyperfine structure (HFS), in spectroscopy, the splitting of a spectral line into a number of components. The splitting is caused by nuclear effects and cannot be observed in an ordinary spectroscope without the aid of an optical device called an interferometer.

### What is the hyperfine effect?

Hyperfine structure (HFS), in spectroscopy, the splitting of a spectral line into a number of components. The splitting is caused by nuclear effects and cannot be observed in an ordinary spectroscope without the aid of an optical device called an interferometer.

Why is it called the fine-structure constant?

If you modeled a hydrogen atom as Bohr did, but took the ratio of a ground-state electron’s velocity and compared it to the speed of light, you’d get a very specific value, which Sommerfeld called α: the fine structure constant.

What is constant in the universe?

Fundamental constants are physical quantities that are universal in nature. For example, the speed of light in vacuum and the charge of a single electron are the same everywhere in the universe.

## How would you account for the hyperfine structure of spectral lines?

Hyperfine structure (HFS), in spectroscopy, the splitting of a spectral line into a number of components. Thus, when the atoms of an element radiate energy, transitions are made between these quantized energy levels, giving rise to hyperfine structure.

## What is G value in ESR spectroscopy?

The g-value of a free electron is 2.0023, and the g-values of most free radicals are very close to this value, since the unpaired electron has very little orbital contribution to the magnetic moment.

When to consider second-order hyperfine coupling constants?

When the hyperfine coupling constants are large and the linewidth is small, second-order hyperfine effects must be considered to explain the observed spectra in many cases. A simple example is the spectrum of a hydrogen atom.

How is the spacing of EPR lines related to the hyperfine coupling constant?

In such cases, the spacing between the EPR spectral lines indicates the degree of interaction between the unpaired electron and the perturbing nuclei. The hyperfine coupling constant of a nucleus is directly related to the spectral line spacing and, in the simplest cases, is essentially the spacing itself.

### Who is the author of the hyperfine coupling constant?

Christopher C. Rowlands, Damien M. Murphy, in Encyclopedia of Spectroscopy and Spectrometry, 1999