fine structure

[fahyn]
noun Physics.
a group of lines that are observed in the spectra of certain elements, as hydrogen, and that are caused by various couplings of the azimuthal quantum number and the angular momentum quantum number.


Origin:
1915–20

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World English Dictionary
fine structure
 
n
Compare hyperfine structure the splitting of a spectral line into two or more closely spaced components as a result of interaction between the spin and orbital angular momenta of the atomic electrons

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Encyclopedia Britannica
Encyclopedia

fine structure

in spectroscopy, the splitting of the main spectral lines of an atom into two or more components, each representing a slightly different wavelength. Fine structure is produced when an atom emits light in making the transition from one energy state to another. The split lines, which are called the fine structure of the main lines, arise from the interaction of the orbital motion of an electron with the quantum mechanical "spin" of that electron. An electron can be thought of as an electrically charged spinning top, and hence it behaves as a tiny bar magnet. The spinning electron interacts with the magnetic field produced by the electron's rotation about the atomic nucleus to generate the fine structure.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
The good news is that the signal has an amazing wealth of fine structure imposed by its environment.
Plus, the fact that the fine structure constant is small.
He put some of the tissue under a microscope to look at its fine structure.
For example, a graph showing the range of possible fine structure constant and then the chance each interval would be represented.
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